Construction method statment

VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 CONSTRUCTION METHOD STATEMENT I EARTH WORK: SECTION GENERAL REQUIREMENT General (a) All necessary measures to prevent abnormal settlement, sliding of slopes and other disasters shall be taken during construction (b) All efforts shall be made to prevent spills and scattering when carrying soil or outflow of mud due to water drainage Cleaning and washing with water shall be performed as required Excavation and backfilling (a) Excavation should be suited to the situation in surrounding areas, geology and groundwater conditions, and slope surface protection or landslide protection shall be employed in accordance with the relevant laws so as to prevent the collapse of sediment (b) Where buildings adjacent to the excavation area are likely to be collapsed or broken, adequate measures shall be taken in advance to prevent such occurrences (c) Where underground water supply or drain pipe, gas pipe or cables are likely to be discovered, a survey shall be conducted In the event that a buried object is found, it shall be carefully handled so as not to cause damage All necessary emergency measures shall be taken, and the final outcome shall be determined through discussing with the Engineer and/or the authority concerned (d) All minor obstacles to construction work shall be removed The treatment of major obstacles shall be discussed with the Engineer (e) The bottom of cutting shall be excavated without disturbing the ground, and inspected by the Engineer upon completion of the excavation Drainage (a) Rainwater, spring water, stagnant water, etc that may hinder construction shall be removed via drain ditches, catching basins or pumps Where unusual freshet is seriously affecting the execution of the work, this matter shall be brought to the attention of the Engineer (b) Appropriate measures shall be taken before draining water from the excavated area so as not to influence the bottom of the cutting, the surface of slope, construction site or neighboring areas Backfilling and Fill (a) 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 3-1 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 (b) Consult the Engineer if the excavated soils are not suited to the backfilling and fill (c) Extra fill settlement or allowance may be required depending on the soils (d) Material filling is met technical requirement stipulated on term 11.2 in 3550-8310-SP0009 Grading Grading (leveling) shall be performed for a width of approximately 2m around the building in order to drain away water Disposal of Earth Generated during Construction (a) Earth generated from the construction work shall be transported outside the premises and disposed of in a suitable manner in accordance with local regulations, (b) In the event that some of earth generated from the construction work can be reused, under consultation with the Engineer and/or the local authority SECTION EARTH WORK SUPPORT Structure and Other (a) Earthwork shall be supported safely and securely in accordance with the local regulations and/or the Engineer’s directions (b) Earthwork supporting system shall be submitted to the Engineer for approval with calculation sheet (c) During execution due attention should be given to the stress and deformation with a view to potential disasters (d) The use of measuring instruments such as earth pressure gauges shall be provided (e) When installing earthwork support works, constantly check and measure the adjacent ground for potential landslides Should any abnormal state be detected, adequate steps shall be immediately taken and a report made to the Engineer (f) Removal of earthwork support structures shall be performed in a careful manner after verifying the safety level The holes left after steel sheet piles are pulled out shall be immediately backfilled with sand or other suitable material directed by the Engineer, thereby preventing deformation of the ground (g) Use open excavation method when excavation depth 2.5m, use support system for slop protection (refer attached drawing) 3-2 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 SECTION METHOD OF EXECUTION REMOVAL OF TOPSOIL: Removal of topsoil shall include excavation to remove the top organic layer, hauling to designated locations and stockpilling or removing as instructed, to permit construction of the Works, all as indicated on the Drawings or as instructed by the Engineer and as specified Prior to commencement of removal of topsoil, the subcontractor shall obtain the Engineer’s written instructions regarding work area and depth limits, and approval for the equipment and materials are to be used and the method of work execution A survey team shall be stationed on site to monitor and control each stage of work All the major setting out works will be carried out jointly with the Engineer’s Surveyor Before commencement of massive cut/fill, the haul roads shall be constructed with two lanes width for to traffic and to ensure smooth flow of the plant The construction of berm drain shall follow closely to the slope trimming and surface water shall be regulated to the temporary earth drains and eventually discharged to the slit traps EMBANKMENT AND BACKFILL METHOD Construction sequence:  Fill material is transported by dump truck to the site and dumped into each heap at the calculated interval and suitable volume with