SECURITY AND SAFENESS NH91 1 CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG 1 BRIDGE; SANG TRANG 2 BRIDGE ` CONSTRUCTION METHOD STATEMENT FOR SUPPORTING SLAB AND RETAINING WALL TABLE OF CONTENTS I CONSTRU[.]
NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE ` CONSTRUCTION METHOD STATEMENT FOR SUPPORTING SLAB AND RETAINING WALL TABLE OF CONTENTS I CONSTRUCTION OF PRECAST REINFORCED CONCRETE PILES II DRIVING OF TEST PILE AND WORKING PILE III CONSTRUCTION OF SUPPORTING SLAB AND RETAINING WALL 1/ PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE Construction of precast reinforced concrete piles 1.1 Formwork Formwork shall be made of steel to ensure rigidity, stability and removable, and will not cause difficulties for installation of reinforcement steel, placing and compacting concrete All joints in shuttering or moulds shall be in either horizontal or vertical planes, and shall be of such a design as to ensure that there is no loss of fine materials or cement laitance during the placing or consolidation of the concrete and and protect the poured concrete under the influence of the weather Fabricating and installation of formwork must be accurate as in accodance with the correct shape and size It is neccessary to limit formwork joints, the joints should not be arranged on the same cross section and at the position of big loads The bracing, strutting and supports should be calculated and arranged appropriately to the overall stability of formwork Installation of formwork should ensure the following requirements: All formwork surfaces which contact with concrete shall be treated with a release agent by covering SEPAROL oil or clean oil Formwork is installed how to match up with the early removal of formwork without affecting to the quality Formwork must be placed firmly on concrete or a hard ground, smooth, non-slip and no deformation when the bearing the load and the impact of the construction process When installation of formwork, the surveying markers, control points or the appropriate measures to facilitate to check the centre line Formwork is only be removed when the concrete have reached the strengths of each type of structures indicated by the technical instructions of the project Removal of formwork should be avoided without causing sudden stress or strong collision, which may affect to: + The inspection of formwork for pile: + Installing tollerance of formwork that complies with standards of the project 1.2 Reinforcing steel 1.2.1 General requirement Reinforcing steel shall comply with the requirements in section 5.5 " Reinforcing steel " in the Specifications Reinforcement steel used in reinforced concrete structures must be ensured the design requirements Reinforcement steel is fabricated at the site Do not use the reinforcement steels of the same shape, geometrical size in the same works, but different physical properties Before fabrication of reinforcement steel and before placing concrete should ensure: 2/ PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE The surface is clean, no sticky dirt, grease, no flakes and rust layers on steel Reinforcement steel were crushed, loss in cross section due to cleaning or other reasons shall not exceed the permitted limit of 2% in diameter If this limit is exceeded that limit reinforcement steels shall be used in actual remained cross section Reinforcement steel should be bent, pulled and straighten 1.2.2 Cutting and bending of reinforcing steel The fabrication of reinforcing steel is in compliance with project standards Cutting and bending reinforcing steel shall be conducted only by mechanical methods Reinforcing steel is bent to fit the shape, size of the design Steel products to be cut and bent must be inspected and approved by the Engineer 1.2.3 Welding reinforcement: welding only when approved by the Engineers Welding joints can be done by several different methods, but to ensure quality of welding seams as in accordance with design requirements When febricating the reinforcing steel grid by welded points, if no special instructions, comply with the following provisions: For the smooth round steel, welding all the points of intersection For spiral steel, welding all the points of intersection in two rows of outer perimeters, the remaining points in between by a welding alternating order; Electrical arc welding is used in the following cases: - Welding the extended hot-rolled steel bars with diameter greater than mm Welding all the built-in details, the component structures and joint connections The welding joints must meet the following requirements: Smooth surface, no uninterrupted fire, no local reduction and there are no bubbles Make sure the length and height of welding seams as required design 1.3 Concrete works 1.3.1 General requirement The concrete materials must ensure the technical requirements under the current standards Concrete materials must comply with the requirements in Section 5.1, "Concrete and Concrete Structures." During the storage, transportation, materials must be stored to avoid contamination or mixed grain sizes and types When encountering such cases, it should be immediately remedied to ensure the stability of quality 1.3.2 Material Aggregate, water, cement, admixture as in accordance with standard of the project 1.3.3 Concrete work: 3/ PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE Concrete is produced by batching plant at construction sites and are transported to the construction location by agitators, or mixed by drum mixer Prior to delivery of concrete, the quality control and testing of concrete must be conducted along with delivery records With different structures: measures for placing concrete are shown in the drawings of the construction methods Manufacture of concrete mix Manufacturing concrete mix by batching plant (or concrete mixer) Cement, sand, macadam and liquid admixture to make concrete mix is weighted by volume Water and admixture weighed by volume Allowed error when weighing not exceed the allowed values The accuracy of measuring equipment must be calibrated