Behaviour of fresh and hardened concrete incorporating marble and granite sludge as cement replacement

Abstract

The present article aims to study the effect of using marble and granite sludge, resulting from ornamental stone industry, as cement replacement on the properties of fresh and hardened concrete mixes. The chemical analysis, mineralogical composition, and physical properties of marble and granite sludge as well as OPC were measured using XRF, XRD, BET, and BT techniques. The experimental work has been conducted through two steps, the first step included preparation of nine mixes of blended cement pastes, and the second step included preparation of nine concrete mixes. The two steps were prepared using different proportions of marble and granite sludge substituting for cement binder by 10%, 20%, 30%, and 40% in addition to the control mixture with 0% sludge. The initial and final setting times of the blended cement pastes were determined using Vicat test. The workability of the fresh concrete mixes was determined using slump test. The physico-mechanical properties of all hardened concrete mixes such as water absorption, porosity, density, compressive, flexural, and splitting tensile strengths were measured at different curing ages starting with 7 days passing through 28 days and ending with 56 days. Regarding the durability performance of the hardened concrete mixes, various tests such as water penetration depth and chloride ion penetration were measured at 28 days of curing, and the acid attack test was determined at 7, 28, and 90 days of exposure after normal curing at 28 days.The results clearly revealed that there is an improvement towards the water penetration depth and sulphuric acid attack resistance at all replacement levels more than the control mixture. Regarding the other properties such as water absorption, density, strengths, and chloride penetration, there is insignificance decline up to 20% marble and granite sludge compared with the control mixes. It is recommended to utilize both marble and granite separately up to 20% as cement replacement in concrete making without adversely impact on its the mechanical or durability performance. The results of all hardened concrete mixes are in compatible with the requirements of concrete bricks and concrete paving units in terms of water absorption and compressive strength.