Effects of sulfuric acid attack on hydrated calcined clay-limestone cement mortars

The paper presents experimental findings on the performance of Limestone Calcined Clay Cement (LC3) in acidic media. LC3 was made by inter-grinding a blend of 50 % clinker with ground 30 % Fired Rejected Clay Bricks (FRCB), 15 % limestone and 5 % gypsum. Compressive strength and water absorptivity of LC3 mortars were investigated vis-a-vis commercial Ordinary Portland Cement (OPC) and Portland Pozzolana Cement (PPC). Microstructural analysis of hydrated LC3 samples was conducted using Scanning Electron Microscope (SEM) before and after immersion in 3% H2SO4. LC3 reported the least water absorptivity than PPC and OPC. Additionally, LC3 exhibited equivalent water absorptivity and resistance to acid attack compared to PPC. Micro-cracks were observed in SEM images from LC3 samples after immersion in acid. In conclusion, strength loss, at w/c = 0.50 and 0.60, LC3 exhibited 12.71 % and 14.06 % respectively, higher resistance to acid attack than OPC.