OPEN UNIVERSIZY
MASTER THESIS:
IDENTIFICATION OF CRITICAL DELAY FACTORS IN READY-MIXED CONCRETE PLANT OPERATION AT THE SOUTH OF VIETNAM TRƯỜNG ĐẠI HỘC tổ 1P.UM THƯ VIỆN i Submitted in partial fulfillment of the requirement for the - VU THIEU TUAN November 2011
Master in Industrial Business Management 1
Trang 2EUROMED TOULON.— HCMC OU > Vu Thieu Tuan $ MIBM-01 '° x5 Acknowledgement : ỷ EUROMED TO bi MANAEEMENT ĐÃ Bode
I would like to thank all people who have helped and inspired me during my study
Firstly, I would like to express my sincere gratitude to my supervisor Professor Dr Jacques
Martin for the continuous support of my Doctoral research, for his patience, motivation, ” ” enthusiasm, and immense knowledge His guidance helped me in all the time of research and
writing of this thesis
Secondly, staff of Hochiminh city open university, particularly Ms Nguyen Thi Viet Ha, deserves special thanks for their support and coordination during MIMB-1 program
Thirdly, I am grateful to academic staff of Toulon University, especially Dr.Hillary Collins as program director who shared useful knowledge and experience in research methodology courses
Fourthly, my sincere thanks also go to all survey respondents for providing me with essential
information and data for my research
- Last but not least, my deepest gratitude goes to my parents for giving birth to me at the first place
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Due to the development of construction in Vietnam, Demand of Ready-mixed concrete products T#NN ApQ are booming up Ready-mixed concrete (RMC) industry is low margin business Thus, operating cost is a competitive advantage However, there are many factors lead to delay in the ready-mix concrete plant operation which reduce productivity and increase operating cost This study
focuses on identify on delay factors in the ready-mixed concrete operation then suggest * recommendation to minimize their effect 16 delay factors have been detected from literature
review Data on opinion about these delay factors were collected from people involving ready- mixed concrete industry at the South of Vietnam to discovery the delay factors Descriptive statistic, factor analysis and reliability test have been used to point out the most critical delay factors Results show that delays due to “management problems” and “unexpected problems” have the highest rank These finding help manager focus the most critical delay factors to improve their ready-mixed concrete plant operation Recommendations are proposed to minimize the effect of delay factors Author also suggests a further research for assessing influence of delay factors on production, efficiency, time, and cost
Word count: 13038
Key word: Ready-mixed concrete, plant operation, delay, delay factors
Trang 4EUROMED TOULON —- HCMC OU MIBM-01 a | Table of Contents Acknowledgment Abstract Contents List of table List of figure Abbreviation Chapter 1: Introduction
1.1-Context of the research (reason for choosing it) 1.1.1-Increase of demand for Ready-mix concrete
1.1.2-Competitive advantages in ready-mixed concrete industry 1.1.3-A need for identification of delay in plant operation 1.2-Purpose and objectives
1.2.1-Project Objectives 1.2.2-Personal Objectives
1.3-Researh Hypothesis or Question 1.4-Scope of study
1.5-Structure of the thesis Chapter 2: Literature Review 2.1-Nature of ready-mix concrete 2.2-What is a ready-mix concrete plant
Trang 5FfNiauw EUROMED TOULON — HCMC OU EE MANAGEMENT MIBM-O1 2.5.1-Nature of Demand 2.5.2-Location 2.5.3-Environnement impact 2.5.4-Traffic 2.5.5-Policy and Legislation 2.5.6-Technological change
2.5.6.1-computerized and automated batching systems 2.5.6.2-Increase in production and delivery capacity 2.5.6.3-Expansion of admixtures
2.5.6.4-improvements in logistical coordination 2.5.6.5-The appearances of Concrete pumps 2.6-Potential sources of delay factors
Chapter 3: Research Methodology 3.1-Research procedure 3.2-Literature review 3.3-Data collection 3.3.1-Questionnaires design 3.3.2-Pilot testing 3.3.3-Sampling 3.3.4-Questionnaires distribution 3.3.5-Survey Target 3.3.6-Study limitations
3.3.7-Difficulty in data collection
3.4-Data statistical methods and analysis methods
Trang 7EUROMED TOULON - HCMC OU MIBM-O1 4 5.4-Unexpected problems 5.5-Demand conditions 5.6-Equipment problems Chapter 6: Conclusion and Recommendations 6.1-Conclusions 6.2- Contribution of study 6.3- Recommendations 6.4-Suggestion for further research + References Appendix Appendix A: Questionnaires
Appendix B: Descriptive analysis Appendix C: Factor analysis Appendix D: Reliability analysis
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Table 2.1: Summary of delay factors in ready-mixed concrete Table 3.1: Finally variables for questionnaires
Table 4:1: Results of return
Table 4.2: Statistics on Age of respondents
Table 4.3: Statistics on number of years working in ready-mixed concrete industry Table 4.4: Statistics on gender of respondents
Table 4.5: Descriptive Statistics on delay factors Table 4.6: KMO and Bartlett's Test
Table 4.7: Total Variance Explained , Table 4.8: Communalities
Table 4.9: Rotated Component Matrix (a) Table 4.10: Reliability statistics of Component 1 | Table 4.11: Reliability statistics of Component 2
Table 4.12: Reliability statistics of Component 3 Table 4.13: Reliability statistics of Component 4 Table 4.14: Reliability statistics of Component 5
Table 4.15: Reliability statistics of Component 6
Table 4.16: Summary of Components | Table Al: Delay factors questionnaires
Table B1: Descriptive Statistics of delay factors (SPSS) Table C1: KMO and Bartlett's Test (SPSS)
Table C2: Total Variance Explained (SPSS) Table C3: Component Matrix (SPSS)
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Table D8: Item-Total Statistics of Unexpected problems (SPSS) 54 ì Table D9: Reliability Statistics of Demand problems (SPSS) 54 | Table D10: Item-Total Statistics of Demand problems (SPSS) 55
Table D11: Reliability Statistics of Equipment problems (SPSS) 55
Table D12: Item-Total Statistics of Equipment problems (SPSS) 55: “
Table El: Ages of respondents (SPSS) - 56
Table E2: Number of years working in ready-mixed concrete industry (SPSS) 56
57 Table E3: Gender of respondents (SPSS)
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List of Figures
Fig 1.1: RMC consumption per Micro market at the South of Vietnam Fig 2.1: Flow diagram for ready-mixed concrete plant and mixer cycles: Fig 3.1: Research procedure
Fig C1: Scree Plot of Eigenvalue (SPSS)
Fig C2: Component plot in Rotated space (SPSS) Fig El: Age of respondents (SPSS)
Fig E2: Number of years working in ready-mixed concrete industry (SPSS)
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Abbreviation
EPA: Environment Protection Authority GPS: Global position system
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Chapter 1: Introduction ; đc
This chapter introduces the context of the research, research objectives, personal objectives, scope of the research, and structure of the thesis The research question is also stated in this chapter
1.1-Context of the research (reason for choosing it)
1.1.1-Increase of demand for Ready-mix concrete ,
The development of construction field, particularly the development of the infrastructure with arate of over 16%/year has made the demand of using concrete urgent (Viet T.B, 2005) Demand — for RMC at the south of Vietnam is fueled by:
(i) High rise building in big cities such as, HoChiMinh (ii) New relocation township in surrounding HoChiMinh area
(iii) Large infrastructure project (iv) New industrial zones
(v) Switch to RMC in house development
Demand volume of Ready-mixed concrete in 2020 at the South of Vietnam market will be close to 20 millions m3, equivalent to Thailand market (Source: Phillipe R, 2011) According to Vietnam infrastructure report (Q2-2010), with the swift recovery both for the construction and infrastructure sector, the annual average construction sector real growth between 2010 and 2014 is forecast to be 8.1% The large number of projects already in the pipeline for Vietnam’s
infrastructure — especially in the transport sector — will sustain growth in the infrastructure
industry in 2011 In addition, there are also many infrastructure projects currently under way or under consideration in Vietnam such as the construction of highway and International Airport According to (Phillipe R, 2011), in HCMC, there is an increase of residential projects in District 2 and District 9 Demand in Binh Duong has recently resumed due to more industrial activities Deamand in Vung Tau province is fueled by harbors projects and residential demand as well as new casino and resorts Demand in Dong Nai province is to focus on plan on urban city at Nhon Trach area These infrastructure projects require large volume of concrete
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In modern construction, ready-mixed concrete is one of the most popular building materials i in construction industry The ready-mixed concrete industry is highly competitive Competitive position in a market depends largely on the location and operating costs of our plants and
