Method statement

CONTENTS I GENERAL METHOD STATEMENT PROJECT GENERAL DESCRIPTION Site preparation (office, fence, other temporary works) 2.1 Temporary Site Office 2.1.1 Temporary internal roads for construction 2.1.2 Temporary internal roads for construction 2.1.3 Temporary storage yard 2.1.4 Temporary lighting, power and water supply systems 2.1.5 Temporary fence and guardhouse 2.1.6 Other works 2.2 Site human organization 2.2.1 Human resource of Vinaconex 2.2.2 Vinaconex site organization chart EXCAVATION AND REMOVE SURPLUS SOIL 3.1 Excavation 3.1.1 Preparation 3.1.2 Unsuitable Materials Encountered 3.1.3 Slope 3.1.4 Final Layer 3.1.5 Quality Assurance and Approval 3.2 Surplus excavated material 3.3 Backfill and filling 3.4 Water drains CONCRETE STRUCTURE WORK 4.1 General introduction of material, equipment and construction capacity of contractor 4.2 Reinforcement 4.2.1 General requirement 4.2.2 Cutting and bending 4.2.3 Welding 4.2.4 Rebar ties 4.2.5 Replacement of rebar 4.2.6 Delivery and installation of rebar 4.2.7 Inspection and approval of reinforcement 4.3 Formwork & Propping 4.3.1 General requirements 4.3.2 Materials for formwork and propping 4.3.1 Design of formwork and propping 4.3.2 Formwork and propping installation 4.3.3 Inspection and approval of formworks and scaffolding systems 4.3.4 Formwork and scaffolding system removal 4.4 Concrete works 4.4.1 Materials for concrete 4.4.2 Transportation of concrete 4.4.3 Placement and vibration 4.4.4 Concrete curing 4.4.5 Construction joint 4.4.7 Concrete placement to workshop floors 4.5 Inspection and approval II METHOD STATEMENT FOR TRANSFER YARD AND WHEEL TRACK Earth work and concrete works for Transfer yards and Wheel track 1.1 Preparation works 1.2 Work procedure Construction method: 2.1 Earthwork method: 2.2 Backfill method 2.3 Concrete method: I GENERAL METHOD STATEMENT PROJECT GENERAL DESCRIPTION The transfer yards and wheel track are among items belonging to the Project Damen Song Cam Shipyard in Hoang Dong and Lam Dong communes of the Thuy Nguyen District in Hai Phong City, Viet Nam PREPARATION WORK 2.1 SITE PREPARATION (OFFICE, FENCE, OTHER TEMPORARY WORKS) 2.1.1 TEMPORARY SITE OFFICE Temporary site offices are furnished with sufficient equipment for the project execution within months such as furniture, shelves, air-conditioning systems, communication systems, internet, computers, printers and other necessary equipment Temporary office using contener 40 feet, provice sit for Project Manager area, Site Manager area, Supervision area, site designing area, meeting room, WC, parking area etc VINACONEX is responsible for cleaning, taking care of, and security to temporary site offices 2.1.2 TEMPORARY INTERNAL ROADS FOR CONSTRUCTION Temporary internal roads are reused the existing road from previous Contractor, otherwise the Contractor also make temporary road for some areas as shown on method statement drawing to service for construction Upon site possession, Vinaconex shall level, compact subgrade and crustone These roads are designed and constructed to facilitate all the transportation, storing, loading, loading and unloading materials and equipment to be incorporated into the project during construction period Temporary road is designed with widths 5m with area for traffic turning The roads are made of backfill soil and 0-4 stones as shown on method statement drawing and compacted well and with sufficient temporary drainage system During construction and installation, temporary roads will be regularly amended to ensure continuous traffic usage for soil erosion and sedimentation control 2.1.3 TEMPORARY STORAGE YARD Temporary storage yard for construction duration of the project shall be located on the plan with the main area as follows: -Temporary storage yards for material and equipment of VINACONEX; -Temporary storage yards for materials and equipment of VINACONEX construction teams; -Temporary storage yards for materials and equipment of VINACONEX of sub-contractors; All above mentioned areas are located next to main buildings to facilitate the construction and installation work later and to ensure no relocations of temporary offices during the execution of the project 2.1.4 TEMPORARY LIGHTING, POWER AND WATER SUPPLY SYSTEMS Temporary power and water supply systems are designed and will be installed with sufficient capacity for all temporary requirements on site In addition, the following areas are installed with temporary lighting systems used at night for Site office, main gate, temporary fences, storage yards, guardhouse, temporary sheds of VINACONEX teams