Nghiên cứu sử dụng cốt liệu đá quartzite ở thanh sơn, phú thọ để chế tạo bê tông xi măng mặt đường tt tiếng anh

MINISTRY OF EDUCATION AND TRAINING UNIVERSITY OF TRANSPORT AND COMMUNICATIONS NGO HOAI THANH RESEARCH ON UTILIZATION OF QUARTZITE AGGREGATE IN THANH SON, PHU THO TO PRODUCE CEMENT CONCRETE FOR ROAD PAVEMENT Discipline Code Major : Transport Construction Engineering : 9580205 : Automobile and urban road construction SUMMARY OF TECHNICAL DOCTORAL THESIS HA NOI – 2019 The study was completed at University of Transport and Communications Academic supervisor Prof Dr.Pham Duy Huu University of Transport and Communications Referee 1: Referee 2: Referee 3: The thesis will be defended in front of the university-level doctoral thesis judgement panel at the University of Transport and Communications At…… , dated ………………………… 2019 The thesis can be found at: - Viet Nam National Library - UTC Library – Information Centre INTRODUCTION Necessity of the research Concrete is a material that accounts for a large proportion in most construction works With the advantages of easy forming, good bearing capacity, long life, being made of local materials, in the construction industry so far, concrete has surpassed all other materials The demand for construction of transport works is very large (hundreds of thousands of kilometers of national highways), but in fact, cement concrete pavement in Viet Nam is insufficient in quantity and does not meet the quality requirements Whereas, many countries in the world, such as the US, Germany, China, etc have been very successfull in construction of road and airport pavement [28] Quartzite in Thanh Son, Phu Tho is a kind of high quality aggregate, with quite large reserves of approx over 10 million tons [2] It is imperative to exploit local materials to manufacture concrete so as to reduce aggregate transportation, which normally raises the construction costs Moreover, there have not been so far any studies and field experiments on cement concrete in Viet Nam, which are systematic and complete regarding the thermal properties of concrete using quartzite, i.e calculation and real measurement of the thermal expansion coefficient (CTE) of cement concrete using quartzite ; investigation into the relationship between the CTE with the age and different kinds of aggregates For such reasons stated above, the research on the physio-mechanical properties of quartzite, design of concrete composition, the thermal properties of concrete determined by the CTE, the strength and the thermal stress of concrete utilizing quartzite aggregate from Thanh Son, Phu Tho has met the demand of traffic works construction for high quality and efficient cement concrete while making use of the local materials Thus, "Research on utilization of quartzite aggregate in Thanh Son, Phu Tho to produce cement concrete for road pavement " is essential with obvious scientific and practical significance Aims of the research The research aims to complete the scientific fundamentals as well as the practice of utilizing quartzite aggregate in Thanh Son, Phu Tho to produce cement concrete for road pavement, which meets the technical requirements of road construction in the north-western region It also contributes to reasonably exploiting the local materials for construction Scope of the research Utilization of quartzite in Thanh Son, Phu Tho as aggregate for cement concrete in road pavement construction; Experiments on main mechanical properties of cement concrete using quartzite in Thanh Son, Phu Tho as required by pavement design and construction The design of cement concrete pavement using quartzite aggregate from Thanh Son, Phu Tho uses data on the load, climate, base and subgrade as set in Decision QĐ3230[5] Research methods - Theoretical and lab-based experimental studies are combined to determine the physio-mechanical properties of quartzite aggregate and the characteristics of cement concrete; - Synthetical analysis method is also employed to clarify the aims of the research as set in the thesis Structure of the thesis The thesis includes the Introduction, four main chapters, the Conclusions and Recommendations, and the Direction for further study as well as the References and Appendices New contributions given in the thesis + Having studied the aggregate characteristics of quartzite from Thanh Son, Phu Tho and affirmed that this material conforms to the current standards, as a result, can be used in cement concrete production for road pavement; + By experimental planning, the author has found out regression equations describing the relationship between the objective functions, including the compressive strength, the bending tensile strength and the influence factor, namely the ratio X/N The two regression equations are: y1  19,19 X  5,62 y2  X  2,77  2,5  X  3,5  2,5  X  3,5 + The experiment results of the compressive strength, tensile strength, elastic modulus, slump of cement concrete using quartzite aggregate can serve as good reference in teaching, design and construction of transport works + Through experiments, the author has determined distortion and the thermal expansion coefficient of concrete using quartzite and concrete using limestone according to the age with strain gauge SDA - 830B In detail, - Concrete using quartzite at Days 3, 7, 14, 28 has the thermal expansion coefficient of 11.1925, 11.2248, 11.2200 and 11.1819 (10-6/0C ), respectively - Concrete using limestone at Days 3, 7, 14, 28 has the thermal expansion coefficient of 7.4791, 7.3830, 7.3996 and 7.4132(10-6/0C ), respectively + Calculations show that the expected sizes of cement concrete plates using quartzite and limestone are 4m x 3.5m x 0.25m and 4.5m x 3.5m x 0.25m as set by Decision QĐ3230[5] by Transport Ministry - In design of the same composition, the strength and the thermal stress of concrete using quartzite increase concurently with those of concrete using limestone, with the tensile strength growing by 1.1% and the maximum thermal stress going up by 