prevailing prices in that market The more densely located are producers in a market, the easier it is for ready-mixed concrete consumers to substitute among producers Therefore competition is expectedly more intense in dense markets, where producers hold less spatial market power If producers have different productivity (cost) levels, it will be harder for inefficient firms to be profitable in dense markets Thus, concrete producers in denser markets should have higher lower-bound and average productivity levels and less productivity dispersion (Syverson C, 2008)
Price is the primary competitive factor among suppliers for small or simple jobs, principally in residential construction However, timeliness of delivery and consistency of quality and service, along with price, are the principal competitive factors among suppliers for large or complex.Jobs Competitors with lower operating costs enable to accept lower margins than others do They will have a competitive advantage over others in the industry that is particularly price-sensitive (U.S
Concrete, 2007)
According a report of U.S Concrete (U.S Concrete, 2007), the operating cost of ready-mix concrete plant is going up year after year due to flowing reason:
(i) Environmental regulations such as \and and water usage; street and highway usage; noise and emission levels; and health, safety and environmental matters
(ii) Various hazards in ready-mixed concrete operation such as internal and external
traffic hazard and materials loading hazard |
(iii) Shortages of qualified personnel such as skilled plant managers, technicians and drivers
In a low-margin, commodity-driven business such as concrete production, plant survival is tied to productivity (Syverson C, 2008) Thus, operation managers are trying to optimize operation of ready-mixed concrete plant as much as possible (Talend D, 2003)
1.1.3-A need for identification of delay in plant operation
There is large number of factors that affect the ready-mixed concrete plant operation To enhance the productivity and cost estimation per concrete unit, wee need to point the delays in plant and construction sites Delay in plant operation causes increase of operating cost and price and decrease quality of delivery service (Zayed T.M, Daniel W.H and Ismail M.B, 2005) These will push a ready-mixed concrete in disadvantage competitive situation Thus, there is a necessity for a detailed investigation to identify the delay factors and choose correct actions to minimize the adverse effects of delays on time, cost and quality of ready-mixed concrete supplying service
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This research tries to identify the identifying the potential sources of delay in the-ready-mixed concrete plant operation
This research is also be written to support people regularly involved in ready-mixed concrete industry who have been made familiar with the ready-mixed concrete plant operation to reduce the delay in ready-mixed concrete plant operation
This research contributes to knowledge on management of ready-mixed concrete plant operation
1.2.2-Personal Objectives
Understand and enrich my knowledge on ready-mixed concrete operation Understand academic and business research then apply into my research
Propose further research
1.3-Researh Hypothesis or Question
Which factors lead to delay in ready-mixed concrete plant operation at the south of Vietnam? _ The research has been undertaken to answer the research question
1.4-Scope of study
The study only focuses on delay factors in ready-mixed concrete plant operation in at the south of Vietnam Thus filed research activities is undertaken at commercial ready-mixed concrete plant around HoChiMinh the biggest city with largest demand of ready-mixed concrete
at the south of Vietnam Í So
The data collection will refers to who experienced in management of a ready-mixed concrete plant such as plant heads, operation managers, dispatch managers or pump fleet managers
1.5-Structure of the thesis
The structure of this thesis is organized into six chapters: introduction, literature review, data
-analysis, findings and conclusion
Chapter 1: Introduction This chapter introduces the context of the research, research objectives, personal objectives, scope of the research, and structure of the thesis The research question is also stated in this chapter 7
Chapter 2: Literature review This chapter seeks for the potential sources of delay in ready- mixed concrete plant operation and outlines RMC batching plant projects issues that are described in current literature, and establishes a platform for the research
Chapter 3: Research methodology This chapter introduces the protocol and methodologies of the research, and discusses the selection of the methodology used to accomplish the research It explains what and how the data was collected and analyzed such as the data collection method,
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Chapter 4: Data analysis This chapter present result of the analyses for collected data The results of data analysis provide insight into the outcome of this study SPSS will be used as tool to analysis |
Chapter 5: Findings This chapter summarizes and validates findings of the research, which | ° were collected from the literature review, survey and data analysis
Chapter 6: Conclusion and Recommendation This chapter draws conclusions from the research, results of the research, and opportunities for the future This chapter provides the
contribution of research by learning which the most critical delay factors on ready-mixed concrete plant operation By focusing on the most critical delay factors, ready-mix concrete manufactures are able to improve their plant operation This study can lead to a better plant operation within
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Chapter 2-Literature Review a
This chapter seeks for the potential sources of delay in ready-mixed concrete plant operation and outlines RMC batching plant projects issues that are described in current literature, and
establishes a platform for the research
2
2.1-Nature of ready-mix concrete
Ready-mixed concrete is one of the most common materials used in the construction sector It - provides the advantages of being cheap and it allows great diversity in the design, because it can
be poured into a mould of any shape in its fluid form (Syverson C, 2008) RMC is prepared generally in a concrete batch plant and ingredient materials for concrete production are weighed and mixed by automated devices consistent with the request of the construction sites
Regrettably, ready-mixed concrete cannot stock at a batch plant, because ready-mixed ~ Concrete is a Perishable Material Ready-mixed concrete consists of coarse aggregates, fine aggregates, cement, and water, plus admixtures if specified Sometimes, admixtures are also added to modify the appearance, workability or physical properties of the concrete
(http://www.portland.co.za/areas-of-operation/readymix) Aggregates, cement, and admixtures separately can be stored for long periods of time However, ready-mixed concrete itself is a perishable material Once water has been added to the mix of dry materials, concrete only has one and a half hours before the hardening process Hence, ready-mixed concrete have little room for variability in terms of time for delivery and placement after water has been added (Tommelein I.D and Li A.E.Y, 1999)
Ready-mixed concrete is convenient for all types and all sizes of construction Ready-mixed Concrete is a Custom Specified Material Designers, usually civil/structural engineers, performing the structural calculations for a project determine the strength and other quality requirements for concrete according to site conditions (Tommelein I.D and Li A.E.Y, 1999) Buyer can specify a concrete mix design or performance and then leave it up to ready-mixed supplier to the proposed design meets the specifications Every project has different requirements and often within a single project, different concrete mixtures are prescribed This affects the type of materials, which have to be used, and it can even influence the production method Accordingly, most batch plants have an on-line database with recipes for hundreds if not thousands of mixes that they can load to program their facility This makes it easy not only to add new mixes or find those that meet an engineer’s requirements, but also to name them based on customer preferences
Availability of Ingredients: While finding a suitable mix recipe may be easy, a batch plant may hot stock all aggregate types or admixtures in quantity or at all (Tommelein I.D and Li A.E.Y,
1999) When given the project specifications, the contractor must recognize when special
Trang 17EUROMED TOULON — HCMC OU MENT - MIBM-01 Gi a re needed and notify the batch plant for advantage so that it will have enough time to a ip Vu Thieu Tuan $ ingredients obtain them
2.2-What is a ready-mix concrete plant?