and sub-contractors 2.1.5 TEMPORARY FENCE AND GUARDHOUSE A temporary fence shall be installed surrounding the site for security reasons Install 01 main gates with guardhouses and barriers Besides, guardhouses can be located along critical areas for security control and protection 2.1.6 OTHER WORKS Besides the above-mentioned, additional facilities shall be installed as listed below: - Telephone system (domestic calls only); - Parking areas for contractors staffs and workers; - WC for all working areas with sufficient temporary drainage systems; - Washing bay to clean vehicles before leaving site to the public road; - Medical & first-aid area; - Safety training area for workers; - Waste Collection points; - Canteen for workers; - Safety signs, project board etc The above-mentioned works may be adjusted or changed in accordance with requirements of construction and installation progress 2.2 SITE HUMAN ORGANIZATION 2.2.1 HUMAN RESOURCE OF VINACONEX Human resource of VINACONEX shall be mobilized on the principle of matching agreed construction schedule According to site workload, workforces can vary from 150 to 200 workers maximum VINACONEX ensures that workforces mobilized for this project are professionally trained, skillful and conducted with safety and industrial hygiene sources by VINACONEX before entering site for work 2.2.2 VINACONEX SITE ORGANIZATION CHART (Refer the chart in tender submission) Attention should be paid to our proposed organization chart of which architects shall be appointed for deploying detailed and shop drawings The chart of Project Team comprises of: Off site management: - Project Director (directly reporting to the General Director) - On site management: - Project Manager - Deputy Project Manager - Site Administrator - Site supervisors - Designers - Quality control representative - Safety control representative General construction teams and sub-contractors - Civil Teams (Structural and Architectural Works) - Structural steel Team - Sub-contractors and Suppliers The Project team will be assigned immediately upon the issuance of commencement instruction However, all members of the Projects of the Project Team are required to make prior studies on the drawings as well as fully aware of all actual conditions on the site so that the works can be implemented properly Experienced on similar projects, Mr Ngo The Hung, Chief of Safety Control Group shall ensure that, prior to any personnel mobilizing to the job site, all VINACONEX staffs and workers and subcontractor personnel are thoroughly grounded in the safety procedures EXCAVATION AND REMOVE SURPLUS SOIL 3.1 EXCAVATION 3.1.1 PREPARATION After receiving construction drawings, taking over the site and bench marks, existing level marks, etc VINACONEX shall setting out position, level of items Theodolite, level equipment and accessories shall be used All topsoil on the site shall be excavated to the average depth indicated, and stored to be reused on the site General excavation shall be carried out to the dimensions, depths or levels as indicated on the Drawings Should any excavation be taken beyond the required lines or levels, or if the soil immediately below the excavated surface is disturbed, the Contractor will at his own cost and expense take steps as directed or as approved by the Engineer to correct the defects The remedial action shall be such that the original bearing capacity and all other desirable soil properties are not diminished in any way by such action 3.1.2 UNSUITABLE MATERIALS ENCOUNTERED Such unsuitable material that is excavated shall not be re-deposited back on site either as general fill or as backfill around foundations, but shall be removed from the site and taken away to a certified dumping ground 3.1.3 SLOPE The Contractor shall protect all slopes, including formed slopes in fill, from soil erosion or softening due to rain or surface water 3.1.4 FINAL LAYER At least the last 5cm – 10cm of soil above the formation is to be excavated by hand on a dry day to the correct levels as shown on the drawings and the bottom is to be trimmed, cleared of loose or soft spoil and rammed if necessary before laying of the concrete blinding The final 5cm – 10cm layer above formation level is only to be excavated on the same day as the laying of concrete blinding 3.1.5 QUALITY ASSURANCE AND APPROVAL Throughout construction progress, the inspection, supervision, approval and quality assurance shall comply with requirements from client, consultants, design drawings and TCVN 4447:1987 – Earthwork-Standard and Inspection for Approval Beside procedures