33.59% - Due to the above stated factors, concrete pavement using quartzite is more likely to crack on the plate surface than concrete pavement using limestone with a deviation rate of 5.41% - Cement concrete plates using quartzite should be shorter than those using limestone The cement concrete slabs using quartzite aggregate should be 3.8m long + Quartzite concrete meets the requirements of the strength and economic efficiency thanks to its lower cost compared to limestone concrete CHAPTER OVERVIEW OF CEMENT CONCRETE FOR ROAD CONSTRUCTION AND UTILIZATION OF QUARTZITE IN CONCRETE PRODUCTION 1.1 History of cement concrete pavement development According to documents [26] and [28], concrete is a kind of building materials often used in large volume and indispensable in modern construction Due to high requirements in harsh conditions, non-reinforced cement concrete pavement has long been used in many countries such as the UK, the USA, Russia, Germany, China, etc In Viet Nam, it was first used on Hung Vuong road in 1975, then in many other projects of National Highway 2, National Highway 18, National Highway 1A and so on 1.2 General overview of cement concrete According to documents [1], [21] and [22], cement concrete is an artificial stony material obtained after the concrete mixture solidifies Concrete mixture includes reasonably-selected componnents, namely cement, water, aggregates and additives In concrete, aggregate acts as a bearing frame to enhance the mechanical properties of concrete while the cost of concrete production reduces 1.3 Structure of cement concrete 1.3.1 Formation of concrete structure 1.3.2 Micro, macro and Nano structures 1.4.Regulations on properties of cement concrete used for road construction 1.4.1 Regulations on aggregates to manufacture cement concrete 1.4.2.Regulations on properties of cement concrete used for road construction The physio-mechanical and slump parameters of cement concrete mixture are regulated by MOT Decision No 1951 [4] 1.5.General overview of methods of designing cement concrete composition 1.5.1 Designing cement concrete composition as per ACI 211.1.91 According to document [34], this method combines theories and experiments The basic theory is the one of absolute volume Concrete is designed in a completely solid state with the total volume including the individual solid volumes of material components and the air volume Tests of the strength and slump are conducted Evaluation of the experiments employs the statistical probability theory on the basis of standard distributions 1.5.2 Designing cement concrete composition as per Bolomey-Skramtaev According to document [15], the composition of cement concrete is designed as follows: Step (Selecting the slump), Step (Determining the amount of water), Step (Determining the ratio X/N), Step (Determining the amount of cement X), Step (Determining the amount of stone D), Step (Determining the amount of sand C), Step (Determining the amount of superplastic additive) 1.5.3 Using the experimental planning method to identify factors influencing the strength of cement concrete for road construction and calculate ratio N/X According to document [30], the output norms used to evaluate objects are often called objective functions Experimental planning is employed for calculation, based on the scientific experiment plan to select the cement concrete composition in order to satisfy objective functions: the compressive strength and the bending tensile strength of cement concrete By experimental planning, it is possible to find out the regression equations describing the relationship between the objective functions: compressive strength and bending tensile strength with influencing factors such as ration D/C, ratio X/N, thereby, calculating ratio N/X 1.6 Investigating the geographic, topographic and geological features of quartzite quarry in Thanh Son, Phu Tho The quartzite quarry is located in Thuc Luyen commune, Thanh Son district, Phu Tho province [2] Figure1.2 Images of quartzite quarry 1.6.1 Geographic and topographic features 1.6.2 Geological features + Mineral geological features The quartzite layer lies on the slate, extending from the North to the South, about 150-200m thick, divided into seams, bottom-up distributed by seams 1,2,3 - Seam 1: Lying on the quartz mica slate, quartzite is yellowish opaque - Seam 2: Lying evenly on the rock clamping between the slate and quartzite schist, quartzite is pinkish gray - Seam 3: Lying evenly on the rock clamping between the slate and quartzite schist, widely distributed, quartzite is yellowish greyish white + Quartzite quality Quartzite available in this area falls into two types: Weathered quartzite and solid quartzite Table 1.6 Chemical composition of weathered quartzite Type SiO2(%) Fe2O3 (%) Weathered quartzite 96,90 0,28 Table 1.7 Chemical composition and physio-mechanical properties of quartzite in different seams Order SiO2 A1203 Water permeability Fire resistant (%) (%) (%) temperature 1.Seam 97.81 1.00 0.45 > 17300 Seam 97.23 0.77 0.54 > 17300 Seam 96.68 1.11 0.97 > 17300 1.7 Studies on quartzite and pavement cement concrete using quartzite 1.7.1 Studies on quartzite and pavement cement concrete using quartzite in the world According to document [39], quartzite is a metamorphic stone from silicon sandstone with crystalline quartz particles bound together Quartzite is white or pink, purple, dark because of impurities Quartzite is well weathered This kind of stone is used for the outer lining of a building, or as stone and crushed stone Quartzite is also found among raw materials for manufacturing fire resistant components Cement concrete for pavement makes use of quartzite, an artificial stony material obtained after the concrete mixture solidifies Concrete mixture is composed of cement, water, coarse quartzite aggregate and fine quartzite aggregate According to K Kavitha [51], the increased construction activities have entailed the increased demand for different materials used in concrete