SECURITY AND SAFENESS NH91 1 CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG 1 BRIDGE; SANG TRANG 2 BRIDGE CONSTRUCTION METHOD STATEMENT FOR ABUTMENTS AND PIERS TABLE OF CONTENTS CHAPTER I PREPARATION WORK[.]
NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE CONSTRUCTION METHOD STATEMENT FOR ABUTMENTS AND PIERS TABLE OF CONTENTS CHAPTER I: PREPARATION WORKS I CONSTRUCTION LAYOUT II ARRANGEMENT OF WORKING TEAMS III MOBILIZATION OF EQUIPMENT FOR CONSTRUCTION OF ABUTMENTS AND PIERS CHAPTER II: CONCRETE WORK, REINFORCEMENT, FORMWORK I FORMWORK II REINFORCEMENT III CONCRETE WORK IV INSPECTION AND ACCEPTANCE CHAPTER III: CONSTRUCTION METHODS FOR ABUTMENTS AND PIERS I BASES FOR MAKING OF TECHNNICAL PROPOSAL AND CONSTRUCTION TECHNOLOGY FOR CONSTRUCTION OF ABUTMENTS AND PIERS II SELECTION OF TECHNICAL SOLUTIONS AND CONSTRUCTION TECHNOLOGIES III THE GENERAL REGULATIONS FOR CONCRETE WORKS IV CONSTRUCTION SEQUENCES FOR ABUTMENTS AND PIERS 1/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE CHAPTER I: PREPARATION WORKS I CONSTRUCTION LAYOUT Tra Noc Bridge - Tra Noc Bridge shall be chosen as the place to gather materials and machinery at the positions of apporach roads on the left side , facilitate the movement of machinery or supply equipment to two bridge branches - Carry out thhe demolition works within the construction range of Tra Noc bridge - Leveling of construction site - Construction of the boundary fence around the site by wire mesh, 1.6 m high - Construction of temporary service roads - Construction of warehouses, accommodation, casting yards - Details of construction plan show in the drawings of construction method Sang Trang Bridge - Sang Trang Bridge shall be chosen as the place to gather materials and machinery at the positions of apporach roads on the left side , facilitate the movement of machinery or supply equipment to two bridge branches - Carry out thhe demolition works within the construction range of Sang Trang bridge - Leveling of construction site - Construction of the boundary fence around the site by wire mesh, 1.6 m high - Construction of temporary service roads - Construction of warehouses, accommodation, casting yards - Details of construction plan show in the drawings of construction method Sang Trang Bridge - Sang Trang Bridge shall be chosen as the place to gather materials and machinery at the positions of apporach roads on the right side , facilitate the movement of machinery or supply equipment to two bridge branches 2/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - Carry out thhe demolition works within the construction range of Sang Trang bridge - Leveling of construction site - Construction of the boundary fence around the site by wire mesh, 1.6 m high - Construction of temporary service roads - Construction of warehouses, accommodation, casting yards - Details of construction plan show in the drawings of construction method II ARRANGEMENT OF WORKING TEAMS Ba Dai bridge Arranging 04 construction teams for execution of Ba Dai bridge - Team 1: Construction of bored piles - Team 2: Construction of abutments, piers and the superstructure - Team 3: Casting beams and launching and installation of beams - Team 4: Casting, driving RC piles and execution of supporting slab and retaining wall Sang Trang bridge Arranging 04 construction teams for execution: - Team 1: Construction of bored piles - Team 2: Construction of abutments, piers and the superstructure - Team 3: Casting beams and launching and installation of beams - Team 4: Casting, driving RC piles and execution of supporting slab and retaining wall Sang Trang bridge Arranging 04 construction teams for execution: - Team 1: Construction of bored piles - Team 2: Construction of abutments, piers and the superstructure - Team 3: Casting beams and launching and installation of beams - Team 4: Casting, driving RC piles and execution of supporting slab and retaining wall Note: Actually, in the Site, the Contractor will gather teams of “Casting beams and launching and installation of beams” into one big team to be incharge of those works III MOBILIZATION OF EQUIPMENT FOR CONSTRUCTION OF ABUTMENTS AND PIERS The contractor will mobilize the entire construction equipment and machinery needed for construction of bridges Detailed mobilization as in the under statics table: 3/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE Item No Description Unit Quantities Remarks A Construction of abutments Bulldozer ≥140CV Nos Excavators 1.25m3 Nos Crane 35 tons Nos Crane 10 tons Nos 4 Vibratory hammer Nos Concrete agitators Nos Water pump 60m3/h Nos Welding machine 23kw Nos Generator 200KVA Nos 10 Trucks 10-12 tons Nos 11 Rebar bending and cutting machine Nos 12 Electromechanical poker vibrators D70 Nos 15 13 Barge 200 tons Nos 14 Barge 400 tons Nos 15 Concrete Mixing Plant Nos 16 Transformer Station Nos 4/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE CHAPTER II: CONCRETE WORK, REINFORCEMENT, FORMWORK I FORMWORK - Prior to construction of the works at least weeks, the Contractor shall submit to the Supervision Consultant detailed construction method of work items, which will clearly state the type of formwork, scaffolding, as well as calculation sheets of applied load (if required) - 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 - Formwork must be designed to withstand horizontal pressure and vertical load in accordance with ACI 347 standards In addition, the formwork must be designed to create the finished concrete surface in accordance with the tolerances specified - All joints in shuttering or moulds must be tight to avoid water loss when poured and compacted cement concrete, at the same time protect the fresh concrete from weather influences - Fabricating and installation of formwork must be accurate as in accodance with the correct shape and size Formwork will be the appropriate design and durable construction The contractor will adjust to get the exact concrete structures to ensure small chamfer, camber, etc - 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, strut and supports should be calculated and arranged appropriately to the overall stability of formwork - Installation of formwork should ensure the following requirements: - The formwork surface in contact with concrete shall be covered by non-stick oil The anti-adhesive oil is applied according to the manufacturer's instructions and not touch either reinforcing steel or prestressed strand and anchors The Contractor shall use only one type of anti-adhesive oil for the concrete structure to ensure uniformity of color concrete Formwork will be cleaned thoroughly before pouring concrete 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 check the centre line Tolerances for installing formwork must be in compliance with project standards 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 (Sub-clause 5.1.9.3 of the Specifications) 5/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - Removal of formwork should be avoided without causing sudden stress or strong collision II REINFORCEMENT General requirement - Reinforcement steel used in reinforced concrete structures must be ensured the design requirements - Reinforcement steel is fabricated at the site in conformity with the Specifications - Do not use the reinforcement steels of the same shape, geometrical size in the same works, but different physical properties - Horizontal steel pin in the cross beams in, diameter 32mm, no screw, in accordance with the requirements TCVN 6284-1: 1997 or AASHTO M164M for bolts, and hot-dip galvanized according to AASHTO M232, Type C The bolts must be tested after plating as required in AASHTO M164M - Before fabrication of reinforcement steel and before placing concrete should ensure: The surface is clean, no sticky dirt, grease, no flakes and rust layers on steel Reinforcement in the yard will be placed on sleepers with canvas cover 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 straightened Cutting and bending of reinforcing steel - The fabrication of reinforcing steel is in compliance with project standards, Manufacturing tolerances comply with ACI 315 - 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 - The size of the hook and bend diameter shall be measured as shown in the working drawings When the size of the hook or bending diameters not shown, we will comply with Section I, Article 8.23 or ACI 318, "The building codes requirements for reinforced concrete." Reinforcement Joints Welding Joints: Welding Joints are permitted only when approved by Consulting Engineer or specified in the drawings - Welding joints can be done by several different methods, but to ensure quality of welding seams as in accordance with design requirements 6/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - - - 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 deformed 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 in-situ details, the component structures and bonding of joints in the assembly The welding joints must meet the following requirements: Smooth surface, no uninterrupted fire, no narrow locally and there are no bubbles Make sure the length and height of welding seams as required design Lap joint: - Lap Joints is the length specified in the drawing If not shown on the drawing, the length of the joint husband will not be less than 40 times of the diameter of the tensile bar and no less than 32 times of the diameter of the compression bar - In Lap Joints, tied with steel wire rods that maintain the minimum distance to the surface of the concrete as shown in the drawing Mechanical fitting connection: - Joints with mechanical connection is only used when there is prior approval or detailed in the Drawings or Consulting Engineer allow to substitute for the weld joint The fitting connection must be tested to get requirements of at least 125% of the yield strength of steel bars III CONCRETE WORK General requirement - The concrete materials must ensure the technical requirements under the current standards - 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 Material for concrete 2.1 Portland cement - Cement shall be Portland cement type I complying with TCVN 40331995 or other types of cement approved by the Engineer On ly approved Cement shall be used for all concrete works throughout the Project unless otherwise authorized by the Engineer 7/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - The source of supply of cement shall be submitted to the Engineer for approval The Cement deliveried to the site shall include manufacturer ‘s test