Common use of Admixtures Clause in Contracts

Admixtures. Usually the water proof concrete specifications are written aiming to achieve a watertight concrete structures. But practically the concrete can sometime be very difficult to place. If agreed by the Engineer, the contractor will be permitted to use concrete with more plastic consistency helping to produce a smoother and denser floor and wall finishes requirements. In heavy reinforced structures, a good and long workability is also important. It is impossible to meet the water/cement ration > 0.5 and a good workability requirements at the same time unless concrete admixtures are used. Contractor may use admixtures and shall use if required by the Engineer admixtures such as: − Retarder − Accelerator − Plasticizer or super plasticizer − air entraining agent − water proofing admixtures − Fluid admixtures − Anti freeze admixtures Plasticizer and super plasticizer gives good workability and correct consistency (even for pumped concrete with extended working times) to enable the concrete to be compacted as fully as possible in as short a time as possible with a high reduction in the water/cement ratio.