Standard Method of Test for. Quality of Water to Be Used in Concrete. This standard has been discontinued due to lack of use. T All rights reserved. Duplication is a violation of applicable law.
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Cements and supplementary cement replacement materials shall be certified by the manufacturers as specified in the requirements of the appropriate standards. The Contractor shall select the mix proportions and, unless otherwise specified, the workability in order to satisfy the strength and other requirements of the Contract.
Cement may be supplied in sealed bags which shall bear the manufacturer's name, type of cement, weight of bag and the date of manufacture. Each consignment of bagged cement shall be kept separate from other consignments. Silos for storing fly ash shall be equipped with aerators to ensure free flow within the silo.
Such sheds or buildings shall be used exclusively for the storage of cement and shall be erected with the floors raised at least 30 cm above the ground. Stacks of cement shall not exceed 10 bags in height. Each size of aggregate shall be stored separately. Accreditation Service or equivalent. For reinforced concrete and mass concrete work the level of soluble sulphates and chlorides in the aggregate shall not exceed the values stated in ACI M.
Chloride levels of the aggregates shall be determined daily, in accordance with BS Part or less frequently when the long term variability has been established. The overall grading shall be controlled throughout the work so that it conforms closely to that assumed in the selection of the mix proportions. Where sacked cement is supplied no fraction of a sack shall be used in a batch of concrete unless the cement is weighed.
Separate weighing machines shall be used for cementitious materials and aggregates. Scales shall be accurate to 1. The discharge chute shall not be suspended from the weighing hopper and shall be so arranged that cement does not lodge in it or leak from it during use.
Continuous mixers shall not be used. In measuring water for each batch of concrete, allowance shall be made for the water contained in the aggregates and for the fluid content of any admixture. The total water in the batch shall be deemed to consist of the water carried by the aggregates and any admixtures plus the water added. The flow of water shall be uniform and all water shall be in the drum by the end of the first 15 seconds of the mixing period. Any admixtures to be added shall be measured and, if solid, shall be measured by weight.
Different types of cement shall not be mixed. Mixing time shall be not less than 60 seconds for mixers having a capacity less than 1. The first batch of concrete through the mixer shall then contain an appropriate additional quantity of cement.
Mixing plants shall be thoroughly cleaned before changing from one type of cement to another. In no circumstances shall the consistency of the concrete be such as to permit a separation of the aggregate from the mortar during handling.
Excess water shall not be permitted and any batch containing such excess shall be rejected. The concrete shall be carried in purpose-made agitators, operating continuously, or truck mixers. The concrete shall be compacted and in its final position within 90 minutes maximum of the introduction of cement to the aggregate.
The time of such introduction shall be recorded on the delivery note together with the weight of the constituents of each mix. Workability shall be measured for each batch.