and forms required by the client and Government, VINACONEX will also apply its own Quality Management System in accordance with ISO 9001-2008 3.2 SURPLUS EXCAVATED MATERIAL Excavated material that is surplus or suitable for filling etc., shall be re-deposited, spread, leveled and compacted elsewhere on site, all as directed by the Engineer or removed off to the Contractor’s own dumping ground 3.3 BACKFILL AND FILLING Prior to Backfilling, remove formwork and other objects located in the area to be backfilled Consult the Engineer in the event that formwork shall remain as they are Consult the Engineer if the excavated soils are not suited to the backfilling and fill Extra fill settlement or allowance may be required depending on the soils 3.4 WATER DRAINS To excavate small canal from foundation to the Song Cam river for water drains CONCRETE STRUCTURE WORK 4.1 GENERAL INTRODUCTION OF MATERIAL, EQUIPMENT AND CONSTRUCTION CAPACITY OF CONTRACTOR Execution of mass reinforced concrete is the most important work in establishing stability and duration of each project It is as continuous works which represent technology and progressive level of each construction company Having understood the importance of mass reinforced concrete VINACONEX has been innovating and investing much more modern equipment in accordance with regional and international standards, thoroughly increasing project quality and construction speed We have experimented and applied new technologies and new materials in fabricating and installing formworks 4.2 REINFORCEMENT 4.2.1 GENERAL REQUIREMENT Rebar for concrete structural works must comply with design requirements and TCVN 5574:1991 “reinforced concrete structure” and TCVN 1651:1985 “Steel reinforcement” To imported steel, certificates shall be required and sampling for test in accordance with TCVN 197:1985 “Metal-Pulling test” and TCVN 198:1985 “Metal-bending test” Rebar can be fabricated at site or at workshop depending on large quantities required for the project Rebar of same dimensions and shapes but different physical properties shall not be used for the same project Rebar before fabrication and concrete placement must ensure: Clean, free of dust, oil, scale or rust; Rebar with sectional area reduced because of cleaning or other causes shall not exceed 2% of diameter If the reduction is over 2%, the rebar shall be used with the remaining sectional areas Rebar must be straight or be bent straight 4.2.2 CUTTING AND BENDING Cutting and bending must be carried out by mechanical methods Rebar must be cut and bent in accordance with design shapes and dimensions Fabricated rebar must be checked by lots Each lot contains 100 rebar Any rebar shall be taken from each lot for verification Discrepancies shall not exceed data in Table 4-Discrepancies of Fabricated rebar (Item 4.2.2-TCVN 4452:1995) 4.2.3 WELDING Weld connection can be carried out by various methods but welds must comply with design requirements Welding method must comply with TCXD 71:1977 “Welding instruction for rebar and member inserted into concrete member” Connection of steel with low weldability shall comply with instruction from manufacturers For butt weld, rebar to be heated by automatic or semi-automatic welding machine in accordance with TCXD 72:1997 “Regulation on butt-well for round bar” Tack weld is applicable to frame and rebar mesh with diameter less than 10 mm (for cold roll rebar) or 12 mm (for hot roll rebar) When fabricating rebar frame and mesh, unless otherwise specified, tack welding shall follow the following requirements: -Round plain rebar: weld all contact points -Deformed rebar: weld all contact points for external perimeters Other areas shall be welded by every two contact points; - Rebar frames for beams: weld all contact points; - Acetylene wielding is applicable to the following cases: - Connection weld to all rebar with diameter greater than mm - Weld all pre-inserted details, element and connections of assembled member - Weld must comply the following requirements: - Smooth surface, no burn, no interruption, no local reduction and no blisters; - Length and height of weld comply with design requirements; - Weld connection is checked in types and lots Each lot contains 100 welds or 100 welds frames or mesh The inspection is as follow: - Each lot takes 5% of welds but not less than samples for dimension inspection, samples for pulling and samples for bending tests; - Tolerances not exceed the data shown on table – allowable tolerance for welds ( clause 4.3.7-TCVN 4453:1995) for weld quality 4.2.4 REBAR TIES Rebar ties are