manufacturing, especially river sand as fine aggregates This study has investigated the effect of quartzite in place of fine aggregate in Grade 30 concrete (M30) Conclusions have been drawn as follows: Quartzite sand used to replace fine aggregate has small density and lower weight than river sand, so the specific weight of concrete can decrease Quartzite sand changes color well and has smooth surface, which cannot be observed in natural sand Quartzite sand is a better alternative than river sand at reasonable costs Therefore, it is acceptable to replace 100% fine aggregate by quartzite sand in construction works According to Simma Ravi Kiran [62], concrete is widely used in infrastructure construction In this study, quartzite is used as an alternative to replace coarse aggregate and its various mechanical properties and technical properties have also been investigated Experimental studies are performed on cement concrete by replacing up to 100% raw aggregates The mixed design and test methods are in compliance with the Indian Standards Bureau Concrete made of quartzite gives higher compressive strength than conventional concrete According to Mark Adom [53] from Ghana, quartzite is kind of rock forming the mountains, locally called Akwapim range running across the eastern region and extending into the Volta region This rocky range forms part of the regional geology called the Togo Series Quartzite is quartz-rich stone The stone has glassy color and its colors can vary from white to black, cream, pink, red and gray Utilization of quartzite to replace rough granite may be in the right direction to preserve the natural resources of conventional coarse aggregates including granite and sandstone According to Abdullahi M [33], concrete is normally produced from different types of aggregates The most important property of concrete is its compressive strength For the purpose of this research, three types of rough aggregate, i.e quartzite, granite and river gravel have been employed Fine aggregate comes from normal sand Test results show that concrete made from river gravel has the highest processing capacity, followed by crushed quartzite and then crushed granite The highest compressive strength at all days of age is achieved in concrete made from quartzite, then concrete made from river gravel, followed by concrete made from crushed granite According to Muhammad Tufail [55], concrete is a non-flammable material, yet high temperatures still affect its mechanical properties This study has investigated effect of high temperatures on the mechanical properties of limestone concrete, quartzite concrete and granite concrete The results show that concrete made from granite has higher mechanical properties at all temperatures, followed by quartzite concrete and limestone concrete According to NIST [56], the study has expanded the comparison with aggregate taken from 11 different quarries across the United States but mainly on the eastern coast, and especially in the MD-VA corridor where quartzite quarries lie + According to documents [52] and [61], quartzite belongs to the group of metamorphic rock Its mineral composition is mainly quartz The stone is white, light pink, yellow or gray The stone is very hard, not easy to get weathered when exposed to the air When super-high strength concrete is studied, quartzite sand is often used + According to G J Verbeck and W E Hass [46], the CTE of a kind of aggregate affects the CTE value of concrete containing that aggregate, meaning the higher CTE of aggregate, the higher CTE of concrete The CTE varies by original stone kind with the common range from approx 0.9×10-6/0C to 16×10-6/0C (0.5×10-6/0F to 8.9 ×10-6/0F) + According to R Rhoades and R C Mielenz [59], each kind of stone has different CTE + According to D G R Bonnell and F C Harper [43], the CTE value of concrete using quartzite cured in water environment is lower than that of concrete using quartzite not cured 1.7.2 Studies on quartzite and pavement cement concrete using quartzite in Viet Nam + The research on composition, mechanical properties of super-high strength concrete and its application in bridge structures conducted by doctoral candidate Nguyen Loc Kha [25] only mentions using quartzite sand crushed from quartzite stone to manufacture super-high strength concrete of 120-140 MPa + According to the research [22] by Prof Pham Duy Huu and his associates at the UTC, quartzite belongs to the group of metamorphic rock 1.8 Conclusions of Chapter and orientation for research CHAPTER INVESTIGATING AGGREGATE CHARACTERISTICS OF QUARTZITE IN THANH SON, PHU THO AND OTHER MATERIALS 2.1 General overview of aggregate Aggregate is a kind of granular rocky materials of natural or artificial origin, such as sand, gravel, crushed stone, etc of different shapes and sizes, used in the manufacture of cement concrete, construction mortar, asphalt concrete for pavement of railways, roadways [19], [21], [48] In order to utilize quartzite in Thanh Son quarry, Phu Tho province as a kind of aggregate for pavement cement concrete production, the author has conducted an investigation into the quartzite mining system and quartzite processing technology as presented below 2.2 Quartzite mining system 2.2.1 Basis for selection of the quartzite mining system Criteria for selection of the quartzite mining system in Thanh Son quarry, Phu Tho are based on actual conditions at the quarry as stated in [2] 2.2.2 Option for quartzite mining 2.3 Quartzite processing technology 2.3.1 Basis for selection of the quartzite processing technology The quartzite processing technology in application at Thanh Son quarry, Phu Tho is selected as follows: Through blasting, raw quartzite rock is directly excavated and transported by truck to the dam station in the North-East, where it is crushed and sieved into sand and stone 2.3.2 Chart of the selected technology and related parameters Chart of the quartzite processing technology is shown in Figure 2.3 Products of the process are quartzite stone