Development of A New Local Mineral Admixture for Enhancing Concrete properties

Abstract

Proceeding from the saying of our God almighty on his book, the holy Qur'an: "Then ignite for me, O Hāmān, (a fire) upon the clay (From which bricks are made) and make for me a tower....". Therefore, this paper presents an investigation on, using calcined ball-clay (CBC) as mineral pozzolanic admixture for concrete production. CBC is obtained from calcination processes for local ball-clay at specified conditions. To evaluate ball-clay calcination process, various temperatures (600–900 ºC) and burning durations (2, 3 and 4 hours) are used and the optimum temperature and burning time for calcination are assessed by strength activity index at age of 28 days. The hardened properties development of concrete mixtures containing 0%, 10%, 15% and 20% CBC as cement partial replacement are analysed in terms of compressive strength at 7, 28, 90 and 180 days, water absorption, ultra-sonic pulse velocity and electrical resistivity. In addition, microstructure by XRD of the cement pastes incorporating CBC was studied. The results showed that the optimum calcination process to obtain CBC are carried out at temperature 800 °C for 4 hours. The replacement of cement by 10% of CBC is an optimal dosage for concrete mixtures since it achieved an increase of compressive strength by 28% as compared with control one. Therefore, adding CBC can lead to a beneficial utilization of natural local resources, which reduces energy consumption and minimizes CO2 footprint during the manufacturing of cement concrete, thus, concrete can become an eco-friendly and sustainable material.

Keywords

• mineral pozzolanic admixture
• calcined ball-clay
• compressive strength
• water absorption
• ultra-sonic pulse velocity and electrical resistivity