A ready-mix concrete plant is a manufacturing plant where the ingredients such as cement, sand, gravel, water and admixtures used to produce concrete are mixed in a central mixer then being transported by trucks to a construction site ready to be placed (http://www.road-
construction-equipments.com/mobile-concrete-batching-plant.htm) According to (Syverson C,2008), a ready-mix concrete plant include facilities for handling raw materials, usually including steel cement silos (cement must be protected from moisture in the air, lest it harden prematurely), storage areas for aggregate such as sand, gravel and rock that sorted by size, a
wheel-loader and conveyor system for moving aggregate, and a water source There is also often a structure with limited office space and rooms that house controls for the batcher, the equipment, that weighs and feeds the various ingredients into the mixer The mixer sits in an elevated structure to allow drivers to drive the mixer trucks underneath for loading
The advantages of concrete batching plant to construction sites are: _(i) Eliminate the problems of inefficiency
(ii) Minimise the risk of waste and therefore of loss of profits (concrete is mixed to exact specifications so no rejection of the final product, there is no over or under supply of concrete, no delivery delays and on site time wastage, no risk of the concrete being too wet or too dry) (http://www.road-construction-equipments.com/mobile-concrete-batching-plant.htm)
Ready-mix concrete plants usually fall into two broad categories:
(i) One is a long-term stay ready-mix concrete plant The long-term plants are often high capacity and generally consist of silos, bins, mixers, conveyors and control system
(ii) The other type of concrete batching plant, which is becoming increasingly popular, is the mobile or portable batching plant Mobile batching plants consist of frameworks carrying batchers, conveyors, scales, control system; small silos and adapted to be transported from site to site
(http://www.projectsinfo.in)
A ready-mixed concrete plant’s capacity is determined by either production capacity or delivery capacity (Tommelein LD and Li A.E.Y, 1999)
(i) The production capacity is determined by the time needed to measure, dispense, and mix ingredients, then load them into a truck The quantity mixed and thus the production time is limited by the actual amount needed, the amount a truck can carry, and weight limitations that may be imposed during transportation or on site The delivery capacity is determined by the truck
fleet size and the number of drivers Today’s ready-mix batch plants are fully automated and
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computer controlled so ingredients can be measured and mixed on demand and in virtually no »
time This makes it possible to batch one truckload at a time, and load one truck after another with a different mix each time when appropriate
(ii) The delivery capacity is determined by the number of trucks and drivers that service the batch plant A typical RMC plant may own around 25 to 30 trucks If needed the plant
operator will rent additional vehicles from a truck rental company to handle extra demand
Needless to say, the operator tries to keep trucks busy at all times
A plant’s batching capacity usually is larger than its delivery capacity The batch time is on the order of a few minutes By contrast, the cycle time for a truck, including the load time, may be on the order of 30 minutes up to an hour or two (Tommelein I.D and Li A.E.Y, 1999) Because of , the significant variability in cycle time, the plant will be idle at times when waiting for trucks to return, while trucks will line up at other times Trucks as well as the plant itself tie up a lot of capital; they are the fixed cost Thus Delivery tends to be the limiting capacity factor - 2.3-The Flow of The ready-mixed concrete supply: Camernt Silo Batch Hopper - oe Mixer
Concrete z Return to Reload
Batch Plant Cornveyor 2 Delivery Storage Area <N= 1 | | | | | va `⁄ - — Transit Mixer Loading CO Trans Miser Travel to Site Fig 2.1: Flow diagram for ready-mixed concrete plant and mixer cycles (Zayed T.M and Halpin D.W, 2001)
As indicated in Fig 2.1, the flow of ready-mixed concrete supply includes flowing steps:
(i) Conveyor belt 1 transports the aggregates from.the storage area to the storage hopper
(ii) A hopper with many compartments stores the different types of aggregates It received
the aggregates from conveyor | and stores them for feeding to conveyor belt 2 After feeding to
conveyor belt 2, it waits for conveyor belt 1 to provide re-supply
(iii) Conveyor belt 2 transports the aggregates from the hopper to the central mixer in the delivery house Cement from silos, water and admixtures will also be fed to the central mixer for batching After a certain time (mixing time), the product (ready-mixed concrete) will be load to
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the truck mixer After feeding the truck mixer, the central mixer waits for next feeding from 5
hopper and silos
(iv) The truck transports the ready-mixed concrete from the plant to the placement sites To deliver the concrete to the pump, if pumping method is used, a truck mixer and a space should be available beside the pump After unloading, the trucks mixer returns to the plant
(v) The pump receives the concrete from the truck and supplies it into pump, which moves it to the placement sites After finishing, the pump waits for other truck mixers to deliver ready-mixed concrete
(vi) Labors at the placement sites, where the ready-mixed concrete is received from the pump, do the spreading operation After finishing the spreading operation, placing crew finishes the ready-mixed concrete surface
2.4-Ready-mixed concrete operation ~
The ready-mixed concrete operation can be divided into five major components (Lai W.S, 2006) which are Material production, Production loading, Truck transport, RMC placement and Truck return
2.4.1-Material production
Ready-mixed concrete consists of coarse aggregates such as gravel, fine aggregates such as sand, cement, and water, plus admixtures if specified These raw materials must be mixed and agitated in the proper mixtures at the ready-mixed concrete plant Different specific RMC products can be made to meet the customer requirements and site conditions According to (PCC Center, 2004), to ensure that high-quality materials are used in concrete mixing; all materials delivered to the site should be inspected to ensure that they meet specification requirements All materials should be delivered with the proper certifications, invoices, or bill of lading These records should indicate when the shipment arrived, the amount and identification of material delivered, and the laboratory report certification number, invoice number, and ticket number Common problems are non-certified materials, materials with outdated shelf life, contaminated materials and frozen or damaged materials
2.4.2-Product loading
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Mixer truck will transports the ready-mixed concrete from the plant to the placement sites A mixer truck, which consists of a concrete mixer and dumping device, is the primary ready-mixed concrete transport vehicle In practice, there are multiple types of mixers Though the carrier may
choose the proper truck type to transport the material, this is limited by actual traffic regulations
2.4.4-Ready-mixed concrete placement
Once the truck arrives at the construction site, the truck mixer moves into position at a concrete pump and discharges its load after which the ready-mixed concrete placement work can be done According to (Anson M and Wang S, 1998), there are three common placing methods: pump, crane and skip and hoist and barrow
2.4.5-Truck-return
When the load has been delivered, the truck returns to the batch plant for cleaning and maintenance Any residue is cleaned from the truck mixer in a washout area in preparation for its
next delivery assignment
2.5-Ready-mixed concrete batching plant operation’s issues 2.5.1-Nature of Demand
The ready-mixed industry is closely tied to the level of activity in the construction sector The basic demand conditions faced by ready-mixed producers in any given local market therefore depend on how robust construction activity is in that same market, not elsewhere (Syverson C, 2008)
Many industries face uncertainty about future demand for their products Ready-mixed concrete industry is one of them Demand of ready-mixed concrete is fluctuate (Tommelein I.D and Li A.E.Y, 1999) Demand for ready-mixed concrete varies day by day, week by week, year by year Orders are called in randomly by contractors Thus from the plant’s perspective, forecasting the actual plant workload for any day is difficult to do