certificates, and shall be carried out frequency tests - Cement shall be delivered to the Site in sealed bags or in bulk by specialized trucks with bulk cement in large quantities - Cement delivered by bulk carriers shall be stored in silos made for cement storage All handling shall be by methods that prevent contamination of the cement The silos shall be provided with interior moisture control devices that keep the cement dry and prevent premature hydration The silos shall be provided with access ladders and access points to enable samples to be taken from various levels of each silo for testing purposes - Cement shall be stored in dry conditions on areas raised above ground level Storage capacity shall be sufficient to hold enough cement for the largest units to be cast Bags shall not be stored more than high and a free passage of at least one meter shall be left between the cement and the side walls of the sheds - The Contractor shall provide weighing machines which shall be kept permanently in each shed for checking the weight of the bags 2.2 Water for Concrete Mixing and Curing - The Contractor’s proposed water source shall be submitted to the Engineer for his approval together with test results confirming that water from the source complies with this specification - Water for concrete mixes, curing concrete and other products containing cement shall be clean water free from oil, salt, acid, sugar, vegetable or any other substance injurious to the concrete unless otherwise authorized in by the Engineer - Frequency tests of water shall be carried out in accordance with the Specification and as required by the Engineer 2.3 Aggregates - Aggregates shall be free of substances that react deleteriously with alkali in the cement sufficiently to cause unacceptable expansion of the concrete The Engineer’s approval of aggregate sources will be based on satisfactory evidence furnished by the Contractor that the aggregate is free from such materials This evidence shall include certified records of tests by a testing laboratory that the aggregates meet the requirements of the Specifications - All aggregates shall consist of tough, hard, durable uncoated particles The Contractor shall be responsible for processing aggregates to meet the requirements of this specification The Contractor’s proposed sources of aggregates shall be submitted to the Engineer for his approval Samples shall be taken in the presence of a representative of the Engineer and the Contractor for testing and approval before materials are brought to the Site - Aggregates shall be stored in stockpiles that ensure the materials remain free draining and are adequately separated to prevent cross contamination Stockpiles shall be placed on a properly prepared surface to ensure no contamination occurs when materials are re- 8/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE handled Materials shall be handled in a manner which avoids segregation All stockpiles are to be labelled with markers indicating the material type in the stockpile Aggregates shall be stored in sufficient quantity to ensure that there is no interruption of concreting work at any time Aggregates shall be stock near mixing plant, before mixing aggregates shall be comply enough moisture, aggregates shall be checked and approved by the engineer - Fine and coarse aggregates shall be tested in accordance with the standards below TCVN 7572-2:06 Sieve Analysis TCVN 7572:06 Organic Impurities TCVN 141 - 86 Soundness Fine aggregates - Fine aggregate for Portland cement concrete shall consist of natural sand or other inert materials with similar characteristics, having hard, strong, durable particles Fine aggregate shall be clean and free from extraneous materials, clay balls, organic matter or other detrimental material in accordance with AASHTO M6 The maximum combined quantity of soluble chlorides and sulphates in the fine aggregate shall not exceed 1000 ppm fine aggregate - The fine aggregates shall be reasonably graded and shall meet the grading requirements contained in Table Table No 1- Grading Requirements of Fine Aggregate Sieve Size Percent Passing by weight (mm) - 9.5 100 4.75 95 - 100 2.36 80 - 100 1.18 50 - 85 0.600 25 - 60 0.300 - 30 0.150 - 10 The fine aggregate shall be of such uniformity that the fineness modulus as defined in TCVN 7572-2:2006 shall not vary more than 0.20 either way from the fineness modulus of the representative samples used in the mix designs 9/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - If required by the Engineer and in order to meet specification requirements, fine aggregates for use in reinforced concrete shall be washed with fresh potable water Coarse aggregate - Coarse aggregate shall be crushed aggregate for reinforced concrete works and unreinforced concrete works and shall be homogeneous, clean, free from extraneous materials, clay lumps, organic matter, and alkaline and detrimental material Coarse aggregate for structural concrete shall meet the requirements of TCVN 7570:2006 The Engineer may order that the coarse aggregate be washed if it is unclean, or may reject any material that does not comply with this Specification - The quarry from which the coarse aggregate is to be obtained shall be approved by the Engineer before material is delivered