to be in conformity with design requirements Do not tie at big load bearing positions and at bending positions At a sectional area of a structural member: not tie more than 25% of load-bearing rebar for plain rebar and not more than 50% of load bearing for deformed rebar Tying must satisfy the following requirements: - Tie wire for load-bearing for frames and mesh shall not be less than 250mm for stretching steel and not less than 200mm for compressing steel Tie wire for other member shall follow date shown on table7-lengths of tie wires (clause 4.4.2-TCVN 4453:1995) - When tying, rebar at stretching area must be hooked (for plain bar) No hooking for deformed rebar; - Tie wire is mild steel with dia 1mm; - At least positions to be tied (2 ends and at the middle) 4.2.5 REPLACEMENT OF REBAR In all cases, replacement of rebar must be approved by designer In case cold-roll rebar are used in place of hot-roll rebar, contractor must have approval from designer and the client 4.2.6 DELIVERY AND INSTALLATION OF REBAR The delivery of fabricated rebar must meet the following requirements: - Do not damage or deform rebar; - Rebar of same types should be tied together to avoid wrong uses; - Large frames and mesh should be divided into small quantities to suit transportation means Installation must meet the following requirements: - Previously installed members not hinder the installation of later members; - Fix rebar firmly to prevent displacement during concrete placement; - When forms and rebar are combined to create a strong member, forms then must be placed at intersection of main rebar and as designed Spacers shall be placed at suitable locations in accordance with rebar density However the density should not exceed spacer per 1m Spacer thickness is equal to cover concrete Spacers shall be made of materials which not erode steel, concrete Connection of rebar must comply with the following requirements: - Number of ties or tack welds shall not be less than 50% of intersections; - In all cases, corners of stirrups and main bars must be tied or welded 100% Connection of separate rebar to frame and mesh must be in accordance with design requirements Connection shall comply with table 8- Connection of rebar with various concrete grades (clause 4.6.5-TCVN 4453:1995) but not less than 250 mm Vertical displacement of rebar when fabrication or installation shall not exceed 1/5 diameter of biggest main bar and ¼ diameter of the bar Tolerance is in accordance with table 9Allowable tolerance for installed rebar (clause 4.6.6-TCVN 4453:1995) 4.2.7 INSPECTION AND APPROVAL OF REINFORCEMENT Inspection of rebar includes the following works: - Conformity of rebar types against design; - Fabrication, cutting, bending and cleaning before fabrication Tolerance for fabricated rebar in Table – Varied dimensions of fabricated rebar (clause 4.2.2-TCVN 4453:1995); - Welding: workmanship, equipment, welding rod, welding technology, and welding quality Tolerance is in accordance with table 5-Allowable tolerance for reinforcement (clause 4.7.1-TCVN 4453:1995) and weld quality in accordance to table 6- Allowable tolerance for welds (clause 4.3.7-TCVN 4453:1995) - Conformity of replacement of reinforcement against design; - Transportation and installation; - Suitable transportation means for fabricated products; - Type, locations, dimensions, and quantities of installed rebar against design Concrete cover is as specified in figure (clause 4.7.1-TCVN 4453:1995); - Suitable starter bars and pre-inserted items against design; - Suitable material for spacers, density and thickness tolerances against design Concrete cover is as specified in figure (clause 4.7.1.-TCVN 4453:1995); - Sequence, requirements and inspection method to reinforcement is as specified in table 10Inspection of Reinforcement (clause 4.7.1.-TCVN 4453:1995); - Inspection and approval of reinforcement must be carried out at site in accordance with requirement of clause 4.7.1 and table 10 to evaluate reinforcement quality against design before concrete placement; - When inspection and approval, the following documents are required: + Design drawings with full notes on changes of rebar during construction and attached with decision for changes; + Test results of steel sample, welds and quality of fabrication + Minute of reinforcement changes at site against design; + Technical inspection and approval minute during fabrication and installation of rebar + Construction diary 4.3 FORMWORK & PROPPING 4.3.1 GENERAL REQUIREMENTS: Formworks and scaffolding shall be designed and installed to form a stable and