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“Plant location can be an important strategic consideration” (Syveron C, 2008) Even though each particular situations demands specific criteria, the most important criteria groups for the location ranking are: economic criteria, market criteria, technical-technological criteria and social - criteria This means that the site for the ready-mix concrete plant should:
(i) close proximity to water and raw materials (economic criteria)
(ii) easy to access to market such as construction sites (market criteria) ° (iii) appropriate plant’s productivity with market size (economic and market criteria)
(iii) near to source of skills labor, near to auxiliary services such as maintenance service and electrical supply service (technical-technological criteria)
(vi) be located in an area where they will not pose a hazard to the environment or the amenity of the local community to (social criteria) Appropriate site selection could minimize environmental impacts
In addition, according to (Bawden A, 2006), a right decision of site selection can facilitate the construction of concrete batching plant:
(i) Reduce effort in getting construction permit and operation license
(ii) Reduce cost in building environmental measure by using by utilizing existing infrastructure and an existing footprint of disturbance
Good site selection also helps in optimization of concrete batching plant afterward: good relationship with market (due to close to market), optimization of materials logistics planning (due to close to materials’ source) and good liaison with local (due to environmental benefits)
2.5.3-Environement impact
Traditionally, these plants could cause air quality concerns from dust, water quality concerns from wash water runoff, and waste concerns from piles of improperly mixed or leftover concrete (Environment Protection Authority (EPA), 1998) Thus, poorly controlled concrete batching plants may discharge highly alkaline wastewater, dust and excess noise Environmental issues relating to the ready-mixed concrete industry such as land, water quality, air quality, noise and solid waste are set out in the following sections:
(a) Land: Highly alkaline wastewater, dust emissions and noise are the key potential impacts associated with concrete batching plants Plants should be located so that contaminated — storm-water and process wastewater can be retained on-site to ensure that wastewater is not
discharged to waterways
(b) Water: Potential pollutants i in batching plant wastewater include cement, sand, aggregates and petroleum products These substances can adversely affect the environment by:
- (i)-increasing soil and water pH
(ii)-increasing the turbidity of waterways
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The main sources of wastewater at batching plants are: contaminated stormwater runoff, Siggy
dust control sprinklers, the mixer washout station; the mixer charging station; the slumping station; cleaning and washing
(c) Air: ‘Dust from cement, sand and aggregate is a source of pollutant Fine dust particles can enter neighbor area Potential sources of dust pollution include: s
(i) Delivery of raw materials in trucks, such as aggregates and cement (ii) Storage of raw materials in hoppers and stockpiles
(iii) Transfer of raw materials for production process such as conveyors, hoppers and agitators
(iv) Leakage or spillage of raw materials from silos and inspection covers
(d) Noise: Noise is a form of pollution and a potential source of conflict between the operators of a concrete batching plant and the local community Noise is unwanted sound The disturbing effects of noise depend on the level-of the noise and its character — such as tones, intermittency, and so on Noise emitted from a concrete batching plant must be managed as carefully as other discharges from the site Because of the potential for noise to affect resident, management should give high priority to liaising with the local community so that it can be aware of, and resolve, noise issues Potential sources of noise include:
- (i) From the operation of equipments such as truck and wheel loader engine noise, hydraulic pumps, conveyor belts, air valves, bag filters, alarms, mixers, compressors etc
(ii) From the loading of raw materials: aggregate and cement
(e) Solid wastes: The main solid waste generated by batching plants is waste concrete Ready-mixed concrete produces should ensure proper disposal of the waste product It may be possible to use-waste concrete for construction purposes at the batching plant If this is not possible, placing the waste concrete to a fully enclosed pit where it can be dried and collected It is better that waste concrete is reused or taken to a recycling facility However, recycling facility may be need huge investment
2.5.4-Traffic
Construction Traffic: During the construction period, there would be a range of vehicles delivering the required equipment and materials to the Project Site
Operational Traffic: The operational traffic associated with the ready-mix concrete plant would be trucks delivering the raw materials not available on site and transit mixers loaded with
concrete to travel to construction sites s
Ready-Mix is a perishable product that needs to be delivered within an hour and a half before
it becomes too stiff to be workable (Wexler A.C, 2006) Traffic jam is a problem in Vietnam Established Transport routes should be optimized for a convenient transport
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2.5.5-Policy and Legislation
The authorize government agency shall make sure that Permit for construction of a ready-mix concrete plant is:
(i) Does not harm public interest;
(ii) Does not interfere with the utilization of the surrounding land; (iii) Complies with the sustainability principle;
(iv) Due regard to the principle of justice;
(v) Comply with the prevailing laws and regulations
The regulation also assigns the different levels of the Land Office to supervise and monitor the implementation of the Permits’ provisions In regard to the Location permit in particularly, the _ results of the aforementioned monitoring may be a critical consideration for the cancellation of a
Location Permit (Refer to Regulation No 12/2009/ND-CP, Regulation No 181/2004/ND-CP and Decision No 2491/QD-UBND)
In addition, Ready-mixed concrete suppliers must pay surcharge for ready-mixed concrete transport According to Vietnam Concrete Association (VCA), the surcharge transport of ready- mixed concrete products is 0.7 to 1.1 USD/m3 There are also many toll plazas for road
transportation (Source: www.vnexpress.vn)
2.5:6-Technological change
The basic process for making ready-mixed concrete has not changed for the past 60 years: dry raw materials are measured, loaded into a bin, mixed, placed into a truck, and water is added The
modest technological advances that have occurred in the industry have come in five areas
2.5.6.1-computerized and automated batching systems
The process of weighing and mixing the raw materials was once a manual control The operator controlled the mechanical material discharge gates by an analogue gauge He had to close the gates manually on time to prevent over dosing of materials With computerized and automated systems, an operator inputs the recipe for a ready-mixed batch into an electronic control system that handles the weighing and mixing operations automatically (Syverson C, 2008) Moreover, the most recent control system uses advanced Graphical User Interfaces (GUI) providing the plant operator with real-time information in an easy to understand visual projection
This user interface gives them the possibility to interfere easily if needed (Odijk S.W, 2010)
2.5.6.2-Increase in production and delivery capacity
According to (Odijk S.W, 2010):
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(i) Approximately 50 years ago, central mixers from ready-mixed concrete plants had a capacity of 0.25 mm? up to 0.50 m3 Nowadays, central mixers have an average capacity of 2.25 mì to 3.3 m’ and in some cases even up to 4.5 m and 9.0 mỶ This greatly reduces the number of batches to fill a truck mixer and hence production time
(i) The truck mixers about 50 years ago had a capacity to load about 2.5 to maximum 6.0 m3 concrete Today the typical truck capacity is 10 m3 and in some cases even 12 to 15 m3 Increasing the capacity of trucks logically decreases the number of trips needed to transport a
typical amount of ready-mixed concrete
2.5.6.3-Expansion of admixtures
