Journals Proceedings

Abstract

This study focused on the effectiveness of Fly Ash (FA) and Silica Fume (SF) as cement replacements in reducing efflorescence on the surface of Ordinary Portland Cement (OPC) mortar. Previous studies have shown that FA and SF can potentially enhance the performance of cement mainly due to their reaction with calcium hydroxide (C-H) to develop more of the strength-carrying compound in cement structure namely calcium silica hydrate (C-S-H). This pozzolanic reaction is crucial in the mitigation of efflorescence by its relation to C-H leaching. The early hydration behavior of Pozzolanic Modified Mortar (PMM) that hypothetically affects efflorescence has been investigated through physicochemical characterization namely Puddle Test (PT), Standard Chemical Method (SCM), Compressive Strength Test (CS) and Scanning Electron Microscopy (SEM). PMM mortar samples were prepared with water-to-cement ratio (w/c) of 0.3, 0.4 and 0.5. FA and SF were used as 10%, 20% and 30% cement replacement by weight. Samples were cured at room temperature (32o C) and 90% relative humidity. Powdered and polished samples were prepared and tested at 28 days of hydration. Compared with conventional mortar, PMM exhibited lesser efflorescence whereby validation from CS and SEM images showed the evidence of pozzolanic reaction.