and quartzite sand as illustrated in Figure 2.4 below Figure 2.4 Quartzite stone and quartzite sand 2.4 Analyzing chemical composition of quartzite in Thanh Son, Phu Tho After studying the geological features of Thanh Son quartzite quarry, the author conducted an analysis of the chemical composition of quartzite Table 2.1 Result of full analysis of chemical composition Order Mineral-chemical index Outcome Unit SiO2 96.95 % Fe2O3 0.32 % Al2O3 1.80 % CaO 0.00 % MgO 0.00 % SO3 0.00 % K2O 0.21 % Na2O 0.05 % P2O5 0.00 % The results of a full analysis of the chemical composition show that substances SiO2, A12O3, Fe2O3, K2O are notable in quartzite while other compounds are very few 2.5.Materials for manufacturing pavement cement concrete using quartzite 2.5.1 Cement 2.5.2 Coarse aggregate and fine aggregate 2.5.2.1 Selecting and sampling for experiment 11 Dust, mud, % ≤ 2,0 TCVN75721.84 Pass clay content 8:2006 Scale 2.2TCVN75722.94 Pass modulus 3.5 2:2006 Granular TCVN7572Chart Pass composition 2:2006 Remarks: The survey and experiment results of quartzite at the quarry show that it is definitely possible to utilize this source of material for pavement cement concrete production 2.5.2.4 Water used for cement concrete production The water used for cement concrete production should be good enough according to TCVN 4506:2012 [14] 2.6 Materials for cement concrete production using limestone To obtain a basis for research and contrast against cement concrete using quartzite aggregate, the author has performed experiments on cement concrete using limestone and Lo river sand Experimental results of the technical specifications of each material are as follows 2.6.1 Limestone 5x20 from Minh Quang quarry, Vinh Phuc as coarse aggregate (for contrast) The experiment results of the technical specifications of quartzite sand are summarized in Table 2.20 of the thesis The results show the requirements (norms) set by Decision QĐ1951[4] are satisfied 2.6.2 Lo river sand in Viet Tri, Phu Tho as fine aggregate The fine aggregate stated in the thesis is Lo river sand The test results of the physio-mechanical specifications of Lo river sand are summarized in Table 2.22 The results show the requirements (norms) set by Decision QĐ1951[4] are satisfied 2.7 Conclusions of Chapter CHAPTER DESIGNING COMPOSITION OF PAVEMENT CEMENT CONCRETE USING QUARTZITE AGGREGATE FROM THANH SON, PHU THO AND DETERMINING COMPRESSIVE STRENGTH, BENDING TENSILE STRENGTH, ELASTIC MODULUS 3.1 Designing composition of pavement cement concrete using quartzite aggregate from Thanh Son, Phu Tho 3.1.1 Employing the experimental planning method to determine influencing factors on strength of pavement cement concrete and calculating ratio N/X 12 3.1.1.1 Selecting parameters for research a Selecting objective functions According to documents [30] and [31], the output norms used to evaluate objects are often called objective functions Experimental planning is employed for calculation, based on the scientific experiment plan to select the cement concrete composition in order to satisfy objective functions: the compressive strength y1 = f ( x1, x2, x1x2 ) with x1, x2, x1x2 as variables and the bending tensile strength of cement concrete y2 = f ( x1, x2, x1x2 ) with x1, x2, x1x2 as variables b Selecting influencing factors Factors that affect the compressive strength and the bending tensile strength of cement concrete are numerous, such as aggregate quality, cement strength, ratio D/C and ratio X/N Since only one kind of cement is used and only quartzite aggregate is taken into account, the cement strength is unchanged So, the factors that most notably affect the two objective functions stated above are elements below: X1: Ratio of stone upon sand (coded as D/C) X2: Ratio of cement upon water (coded as X/N) The experimental plan includes experimental sites, also known as plan points Specific values of the input factors are set at the plan points, called factor levels, with the upper, lower and basic levels The basic level X0j of the factors is the experimental conditions that the researcher is particularly interested in Along with the input factor level, we also have to determine the changing interval (step) of input factor ΔXj Based on the cement concrete aggregates selected by some countries and surveyed in some projects in Viet Nam, the author of the thesis has chosen the variable values of influencing factors X1 (1,4 ≤ X1 ≤2,0); X2 (2,5 ≤ X2 ≤3,5) with X10 = 1,7; X20 = 3,0; ΔX1= 0,3; ΔX2= 0,5 Table 3.1 Value and variable interval of influencing factors Value X1 X2 Variable interval 1.4 ≤ X1 ≤2,0 2.5 ≤ X2 ≤3.5 X0j 1.7 3.0 ΔXj 0.3 0.5 To facilitate calculation of experimental coefficients of the regression mathematical model and conduct other data processing steps, we turn to dimensionless encoded values, with the upper and lower bound values being +1 and -1, average value: : x0j = (origin of the coordinate) Since there is no prior information, a linear description is the start The experiment results follow Box-Wilson's Tier plan with optimal levels, also known as full-scale plan or 2k plan The number of possible combinations of two 13 factors with two levels of N = 2k = 22 = The descriptive linear regression equation has the form: y = b0 + b1x1+ b2x2 + b12x1x2 (3.1) 3.1.1.2 Experimental plan for correlation between real code and encoded variable Table3.2.Experimental plan for correlation between real code and encoded variable Option Real code Encoded variable y1 y2 (MPa) (MPa) X1 X2 x0 x1 x2 x1x2 1,4 2,5 + + y11 y12 2,0 2,5 + + y21 y22 1,4 3,5 + + y31 y32 2,0 3,5 + + + + y41 y42 With y1 and y2 as the compressive strength and the bending tensile strength of concrete, b as the descriptive parameter is determined by formula (3.2) given in the thesis To specify significance of the parameters, we have to repeat experiments at the plan centre, as depicted in Table 3.3 below Table 3.3 Experimental plan at the centre Option Real code Encoded variable y1 y2 (MPa) (MPa) X1 X2 x01 x02 1,7 3,0 0 y110 