A second change is a continuing expansion in the variety of chemical admixtures that affect its properties for many applications For example, admixtures can affect workability (how easily the concréte can be formed into shapes), curing times, color, porosity, and other attributes This _ flexibility in the physical attributes of the final product has increased the range of uses of ready- mixed concrete (Syverson C, 2008) Thus, ready-mixed concrete can be custom-made to suit
different applications
2.5.6.4-improvements in logistical coordination
Ready-mixed concrete producers are not only just manufacturers but also logistical service suppliers (Syverson C, 2008) Ready-mix concrete is a prototypical example ofa JIT production (Tommelein I.D and Li A.E.Y, 1999) They deliver a perishable product to time- - sensitive buyers in multiple locations However, ready-mixed concrete produce receive order on short notice Buyers have to rely on the timing and reliability of their service Some producers moved towards centralized delivery dispatching, which means they coordinate their deliveries centrally for all their production facilities and make more efficient use of the available resources Owning several plants in a local area and coordinating their deliveries through a central office offers potential productivity and allowing more efficient use of available resources through cross- plant substitution of production and deliveries (Syverson C, 2008) Site selection of ready-mix
concrete plant also reflects attempts to harness such efficiency benefits
2.5.6.5-The appearances of Concrete pumps
According to (Odijk S.W, 2010), concrete pumps allow an uninterrupted placement of concrete, making it possible to reach difficult locations and are easy to move from one site to another According to a study of Anson and Wang (Anson M and Wang S, 1998), pumping is less labor-intensive than other placing methods and gets the job completed more And Labor
productivity during pumping is roughly twice that of carne-and-skip or hoist-and-barrow placing The only restriction in placing concrete with a pump is the capacity of the pump and the length of
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to 0 (Odijk S.W, 2010), typical pumps have a boom length of 42 meters anda placing capacity of more than 100 m3 per hour, although pumps are available with a maximum boom length of 70 m In addition; some certain admixtures could increase the flowability of wet concrete, improving
pumping performance
The clear understanding about RMC plant issues and technological changes of RMC plant would enable us to determine the factors causing the delay of RMC plant operation
2.6-Potential sources of delay factors in ready-mixed concrete operation
The delay factors cause delays in the ready-mixed concrete operation that result in low production, delivery and placement efficiency As mentioned above, ready-mixed concrete operation includes five major components Delays can be occurred in any of the five major
components
- Ready-mixed concrete delivery activities must be connected with truck service In practice, truck service is limited in a given area; the trucks must be carefully dispatched in order to avoid concrete setting Therefore, quality of truck service is not only affect delivery efficiency, but also the operating cost Truck service is not only constrained by the availability of plant resources (such as number of the truck mixers), but also driven by the demand pattern of concrete by the sites (Lu M and Lam H.C, 2009) According to (Sakchai S and Thammasak R, 2010), the speed of the mixer trucks, loading capacity of mixer trucks, road bearing limit, duration of pouring
(placing rate) and quantity of read-mixed concrete (placing size) and the traffic conditions could
impact on the truck service
According to (Lai W.S, 2006), the number of deliveries needed depends on the amount of RMC requests, the loading capacity of the truck, and the road weight limit permitted by
regulations A given example will make it clear One construction site orders a quantity of 210 m? ready-mixed concrete Although, the mixer truck can be loaded with up to 7 m 3 of ready-mixed concrete, the road regulations only permit the mixer truck to be loaded maximum 6 mỶ As a result, the number of RMC deliveries to this construction site must be increased from 30 to 35 trucks, which extends the duration needed to finish the delivery process at that construction site
According to (Lu M and Lam H.C, 2009), Ready-mixed concrete production and delivery is essentially a problem of materials logistics planning, which is “a decision process for
strategically managing the procurement, movement and storage of raw materials, finished product inventory and the related information flows throughout the organization and its
marketing channels in such a way that the current and future profitability is maximized by cost- effective fulfillment of orders” (Christopher M, 1992) (LuM and Lam H.C, 2009) also
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SHigiapclas
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emphasized on traveling distances (road conditions) or times (traffic conditions) from the plant to each site, contractors’ placement methods (placing method) and particular pour-start schedules
and progress rates on each pour (placing rates)
Concrete placing activities also affect the ready-mixed concrete plant operation Concrete placing productivity is influenced by many factors: the placing method, the placing speed, the skill of placing screw, accurate estimate of placing size, parking arrangements of mixer truck at discharge point (spaces beside the pump), site congestion and site access conditions (Anson, M., and Wang, S 1998) According to (Gehbauer E, Zulch G, Micheal O and Borkircher M 2007), constructions site work (including placement work) is influenced by weather, available space and traffic conditions Placing concrete in rainy is not recommended And too hot weather or to cold weather can increase batching time and reduce quality of ready-mixed concrete products
' According to (PCC Center, 2004), Hot weather (air temperatures over 90°F) during concrete batching can reduce mix workability Many states specify a maximum concrete temperature limit of 90°F And cold weather (air temperatures under 50°F) during concrete batching can cause plastic shrinkage cracking, especially if the concrete temperature is much warmer than the air or if the wind is blowing The concrete mixture must be kept at a temperature of at least 50°F helps to
maintain mix workability
According to (Tommelein I.D and Li A.E.Y, 1999), flowing factors affect negatively production and delivery productivity of ready-mixed concrete: demand fluctuation, number of mixer trucks, placing size and bad condition of haul roads Large placements may tie up a considerable number of trucks and thus a plant’s capacity (Tommelein LD and Li A.E.Y, 1999) Large placements require uninterrupted supply of concrete in order to avoid unplanned -
construction joints To achieve the required continuity of delivery, plant and construction contractor must communicate in real time to relay when a placement is being delayed and to prevent that trucks would stuck at the site.As mention above (refer to 2.1), concrete should be placed no later than ninety minutes after the addition of water, travel from the batch plant to a site should not take much more than half an hour or so A plant’s operating radius therefore tends to be limited based on the nature and condition of haul roads (Tommelein LD and Li A.E.Y, 1999)
(Zayed T.M and Minkarah I, 2004) emphasize on design its site conditions such as site congestion and site access conditions, and plan materials delivery The site congestion (at the ready-mixed concrete plant) is occurred where there is little room for mixing concrete and movement in and storing cement and aggregate Site access conditions are restricted by room for truck parking and movement in the ready-mixed concrete plant (Zayed T.M and Halpin D.W,
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aoe
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2001) emphasizes on number of trucks, availability of cement and aggregates, labor crew skills a and transport distance (road conditions)
According to (Zayed T.M and Nosair I.A, 2004), the major delay factors are: low demand, placing method,-weather conditions, insufficient number of trucks, mechanical problems, cement and aggregates delivery problems Mechanical problems is not just for plant’s equipment but also , for trucks mixer and pumping equipment, if ready-mixed concrete supplier supply pumping services Table 2.1: Summary of delay factors in ready-mixed concrete plant operation No j Description - , Literature