firm system, easy to dismantle, causing no difficulties to the installation of reinforcement bars, concrete pouring, vibration and installation of inserts Formworks must be tight to avoid water loss during concreting and protect newly placed concrete from adverse compacts from weather conditions Formworks and propping must be installed as designed and dimensioned Manufacture and Fabrication of formworks and propping shall be carried out at workshop or on site 4.3.2 MATERIALS FOR FORMWORK AND PROPPING Materials for formwork and scaffolding shall be plywood and steel frames, braces, rods made of 50x5mm, 50x100, U100, L50x50 sections, steel pipes D42, D49 etc standard thickness of plywood are 12 mm to 18 mm with surfaces being coated with waterproofing and anti-stick layers For this particular project a cup-lock system will be applied for propping 4.3.3 DESIGN OF FORMWORK AND PROPPING Design must comply with requirements mentioned in item a of this section All calculations, date inputs, loads, excessive loads factors, allowable sagging, stability etc shall comply with requirements of TCVN 4453-1995, as well as other current standards and construction drawings issued by consultants 4.3.4 FORMWORK AND PROPPING INSTALLATION Installation of formwork and propping shall comply with the following requirements: - Contact surface between concrete and form must be treated with release agent; - Forms for sides of walls, slabs, beams and columns shall be installed in a way that does not affect the early removal without impact to other forms such as bottom forms, slab forms and shoring systems; - Installation of forms for multi-story buildings must ensure that formworks can be dismantled and moved up for new formwork installation during construction progress and curing progress; - Scaffolds and props must rest firmly on solid base without any displacement or buckling during concrete placement During installation of formwork and propping systems there will be proper method of surveying marks and positions and levels of all works In case forms are stabilized by bracing cables and hooks calculations must be performed to ensure the load bearing capacity of the formwork system during concrete placement Form openings at base of formworks for the drainage of dust and other rubbishes during installation These opening shall be covered before concrete placement Construction drawings and method statement drawings of the following works must be referred to: - Formwork for foundation (pad footings, piled foundation etc.); - Formwork for columns; - Formwork for beams and slabs; - Formwork for walls; - Formwork for staircase; - And other works 4.3.5 INSPECTION AND APPROVAL OF FORMWORKS AND SCAFFOLDING SYSTEMS Inspection of formworks and scaffolding systems shall comply with table (clause 3.5.1) and table (clause 3.5.2) in respect of tolerances to formworks and scaffolding system in accordance with TCVN 4453-1995 Additionally inspection and approval shall also comply with VINACONEX quality management system ISO-9001-2008 and other requirements of consultants and client Please refer to attached VINACONEX ITP forms 4.3.6 FORMWORK AND SCAFFOLDING SYSTEM REMOVAL Formwork and scaffolding systems can be removed only when concrete reach sustainable strength to withstand its own loads and other loads arising out of construction progress When removing formwork, abrupt stresses or impacts which may cause damages to concrete must be prevented Formworks and scaffolding systems which will not withstand any loads and forces after concrete reaching 50daN/cm2 (formwork for side of beams, columns, walls etc.) will be removed For load-bearing formworks (bottom of beams, slab, supporting columns, scaffolding etc.), unless otherwise specified, shall comply with table 3-Minimum strength for formwork removal as started in clause 3.6 TCVN 4453-1995 Formworks and scaffolding of canopy, reinforced concrete gutter, cantilever beams are removed only when the concrete reach designed strength and counter weights are installed When loads are placed to structures of which formworks have just been removed, calculations must be carried out to ensure that such loads shall not cause any cracks or any damages to structures 4.4 4.4.1 CONCRETE WORKS MATERIALS FOR CONCRETE Material for concrete must comply with technical requirements of current standards and additional requirements from the design During storage, transportation and mixing, materials must be maintained to avoid spoiling, or mixing up aggregate and types In case such mix-ups happen, amendment solutions must be carried out to