USE OF STABILIZER AGENTS IN MIXER DRUM WASH WATER

This project was undertaken to study the potential of using overnight-stabilized wash water in the production of fresh concrete. Main tasks of this study were: review of literature on the use of stabilizer systems, determination of properties of concrete containing stabilized wash water, and evaluation of this concrete compared with control mixtures not containing a chemical stabilizer. Information from the literature review revealed that the properties of concrete made from stabilized wash water and/or stabilized waste concrete ranged at comparable levels to the control mixtures. Literature showed there were no significant differences in compressive strength, flexural strength, or modulus of elasticity. However, stabilized mixtures had slightly higher drying shrinkage values and reduced set times due to the use of an activator. Properties of stabilized concrete and their control mixtures were evaluated using a number of fresh and hardened concrete tests (temperature, slump, unit weight, air content, set time, compressive strength, flexural strength, drying shrinkage, resistance to chloride-ion penetration, time to corrosion, and sulfate expansion). Mixtures were evaluated in the laboratory under conditions that simulated overnight stabilization of their wash water to determine how the fresh and hardened properties changed. The objectives of this Florida Department of Transportation (FDOT) project were to verify the performance test results reported by Master Builders for concrete produced with Florida aggregates and DELVO Stabilized wash water. Through this supporting data perhaps FDOT will develop the use of DELVO technology in the reuse of mixer wash water in order to reduce concrete mixture costs, increase concrete construction productivity, and reduce the adverse environmental impact associated with the disposal of mixer wash water. The results of this study indicated that the use of DELVO Stabilizer in overnight applications is a viable means of reducing the disposal of wash water for concrete.