1 Speed of mixer trucks (Sakchai S and Thammasak R, 2010),
2 | mechanical problems (Zayed T.M and Nosair I.A, 2004) ~ (Lu M and Lam H.C, 2009), (Sakchai S and
Thammasak R, 2010), (Gehbauer F, Zulch G,
3 Heavy Traffic Micheal O and Borkircher M 2007)
(Zayed T.M and Nosair I.A, 2004), (Gehbauer 4 Bad conditions of weather F, Zulch G, Micheal O and Borkircher M 2007)
(Lu M and Lam H.C, 2009), (Zayet T.M and 5 Bad Road conditions(*) Halphin D, 2001), (Lai W.S, 2006)
6 | No demand (Zayed T.M and Nosair I.A, 2004)
(Tommelein I.D and Li A.E.Y, 1999), (Lu M 7 Fluctuate demand - and Lam H.C, 2009),
(Tommelein I.D and Li A.E.Y, 1999),
8 insufficient number of truck mixers | (Zayed T.M and Halpin D.W, 2001), (Anson M and Wang S, 1998) 9 labor crew skills (Zayed T.M and Halpin D.W, 2001),
(Anson, M., and Wang, S 1998), (Zayed T.M 10 | Site conditions(**) and Minkarah I, 2004)
(Lu M and Lam H.C, 2009), (Sakchai.S, - Thammasak.R 2010),
(Anson M and Wang S, 1998) 11 | Inaccurate Placing size and rate (Tommelein I.D and Li A.E.Y, 1999),
the available spaces for-mixer trucks | (Anson M, and Wang S, 1998), (Gehbauer F, 12 (for parking and movement) Zulch G, Micheal O and Borkircher M 2007) 13 | The method that is used to pour - (Lu M and Lam H.C, 2009),
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ED NT MIBM-01 concrete EUROMED TOULON — HCMC OU Vu Thieu Tuan (Anson M and Wang S, 1998),
14 | Admixture delivery problems
(Lu M and Lam H.C, 2009),
(Zayed T.M and Halpin D.W, 2001), (Zayed T.M and Minkarah J, 2004)
15 | aggregates delivery problems
(Lu M and Lam H.C, 2009),
(Zayed T.M, and Halpin D.W, 2001), (Zayed T.M and Minkarah I, 2004),
16 | Cement delivery problems
(Lu M and Lam H.C, 2009),
(Zayed T.M and Halpin D.W, 2001),
(Zayed T.M and Minkarah I, 2004),
17 | loading capacity of mixer trucks
(Sakchai.S and Thammasak.R 2010), (Lai W.S,
2006)
(*) Road conditions include road bearing limit, spaces and distances
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Chapter 3: Research Methodology
This chapter introduces the protocol and methodologies of the research, and discusses the selection of the methodology used to accomplish the research It explains what and how the data was collected and analyzed such as the data collection method, analysis techniques and statistics _ used to identify the delay factor in ready-mixed concrete plant operation
3.1-Research procedure
There are many recommendations from the literature that a structured framework is of necessity for research implementation Such a framework helps readers to understand the general procedure for implementing the research, and provides the author with a tool to manage it successfully In addition, it illustrates a set of different research activities and what kind of - research activities can be used to produce specific outputs
Research procedure includes following steps: ~ Literature review Define research objectives, scope of research v
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Reviewing the literature critically will provide the foundation on which your research is built Main purpose of literature review is to help you develop a good understanding and insight into relevant previous research and the trends that have emerged (Mark S, Phillip L, and Adrian T, 2007) This reviéw determined the context of the research and positioned this research relatively to previous research Literature review also helps to identify theories and ideas that will be used in data collection, validation and analysis (Mark S, Phillip L, and Adrian T, 2007) The activities
included in this stage are: :
(i) Develop a clear understanding of research study (ii) Identify and describe the problem being studied (iii) Construct and refine the research questions
(iv) Consolidate and extract information from literature for the main topic of
investigation: delay factors; ready-mixed concrete operation The research questions will be ~ deconstructed into key words to define the areas of searching Which factors lead to delay in ready-mixed concrete plant operation at the south of Vietnam?
Ready-mixed concrete: what is ready-mixed concrete? Plant operation: what are components included operation? bo Delay: Potential sources of delay in plant
Base on these key words, potential sources of delay will be find out for further investigation |
(iv) Develop research methodology such as: research procedure; scale and sampling
selection; data collection 3.3-Data collection
3.3.1-Questionnaires design
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To adjust to ready-mixed concrete industry in Vietnam, a pilot testing is undertaken for the _ preliminary questionnaire According to (Mark S, Phillip L, and Adrian T, 2007), the aim of pilot testing is to verify refine the questionnaire so that respondents will have no problems in
answering the questions and there will be no problem in recording the data In addition, it enables , to obtain some comments of the questions’ validity and assessments of data reliability Pilot test also help to estimate time to answer all questions or identify any issues with questionnaire format Four experienced professionals in the practice of ready-mixed concrete plant operation were involved in the pilot test They were two plant heads, one operation manager and one customer service manager from Holcim Beton, one plant head from Sunway beton They were asked to review the design and structure of the questionnaire such as scale and factors Their valuable comments were used to revise the research questionnaire Two factors have been eliminated (the — speed of truck mixers and loading capacity of mixer trucks) due to unreality In Vietnam, the speed of truck mixer usually is greater than the limit speed of roads and almost mixer trucks are 6m? of capacity One factor has been added by experts’ propose (Automatic control system problems) It is logical due to the trend of automation in control system of ready-mixed concrete plant (refer to article 2.5.6.1) Finally, 16 factors has been using for questionnaires
Table 3.1: Finally variables for questionnaires Variable name No } Description ‘| (code)
1 | Automatic control system problems Equip01
2 | mechanical problems Equip02
3 | conditions traffic Ex03
4 | conditions of weather - Ex04
5 | road conditions Ex05
6 | No demand De06
7 | Fluctuate demand De07
8 | insufficient number of truck mixers Ma08
9 | labor crew skills Ma09
10 | Site conditions Mal0
11 | Placing size and rate Plall
the available spaces for mixer trucks (for parking and
12 | movement) ~ Plal2
13 | The method that is used to pour concrete Plal3
14 | Admixture delivery problems In14
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Because of budget and time constraints, it is impracticable to collect data from entire the population, there is need to select a sample (Mark S, Phillip L, and Adrian T, 2007)
Process of sampling: , |
(a) Sampling frame: In this research, probability sampling is chosen The study only
involve people who familiar with ready-mixed concrete industry at the South of Vietnam
(b) Sample techniques: Probability sampling
(c) Sample size: The larger sample size the lower the likely error in data collection With probability samples, it is important that sample size is large enough to provide the necessary confidence in collected data (Mark 8, Phillip L, and Adrian T, 2007) There is a compromise ~ between the accuracy of findings and the amount of time and money investing in collecting, checking and analyzing the data According to Hair et at 1998, the minimum sample size is from
100 to 150 The suggested response rate from (Mark S, Phillip L, and Adrian T, 2007) is 50 to
65% To ensure the sample size, 295 questionnaires have been sent out
(d) Classify respondents according to: (for further analysis) Age; Gender and Number of
years involving ready-mixed concrete industry
3.3.4-Questionnaires distribution
Several means were employed to deliver the questionnaires and to receive responses (i) Internet-mediated questionnaires: via email and via websites
(www.suverymonkey.com)
(ii) Direct personal delivery:
(iii) Telephone questionnaires:
However, the direct personal (face-to-face) delivery was preferred by participants The direct personal delivery motivates the respondents to participate in answering questionnaires Thus, it improves response rate Not much people like telephone questionnaires With internet-mediated questionnaires method, to increase the response rate, a cover letter is written by authors to explain clearly the objectives of the survey then enhance confident of participants According to (Mark S, Phillip L, and Adrian T, 2007), the message contained in a self-administered questionnaire’s covering letter will affect the response rate Each participants was initially given two weeks to complete the survey and then a remind email was sent allowing an-additional two weeks for completion