guarantee quality stability Materials that are not suitable as specified by standards may be used for concrete mixing if they are justified by a legal testing agent and approved by the client 4.4.2 TRANSPORTATION OF CONCRETE Concrete shall be transported by concrete suppliers by ready-mixed concrete trucks with volume capacity of 5m3 to 6m3 Durations calculated from the time of mixing to the time of placing will be determined in accordance with weather conditions, cement type and additive as specified in table 14, part 6.3 TCVN 4453-1995 4.4.3 PLACEMENT AND VIBRATION Concrete placement shall satisfy the following requirements: - Do not displace reinforcement, formwork or thickness of concrete cover; - Do not use vibrator-submergence type to move concrete horizontally; - Concrete to be placed continuously until the completion of one structural member as specified by design To prevent separation free falling height of concrete shall not exceed 1,5 m When placing concrete with free falling height more than 1,5m, trench or tremies must be used If the falling height is more than 10 m, tremies with vibration device must be used Tremies shall not slant more than 0.25 m per 1m of tremie In all case, the end section must be vertical When sloping trench is use, trench must be smooth and tight Width of trench must not smaller than 3-3,5 times of the biggest aggregate Slope of trench must ensure no blocking appeas or too fast sliding speeds resulting in separation At the end of trench a funnel is required to guide concrete to place Trench needs to be cleaned regularly When concreting, the following requirements must be follow: - Closely supervise formwork, scaffolding and reinforcement during concreting to timely handle when an incident happen; - Formwork must withstand lateral forces caused by fresh concrete - Only vibrating manually where mechanical method is not applicable; When it starts raining during placement, concrete must be covered In case concrete is stopped form placement longer than specified durations, concrete will only be placed again when it reach 25 daN/cm2 Before re-concreting, surface must be toughened Concrete pouring at night or in mist must be lighted with lighting systems at mixing and pouring places Thickness of concrete pouring must comply with table 16-thickness of concrete layer (clause 6.4.6-TCVN 4453-1995) Concreting to footing: clause 6.4.1 must be respected during concrete placement to foundation Concreting to column and wall: - Columns with height less than m and wall with height of less than 3m shall be poured continuously - Columns with one side less than 40 cm, and other side less than 15cm and columns with any sectional area and concrete overlapping shall be poured in 1.5 m section - Columns with height more than m and wall with height more than 3m shall be poured in section with suitable construction joints Concreting to frame: continuously poured Only form construction joints when necessary but must comply with TCVN 4453-1995 Concreting to beams and slab: When necessary pour concrete continuously to beams or wall Firstly concreting to columns or wall, then stop pouring for 1-2 hours for initial shrinkage then start pouring beams and slab In case of non-continuous concreting, construction joints shall be placed at 2cm-3cm away from beams and slab soffits Concreting to beams and slab must be at the same time When slab and beams are large (height more than 80 cm) concreting may be divide into many sections but construction joints must be reasonable as specified in TCVN 4453-1995 Concrete vibration: comply with the following requirements - Various vibrators can be use but must ensure that after vibration concrete becomes solid without honeycomb; - Vibration duration must be sufficient Sign of sufficient vibration is cement grout appearance and no bubble appear; - When using vibrator submergence type, vibrating for each time shall not exceed 1,5m radius and must penetrate 10 cm into concrete; - When re-vibration requires, the work can be carried out after 1.5-2 hours Re-vibration is only suitable for large area elements like roof slab, yard, road etc No re-vibration to massed concrete element 4.4.4 CONCRETE CURING: After concreted, concrete must be maintained to protection from the sun, wind and rain until it has set properly, and it shall be prevented from drying quickly by being kept covered with constantly dampened sacking or other approved means for at least days after placing Alternatively, a curing membrane which eventually disintegrates and breaks away without affecting the surfaces of the concrete