Calcined kaolinitic clay as a supplementary cementing material and its pozzolanic effect on concrete blends characteristics (Part 2)

Abstract

Part II included using of calcined kaolinitic clay (CKC) prepared by a fluidized bed kiln as a supplementary cementing blend and assessing its effect on the OPC and the durability of concrete.The experimental protocol included optimization of the mixes of CKC/OPC containing 10 and 15% CKC for the production of hardened concrete as determined in part I, and in this work, the durability against chlorides, sulfate, seawater, and heating was studied.The effect on the reinforcement steel was also assessed.It was found that the partial replacement of cement with CKC (10 and 15%) caused slight expansion of concrete within the limits and there was no significant effect on the alkaline silica reaction or alkalinity of the concrete medium.The ratio of 15% CKC/OPC achieved a higher percentage of CSH that enhanced the compactness of the concrete matrix.When using CKC in plain concrete, the ratio of 10% CKC/OPC resulted in better resistance against the aggressiveness of salt solution attack and the highest compressive strength under the different conditions, whereas it reached 24.6 and 21.5% for 10 and 15% CKC/OPC respectively compared with the control concrete after aging of 180 days.The ratio of 10% CPDK/OPC achieved high resistance to heating.The porosity for the concrete modified with CKC was minimal resulting in low permeability of concrete for the salt solutions causing protection of the reinforcing steel against corrosion.