Use of recycled cement-based slurry water for making concrete

Abstract

Due to limited water resources in Singapore and the escalating cost of potable water, industries are constantly encouraged and challenged not only to generate less wastewater, but to recycle, reuse or reclaim as much as possible. In the construction industry, a substantial amount of potable water is consumed annually. If the wastewater generated from some construction-related activities could be recycled and re-channelled as part of their consumption needs, a lot of savings would be realised and environmental sustainability practised. Unfortunately, due to a lack of performance-based industrial standards and emphasis, limited research data and inappropriate wastewater management practices, the use of recycled cement-based slurry water for making concrete has not been widespread. Thus the aim of this paper is to define the limits and extent to which cement-based slurry water from the concrete batching plant can be recycled and totally reused for making concrete without the need for further treatment. The study focused on the effects of using such mixing water on the fresh and hardened properties of concrete with reference to acceptance criteria of existing standards. Results showed that concrete produced with slurry water was able to meet the performance criteria in terms of compressive strength, setting time and drying shrinkage when the S.G of the slurry water used was less than 1.03.