Production & Supply Concrete To Site

The Parameters used in the trial mix must be maintained during actual production & supply concrete to the site. Adjustment are allowed within Cl. 3.2.4

It is the responsibility of the Contractor to ensure the supplier produce and deliver to the site, concrete in compliance with the requirements of the specifications and providing information as required by SPK

However, for the smooth flowing of concrete works at the site, the following process of approval and verification shall be clarified and agreed upon between S.O and Contractor. (* Delete where applicable)

1. Batching Plant : The Contractor shall ensure his supplier permits access for the S.O to enter the premises periodically to inspect the production of concrete.

2. Delivery Note : The time of batching for all concrete delivered to site shall be noted. Maximum allowable duration is Two Hours (2 jam). Concrete must immediately be rejected after the expiry of this duration. ( Nota : Duration of 2 hours means the time between batching and completion of placing vibrated concrete)

3. Batching Record : For every load of concrete delivered to Site and shall be given to the Contractor and jointly verified for compliances by the S.O. *during delivery / at the end of the day's concreting / within 2 days

4. Workability : Verification of every load of concrete is by slump test. * truck driver / Contractor / S.O shall carry out the test and verified for placement or reject by * Contractor / S.O

5. Test Cubes : Prepared by * truck driver / Contractor / S.O. Record and markings by *truck driver / Contractor/S.O Must be cured and kept in curing bed constructed at/near S.O's site office. Testing at *supplier's lab / IKRAM / Independent lab. Testing witnessed, verified and recorded by *S.O, Contractor & Supplier / Contractor & Supplier / Supplier only. Test must be carried out at the 7th and 28th day.

6. Additional Cubes : For earlier removal of forms other than specified in Table 10 or for pre-stressed concrete before transfer. However, Cl 4.9 & 8.4 must be complied. Two cubes required from each sample (nota: The curing of the cube shall not followthe normal condition but to simulate the actual field condition and kept separately from the curing bed)

7. Rate of Sampling : Must comply with Cl 4.3. Three (3) cubes taken from each sample. One(1) tested for 7 day strength and Two(2) for 28 day strength. First day of concreting, twelve (12) cubes from four (4) samples must be taken regardless of volume for each grade of concrete.

8. Tempreture : Cl 5.6 shall be observed. For Cl. 5.5-c *plastic sheet / tarpaulin shall be used for cast in-situ slabs, prestressed slab, slab toppings, cast insitu beams and post tensioned beams.

9. Curing & Protection : Must start by final set time of concrete ie 600min. Method of curing is by *wet gunny sack / impermeable sheeting / continuous wetting of surface / membrane forming curing compound. Curing period shall not less than 5 days.