length and thickness of the section to be constructed within a day to secure leveling and compacting work at least and most effectively to avoid encountering inconvenient weather when leveling and compacting work is not finished within day  Use bulldozer and grader to level fill material into even layers along the length of the section to be constructed Form smoothness, crown, longitudinal slope and horizontal slope to the design  The thickness of each layer is 20cm, otherwise instructed by the Engineer Compacting fill material: - Rolling is performed along the laid section, from edge to the centerline, from lower point to higher point Successive passes 3-3 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 shall overlap the previous passes from 25cm to 50cm (in parallel direction to centerline) - Successive passes shall overlap the previous passes from 50cm to 100cm (in perpendicular direction to centerline) - Rolling at the super-high section shall be carried out from the curved-road lower point to the curved-road higher point - Layers are compacted to the required density in the Specifications, and then the Engineer will be invited to check the density by sand cone method at site Subsequent layers will only be carried out when previous layers are approved by the Engineer Compaction work will be complied with the Specifications - Completion of embankment and slope: Embankment slope will be shaped to the required slope and density by suitable tools The surface of embankment shall be smooth, free from crack meeting the requirements shown on drawings or as instructed by the Engineer - Acceptance work will be executed following the sequence:  Check elevation of fill embankment by level machine  Check geometry dimensions by steel tape  Check smoothness by 3m straight edge  Check density by sand cone method at site - Prior to construction on a large scale is commenced the Contractor will perform a trial section with the area of not less than 500m2 (the length of 50m, the width of 10m) The results of trial section to be submitted to the Engineer are included:  Construction equipments  Design of rolling diagram, rolling sequence: rolling speed of various stages, number of passes on one point with the best moisture for trial section 3-4 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8  Test results of density attained with the designed rolling diagram for sand material used - The parameters attained from the trial section, if satisfied the requirements, it will be applied to construct on a large scale on site - Other requirements for embankment fill are complied by the Contractor with the Specifications, Section 3550-8310-sp-0009 EXCAVATION All excavation shall be carried out to the required lengths, depths, inclinations and curvatures as may be necessary for the constructions of the work or as shown on the drawings in whatever material that may be found, including top soil and the surplus soil shall be disposed of as Main Contractor engineers may instruct Excavation for foundation shall extend a sufficient distance from the footing (approximately 30 cm) to create appropriate space for placing and removal of forms The bottoms of all excavation shall be leveled carefully, unless otherwise on the drawing or by Main Contractor’s engineers’ instruction EXCAVATION PROCESS MACHINE EXCAVATION The purpose of machine excavation is to speed up the process Follow this procedure, excavation machine can not break the under ground soil structure which according to the design of foundation Excavator will not be able to excavate the small space, but that soil will be excavated by hand Anyway, after excavator has finished its work, the excavation pit is to be repaired by hand 3-5 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 HAND EXCAVATION Hand-excavation can keep the ground surface of excavation pit evenly and the under ground soil not to be broken Hand excavation is the only choice in the areas where excavator could not work The purpose of hand excavation is to make the surface of excavation pit to be smooth with small tolerance Checking-level pole will be used to correct the level of ground during excavation by hand 3-6 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 INSPECTION OF EXCAVATIONS All excavations are to be inspected and must be approved by Main Contractor’s engineer before gravel and lean concrete is laid (in case the work is carried out by a sub contractor of VINACONEX) The sub contractor shall inform Main Contractor’s engineer in time to allow VINACONEX’s inspector to make the visual inspection of the excavation works (See attached check list ) ADDITIONAL EXCAVATION If it is necessary for any reason to form, extend and/or deepen foundations under or around any part of the work, the additional excavation shall be processed INSPECTION BEFORE FILLING IN No filling in shall be commenced until the concrete foundations have been inspected by Main Contractor’s engineer in charge UPHOLDING SIDES OF EXCAVATION When it is necessary, upholding the sides of excavations shall be processed to prevent any damage to adjacent structure and buildings caused by collapsing of sides and embankments of excavations TIMBER, Etc LEFT IN EXCAVATIONS Timbering, dust, debris, rubbish, etc Shall not be left in when excavations are being filled 10 REMOVAL OF SURPLUS SOIL All surplus excavated material, rubbish and waste matter shall be