Impact of Mechanical and Thermal Treatment of Kaolin Clay on the Engineering Properties of Concrete

Kaolin Clay, an economical alternative to nanofillers, is an innovative mineral employed as a concrete additive. Historically, this material was used primarily as a cement substitute in concrete, owing to its inherent cementing properties. This study explores the potential of using Kaolin Clay as a partial replacement for ordinary Portland cement (OPC) and a supplemental cementitious material (SCM), potentially enhancing concrete's affordability, environmental sustainability, and overall mechanical performance and durability. Kaolin Clay exhibits pozzolanic properties, produces a significantly smaller carbon footprint compared to OPC, and is readily available in nature. This research employed thermally and mechanically activated clay, ranging from 0 to 15% (in 2.5% increments), as a partial cement substitute in concrete for performance evaluation. The evaluation encompassed mechanical properties (split tensile strength, compressive strength) and durability performance measures (water absorption, sorptivity coefficient, and acid attack resistance). It was found that concrete with 15% thermally activated (TAK) and mechanically activated (MAK) Kaolin Clay performed admirably compared to the control mix (having no kaolin clay). At 28 days, the strength of the MAK-150 (15% mechanically activated kaolin clay) mix improved by 26.8% and TAK-150 by 30% compared to the control. Likewise, the tensile strength of MAK-150 increased by 25.9% and TAK-150(15% thermally activated kaolin clay) by 33%, revealing the promising potential of Kaolin Clay in enhancing concrete performance. Furthermore, the MAK-150 absorbs 21% less water than the control mix, whereas the TAK-150 absorbs 26% less. The utilization of a composite blend TAK-150, comprising of Kaolin clay, results in a reduction in costs by 8.4% in comparison to the M0 (having no kaolin clay) blend, which includes cement.