Mechanism analysis and effect of styrene–acrylate copolymer powder on cement hydrates

Abstract In this paper a styrene–acrylate copolymer (SAE) powder was used to modify Portland cement paste. The concentration of the products of hydration was investigated using X-ray diffraction (XRD). Also the physical and chemical interactions occurring in the modification process were studied using Fourier-transform infrared spectrometer (FTIR). The results show that the addition of SAE powder facilitates the formation of ettringite (AFt). The hydration product tetracalcium aluminate hydrate (C 4 AH 13 ) begins to appear in the cement paste after 7 days, its formation slightly decreases with an increase in the SAE powder–cement ratio ( m p / m c ). Single-sulfur hydrated calcium sulphoaluminate (AFm) is also found in the cement paste beginning after 7 days; however its content is very small. Also as the m p / m c is increased the amount of calcium hydroxide (Ca(OH) 2 ) in the hydrating cement paste decreases, this effect is more pronounced at earlier ages. FTIR analysis indicates that Ca 2+ –carboxyl complexes form during the hydration of cement paste containing SAE powder.