removed from the site The 3-7 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 place for disposal shall be selected by site manager or by sub contractor 11 KEEPING EXCAVATION FREE FROM WATER Powered pumping, drainage or otherwise shall be used to keep the whole of the excavation free from water arising from rain, flood, drain, springs or any other cause If the work is carried out by a sub contractor of VINACONEX, he shall convince VINACONEX engineer in charge before he starts with the excavation works that suitable equipment, in good working condition is available on the project site 3-8 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 II ROAD AND PAVEMENT WORK: B Construction of road AND PAVEMENT system: Clearing and grubbing: a Site clearance: Site clearing generally consists of the cutting and /or taking down, removal and disposal of everything above ground level, including objects overhanging the areas to be cleared such as tree branches, except such trees, vegetation, structures or parts of structures and other things which are designated in the contract to remain, or be removed by others or which the Employer Representative directs to be left undisturbed The material to be cleared usually include but not necessarily be limited to trees, stumps, logs, brush, undergrowth, long grasses, crops, loose vegetable matter and structures The entire road reserve and platform area shall be cleared as described above, unless otherwise shown on the Drawings and I or directed by the Employer Representative b Setting out: The right of way (ROW) shall be surveyed and set out before any site clearance is carried out Wooden pegs usually indicate the surveyed right of ways c Plant and equipment: Sites clearing of trees, vegetation, undergrowth, bushes and minor structures are carried out by bulldozers and or hydraulic excavators Trees that cannot be felled by the aforesaid equipment shall be felled by using chainsaws Major structures that cannot practicably be cleared by hydraulic excavators and/ or Bulldozers, these demolitions can be carried out using pneumatic tools and/ or other specialised equipment depending on the size and type of structures d Sequence of works: Prior to the commencement of site clearance, the followings shall be carried out either independently or jointly with the Employers Representative - The right of ways (ROWs) shall be surveyed and set out according to the coordinates stated in the drawings 3-9 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 - Photographs shall be taken of structures, landscaping trees and shrubs, fences, telephone and electrical poles and others that are payable under individual measured item apart from the general site clearance in the bill of quantities - The above site clearance items shall be measured according to the method of measurement jointly with the Employer’s Representatives The locations of these items shall be identified according to the surveyed coordinates or offsets from the centerline of the proposed alignments in road construction - Prior to demolition of existing buildings, liaison with the respective authorities to terminate the utilities supplies to the buildings - Prior to removal of landscaping trees end shrubs, a joint inspection shall be carried out with the local authority - Fencing or others that are to be relocated or salvaged shall be carried out according to the drawings or as per instructions given by the Employer Representative - Ensure that the right of way lands have been acquired by the Employer or relevant authorities - Access roads to the site shall be constructed if required to enable vehicles, equipment and plants to be brought into the site - Solid waste dump sites shall be predetermined within or outside the site for the dumping of the site clearing materials These dumping sites shall be approved by the Employer's Representatives or the relevant authorities The site clearance shall then proceed to clear the trees, vegetation, undergrowth, bushes and minor structures by hydraulic excavators and or dozers All unwanted materials shall be piled up and disposed off in a safe tidy manner at the designated dumping areas All burning shall be subject to the prior approval of the relevant Government Authorities, and shall be carried out in conformance with all pertinent regulations Material designated in the Contract or direct by the Engineer to be salvaged, shall be carefully removed and stored, and shall be the property of the Employer or Government whichever is specified in the contract 3-10 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 (2) No water shall be added when sending concrete by conveying or forced feed (3) Immediately before unloading concrete, rotate the truck agitator at high speed to agitate the concrete and make it uniform (4) Always carefully check the quality of concrete to be unloaded Forced Feeding and Transport on Site (a) Forced feeding of concrete (1) Conveying pipes shall be held using walking boards on supporting bases, supporting bases, trestles, suspending hardware, etc No hazardous vibration of conveying pipe shall be transmitted to concrete forms or reinforcing bars (2) The size of the conveying pipe shall be determined in consideration of the following (minimum nominal diameter of conveying pipe for the maximum size of coarse aggregates 1) Distance and height of forced feed, affect on concrete of