to the Site of the Works - Coarse aggregate shall meet the requirements of TCVN 7570:2006 - The coarse aggregates shall be reasonably graded and shall meet the grading requirements in Table 2 Table No Grading Requirements of Coarse Aggregates Sieve Size (mm) Percent Passing by Weight Concrete Concrete Class A, B, C and D Class and F 37.5 - E Concret e Class G and P 100 100 90 - 100 95 - 100 25 100 19 90 - 100 12.5 30 - 70 25 - 60 25 - 60 4,67 - 10 - 10 - 10 The percentage of wear of the aggregate shall not be greater than 50 as determined by TCVN 7572-12:2006 The coarse aggregate shall withstand at least five cycles of immersion and drying in both sodium sulphate and magnesium sulphate solutions, as prescribed in the soundness test, and shall show an average weight loss of not more than 15 percent 2.4 Admixtures - The use of any admixtures will require the approval of the Engineer Each type and each location or purpose shall be approved individually Approval will be dependent upon the submission of mix designs and satisfactory trial mixes to demonstrate the function of the admixture 10/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - To avoid cold joints the Contractor shall provide sufficiently large capacity in his concrete producing plant and concrete transporting arrangements and use an appropriate retarder when deemed necessary by the Engineer The retarder shall be of a type approved by the Engineer and shall comply with the requirements of TCXDVN 325:2004 The Contractor shall be entirely responsible for the use of any approved retarder in strict accordance with the manufacturer’s instructions, and previously tested to receive the approval of the Engineer - Retarders shall not be used together with other admixtures in the same mix unless approved by the Engineer The fluid content of admixtures shall be considered in the determination of water/cement ratios of the mix-design - Preliminary tests of cylinder strength and any other tests shall be carried out for all concrete with admixtures When the Engineer approves changing the brand or type of cement, the Contractor will be required to carry out further tests and establish a relative mix design - Water reducing and water reducing-retarding admixtures, in accordance with TCXDVN 325:2004 and plasticizing and plasticizing and retarding admixtures in accordance with 22 TCN 202-1998 may be used with written permission of the Engineer in accordance with mix designs and slump requirements as approved by the Engineer - Calcium chloride or admixtures containing calcium chloride will not be permitted Concrete work - The contractor will submit the Consulting Engineer for approval of position and qualifications of batching plant, and collected yards Contractor shall also submit details on the type of mixer and mixing plant and transportation plan from concrete batching plant to the Site - Samples of all materials to be used in the mix shall be submitted to the Engineer for testing and such samples shall be tested in the site laboratories as directed by the Engineer No materials forming any part of this mix shall be delivered to the Site before the Contractor receives prior approval of the Engineer for such materials - Concrete mix designs shall be submitted in writing by the Contractor to the Engineer, for approval 14 days before production (covering two possible trials for sampling and testing of concrete at 28 days), or at least within a period of time enough to allow the Engineer to check twice the proposed mix design before approval according to the procedure specified in sub-section 3.1.2, “Approved Mix Design” of this Specification - Concrete is produced by batching plant at construction sites and are transported to the construction location by agitators Prior to delivery of concrete, the quality control and testing of concrete must be conducted along with delivery records - At construction sites quantities of concrete are not so big and scattered, the Contractor propose to use small concrete mixer 500lit or 750 lit 11/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - With different structures: measures for placing concrete are shown in the drawings of the construction methods 3.1 Components of concrete - Material sources as well as concrete mix design shall be in accordance with article 5.1.6 “Approved Mix Design” of the Specifications - Calculate and take casting samples in the laboratory - Adjusting concrete components at the site: Adjusting concrete components at the site are conducted on the principle that does not change the water / cement ratios of design concrete component When moist aggregates should reduce the amount of mixing water, keep the required slump - The amount of chlorides in the concrete mass shall not exceed 1,000 ppm when calculated on the total concrete mass, or 6,000 ppm when calculated on the amount of cement in the actual mix The amount of sulphate in the concrete shall not exceed 800 ppm when calculated on the total concrete mass, or 5,000 ppm when calculated on the amount of the cement in the actual mix For the above-mentioned calculations, the amounts of chlorides and sulphates shall be determined by laboratory analyses of the cement, aggregates, water and admixtures The analyses shall be carried out by recognized