y120 1,7 3,0 0 y21 y22 To determine values of y1 (compressive strength) and y2 (bending tensile strength) for calculation by experimental planning, we have to design composition of cement concrete and perform experiments that specify the compressive strength and the bending tensile strength of cement concrete as described below 3.1.1.3 Designing composition of cement concrete using quartzite from Thanh Son, Phu Tho The composition of cement concrete for mixtures is designed as follows + Mixture includes Grade 40 concrete, Chinfon PCB40 cement, coarse aggregate of quartzite rock from Thanh Son, Phu Tho, fine aggregate of quartzite sand from Thanh Son, Phu Tho, original slump of 4cm, ratios D/C=1.4; X/N=2.5 Mixture is composed of N= 185 (litre), X = 463 (kg), C = 711 (kg), D = 996 (kg) + Mixture includes Grade 40 concrete, Chinfon PCB40 cement, coarse aggregate of quartzite rock from Thanh Son, Phu Tho, fine aggregate of quartzite sand from Thanh Son, Phu Tho, original slump of 4cm, ratios D/C=2.0; X/N=2.5 Mixture is composed of N= 185 (litre), X= 463 (kg), C= 569 (kg), D = 1138 (kg) + Mixture includes Grade 40 concrete, Chinfon PCB40 cement, coarse aggregate of quartzite rock from Thanh Son, Phu Tho, fine aggregate of quartzite 14 sand from Thanh Son, Phu Tho, original slump of 4cm, ratios D/C=1.4; X/N=3.5 Mixture is composed of N= 150 (litre), X = 525 (kg), C = 700 (kg), D = 980 (kg) + Mixture includes Grade 40 concrete, Chinfon PCB40 cement, coarse aggregate of quartzite rock from Thanh Son, Phu Tho, fine aggregate of quartzite sand from Thanh Son, Phu Tho, original slump of 4cm, ratios D/C=2.0; X/N=3.5 Mixture is composed of N= 150 (litre), X= 525 (kg), C= 560 (kg), D = 1120 (kg) + Mixture includes Grade 40 concrete, Chinfon PCB40 cement, coarse aggregate of quartzite rock from Thanh Son, Phu Tho, fine aggregate of quartzite sand from Thanh Son, Phu Tho, original slump of 4cm, ratios D/C=1.7; X/N=3.0 Mixture is composed of N= 165 (litre), X= 495 (kg), C= 628 (kg), D = 1067 (kg) + Mixture includes the same materials as Mixture 5, so its composition is the same with N = 165 (litre), X = 495 (kg), C = 628 (kg), D = 1067 (kg) Mixture will be randomly selected for later design of cement concrete using limestone The reason to select the same components for cement concrete using quartzite and cement concrete using limestone is for easy comparison and contrast Experiments on compressive strength, bending tensile strength, elastic modulus, thermal expansion coefficient all adopt the composition designed for Mixture Remarks: By experimental planning, we have found the aggregate composition of Grade 40 concrete with the data given above 3.1.1.4 Experimenting to determine physio-mechanical properties of pavement cement concrete using quartzite from Thanh Son, Phu Tho by experimental planning + Slump is used to evaluate the easy flowing ability of concrete mix under the effect of self-weight or vibration Slump is specified by TCVN 3106-93 [7] The test resuts of slump is given in Appedix and summarized in Table 3.9 below Table 3.9 Results of slump by experimental planning Order Average slump (cm) Mixture 3.2 Mixture 3.1 Mixture 3.6 Mixture 3.7 Mixtures and 3.4 + Moulding, curing and selecting the size of test samples are done as per TCVN 3105-93 [6] Images of sample moulding and curing can be seen below Figure 3.2 Sample moulding Figure 3.3 Sample curing and up-picking 15 + Experimenting to determine compressive strength and bending tensile strength Experiments to determine the compressive strength and the bending tensile strength of cement concrete were carried out by the author according to TCVN 3118-93 [8] and TCVN 3119-93 [9] Images of those experiments can be seen below Figure 3.4 Sample pressing Figure 3.5 Sample bending and pulling Experiment results of the compressive strength are summarized in Table 3.10 below Table 3.10 Results of compressive strength of concrete Order Concrete mixture Average compressive strength (MPa) Mixture 41.14 Mixture 43.58 Mixture 60.60 Mixture 62.50 Mixture 52.70 Mixture 50.80 Experiment results of the bending tensile strength are summarized in Table 3.11 below Table 3.11 Results of bending tensile strength of concrete Order Concrete mixture Average bending tensile strength (MPa) Mixture 5.26 Mixture 5.28 Mixture 6.23 Mixture 6.32 Mixture 5.81 Mixture 5.7 Remarks: The experiment results and the evaluation as per Decision QĐ1951[4] have proved that quartzite concrete meets the requirements of bending tensile strength + Experiments of elastic modulus: The experiments were performed as per TCVN 5276-93 [10] To obtain data for later calculation in the next chapter, the author conducted elastic modulus experiments for cement concrete using quartzite aggregate of the same composition as Mixture with X = 495 kg, Đ = 1067 kg, N = 165 litre, C = 628 kg The experiment results are illustrated in Table 3.12 16 Sample Sample Sample Sample ε0 Table 3.12 Elastic modulus of quartzite concrete σ0 (MPa) ε1 σ1 (MPa) Elastic modulus E (MPa) 10.7 x10-6 0.05 446 x10-6 16.00 36641.4 3.8 x10-6 0.05 479 x10-6 16.00 33564.81 8.9 x10-6 0.05 437 x10-6 16.00 37257.65 ETB: 35821.29 3.1.1.5 Calculation process by experimental planning The calculation process by experimental planning is described in detail in the thesis By experimental planning, the author has found the regression equations describing the relationship between the objective functions: compressive strength y1, bending tensile strength y2 with the influencing factor of ratio X/N The two regression equations are: y1  19,19 X  5,62 y2  X  2,77  2,5  X  3,5  2,5  X  3,5 The formula describing the relationship between Rn and ratio X/N is: X Rn  19,19  5, 62 N This formula is used to calculate ratio N/X in design of quartzite concrete composition mentioned in the following parts 3.1.2 Experimenting to determine compressive strength, bending tensile strength, elastic modulus of cement concrete using limestone from Minh Quang quarry, Vinh Phuc To facilitate the comparison between