forced feed, difficulty of using forced feed, air temperature 2) Volume of forced feed per unit time and maximum size of coarse aggregates (3) The length of the flexible hose shall be less than 6m as a rule when the nominal size of the conveying pipe is less than 100mm For pipes over 100mm the hose shall be less than 5m except for pump vehicles with booms (4) The maximum horizontal transportable distance of the forced feed machine shall be more than the horizontal equivalent of the total piping distance plus a certain allowance (5) Prior to force feeding concrete, rich mortar shall be input in order to prevent change in concrete quality Prior to force feeding mortar the inner surface of the equipment should be wet (6) The following sections of forced feed concrete shall be discarded Good sections of forced feed mortar prior to the forced feed of concrete can be poured in concrete forms if scattered so that only a small quantity is present at any one place 1) Concrete changes significantly during forced feed 2) Altered portion of mortar stated in (5) first ejected (b) Transport by handcart (1) Concrete materials shall not be separated during transport nor leak out from the receiving sump (2) If separation of the materials is observed during transport the concrete shall be mixed again to make it homogeneous 3-34 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 (3) When using a sloped chute the following requirements shall be met: 1) Section is U-shaped and made from steel or iron sheet 2) Slope is 4/10 to 7/10 3) Funnel longer than 600mm used at chute outlet (4) When discharging concrete from high places longitudinal flexible chutes shall be used Placement (a) Prior to concrete placement, clean the area when concrete will be placed, remove miscellaneous objects, and spray water to moisten the sheathing boards and construction joints (b) If a rainfall that may affect the quality of concrete is predicted curing shall be performed When curing is not possible concrete shall not be poured (c) Placement shall be carried out mainly by (1) as stated below for ordinary story heights or, depending on the situation, (2) after obtaining approval from the Engineer (1) Each story is divided into the portion below the beam and the portion below the top of the floor slab Placement shall be varied so that each portion is horizontal When there is a portion from which a wall beam rises up the concrete shall be placed in succession in accordance with the setting conditions of floor slab concrete (2) Concrete forms are to be strengthened to prevent deformation, and concrete is to be placed on the floor slab one at a time, from the end to the whole Use (1) for wall and beam concrete placement (d) Parapet or eaves shall be poured as one body with the structure supporting it as a rule (e) Do not pour concrete directly from the flexible hose to the column (f) When interruption to concrete placement is necessary, predetermine the pouring section and limit the interrupting time to one hour as a general rule (g) Compaction of concrete shall be performed to all parts of the concrete form Normal allocation shall be at least two bar-type vibrators per concrete conveying pipeline system, and two or more vibrator-operating workers plus more than seven workers for tapping compaction (h) Floor slabs shall be compacted by tapping the surface with tamper after rough leveling but before concrete setting to prevent cracking due to settlement, and shall be made to level surface 3-35 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 Joints of Successive Pours (a) Joints of successive pours (construction joints) shall be horizontal or vertical and located near the center of the span for beams and floor slabs, or on top of the floor slab, wall beam or foundation for walls and girders (b) Partition plates shall be used for the joints of successive pours such that mortar, cement paste will not leak out Where the horizontal construction joint is on the outer surface, it shall be made straight using driving rulers (baby squares) (c) Latinate and weak concrete shall be removed from the surface of construction joint to expose sound concrete Curing (a) Concrete shall be kept moist by water spraying or other method for more than five days after concrete placement (b) After placing concrete, hazardous vibration and impacts shall be avoided Repair of Concrete (a) Any defective sections discovered after removing partition plates shall immediately be repaired (b) In the event that a serious defect is found in the principal structure, approval for repair technique shall be sought from the Engineer and the work shall be subject to inspection by the Engineer after repair SECTION HANDLING CONCRETE IN HIGH-TEMPERATURE SEASON General (a) This Section shall apply when the air temperature during placement of ordinary or lightweight concrete exceeds 250C (b) Items other than those prescribed in this Section shall conform to Section Material Handling (a) Do not use high-temperature cement (b) Do not use aggregates that have been exposed to hot air over a long period Use coarse aggregates after spraying with water (c) Water temperature shall be as low as possible (d) After producing concrete, delay type, air-entrained water reducing agent (chemical admixture for concrete) as required by the time required until placement 3-36 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 