may be used A fugitive dye shall be added to this emulsion It shall be applied as a spray while the surface is still soft but after the surface water has evaporated or, for surfaces where the shutters are removed within seven days after casting, immediately after removal of the formwork In the case of concrete made with high early 4.4.5 CONSTRUCTION JOINT General requirement: construction joint must be placed at locations where shear and moment are minimum and the joint must be perpendicular to direction of compressive forces Transverse construction joints: - Transverse construction joint should be place at level equivalent to formwork level; - Before pouring, previous-poured concrete must be toughened and make humid and during pouring, vibrate in the way that ensure proper binding between new concrete and the old one, ensuring the massiveness of the structure - Verticals construction joints: - Vertical or sloping construction joint should be made of chain-link mesh with link of 5mm-10 mm and placed in retaining mold; - Before new pouring, watering the previous concrete, toughen, clean and during pouring, vibrate in the way that ensure proper blinding between new concrete and the old one, ensuring the massiveness of the structure Column construction joints should be placed at the following locations: - At the upper part of foundation; - At the underside of beams or cantilever beams supporting bridge crane; - On upper side of beams Construction joints for large beams shall be placed at 2cm-3cm away from underside of beam When pouring concrete to flat slab, constructions joints can be placed anywhere but the joints must be parallel to the shorter edge of slab When pouring concrete to slab with ribs parallel to sub-beams, construction joints shall be placed at 1/3 of beams When concreting in parallel with main beams construction joint is to be placed at between two beams (each construction joint equivalent to ¼ span) 4.4.6 CONCRETE PLACEMENT TO WORKSHOP FLOORS Conventionally workshop floor shall be constructed after the completion of roofing, equipment plinths, underground services etc sequences are as below: - Grading and compaction to designed density; - Check sub-grade levels, if satisfied carry out termie treatment; - apply of damp-proof membranes and start lean concrete works and formwork for expansion joints; - Next, install reinforcement (or weld mesh) as designed Install rails for screeding machine This rail installation must be strictly supervise cause it decides the precision of floor levels This work shall be carried out by professional workers Concurrently other equipment shall also be prepared such as power floating machines, power screeding machine, rules, theodolite, etc.; - If designed with hardener, the additive shall be prepared sufficiently for the hardening process; - After all preparation works are checked and approved the contractor shall start concreting Ready-mix concrete shall be pumped to 5-6 m wide sections with installed rails Initial vibration shall be done by vibrators-submergence type Then final vibrator shall be carried out by professional vibrators and screeding machines Once again theodolites and accessories shall be used to re-check the completed works Concurrently rails shall be removed out of concreted surfaces If levels of concreted surface is lower than the design level, then it will be compensate with high grade mortars and vice versa; - Floating to corners and edges shall be manually carried out right after the power floating This works shall be carried out by professional teams; - After the completion of floor floating, the surfaces must be cured by watering, converting or spraying with curing compound Curing period shall be days minimum; - Saw cuts shall be carried out within 24 hours after completion of concreting According to our experience late cutting may cause cracks on concrete surface because concrete shrinkage is most within 24 hours after concreting Besides expansion joints as designed, saw cuts must be calculated, designed and approved during the execution of sub-grades - Workshop slab is considered practically completion when saw cuts are completed When the project is about to be handed over to the client the contractor shall clean floors and fill expansion joints and saw cuts with sealants before handing over the project 4.5 INSPECTION AND APPROVAL Inspection: - Inspection includes the following steps: formwork, scaffolding, reinforcement, concrete and tolerance; - Formwork and scaffolding shall be inspected against technical requirements mentioned in formwork section; - Reinforcement