methods - When measuring the amount of water in each batch of concrete, the Contractor shall take into account the amount of water contained in the aggregate The total amount of water in each batch must include the amount of water contained in the aggregate and added water 3.2 Manufacture of concrete mix Manufacturing concrete mix by batching plant (or concrete mixer) - Cement, fine aggregate, coarse aggregate 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 - Regularly check the slump of the concrete mix Slump will be determined according to AASHTO T-119 Method of testing slump must comply TCXDVN 3107-1993 3.3 Transportation of concrete mix The transportation of mixed concrete from the batching plant to the Site 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 12/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - Allowable time to keep the concrete mix during transport should be determined by tests on the basis of weather conditions, type of cement and admixture used - The Contractor shall mobilize sufficient mixer trucks as the request of the construction site 3.4 Placing concrete When placing concrete must meet the following requirements: - Ensure that reinforcement and formwork has completed before the concrete work start according to the technical requirements - 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 - Divide of the concreting level will be based on the volume of concrete and structural cross section changes - The concrete surface will be smooth at the request of the project by the suitable tools - The placing concrete: for each type of structure, placing concrete can be used buckets or pumps (details shown in the drawings) 3.5 Compacting concrete - Compaction time for each location must ensure that the concrete is thoroughly compacted Signs to identify concrete is thoroughly compacted that no more cement laitance and air pockets on the surface - The concrete shall be compacted by mechanical or electromechanical poker vibrators, of a type approved by the Engineer Over-vibration of concrete in the formwork by means of vibrators will not be permitted When required, vibrating shall be supplemented by hand spading with suitable tools to assure proper and adequate compaction - The poker vibrators shall have a diameter compatible with the spacing of the reinforcement, shall be of sufficiently high frequency, and shall be properly handled by experienced personnel They shall be immersed at regular intervals of approximately 10 times the diameter of the vibrator and to such a depth that the fresh concrete will be worked into that previously placed Care shall be taken not to displace the reinforcement nor to disturb or affect partially set concrete Vibrators shall not be attached to the reinforcement in any circumstances Each immersion shall continue until shortly after air bubbles cease to appear on the surface of the concrete, but shall not last more than 30 seconds The vibrators shall be withdrawn gradually and vertically to ensure that no air pockets are formed - Vibrators shall be capable of transmitting vibration to the concrete at frequencies of not less than 4500 impulses per minute (75 Hz) and visibly affecting a properly designed mixture with a 25 mm slump for a distance of at least 45 cm from the vibrator - The Contractor shall provide “stand-by” vibrators during all concrete pours In all cases, at least two vibrators shall be available at the site of 13/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE the structure in which more than 25 cubic meters of concrete is to be placed - All vibration, compaction and finishing operations shall be completed immediately after the placing of concrete in its final position 3.6 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 Time to protect concrete from external forces at least 24 hours or as directed by the Consulting Engineer - 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 - All newly placed concrete shall be cured, and curing shall begin immediately after finishing and continued for at least days Curing shall be done so that moisture is always present, and shall be an integral part of the concreting operations - The contractor will use cure method as cover of jute sacks, sand to keep moisture Water shall be sprayed on the covered concrete surfaces These methods shall be submitted to the Consulting Engineer for approval before starting IV INSPECTION AND ACCEPTANCE Inspection of formwork - Check the geometrical dimensions, the roughness, tightness, stiffness and eccentricity of the formwork 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 joints of reinforcement: Quality of joints are complied with the Specifications - The installation 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 reinforcing works 14/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE 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 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 plump location - To test the strength of the placed concrete by testing concrete compression samples taken during the placing of concrete of the concrete in the batching plant and placing 15/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE CHAPTER III: CONSTRUCTION METHODS FOR ABUTMENTS AND PIERS Bases for making of technnical proposal and