3.3 5-Survey Target -
Trang 33EUROMED TOULON — HCMC OU Vu Thicu Tuan 1Í MANAGEMERT MIBM-01 ~ The questionnaire was then finalized and distributed to professionals experienced in ready- dc
mixed concrete plant operation at the south of Vietnam A question involving number of year working in ready-mixed concrete industry is used to eliminate unsuitable participants Survey site is Hochiminh city and around areas such as: Binh Duong, Dong Nai and Vung Tau
%
3.3.6-Study limitations
The survey was conducted on ready-mixed concrete plant located in the south of Vietnam It may be inappropriate to generalize for the whole on Vietnam on data from this study However, a larger proportion of commercial ready-mixed concrete plants are located at the south of Vietnam It is recommended further research to determine the extent of study to which can be apply to other parts of Vietnam
In Vietnam, the literature review material on ready-mixed concrete was limited, especially on ready-mixed concrete operation Some academic paper has been found in Vietnam but they only | refer to quality and application aspect of ready-mixed concrete product Majority of the literature found only is come from other country such as China and USA
3.3.7-Difficulty in data collection
I had created questionnaires on www.surveymonkey.com First, I send to a group of ten through but I have only received no-feedbacks Not much people in Vietnam is familiar with
www.surveymonkey.com
Almost respondents like to receive directly questionnaires in paper forms Some like to
receive questionnaires through their personally email with cover letter to explain survey Thus, the duration of collecting data cost much than estimate
3.4-Data statistical methods and analysis methods
Quantitative data in a raw form convey very little meaning to most people These data need to be processed and analyzed to make them useful, that is, turn into information Questionnaires are collected and statistically processed by SPSS V16 Before analyzing, the incomplete data are eliminated to ensure they are adequate and appropriate for statistical testing
3.4.1-Data coding and entering
All data types should be recorded using numerical codes This enables to enter the data
quickly with few errors (Mark S, Phillip L, and Adrian T, 2007) Once data has been code, it is entered into SPSS spreadsheet Nowadays, data analysis software contains algorithms that check the data for obvious errors as it is entered Despite this, it is essential that people should take consideration to ensure data are entered correctly
3.4.2-Descriptive statistic
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Descriptive statistics are used to describe the basic features of the data in a study They provide simple summaries about the sample and the measures Together with simple graphics analysis, they form the basis of virtually every quantitative analysis of data“
(http:/Avww.socialresearchmethods.net) Descriptive statistics provide a powerful summary that may enable comparisons across variables In this study, descriptive statistic is used to rank delay factors according to their mean Base on descriptive statistics, the most influencing delay factors will be point out Descriptive statistic is also used to summarize characteristics of respondents There are a number of tools in SPSS to summary data In this study, frequency analysis and descriptive analysis are chosen
- 3.4.2.1-Frequecy analysis
Frequency analysis is a descriptive statistical method that shows the number of occurrences of each response chosen by respondents When using frequency analysis, SPSS can also calculate_ the mean, median and mode to help users analyze the results and draw conclusions (Trong H and |
Chu N.M.N, 2005)
3.4.2.2-Descriptive analysis
The descriptive analysis can be used to determine measures of central tendency (mean), ˆ measures of dispersion (range, standard deviation, variance, minimum and maximum) (Trong H
and Chu N.M.N, 2005) 3.4.3-Factor analysis 3.4.3.1-Overview
Factor analysis attempts to identify underlying variables, or factors, that explain the pattern of correlations within a set of observed variables Factor analysis is often used in data reduction to identify a small number of factors that explain most of the variance observed in a much larger number of manifest variables Factor analysis can also be used to generate hypotheses regarding causal mechanisms or to screen variables for subsequent analysis (Trong H and Ngoc C.N.M,
2005)
According to (Tryfos R, 1997) Factor analysis usually includes two stages:
(i) Fist stages: one set of loadings is calculated which yields theoretical variances and covariances that fit the observed ones as closely as possible according to a certain criterion These loadings, however, may not agree with the prior expectations, or may not lend themselves to a reasonable interpretation A method widely used for determining a first set of loadings is the principal component method This method seeks values of the loadings that bring the estimate of
the total communality as close as possible to the total of the observed variances
23
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Trang 35= TOULON EUROMED TOULON — HCMC OU Vu Thieu Tuan i MANAGEMENT MIBM-01 (ii) Second stage, the first loadings are “rotated” in an effort to arrive at another set of
loadings that first equally well the observed variances and covariances, but are more consistent with prior expectations or more easily interpreted The varimax rotation method encourages the detection of factors each of which is related to few variables It discourages the detection of factors influencing all variables
3.4.3.2-Statistics Associated with Factor Analysis
According to (Trong H and Ngoc C.N.M, 2005), following statistics is associated
Bartlett's test of sphericity: Bartlett's test of sphericity is a test statistic used to examine the hypothesis that the variables are uncorrelated in the population In other words, the
population correlation matrix is an identity matrix; each variable correlates perfectly with itself (7 = 1) but has no correlation with the other variables (7 = 0)
Correlation matrix: A correlation matrix is a lower triangle matrix showing the simple correlations, r, between all possible pairs of variables included in the analysis The diagonal elements, which are all 1, are usually omitted Inspection of the correlation coeffcients on the diagonal reveals that all the measures of sampling are well above the acceptable level of 0.6 If | any of the variables are < 0.50, you are advised to drop the individual variable with the lowest
individual statistic until the overall statistic rises above 0.60
Communality: Communality is the amount of variance a variable shares with all the other variables being considered This is also the proportion of variance explained by the common factors (Communaltiy >=0.5)
Eigenvalue: The eigenvalue represents the total variance explained by each factor (Eigenvalue >=1)
Factor loadings: Factor loadings are simple correlations between the variables and the factors A factor is reliable if it has:
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Factor matrix: A factor matrix contains the factor loadings of all the variables on all the
factors extracted
Factor scores: Factor scores are composite scores estimated for each respondent on the
derived factors °
Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy: The Kaiser-Meyer-Olkin (AMO) measure of sampling adequacy is an index used to examine the appropriateness of factor analysis High values (between 0.5 and 1.0) indicate factor analysis is appropriate Values below 0.5 imply
that factor analysis may not be appropriate |
KMO Value Degree of Common Variance 0.90 to 1.00 Marvelous 0.80 to 0.89 Meritorious - 0.70 to 0.79 Middling 0.60 to 0.69 Mediocre 0.50 to 0.59 Miserable 0.00 to 0.49 - Don't Factor
Percentage of variance: The percentage of the total variance attributed to each factor
Residuals are the differences between the observed correlations, as given in the input correlation matrix, and the reproduced correlations, as estimated from the factor matrix
Scree plot: A scree plot is a plot of the Eigenvalues against the number of factors in order
of extraction
3.4.4-Reliability Analysis 3.4.4.1-Overview
