Microstructural study on the effectiveness of commercial polymer emulsion as cement additives to mitigate efflorescence

Abstract

The occurrence of calcium carbonate (CaCO 3 ) effl orescence phenomenon is not new and is generally found in the form of unsightly white deposits on the surface of cement products. It appears just after completion of building construction and causes aesthetically unpleasant sight. This paper presents and discusses the results of microstructural study on the effectiveness of commercial polymer emulsion as cement additives to mitigate effl orescence on cement-based products that are dry-cured in the concrete laboratory at daily room temperature (T) and relative humidity in the range of 18°C‐28°C and 65%‐90%, respectively. Polymers used as cement additives were styrene acrylic ester (SAE) and styrene butadiene rubber (SBR) emulsion. Due to their pore-blocking characteristics and interaction with cement to improve mortar quality, they are added into cement to form mortar used for repair purposes. In order to investigate on how they can microstructurally infl uence effl orescence formation, effl orescence intensities (EI) in terms of percentages of CaCO 3 resulting from the combination of puddle test and standard chemical method were compared systematically between all samples on 28, 60 and 90 days and the fi ndings were discussed and corroborated physicochemically using initial surface absorption test, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and morphology using scanning electron microscopy (SEM). Results indicated that 10% and 5% SAE addition signifi cantly reduced primary effl orescence and secondary effl orescence, respectively, in comparison to SBR and Control. The infl uence were on chemical reactivity, interaction between polymer and cement and on the movement of the polymer particles within the hydrating mortar as hydration progressed to form pore-blocking effects in the microstructures of cement-based materials and were refl ected in the XRD patterns, TGA/DTG analysis, SEM images and the decreased initial surface water absorption.