technology for construction of abutments and piers construction - According to technical design: Tra Noc, Sang Trang 1, Sang Trang bridges are double branches, one branch is on the existing bridge New branch shall be executed first The existing bridge shall be used as service road and traffic assurance - Branch on the existing bridge shall be executed when the new branch can be used for traffic movement - All abutments and piers place on foundation of bored piles system, D1.2m - All abutments and piers, the Contractor will propose the method of blockage by steel sheet piles for construction Note: No construction at the same time in two branches, the construction method is presented in the drawings of construction sequence Selection of technical solutions and construction technologies 2.1 Construction of footing of abutments and piers 2.1.1 For the abutments and piers on land: Abutment M1, M2 of Tra Noc, Sang Trang 1, Sang Trang bridges; Pier T1, T2 of Sang Trang 1, Sang Trang bridges; Pier T1, T of Tra Noc bridge - Based on the depth of foundation pit and geological conditions, the contractor shall propose method of blockage by using steel sheet piles to prevent soil, water before excavation Cofferdam may be closed or open depending on the positions of abutments and piers The details are shown in the methods of construction drawings - The excavation of foundation pit shall be carried out by machines together with labor During excavation process, the Contractor will install the support of steel framework, braces to ensure stablility of steel sheet piles After excavation by machine, remained works will be completed by manual labour and manually create a flat bottom of foundation pit - Placing the lean concrete layer - In cases, the work is executed while pumping water out from the pit, pumping water from the bottom of the pit with the depth lower than bottom level at least 0.5 m, capacity of the pumps must be bigger than the leakage water Pump out the water and let water flow into the conduits or channels to prevent water overflow back into the pit causing erosion of the pit - Dimension of pit must ensure the space for working such as installation and removal of formwork, stagnant water hole to pump out water to dry pit - The excavated material must be hauled to the regulated places - Framework system must ensure bearing load 16/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - All the designs of pit shall be submitted to the Engineer for his consideration and aprroval in writing prior to execution of the works - After construction completion, all construction materials will be removed and backfill as requirements 2.1.2 For Piers under water: Pier T2, T3 of Tra Noc bridge - The contractor will execute bored piles by construction method of drilling on river The position of the bored piles will be located by a positioning framework system - After installation of close cofferdam of steel sheet piles, excavating the pit by machines combined with manpower - For piers under water, the Contractor shall keep equality of the water level inside and outside - Placing seal concrete to covere the pit bottom, then dry pit bottom by pumping - The other steps of construction will be conducted similarly as construction of abutment and piers on land 2.2 Construction bodies of abutments and piers: - Contractor use shaped scaffolding and formwork system, which were fabricated in the workshops - The fabrication of scaffolding formwork must satisfy the following requirements: Formwork used for concrete is made of the steel or other materials approved by the Engineer Formwork must be accepted by the Engineer prior to installation Only removal of scaffolding and formwork when the concrete reaches the calculation strength (normally 75 % to 90% of design strength) Scaffolding used as supports, bracings and stringers for the construction of concrete items shall be steel scaffolding For special items scaffolding will be closely inspected about load capacity and deflection The general regulations for concrete works 3.1 Preparation work - Prior to commencement of work items must conduct: Design of concrete mix Establish detailed drawings of construction methods including schedule, equipments, manpower, formwork, etc - After getting the approval of the Engineer, start work - Concrete batching plant or concrete mixer must work well and there are standby concrete mixers - The construction equipments such as: Electrical poker vibrators, vibratory tampers, concrete pumps, concrete agitators, welding machines, generators all in good condition 17/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - The testing equipment for checking and inspection of quality such as tachometer, surveyor's level, steel rulers, slump measuring device - Materials for the production of concrete is placed into separate stockpiles, cement and steel must be placed in good condition - After completion of concrete work, the contractor will complete the asbuilt documents and move to the next works Construction sequences for abutments and piers Tra Noc bridge: Stage 1: execution of left branch Stage 2: execution of right branch Sang Trang bridge: Stage 1: execution of left branch Stage 2: execution of right branch Sang Trang bridge: Stage 1: execution of right branch