Concrete Production and Placement (a) Concrete temperature during placement shall be below 350C (b) Water spraying on partitions and surfaces of construction joints before placement shall be performed carefully and thoroughly (c) Conveying pipeline shall be covered and curried with wet cloth or wet straw mats so as to prevent direct exposure to sunlight (d) Time from the start of mixing to the completion of pouring shall be less than hour (e) Do not pour concrete directly on heated concrete or foundations Curing Take special precautions when spraying water on the concrete surface and cure the concrete completely by making it moist at all times SECTION CONCRETING IN COLD WEATHER General (a) Cold weather concreting in this Section refers to the situation where there is the potential for concrete to be frozen during the curing period after pouring As a general rule control is by the integrating temperature method (b) Items not prescribed in this Section shall conform to Sections to 5,7 and (c) Before starting construction, documents setting out methods of curing and thermal insulation control shall be submitted to the Engineer for approval Material Handing and Storage (a) Cement shall be stored without cooling whenever possible (b) Aggregates shall be stored in appropriate protection facilities to prevent freezing or mixing with ice and snow Design Mix The Contractor shall submit design mix proportion to the Engineer for approval Production and Placement (a) The temperature of concrete at completion of mixing shall be adjusted so that immediately after the mixing it is over 10oC but less than 20oC, taking into account carrying time, working conditions and weather conditions (b) Cement shall never be heated by any means Aggregates shall not be heated by direct flame 3-37 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 (c) When mixing heater materials together, the temperature of water and aggregates before putting in mixer shall not exceed 40oC (d) Receiving, pouring and conveying facilities for concrete shall not be cooled as far as possible (e) Forms shall be covered with sheets if it considered that snow may accumulate inside Any ice or snow stuck inside forms or on the surface of reinforcing bars shall be removed before pouring concrete (f) Supports for forms shall not be placed on frozen ground soil If the ground is likely to become frozen, the leg sections of the supports shall be protected with thermal insulation Curing (a) General (1) The curing method for poured concrete shall be capable of achieving the required integrating temperature (2) During the initial curing period the temperature of the concrete, the insulated space and the air shall be recorded by self-recording thermometers or similar devices for the purpose of thermal insulation control (3) The degree of thermal insulation or heating required for thermal insulation and curing shall be determined by referring to weather records and forecasts, and heating tests shall be conducted in advance as needed (4) When heating for curing purpose, concrete shall be uniformly heated without rapidly drying (b) Initial curing (1) Curing shall be performed until the compressive strength of concrete set out in Paragraph 6.7.5 reaches 50kgf/cm2 (5N/mm2) (2) The method used for initial curing shall be capable of maintaining a temperature of over 2oC over all sections of concrete poured, and shall conform to the following procedure : 1) Immediately after pouring concrete, the exposed surface shall be covered with suitable materials such as sheets without gaps 2) When the air temperature is expected to drop below 0oC (not applicable), exposed concrete surfaces and openings shall be covered with suitable materials such as sheets without gaps 3) If air temperature is expected to drop below 0oC for several days or below 10oC temporarily, then the whole structure shall be covered with suitable materials, such as sheets and plywood, and the indoor and outdoor sections shall be heated to 3-38 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 predetermined temperature (3) If a particular curing temperature has to be maintained regardless of the air temperature, then heating shall be provided by suitable curing method (c) Curing performed directly after initial curing (1) Curing upon completion of the initial curing shall be performed by a suitable method which will not lower the temperature below 0oC in any section, and shall conform to (b) (2) above (2) In the case of (b) (3), the same curing shall be carried out for the required period (3) Sudden cooling of concrete after the completion of heated curing shall be avoided (d) Termination of insulated curing shall be after planned curing, and not until the required concrete strength has been verified through concrete strength tests (Paragraph 6.8.6) and insulation control records, and approval has been obtained from the Engineer Testing Concrete Strength Curing method, age and number of times of testing for test pieces shall conform to Design Document Tests to determine when to remove forms and terminate initial curing may conform to Test method for tensile strength of concrete instead of compressive strength tests In this case compressive strength shall be eight times the value obtained from the tensile test Removal of Concrete Forms Time for removing the forms shall conform to the method of making decision from the compressive