cement concrete using quartzite and cement concrete using limestone, as well as the calculation and analysis in the next chapter, the author adopted the same composition design for cement concrete using limestone as for Mixture of cement concrete using quartzite with X = 495 kg, Đ = 1067kg, N = 165 litre, C = 628 kg The test results of the compressive strength, bending tensile strength of limestone cement concrete are given in Appendix while the results of elastic modulus are given in Appendix of the thesis Remarks: The experiments of compressive strength, bending tensile strength, elastic modulus of cement concrete show that the quality of quartzite cement concrete is high and equals to that of limestone cement concrete, as a result, quartzite cement concrete can be well applicable in road construction 3.1.3 Designing composition of cement concrete using quartzite from 17 Thanh Son, Phu Tho by method ACI 211.1.91 [34] 3.1.3.1 Designing composition of cement concrete Grade 40 concrete is designed to be composed of coarse aggregate of quartzite rock from Thanh Son, Phu Tho with Dmax = 20mm (stone 5x20mm), fine aggregate of quartzite sand from Thanh Son, Phu Tho and Chinfon PCB40 cement Ratio N/X=0.358 is specified by the regression equation from experimental planning (Formula 3.10) The composition of concrete mix is N=165 (litre), X=461(kg), C= 618 (kg); D=1111 (kg) 3.1.3.2 Experimenting to determine the physio-mechanical properties of concrete The slump of concrete was measured before sample moulding, curing and testing The result shows the average slump is 3.6 cm (data given in Table 3.19 of the thesis) + Compressive strength: The data of the compressive strength of concrete follows Table 3.20 of the thesis After obtaining the experiment results, the author conducted evaluation of the results, which yield the average strength of X  49,87 MPa, deviation S = 4.876 MPa, distribution coefficient CV  S / X  0,098 , Rđt = Xo = X - 1.64, S=41.9 > 40, satisfying the requirements + Bending tensile strength: The data of the bending tensile strength of concrete follows Table 3.22 in the thesis The evaluation of concrete quality as per Decision QĐ1951[4] shows that quartzite concrete meets the requirements of bending tensile strength + Determining coefficient K in the formula (3.13) [19] describing the relationship between the compressive strength and the bending tensile strength of concrete The experiment and calculation results show that coefficient K in the experiment exceeds coefficient K as regulated, i.e Ktn > Kqd = 0.7 Hence, in practice, coefficient K = 0.7 is still applicable and ensures safety 3.1.4 Conclusions of Chapter CHAPTER STUDYING THERMAL EXPANSION COEFFICIENT OF CEMENT CONCRETE AND ECO-TECHNICAL EFFICIENCY OF CONCRETE PAVEMENT UTILIZING QUARTZITE AGGREGATE FROM THANH SON, PHU THO 4.1 Thermal behaviour of cement concrete pavement plates 4.1.1 Overview of thermal effects (impact of temperature) 4.1.2 Grounds for temperature description 4.1.3 Boundary conditions 18 4.1.4 Heat exchange model and input data 4.2 Calculation of thermal expansion coefficient One of the impacts of temperature during concrete strength formation in a structure is characterized by the coefficient of thermal expansion (CTE) 4.2.1 Thermal expansion coefficient of cement mortar The CTE of cement mortar ranges from 18 to 20µ/°C 4.2.2 Thermal expansion coefficient of aggregates Normally, the thermal expansion coefficient of aggregates is not as high as the CTE while the strength of Portland cement is being formed [54] The CTE relies on the chemical-mineral composition of aggregates [44] The CTE of limestone is between 4-8µε/°C while that of gravel is 7-12µε/°C [47] 4.2.3 Thermal expansion coefficient of concrete Earlier studies show that the CTE of concrete during strength formation relies on the volume of coarse aggregate and cement mortar [43] By using certain type of cement, aggregate and composition design, a formula that relates to the relationship between the CTE and the age function of concrete is developed (4.12) It is useful to refer to the CTE values of concrete researched by Hak Chul Shin [49] or those set in Decision QĐ3230[5] by MOT 4.2.4 Thermal expansion coefficient of cement concrete according to Document [58] Ratio X/C affects the CTE of concrete Figure 4.4 Relationship between CTE of aggregates and CTE of concrete [58] Remarks: Figure 4.4 shows the CTE of limestone concrete not cured and that of limestone concrete cured in water environment are similar, with the value of approx 7.2(10-6/0C) The CTE value of quartzite concrete cured in water environment is approx 12.3(10-6/0C) and that of quartzite concrete not cured is approx 12.8(10-6/0C), which is an increase of about 4% compared to water-based curing 4.3 Stress of cement concrete pavement 4.3.1 Stress of cement concrete pavement in early age 4.3.2 Stress of cement concrete slabs as per current standards 4.4 Formula to calculate thermal expansion coefficient of cement concrete by AASHTO TP 60 (2006) [32] The formula to calculate CTE is as follows 19 (4.19) In which, ∆La = the sample length changing in reality during temperature changing, mm; Lo= the sample length in room temperature, mm; ∆T= variation of temperature The experiment results are achieved by the average value of CTEs obtained CTE1  CTE2 from experimental segments: CTE  4.5 Experimenting to determine distortion and thermal expansion coefficient of cement concrete by AASHTO TP 60 (2006) Currently, the method of determining the CTE of cement concrete by AASHTO T336-15 is being applied worldwide In Viet Nam, due to the lack of qualified samples to standardize the CTE, the doctoral candidate had to employ AASHTO TP 60 (2006) The experiments as per AASHTO TP 60 (2006) still abode by the regulations set in AASHTO T336-15, therefore, AASHTO TP 60 (2006) is recommended according to document [32] 4.5.1 Experimental equipment Sample forming and experiments were performed at the laboratory of the University of Transport Technology