Influence of Waste Slurry as Mixing Water on the Properties of C80 Concrete with Different Mineral Admixtures

Abstract

This paper mainly explores how waste slurry as mixing water affects the properties of C80 concrete. The waste slurry was collected from a mixing station. Two types of C80 concrete were prepared with different mineral admixtures: type I concrete mixed from 15% fly ash and 20% slag powder, and type II concrete mixed from 20% fly ash and 10% silica fume. The properties of the two types of concrete were evaluated in terms of working performance, mechanical properties, and durability. In addition, the influence of waste slurry on microstructure of concrete was analyzed through X-ray diffraction (XRD). The results show that, with the growing content of waste slurry, slump and expansion were declining; the initial and final setting times gradually increased, but the increments were not significant; with the growing content of waste slurry, the 7d compressive strength of type I concrete stayed below that of reference concrete, and gradually decreased, but the later compressive strengths increased rapidly; the 7d compressive strength of type II mineral admixture concrete gradually increased, while the later compressive strengths increased first and then decreased. Besides, the addition of waste slurry enhanced the resistance to chloride ion penetration (CIP), and increased the carbonization depth of concrete. The 7d XRD peak of using tap water as mixing water was slightly higher than that of using waste slurry as mixing water; the 28d XRD peak of the former was slightly lower than that of the latter. The research provides reference for applying waste slurry in concrete production.

Treatment of Mixer Truck Wash Water of a Ready-mix Concrete Batching Plant Using a Low Cost Modified Sand Filter

“…Existing palm fibre filters can only reduce the COD to 146 mg/L (Table 2), which does not meet the requirements for disposal into the environment. The high COD value may be contributed by the solid content derived from cement and other admixtures (Holley et al, 2019, Tsimas, & Zervaki, 2011, He et al, 2020, Mohamed et al, 2015, Chen et al, 2020. The first trial of the wastewater treatment used alum as the coagulant.…”

“…Reused waste slurry improves the permeability and carbonation resistance of concrete and increases the compactness of concrete (Chen et al, 2020), decreasing setting time (Aldossary et al, 2020). Moreover, higher Total Dissolved Solid/TDS (in the range of 500; 1,000; 5,000 ppm) increase compressive strength by up to 20%.…”

“…The existing final filtrate still has high turbidity and high COD, polluting the surrounding mangrove areas. In fact, this water still can be processed further to be reused for washing vehicles transporting liquid concrete, for domestic use in bathrooms and toilets, even as processing water (Chen et al, 2020Klus et al, 2017;Ekolu & Dawneerangen, 2010)…”