strength of concrete of Paragraph 6.14.4 SECTION PLAIN CONCRETE General Items not prescribed in this Section shall conform to Section to Section Materials Maximum size of coarse aggregates shall be less than one-fourth of the minimum diameter of the section of concrete and also less than 40 mm Unless otherwise shown on the structural drawings in the Design Documents, 25mm shall be used for leveling concrete and waterproof 3-39 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 covering concrete Design Mix (a) Design standard strength shall be 16 N/mm2 and the slump shall be 15cm or 18cm (b) The minimum value for cement weight per unit volume and water/cement ratio is not restricted Also, correction of concrete strength due to air temperature is not required Applications Unless otherwise shown on the structural drawings in the Design Documents, the following shall be applied (1) Concrete for drainage ditch for rainwater, curbs and side ditches for parking and road, and associated footing concrete (2) Leveling concrete (3) Concrete for embedding pipes in machine rooms, etc (4) Covering concrete for waterproof materials SECTION TESTING General (a) This Section applies to the testing of concrete and concrete materials Some of the tests may can be omitted if the concrete is light, or for smaller sections, if approved by the Engineer (b) Areas used for testing of materials shall comply with the following as far as possible : (1) For cement and aggregates, the location of concrete production (2) For normal weight concrete, location where unloading takes place on site (3) For lightweight aggregate concrete, immediately before placement at the location where placement of concrete forms takes place on site Material Tests Material tests shall be conducted in accordance test reports shall be submitted to the Engineer for approval In case of the following result, the Contractor shall consult with the Engineer for solution.: (1) Total alkali content is as described in Paragraph 6.4.4 (b), because sand and 3-40 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 gravel or crushed sand and crushed stone designated as type A is found to be harmful (2) Crushed sand and crushed stone designated as type B is found to be unharmful (3) Immutable weight control is specified as the measure for restricting kind B and alkali aggregate for crushed sand and crushed stone, and the total alkali in concrete in Paragraph 6.4.4(b) exceeds 3.0kg/m3 without being judged unharmful General Rules for Strength Tests for Concrete General rules for concrete strength tests shall be as follows : (1) Number of test pieces and collection of test samples 1) The number of test pieces shall be three for each type of test : age days, age 28days, assessing time to remove forms, etc 2) Test samples shall be collected three times separately from dollies at suitable intervals for the purpose of preparing the test pieces required in (i) 3) Of the test pieces in (ii), three are taken out one at a time and seed for one age in one test 4) Slump and air content to be tested each time samples are collected according to (ii) above (2) Test pieces shall be prepared in accordance with Method for preparing specimens for concrete strength and cured according to the purpose of each test Removal of forms shall be performed two days after producing specimens (3) Curing method and temperature for test pieces shall be as follows : 1) For curing conforming to Method of producing specimens for concrete strength test the curing temperature shall be 20 3oC (20 2oC for winter concreting) itself for water, moist sand or saturated moisture The curing temperature shall be the mean of all maximum and minimum temperature values of water in curing water tank, moist sand or saturated moisture as measured during the curing period Avoid direct sunlight on curing water tank or the like (4) Compression strength test shall conform to Test method for concrete compression strength (4) Curing method, age an number of test shall conform to Table 6.12.4 (Table 6.8.2 for winter concreting) Table 6.12.4 Curing method, age and number of test 3-41 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC Type Purpose Control test for specified strength of mix Control specific strength mix Test for determining concrete strength in a structural body NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 Curing method of Curing conforming of Method producing specimens strength test concrete Determining 28day compression strength of concrete in a structural body Age Number of test days (Normal weight concrete) More than once per day when concrete type changes and more than once every 150m3 or fraction thereof (Lightweight concrete) More than one in the morning and also in the afternoon when the type of concrete changes, and more than once for 100m3 or fraction thereof to for for of Curing on-site 28 days The above standard applies to foundation work, pavement work and plain concrete work Determining As above time of concrete form removal To be determined as required SECTION 10 TROWEL FINISH FOR FLOOR CONCRETE General This Section applies to metal trowel finishing of poured concrete floors, providing bed for carpet and other finish materials as shown on the Drawings in the Design Documents, as well as bed for waterproofing work Types Types of floor concrete shall conform to Table 6.13.1 and Type A shall be