The effects of using metakaolin and micro-nanobubble water on concrete properties

Abstract

The concrete industry is one of the major producers of carbon dioxide (CO2) in the world while being one of the main consumers of drinking water. The new technologies and methods which reduce air pollution and water consumption may be helpful to achieve the goals of sustainable development. Pozzolanic materials are one of the primary substitutes of cement in concrete. In this study, the cement was partially replaced by meta-kaolin (pozzolan) while the water for concrete mixture was enriched with micro-nano bubbles to reduce the consumption of drinking water. Superplasticizers in all concrete samples were used. In the next step, compressive, flexural, and tensile strengths, concrete resistivity, and water absorption were measured. Rapid Chloride Permeability Test (RCPT) and scanning electron microscopy (SEM) of concrete samples were carried out to have an insight into the microstructure of the concrete. The results indicated that adding 10% (w/w) meta-kaolin as cement replacement, after 28 days, increases compressive strength, tensile strength, concrete resistivity and water absorption of concrete samples up to 4.75%, 25%, 123%. 52%, 7.82%, respectively, compared to the control samples. Furthermore, replacing 100% of drinking water by water containing micro-nano bubbles in the concrete samples increased compressive strength, tensile strength, concrete resistivity and water absorption of concrete samples up to 13.2%, 19.64%, 164.7%, and 66.95%, respectively, compared to the control samples of the same age, 28 days. The simultaneous application of meta-kaolin and micro-nano bubbles of water in the concrete improved mechanical properties of concrete samples, compressive and tensile strength, by 15% and 39.28%, respectively. The durability of the concrete samples, including concrete resistivity, water absorption and the RCPT results at the age of 28 days improved up to 194.11%, 84.75%, and 25.21%, respectively, while using superplasticizer, compared to the control samples.