with following equipment: Strain gauge SDA– 830B (TML, Japan) using LVDT measuring head, thermostatic tank, electronic scale, thermometer, cylinder of 100 mm in diameter and 200 mm high, electronic measuring clamp, measuring head locator 4.5.2 Introduction of strain gauge Figure 4.8 Strain gauge SDA - 830B 4.5.3 Preparing test samples To facilitate comparison and contrast among aggregates, the author used quartzite cement concrete and limestone cement concrete of the same concrete composition X = 495 kg, Đ = 1067 kg, N = 165 litret, C = 628 kg with samples measured by age and sample cylinder of 100 mm in diameter and 200 mm high 4.5.4 Experimental order The order of experiments is described in detail in the thesis Figure 4.12.Samples Figure 4.13.Measuring sample length Figure 4.14.Sample cooling Figure 4.18 Operating measuring device Figure 4.19 Data displayed on PC 20 4.6 Experiment results The results drawn from experiments are given in Appendix 10 The results show that quartzite concrete at Day 3, 7, 14, 28 has the CTE of 11.1925; 11.2248; 11.2200; 11.1819 (10-6/ 0C), while limestone concrete at Day 3, 7, 14, 28 has the CTE of 7.4791; 7.3830; 7.3996; 7.4132 (10-6/ 0C) 4.7 Analysis of experiment results CTE (10-6/OC) CTE relies on age 12 10 Days Days 14 Days 28 Days Quartzite stone Limestone Figure 4.20 Relationship between CTE and age of concrete Remarks: Basing on the experiment results and the chart in Figure 4.20, it is obvious that the CTE of quartzite concrete and limestone concrete does not rely on the age of concrete CTE (10-6/OC) CTE relies on kind of aggregate 12 10 Quartzite stone Limestone Days Days 14 Days 28 Days Figure 4.21 Relationship between CTE and kind of aggregate of concrete Remarks: The CTE of concrete relies on kind of aggregate, and the CTE of quartzite concrete is higher than that of limestone concrete 4.8 Analyzing effect of the size of cement concrete plates and quartzite stone on strength and thermal stress of cement concrete pavement 21 In the thesis, the author presented the calculation of cement concrete plates as per Decision QĐ3230[5] While calculating cement concrete plates using limestone and those using quartzite, the author employed the experiment results of the CTE of limestone cement concrete and quartzite cement concrete measured at Day 28 to compute the maximum bending tensile stress caused by thermal gradien [σtmax] (MPa) Note that the CTE αc given in QĐ3230[5] equals to the CTE in the experiments stated at Item 4.6 of the thesis 4.8.1 Design calculation of pavement cement concrete slabs 4.8.2 Calculating cement concrete plates of 4.5m x 3.5m x 0.25m using limestone 4.8.3 Calculating cement concrete plates of 4.5m x 3.5m x 0.25m using quartzite 4.9 Result analysis 4.9.1 Analyzing effect of aggregate on concrete strength development + Remarks: The compressive strength of limestone concrete corresponds to 98.9% that of quartzite concrete 4.9.2 Analyzing effect of aggregate on thermal stress development + Remarks: In the plate of 4m x 3.5m x 0.25m, the thermal stress in limestone concrete achieves only 66.41% compared with quartzite concrete, and in the plate of 4.5m x 3.5m x 0.25m, the thermal stress in limestone concrete achieves only 66.23%, compared with quartzite concrete 4.9.3 Analyzing effect of plate size on crack resistance of cement concrete pavement Remarks: For cement concrete pavement using quartzite, ratio [σp,t max] / Rku % is 16.46%; for cement concrete pavement using limestone, ratio [σp,t max] / Rku % is 11.05% When designed of the same composition, the strength and the thermal stress of quartzite concrete increase concurrently with those of limestone concrete The tensile strength increases by 1.1% and the max thermal stress increases by 33.59% Due to the above stated factors, concrete pavement using quartzite is more likely to crack on the plate surface than concrete pavement using limestone at deviation rate of cracking possibility of 5.41% Cement concrete plates using quartzite should be shorter than those using limestone The cement concrete slabs using quartzite aggregate should be 3.8m long 4.9.4 Conclusions 4.10 Analyzing eco-technical efficiency of cement concrete pavement using quartzite from Thanh Son, Phu Tho 4.10.1 Ability to meet requirement of strength 22 Strength is an important property of pavement cement concrete and evaluated by means of specifications of compressive strength, bending tensile strength and elastic modulus The experiment results are summarized in Table 4.24 and compared with requirements of Grade III roads as set in Decision QĐ3230 [5] Table 4.24 Summary of concrete strength Limestone Order Specifications Quartzite concrete Required concrete Compressive strength 50,8 49,83 ≥36 (MPa) Bending tensile strength 5,7 5,64 ≥4,5 (MPa) Elastic modulus (MPa) 35821,29 35469,69 ≥29000 Evaluation Meeting the requirements Remarks: Concrete using quartzite aggregate meets the requirements of strength as regulated 4.10.2 Analyzing economic efficiency + To analyze the economic efficiency of cement concrete pavement using quartzite aggregate from Thanh Son, Phu Tho, the author supposed a Grade III section with length L=1km, pavement width B = 7m and average thickness h = 0.25m The concrete volume in need V = 1750m3 Basing on the design of component materials for 1m3 concrete, the author calculated the material volume for 1km of road as given in Table 4.25 of the thesis + To analyze the economic efficiency, the author merely evaluated the material price with the price unit recorded in Phu Tho area in Quarter II, 2017, resulting in the data given in Table 4.26 The results show that quartzite concrete costs 845355.94 (vnd/m3) while limestone concrete costs 917510,43 (vnd/m3) Remarks: Quartzite concrete costs less than limestone concrete It is possible to utilize quartzite aggregate for concrete production so as to take advantage of the local material of low price and boost up economic development in the region 4.11 Conclusions of Chapter CONCLUSIONS, RECOMMENDATIONS