applied, unless otherwise shown on Drawings in the Design Documents However, Type B shall be used for the backing of ordinary roof waterproof layers Table 6.13.1 Types of Trowel Finishing Type Number of trowel finishes Wooden trowels Metal trowels 3-42 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 Type A Type B 1 Methods (1) Leveling method 1) Determine origin of reference height for each story 2) Determine reference height for finishing work before pouring concrete (2) Leveling with ruler : 1) Maintain accurate height reference to either level or required gradient 2) After pouring concrete, level roughly with a scoop or shovel and tamp concrete with tamper until coarse aggregates sink below the surface Level the surface with a long straight board while accurately maintaining height in alignment with reference height using level or leveling string (3) Elimination of irregularities in the middle After using the straight board level the surface flat with wooden trowel (4) Trowel finish 1) Rubbing with wooden trowel After eliminating irregularities rub the surface with wooden trowel, gauging the timing correctly with surface hardening/ 2) Metal trowel finish After rubbing with wooden trowel, finish the surface smooth with metal trowel This finish work shall be performed before concrete has hardened too much so that the troweling is still possible (b) Do not spray water, cement or the like on the surface during finishing (c) In the case of trowel finishes use walking boards or stepping boards to avoid stepping directly on concrete surface (d) Take extra care at construction joints to avoid contaminating the finish surface (e) Finish smoothly with grinder after concrete sets in places where significant irregularities caused by trowel finishing are discovered Curing (a) After surface finishing, perform the curing specified in Paragraph 6.5.7 Gauge timing in accordance with degree of setting of concrete Also in the case of Type A, provide curing and surface protection by covering with vinyl sheets or the like (b) When installing concrete forms for upper stories or transporting reinforcing bars, take special care not to damage the finished surfaces 3-43 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 CHARPTER FORMWORKS Materials and Construction (a) Sheathing boards and timbering shall be used These shall be able to withstand external forces such as working load, deadweight of concrete, lateral pressure, vibration and horizontal load, and have a form which does not bring about dangerous levels of distortion or strain (b) Metal or wooden member shall be used in timbering (c) The following items shall be satisfied (1) For exposed concrete finishes, the finish on the concrete surface shall conform to the concrete finish surface specified in Table 6.14.1 (2) In all other cases Paragraph (d) (3) shall apply (d) When using plywood as a material for sheathing boards, the following requirements shall be satisfied: (1) Standard 15mm Plywood for concrete forms (2) Standard 12mm of Plywood for concrete forms (e) When using a steel deck instead of sheathing boards the plate for floor concrete forms shall be provided at a stable floor surface (f) Form tightening parts shall be bolt type, although annealed wire may be used for catch basins (g) Release agent (such as form oil), if applied, shall be obtained approval form the Engineer before application (h) Size and intervals of concrete form components shall be determined by structural calculations as required (i) Old members may be used in some cases as concrete forms When using old sheathing boards, tightening holes or the like shall be repaired as required and surfaces completely cleaned Assembly (a) Working drawings for concrete works shall be submitted to the Engineer for approval (b) The required setting-out shall be performed prior to assembly, and the most important setting shall be inspected by the Engineer (c) Sheathing boards shall be assembled in accordance with the location, shape and dimensions of concrete to be molded (d) All sleeves, boxes, metal parts to be embedded and other objects inside forms shall be firmly attached before pouring concrete Sleeves shall conform to "through holes and other" (Section Chapter 22) 3-44 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 (e) Supports shall be fixed vertically and directly above other supports in the lower story as a general rule (f) Forms shall not be connected to other temporary works such as scaffolding, batter boards, etc (g) When using steel deck plates as floor concrete forms, and appropriate strength shall be provided for form members to be connected together (h) Cones shall be used for form - tightening parts in the following locations : (1) Face directly touching earth (except footings, foundation beams without basement, etc.) (2) Backing for waterproof (3) Exposed finish concrete surface (Types A and B in Table 6.14.1) (4) Surface to be directly finished with thin finish material such as paint coat, wall paper, etc (5) Surface on which an insulating material is to be attached Concrete forms shall be inspected by the Engineer prior to concrete placement (g) FABRICATION OF STEEL FORM In order to achieve high quality of concrete work, steel form will be used for the project Our amount of steel form is enough to meet requirement of the project In case of lack of form, additional form will be fabricated The