Purpose of Work This work procedure describes the method to be adopted for Basement Raft concreting work for the General Area as shown in the drawings and as directed by the engineer in charge.
Reference Contract Specification. o C40/20 OPC (120kg)+70% GGBS(280KG) Applicable drawings. o DM Approved drawing
Equipment’s Required Concrete Placer Pump with 48m arm length -01 No. Concrete Placer Pump with 56m arm length -02 Nos. and 1 no. standby Concrete Vibrators with needles – 03 Nos. 60 needle and 03 Nos. 80 needle( 2 Nos. Extra) Air compressor -04 Nos. Survey Instrument / Dumpy level & leveling Staff Required Cube Molds (6:100) ; 90 cube molds for1, 500m3 Slump Test Accessories/ Temperature Machine – 3 sets Man Power Deployments Staff Details: Project manager Project Engineer Q/A –Q/C Site Engineer Surveyor Gen. Foreman Concrete Foreman Labour Details: Mason – 10 Nos. Helper – 20 Nos. Shuttering Carpenter – 8 Nos. Steel Fitter – 10 Nos. Electrician – 02 Nos. Plumber – 02 Nos.
Method / Procedure : The formwork & reinforcement will be offered for Client/ Engineer inspection before commencement of concrete. Upon clearance from Consultant’s Engineer, each concrete truck shall be dispatch within 90 minutes from the Batching time. Approved surface and central water stoppers shall be fixed in external and internal walls respectively and this will be fixed as per manufacturer specifications before concrete. Concrete temperatures are recorded for each truck load of concrete and concrete temperature shall not exceed 30 ºC at the time of placing. ( Due care will be taken during summer to keep the concrete temperature with in specified limits). Slump will be taken for every truck and recorded to comply with the approved concrete mix design ie. 150mm +/- 25mm. Concrete cubes will be made in the ratio of 6 cubes per 100cum of concrete, shall be properly marked and cured for the cube crush test. Cubes will be crushed in the laboratory at 7days & 28 days to check for the compressive strength of concrete. The Concrete should not be laid not more than 450mm depth the first layer shall be 450mm depth and the same shall be follow up to Completion and the plan dimension of these layers shall not exceed 5.0m x 5.0m at any time. As shown in the drawing plan, we required three ( 3) Concrete Pump designated in different locations and area of pouring (as shown the sequence of pouring/casting from designated Concrete Pump). Casting of raft in AREA 2 the Retaining External Wall with the same height of raft 1.5m following with the same process of concrete laying. After the Casting of Raft in General Area followed by casting of External Retaining Wall and Internal Walls in Pump Area and Water Tank Area as shown in the Plan Drawing. The fall of concrete during placing will be kept less than 2.0 m to avoid segregation of concrete, if height exceeding 2.0 m, trucking & shall be used to prevent segregation of materials. Compaction will be done immediately after pouring using vibrators. Concrete shall be vibrated immediately after pouring. Petrol vibrators of frequency 8000 cycles/minute, and 60 mm in diameter for normal use. Formwork fixers & materials shall be made available stand-by during concreting operations. Hessian shall be kept wet by adding water or by ponding/ applying approved concrete curing chemical ensuring to follow the proper application procedure. A separate pouring sequence including positioning of concrete placers, rate of pour, location of concrete truck inspection, cube casting etc will be prepared and submitted separately for major pours. Formwork to the sides of concrete surface (vertical sides) shall be removed after 12 hrs and the vertical sides will be kept wet by wrapping with wet hessian cloth. After required finishing, cover it with polythene sheet for further dust protection.
INSPECTION PROCEDURES: Inspection Test Procedures shall be according to the QA/QC Inspection & Test Plans. Upon completion of formwork & rebar the relevant inspection points are checked by Client/Engineer representative and cleared for concreting. Attached copy of pour card and slump, temperature record will be maintained.
STRIKING/REMOVAL OF FORMWORK Stripping of forms, supporting props above and below ground shall be confirmed with respect to calculated strength from the tests performed on field cured cubes. Forms will be removed in such a manner as not to damage the concrete but only after the concrete has gained sufficient strength to support itself.
SAFETY REQUIREMENT Well trained, experienced and appropriate personnel shall be deployed to carry out jobs and experienced supervisors the jobs. Appropriate personnel protective equipments like gloves, goggles should be worn apart from the safety shoes and helmets which are mandatory. While placing the concrete out of direct line sight of pump, crane or delivery truck operator a suitable experienced person shall be present till concreting is finished. During work at heights more than 2m height, a working platform or staging shall be provided. Proper working platform of the following standard shall be erected. The working platform shall be strong enough to support the machinery and the weight of the personnel working. The platform should be properly supported by standard scaffolding tube made up of steel, with out any cracks, splits and surface flaws. Hand rails at the height of 1m from the edge of the board shall be provided at the free ends of platform. Working platform shall be kept clean at all times and under no circumstances should they be utilized for stockpiling of materials.
ENCLOSURES Pour card Slump and temperature record.