International Journal of Engineering Research in Africa Submitted: XX ISSN: 1663-4144, XXX Revised: XX Accepted: XX © 2020 Trans Tech Publications Ltd, Switzerland Online: XX Rheological, Mineralogical and Strength Variability of Concrete Due to Construction Water Impurities Paul O. Awoyera 1,a* , Oyinkansola Awobayikun 1,b , Ravindran Gobinath 2,c , Amelec Viloria 3,4,d,e , Emmanuel I. Ugwu 5,f 1 Department of Civil Engineering, Covenant University, Ota, Nigeria 2 Centre for Construction Methods and Materials, S R Engineering College, Warangal, India 3 Univeridad de la Costa, Barranquilla, Colombia 4 Universidad Peruana de Ciencias Aplicadas, Lima, Peru 5 Department of Civil Engineering, Michael Okpara University of Agriculture, Umuahia, Nigeria a paul.awoyera@covenantuniversity.edu.ng, b oyinkansolaawobayikun@gmail.com, c gobinathdpi@gmail.com, d aviloria7@cuc.edu.co, e amelec.viloria@upc.pe f emmanuelugwu@mouau.edu.ng Keywords: Concrete Mixing; Hydration; Mineralogy, Morphology; Rheology; Strength; Water Abstract. Various national and international standards recommend potable water for mixing concrete; however, the availability of potable water is virtually a daunting task in some developing communities. Concrete workers in such environments tend to utilize any available water for mixing concrete, and this may be detrimental to the quality of the concrete being produced. This study investigates the rheological, mineralogical and strength variability of concrete due to construction water impurities. Water samples were collected from four different construction sites within Southwestern region of Nigeria for production of concrete. The physical and chemical properties of the waters were determined so as to measure their rate of contamination, prior to their use for mixing concrete. The rheological properties of the fresh concrete, compressive strength, split tensile strength, and microscale features of hardened concrete, that were produced with each water sample were determined. From the results, the rheological features of concrete were found not to be affected by water impurities, however, the mechanical test results revealed about 10% reduction in strength between concrete made with water having least and higher concentration of impurities. Also, it was evident from the microscale tests that the water impurities do alter the hydration rate of concrete, which results in strength reduction. The study suggests pretreatment of concrete mixing water before use in order to avoid its damaging effect on concrete life. 1. Introduction Concrete mixing water is so significant in projects, in that it influences workability, hydration process, and overall strength development in concrete. However, when impurities are present in construction water, the aforementioned properties may be consequently hindered. One of the most important factors that determine the life span of any structure is the strength of the concrete used for construction; however, the strength of any concrete is determined by the combined efficiency and adequacy of each of its constituent materials. This research is focused on the quality of water used in mixing concrete and its effects on the workability and strength of the concrete. Water serves a vital role in concrete mixture, for instance, it is used for wetting the aggregate surfaces in order to enhance adhesion between the cement and the aggregates, as adhesion will surely be poor on a dry surface, and also used when moisturizing the cementing materials temporarily to harden properly during the curing period. The quality of water used during the concrete mixing process could maintain or alter the expected level of strength of concrete. Certain chemical compounds, when present in water may seriously alter the strength, durability and setting time of concrete. Some of these compounds include nitrate [1], limestone and anhydrite [2, 3], sulfate and sulfate–chloride [4].The rheological properties of All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (#540667285, Covenant University, Nigeria-03/07/20,16:58:40)