AND DIRECTION FOR FURTHER RESEARCH Conclusions Having studied and utilized quartzite as aggregate for pavement cement concrete, the author has come to conclusions as follows 1.1 Affirming that quartzite rock in Thanh Son, Phu Tho is a kind of high quality aggregate with quite large reserves of over 10 million tons, which has not 23 ever been investigated by any research to use this aggregate for pavement cement concrete production Exploiting and taking advantage of local materials to manufacture concrete for road construction is imperative, aiming to reduce the aggregate transportation that adds up to construction costs while enhance exploitation efficiency This material is affirmed to be in accordance with the current standards and can be utilized to produce pavement cement concrete (regarded only in conditions of studied norms and experiments conducted in the thesis) Usage scope of quartzite and cement concrete using this aggregate is limited to Grade III roads, heavy traffic roads, quartzite entirely replacing limestone .1.2 By experimental planning, the author has found the regression equations describing the relationship between the objective functions: compressive strength, bending tensile strength with the influencing factor of ratio X/N The two regression equations are: y1  19,19 X  5,62 y2  X  2,77  2,5  X  3,5  2,5  X  3,5 The composition of Grade 40 cement concrete using quartzite from Thanh Son, Phu Tho has been designed as per ACI 211.1.91with ratio N/X selected by formula (3.10), which has been established by experimental planning 1.3 The experiment results of compressive strength, bending tensile strength, elastic modulus, slump of cement concrete using quartzite show that quartzite concrete achieves high quality and meets the requirements at a similar level to limestone concrete 1.4 Studying the thermal property of cement concrete using quartzite Through experiments, the author has identified the distortion and the CTE of quartzite concrete and those of limestone concrete by age with strain gauge SDA – 830B In detail, - Quartzite concrete at Days 3, 7, 14, 28 achieves the CTE of 11.1925; 11.2248; 11.2200; 11.1819 (10-6/0C), respectively - Limestone concrete at Days 3, 7, 14, 28 achieves the CTE of 7.4791; 7.3830; 7.3996; 7.4132(10-6/0C) - Quartzite concrete has higher CTE than limestone concrete (1.5 times higher at Day 28) 1.5 Calculation of cement concrete plates using quartzite and limestone with expected sizes of 4m x 3.5m x 0.25m and 4.5m x 3.5m x 0.25m, according to MOT Decision QĐ3230 24 - The calculation results show that all cement concrete plates are qualified in terms of strength, thermal stress, fatigue stress - When designed of the same composition, the strength and the thermal stress of quartzite concrete increase concurrently with those of limestone concrete The tensile strength increases by 1.1% and the max thermal stress increases by 33.59% - Due to the above stated factors, concrete pavement using quartzite is more likely to crack on the plate surface than concrete pavement using limestone at deviation rate of cracking possibility of 5.41% - Cement concrete plates using quartzite should be shorter than those using limestone The cement concrete slabs using quartzite aggregate should be 3.8m long - Quartzite concrete meets all requirements of strength, achieves high economic efficiency due to lower price of quartzite than that of limestone Recommendations and direction for further research 2.1 The experiment results of compressive strength, bending tensile strength, elastic modulus, slump of cement concrete using quartzite and limestone can serve as useful reference for teaching, design and construction of transport works as well as automobile roads in the future 2.2 The CTE value of quartzite concrete is recommended to be included in MOT Decision QĐ3230 2.3 Standards of the thermal property of cement concrete should be developed 2.4 The design of material composition and experiments to determine properties of quartzite cement concrete are only limited to application to Grade III automobile roads Therefore, there should be further research on its application to high-grade roads, motorways 2.5 In the future, there will be further study on partial replacing of concrete mixture with quartzite, weathered quartzite, which can be found in foundation layers, and such issues as the content of Cl ions, sulfate rocks and sulfate salts, alkali reactions of quartzite, its abrasion and fatigue resistance PUBLICATIONS BY THE AUTHOR Ngo Hoai Thanh, Pham Duy Huu, “Technical specifications of quartzite in Thanh Son, Phu Tho”, Viet Nam Bridge and Road Magazine, No 10, 2015 Ngo Hoai Thanh, Pham Duy Huu, “Designing composition of cement concrete for road pavement using quartzite in Thanh Son, Phu Tho by experimental planning”, Viet Nam Bridge and Road Magazine, No 11, 2017 Ngo Hoai Thanh, Pham Duy Huu, “Investigatingthermal properties ofcement concrete using quartzite in Thanh Son, Phu Tho”, Viet Nam Bridge and Road Magazine, No5, 2018 Ngo Hoai Thanh, Pham Duy Huu,“Analyzing effects ofthe size ofcement concreteplates made of quartzite aggregate on the strength and thermal stress in cement concrete pavement”, Viet Nam Bridge and Road Magazine, No 9, 2018 Ngo Hoai Thanh, Pham Duy Huu,“Studying characteristics of the quartzitequarryin Thanh Son, Phu Tho”, Viet Nam Bridge and Road Magazine, No 11, 2018 ... geological features of quartzite quarry in Thanh Son, Phu Tho The quartzite quarry is located in Thuc Luyen commune, Thanh Son district, Phu Tho province [2] Figure1.2 Images of quartzite quarry 1.6.1... composition of quartzite in Thanh Son, Phu Tho After studying the geological features of Thanh Son quartzite quarry, the author conducted an analysis of the chemical composition of quartzite Table... PUBLICATIONS BY THE AUTHOR Ngo Hoai Thanh, Pham Duy Huu, “Technical specifications of quartzite in Thanh Son, Phu Tho”, Viet Nam Bridge and Road Magazine, No 10, 2015 Ngo Hoai Thanh, Pham Duy Huu, “Designing