Researchers must demonstrate the selected scales are reliable since without reliability Reliability is fundamental to the scientific method Reliability is the correlation of an item, scale, or instrument with a hypothetical one which truly measures what it is supposed to Since the true instrument is not available, reliability is estimated in one of four ways:
(i) Internal consistency: Estimation based on the correlation among the variables comprising the set (typically, Cronbach's alpha)
(ii) Split-half reliability: Estimation based on the correlation of two equivalent forms of the scale (typically, the Spearman-Brown coefficient)
~ (iii) Test-retest reliability Estimation based on the correlation between two (or more)
administrations of the same item, scale, or instrument for different times, locations, or populations, 25
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when the two administrations do not differ on other relevant variables (typically, the Spearman
Brown coefficient)
(iv) Inter-rater reliability: Estimation based on the correlation of scores between/among two or more raters who rate the same item, scale, or instrument (typically, intra-class correlation, of which there are six types discussed below)
These four reliability estimation methods are not necessarily mutually exclusive, nor need they lead to the same results In this study, internal consistency method is chosen for reliability analysis
3.4.4.2-Cronbach’s alpha
According to (Trong H and Ngoc C N M, 2005), Cronbach's alpha is the most common measure of internal consistency It is most commonly used when you have multiple Likert-scale questions in a survey/questionnaire to determine if the scale is reliable _ `
Characteristics: | |
(i) Cut-off criteria: By conventional, a cronbach’s alpha of 0.60 is acceptable in exploratory research (Trong H and Ngoc C.N.M, 2005)
(ii) Number of items: Cronbach's alpha increases as the number of items in the scale increases research (Trong H and Ngoc C.N.M, 2005) Increasing the number of items can be a way to adjust alpha to an acceptable level Scales with a greater number of items are more reliable It also means that comparison of alpha levels between scales with differing numbers of items is not appropriate
(iii) Alpha if deleted If "alpha if deleted" is lower for all items than for the computed overall alpha, then no items need be dropped from the scale If "alpha if deleted" for an item is higher than the computed alpha, the researcher can drop that item
(iv) The item-total correlation : A low item-total correlation means the item is little correlated with the overall scale According to (Trong H and Ngoc C.N.M, 2005) an item with the item-total correlation < 0.3 should be considerer dropping it A negative correlation indicates the need to recode the item in the opposite direction The reliability analysis should be re-run if an item is dropped or recoded Note a scale with an acceptable Cronbach's alpha may still have one or more
items with low item-total correlations |
(v) The squared multiple correlation ( R’) : the larger the RỶ, the more the item contribute to internal consistency The lower the R’, the more the researcher should consider dropping it Note the R? of some items may be low even on a scale which has an acceptable Cronbach's alpha overall
(vi)Negative alphas Note also that a negative Cronbach's alpha indicates inconsistent coding (see assumptions) or a mixture of items measuring different dimensions, leading to negative inter- item correlations
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Result of Data analysis was presented in this chapter The data from questionnaires were used “mainly for the analysis The quantitative data from the questionnaire survey were entered into
Microsoft Excel and analyzed by SPSS statistical packages V.160 Data analysis includes:
_ descriptive analysis, factors analysis and reliability analysis Firstly, descriptive analysis is used to ranking the delay factors Secondly, Factor analysis is used to extract and summarize identified delay factors to convenience components Finally, reliability analysis is used to checking the reliability of scale for each component Through result of data analysis, the most critical delay factors and factor groups (components) should be detected
4.1-Characteristics of respondents 4.1.1-Overview
As mentioned above, incomplete questionnaires have been eliminated before analyzing A total of 295 questionnaires have sent to people who involved in ready-mixed concrete operation 224 questionnaires have returned But 23 questionnaires are invalid due to incompletion Finally, 201 full responses were obtained achieving a response rate of 68.13% The result is showed in table 4.1 Table 4.1: Results of return
Item Quantity | % percentage
The total of questionnaires 295 NA The return of questionnaires 224 75.9%
Invalid questionnaires 23 7.8%
The full response of questionnaires 201 | 68.13% -
4,1.2-Age
Table 4.2: Statistics on Age of respondents
Age Quantity % percentage Under 23 0 0.00% From 23 to 29 116 57.11% From 30 to 39 75 37.31% From 40 to 49 9 4.48% Above 50 i 050%
Statistics on age showed the majority of respondents (95%) aged between 20 and 40 years No respondents under 23 years old Respondents that are over 40 years old accounted for 5% The
respondents are mostly young
Trang 39Vu Thieu Tuan EUROMED TOULON — HCĐC OU MIBM-01 QULON UROMED « MANAGEMENT Table 4.3: Statistics on number of years working in ready-mixed concrete industry Years Quantity % Percentage Average 1 69 34.33% 2 46 22.89% 3 Al 20.40% 4 26 12.94% 2.44 5 14 6.97% 6 2 1.00% 7 3 1.49%
The average number of years working in the ready-mixed concrete industry is 2.44 More than
90% sample is 4 years or less *
4.1.4-Gender +
Table 4.4: Statistics on gender of respondents
Gender _ | Quantity % Percentage Female 184 91.5% Male 17 8.5% The statistical results showed that 91.5% of respondents were male and 8.5% female Almost respondents are-male
4.1.5-Summary on characteristics of respondents
Almost respondents are young and male The number of years working in ready-mixed concrete is usually smaller than 4 These appropriate with practice of ready-mixed concrete industry:
(i) Ready-mixed concrete industry just has developed in Vietnam in recent years (Viet T.B, 2005) Thus, not much people have been working long time in this industry and many of them are young
| (ii) Ready-mixed concrete industry is heavy and hazard industry Thus, not much female is working in this industry
Furthermore, the respondents were asked to add other factors that they perceive as being necessary However, they did not make significant additions
4.2-Descriptive analysis
Descriptive analysis includes the mean, standard deviation and number of respondents who participated in the survey is given Table 4.5 shows the rankings of 20 success factors by all
the respondents Looking at the mean, we can conclude that:
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, UROMED MIBM-01
(i) “heavy traffic”, “site conditions”, “labor crew skills”, “bad road conditions” and “insufficient number of truck mixers” are the five most significant factors to ready-mixed concrete plant operation The means of all the five factors are greater than 3 — equivalent to “very significant” on a five-point Likert-scale in the questionnaire Thus, they are considered to be critical delay factors in ready-mixed concrete plant operation in the south of Vietnam
(ii) “Mechanical problems”, “Inaccurate Placing size”, “No demand”, “Fluctuate demand”, and “the available spaces for mixer trucks (for parking and movement)” are the five least significant factors to ready-mix concrete plant operation
Table 4.5 : Descriptive Statistics on delay factors Factors Std N Mean } Rank Deviation heavy traffic 4201 | 3.56 1 0.888 ~ Site conditions , 201 | 3.49 |2 0.965
labor crew skills 201 13.36 |3 0.73
bad road conditions 201 |336 |4 0.954
insufficient number of truck mixers 201 | 3.35 5 0.836
Cement delivery problems 201 | 3.32 | 6 0.767
aggregates delivery problems 201 |3.13 |7 0.757 The method that is used to pour concrete 201 |3.00 | 8 0.822 bad conditions of weather 201 | 2.99 19 0.784 Automatic control system problems 201 | 2.85 10 0.933 Admixture delivery problems 201 12.85 1] 0.807
mechanical problems 201 | 2.82 12 1.01
Inaccurate Placing size and rate 201 | 2.81 13 0.864
No demand 201 | 2.80 | 14 0.868
Fluctuate demand 201 | 2.78 15 0.93
the available spaces for mixer trucks (for
parking and movement) 201 | 2.76 16 0.93
Valid N (listwise) 201
4.3-Factor analysis
4.3.1- Kaiser-Meyer-Olkin and Bartlett's test
According to Table 4.6, KMO test tells us that the sampling adequacy is 0.649 > 0.5, in other