Stage 2: execution of left branch 4.1 Construction sequences for abutments: Step 1: Leveling and cleaning the site for construction Step 2: Execution of steel sheet piles and bored piles - Drive steel sheet piles as shown in the construction drawings - Drill bored piles Step 3: Excavation of foundation pit - Excavate pit by machine combined with manpower - Complete and cleaning pit Step 4: Execution of lean concrete and break pile head - Placing lean concrete - Break the pile heads by machine and manpowers - Complete and cleaning pit Step 5: Construction of abutments footings - Installation of scaffolding and steel formwork - Placing concrete by cranes together with pouring buckets or concrete pumps, use chute for pouring concrete in some possible positions Concrete is mixed by batching plant and transport to the Site - Cure concrete - Backfill pit and construction of next items Step 6: Construction of abutments body and wing wall - Installation of scaffolding and steel formwork - Placing concrete by cranes together with pouring buckets or concrete pumps Concrete is mixed by batching plant and transport to the Site 18/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE - Cure concrete Step 7: Completion of abutments - Construction of head wall, diaphragm anchor, bearing plate - Cure concrete 4.2 Construction sequences of piers on land Step 1: Leveling and cleaning the site for construction Step 2: Execution of steel sheet piles and bored piles - Drive steel sheet piles as shown in the construction drawings - Drill bored piles Step 3: Excavation of foundation pit - Excavate pit by machine combined with manpower - Complete and cleaning pit Step 4: Execution of lean concrete and break pile heads - Placing lean concrete - Break the pile heads by machine and manpowers - Complete and cleaning pit Step 5: Construction of pier footings - Installation of scaffolding and steel formwork - Placing concrete by cranes together with pouring buckets or concrete pumps, use chute for pouring concrete in some possible positions Concrete is mixed by batching plant and transport to the Site - Cure concrete - Backfill pit and construction of next items Step 6: Construction of pier body - Installation of scaffolding and steel formwork - Placing concrete by cranes together with pouring buckets or concrete pumps Concrete is mixed by batching plant and transport to the Site - Cure concrete Step 7: Construction of pier head - Installation of scaffolding and steel formwork - Placing concrete by cranes together with pouring buckets or concrete pumps Concrete is mixed by batching plant and transport to the Site - Cure concrete Step 8: Completion of piers - Construction of diaphragm anchor, bearing plate - Cure concrete 4.3 Construction sequences of piers under water Step 1: Leveling and cleaning the site for construction 19/ 21 PHUONG THANH TRANCONSIN NH91-1: CONSTRUCTION OF TRA NOC BRIDGE; SANG TRANG BRIDGE; SANG TRANG BRIDGE Step 2: Execution of steel sheet piles and bored piles - Drive located supporting frameworks and casing by vibrating hammer as shown in the construction drawings - Drill bored piles Step 3: Excavation of foundation pit - Drive steel sheet piles as shown in the construction drawings - Excavate pit by machine combined with manpower - Complete and cleaning pit Step 4: Execution of seal concrete, lean concrete and break pile heads - Placing seal concrete by method of pouring concrete under water as shown in the construction drawings - Pumping out water together with installing horizontal supporting frameworks as shown in the construction drawings - Placing lean concrete - Break the pile heads by machine and manpowers - Complete and cleaning pit Step 5: Construction of pier footings - Installation of scaffolding and steel formwork - Placing concrete by cranes together with pouring buckets or concrete pumps, use chute for pouring concrete in some possible positions Concrete is mixed by batching plant and transport to the Site - Cure concrete Step 6: Construction of pier body - Installation of scaffolding and steel formwork - Placing concrete by cranes together with pouring buckets or concrete pumps Concrete is mixed by batching plant and transport to the Site - Cure concrete Step 7: Construction of pier head - Installation of scaffolding and steel formwork - Placing concrete by cranes together with pouring buckets or concrete pumps Concrete is mixed by batching plant and transport to the Site - Cure concrete Step 8: Completion of piers - Construction of diaphragm anchor, bearing plate - Cure concrete - Channelize the river if necessary The regulations for construction of abutments and piers: 20/ 21 PHUONG THANH TRANCONSIN ... solutions and construction technologies 2. 1 Construction of footing of abutments and piers 2. 1.1 For the abutments and piers on land: Abutment M1, M2 of Tra Noc, Sang Trang 1, Sang Trang bridges; Pier. .. Weight Concrete Concrete Class A, B, C and D Class and F 37.5 - E Concret e Class G and P 100 100 90 - 100 95 - 100 25 100 19 90 - 100 12. 5 30 - 70 25 - 60 25 - 60 4,67 - 10 - 10 - 10 The percentage... be conducted similarly as construction of abutment and piers on land 2. 2 Construction bodies of abutments and piers: - Contractor use shaped scaffolding and formwork system, which were fabricated