prior to placing concrete During weighing, regular monitoring to detect and correct promptly Transportation of concrete mix The transportation of mixed concrete from the batching plant to the work should ensure the following requirements: Use a reasonable means of transport, to prevent the concrete mixture from segregation, loss of cement grout and water loss from wind and sun Using the equipment, manpower and transportation should be arranged to suit the volume, speed mixing, pouring and compacting concrete Allowable time to keep the concrete mix during transport should be determined by tests based on weather conditions, type of cement and admixture used Placing concrete When placing concrete must meet the following requirements: - The Contractor shall pay particular attention when concrete piles to avoid leaving air holes, honeycomb, or other defects - The shape of RC pile must be completed as indicated on the drawings and described in the Technical Standard 5.1 - "Concrete and Concrete Structures." Finish Surface is smooth, flat, no defect, and the size as shown on Drawings - Closely monitor the status of formwork during the construction process to settle in time if problems occur - When it rains, measures to cover in order not to let the rain water into the concrete - The placing concrete: for each type of structure, placing concrete is shown in the construction method drawings Compacting concrete - Different kind of vibrators may be used, but to ensure that after the concrete is compacted the surface free from honeycombing - Compaction time for each location must ensure that the concrete is thoroughly compacted 4/ PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE Curing concrete - After placing conrette, concrete must be cured in conditions of humidity and needed temperature for curing and preventing the harmful effects during curing of the concrete - Moisture curing: is the process for keeping concrete with moisture necessary to the setting and hardening after shaping During curing, the concrete shall be protected against mechanical impacts such as vibration, shock forces, loads and impacts, which are likely to cause other damage 1.4 Inspection and Acceptance 1.4.1 Inspection of formwork - Check the geometrical dimensions, the roughness, tightness, stiffness and eccentricity of the formwork 1.4.2 Inspection of reinforcement - Type of reinforcing steel in use compared with the design - The fabrication of steel and methods of cutting, bending and cleaning steel surface before fabrication - The welding: Equipment, welding rods, welding technology and quality of welds are specified in building regulations - The fixing of reinforcing steel: The location, size and numbers of reinforcing steel, which have been fixed, shall not exceed the allowed values - The inspection of reinforcing steel must be conducted at the site according to the above requirements to assess the quality of reinforcement before placing concrete - When conducting the inspection, records must include: The design drawings are mentioned of changes in the reinforcing steel in the construction process and attached with minutes of change decisions The results of test samples of steel quality, welding and quality of fabrication steel The minutes of the change of reinforced at the site as compared with the design The technical inspection records during process of fabrication and fixing steel 1.4.3 Inspection of concrete - Check consistency of the aggregate when batching in the batching plant (or concrete mixer) - Check the measurement of material for concrete mix, mixing time, the transportation and placing - Check the fine mix of the concrete in place and placing location - To test the strength of the placed concrete by testing concrete compression samples taken during the placing of concrete 1.4.4 Overall inspection 5/ PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - Tolerance of pre-cast concrete piles when manufactured Length: 1% Dimension of cross sectional area: mm Ecentricity of pile head : - - Piles tried before closing to check the quality of the pile and the pile driving equipment serving The length of the pile, depending on the actual conditions may vary, but must be accepted design consultancy - - When there is a combination of pile length and pile test results the contractor will carry out mass pile in sequence and technology under the plan approved TCTC CONSTRUCTION OF SUPPORTING SLAB AND RETAINING WALL 3.1 Excavation of pit - Conducting the excavation of pit for the location to be pressed piles - Use excavators combined with manpower to execute the pit - Placing lean concrete for foundation, 10 cm thick - Breacking the concrete head piles - Inspection and acceptance of the work as specified 3.2 Construction of Supporting Slabs - Installation of reinforcing steel, formwork for the Supporting slabs 8/ PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - Installation of projecting reinforcement of Retaining wall for Tra Noc bridge - Inspection and acceptance of reinforcing steel, formwork of the supporting slabs - Placing concrete for the supporting slabs - Curing concrete for the upporting slabs 3.3 Construction of Retaining Wall - Installation of reinforcing steel, formwork for the Retaining Wall - Inspection and acceptance of reinforcing steel, formwork of the Retaining Wall - Placing concrete for the Retaining Wall - Curing concrete for the Retaining Wall 9/ PHUONG THANH TRANCONSIN ... upporting slabs 3.3 Construction of Retaining Wall - Installation of reinforcing steel, formwork for the Retaining Wall - Inspection and acceptance of reinforcing steel, formwork of the Retaining Wall. .. projecting reinforcement of Retaining wall for Tra Noc bridge - Inspection and acceptance of reinforcing steel, formwork of the supporting slabs - Placing concrete for the supporting slabs - Curing concrete... of pile length and pile test results the contractor will carry out mass pile in sequence and technology under the plan approved TCTC CONSTRUCTION OF SUPPORTING SLAB AND RETAINING WALL 3.1 Excavation