fabrication process includes material, tools and machine's preparation Special form will be made especially according to structure design All of additional form is to meet the general requirements, stiff and hard enough MARKING Marking is the first step of setting form process A grid line system must be established in advance so that marking work can base on Center- lines of structure will be made base on the established grid line's system ASSEMBLY WORK All steel form must be sufficiently prepared in advanced Steel form must be cleaned and applied a thin layer of special oil to avoid concrete remaining when remove form FOUNDATION Sequence of work includes placing steel form for foundation, adjust the level and verticality with a plumb bob After everything is set, start fixing with form ties and support Form after being set must be vertical Top level of potential concrete must be marked on form surface COLUMN AND WALL Before setting, form must be cleaned carefully at its bottom 3-45 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 During process of erection form for wall and column, verticality must be checked with a plumb bob After everything is set, start fixing with form ties and diagonal support and bracing Form after being set must be vertical Top level of potential concrete must be marked on surface of form TIME OF KEEPING FORM IN ITS PLACE Form can only be stripped when it meets the requirements about concrete strength as stated below: Form location Foundation, side of beam, column, wall Type of cement Portland cement Minimum compressive concrete in condition temperature strength of 50 Kg/cm2 of 25o C Minimum concrete curing period days FORM REMOVAL Before removal of form, engineer must confirm the strength of concrete whether it is enough or not (Reference the next table) During process of removing, people must be kept away the area All of material after being taken out must be well arranged and cleaned up by the form oil to the next using FORMWORK REMOVAL TIMES No TYPE OF FORMWORK Vertical frame work to column walls and large 12 hours beams Soffit frame work to slabs days Props to slabs 10 days Soffit frame work to beams 10 days Props to beams 14 days MINIMUM TIME 16 C REMOVAL Notes: The stated time is based on maturity time at 16o C and shall be adjusted in 3-46 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 accordance with actual temperature The stated time is a guideline only and additional time may have to be added to obtain sufficient bearing capacity for dead load and construction load Removal of forms (a) Forms shall not be removed until the minimum standing time was elapsed (b) Minimum standing time shall be determined in terms of the age or compression strength of concrete Data and calculation sheets used in verifying safety and concrete test results in Paragraph 6.12.4 shall be submitted to the Engineer for approval If the onset of strength is considered to have been delayed due to cold weather, the above shall be determined by compression strength instead (c) Supports of a cantilever beam, canopy, beam with a large span, large-size floor slab or an extremely large working load shall be kept for longer periods as required (d) Supports shall not be re-shored Sheathing boards below floor slabs and beams shall be removed after taking out supports Table 6.14.3 Minimum keeping time for supports Below floor slab Mean air temperatur e during keeping period Based on Over 15oC age of Over 15oC concrete Over 0oC (days) Below beam High-earlystrength Portland cement Normal Type B All cement shown Portland Portland on the left cement, blast Type A furnace blended slag cement cement 17 12 25 15 28 28 28 3-47 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC Based on compressio n strength of concrete NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 Compression strength is over 85% of design standard strength or over 120 kgf/cm2 {12N/mm2} and load and external force during work was verified to be safe through structural calculations Compression strength is over design standard strength or over 120kgf/cm2 {12N/mm2} and load and external forces during work were verified to be safe through structural calculations Head Treatment for Form Tightening Parts (a) When there is no finish on a visible face after forms are removed, the heads of form-tightening parts shall be removed and a rustproof paint shall be applied (b) Cones used form-tensioning parts shall be removed and the recessed portions shall be filled with mortar containing a water retaining agent or waterproof agent Portions with insulation shall be treated in accordance with Paragraph 18.9.3 "Placement method (f)" Mortar filling shall be generally performed below the face For a thin finish such as paint coat, the mortar bed shall be flush with concrete surface 3-48 ... the Employer’s Representative Construction of Subgrade, subbase, Base, Asphalt concrete: Content of works: - Construction of embankment Construction of Subbase course Construction of Base course... describe in Technical specification - construction method  Before carrying out embankment construction in large area, We will prepare trial area for embankment construction (at least 500 m2 or as... 3-11 VINACONEX ENGINEERING CONSTRUCTION AND INVESTMENT JSC NGHI SON REFINERY AND PETROCHEMICAL COMPLEX PROJECT PACKAGE CV8 Mechanical Tamper Construction process  Construction procedure will