shall be inspected against technical requirements mentioned in reinforcement section; - Concrete inspection includes materials, equipment, manuafacturing sequences, properties of concrete mix and harden concrete in compliance with table 19-inspection requirements for concrete quality (clause 7.1-TCVN 4453:1995); - Slump shall be inspected in accordance with the following requirements: + Site-mixed concrete: inspect the firs batching; + Ready-mixed concrete: inspect for each delivery at site; + When mixed concrete in changing humid and temperature condition, inspection shall be carried out once per shift; + When mixed concrete in changing humid and temperature conditions, inspection shall be carried out once per shift in addition to inspection of first batching - Concrete samples for inspection must comply TCVN 3105:1993 - Samples shall be taken in sets by cylinder sample Number of sets are taken in line with quantities as below: + For massive concrete: set per 500 m3 for massive concrete of more than 1000 m3 and set per 250 m3 for massive concrete of less than 1000 m2; + For large foundation: set per 100 m3 but not less than set for one footing; + For equipment plinth with concrete quantity of more than 50m3:1 set per 50m3 but one set is also taken for a quantity of less than 50 m3; + For frames and slim structures (columns, beams, slab, dome etc.): set per 20m3; + For road (automobile, take-off lane etc.) set per 200m3 but one set is also taken for a quantity of less than 200 m3; + For inspection of waterproofing, set per 50 m3 but one set is also take for a quantity of less than 500 m3; - Concrete strengths after 28 days are considered acceptable when average value of each set is not less than designed strengths and none of samples has strength less than 85% of designed strength - Approval shall be carried out at site and the following documents are required: + Quality of Reinforcement (in accordance with inspection minute before concreting); + Concrete quality (Testing and visual view at site); + Dimensions, shapes, locations, inserts, joints against designs; + As built drawings for each elements; + Fully noted construction drawings; + Instructions for changes and adjustment + Test results for concrete and other materials; + Approval of reinforcement, formwork before concrete pouring + Foundation and slab approvals; + Process approval of structural elements; + Site diary; - Tolerance: in accordance with table 20 (clause 7.2.2-TCVN 4453:1995) These tolerances shall be determined by measurement equipment II METHOD STATEMENT FOR TRANSFER YARDS AND WHEEL TRACK The Works of this Project comprises in general the supply and installation of the following, and as shown on the method drawing, the method drawing comprises all works that mention on the construction cost, Specifications and other Tender Documents: Earth work and concrete works for Transfer yards and wheel track : 1.1 Preparation works - Material submission - Method statement drawing - Trial mix - Shop drawing - Job safety analysis 1.2 Work procedure Construction method: 2.1 Earth work method: Transfer yard is divided into zones, the same as Transfer yard 2.2 Backfill method - Backfill material shall be tracked up along both side of service road Then the excavator will transfer to backfill location - Hand roller shall be used for compacting - Water shall be combined with compacting to obtain required density 2.3 Concrete method - For Concreting foundations and ground beams, the pump truck shall be used for pouring concrete - For ground slabs, the pump truck shall be used for concreting o The Transfer yard is divided into zones for pouring concrete Each time we shall pour concrete for zones with concrete teams o The Transfer yard is divided into zones for pouring concrete Each time we shall pour concrete for zones with concrete teams o The Wheel track is divided into zones for pouring concrete Each time we shall pour concrete for zones with concrete teams  ... Preparation works 1.2 Work procedure Construction method: 2.1 Earthwork method: 2.2 Backfill method 2.3 Concrete method: I GENERAL METHOD STATEMENT PROJECT GENERAL DESCRIPTION The transfer yards and wheel... II METHOD STATEMENT FOR TRANSFER YARDS AND WHEEL TRACK The Works of this Project comprises in general the supply and installation of the following, and as shown on the method drawing, the method. .. Preparation works - Material submission - Method statement drawing - Trial mix - Shop drawing - Job safety analysis 1.2 Work procedure Construction method: 2.1 Earth work method: Transfer yard is divided