Effects of cement paste viscosity on the properties of lightweight expanded polystyrene concrete

Lightweight expanded polystyrene concrete (EPS-C) offers several advantages, including low density, sound resistance, and good thermal insulation. These characteristics are contributed by the use of expanded polystyrene (EPS) with a closed cellular structure, which is non-absorbent, hydrophobic, and low-density (around 6.9 kg/m³). Since EPS is much lighter than cement paste, the viscosity of the paste plays an important role indirectly affecting segregation and the properties of EPS-C mixtures. This paper presents the experimental results of the viscosity and its influence of cement paste on both the segregation of the concrete mixture and thecompressive strength of EPS-C. The research revealed that a viscosity of cement paste below 50 mPa.s resultsin segregation of the concrete mixture. As the viscosity increases, the degree of segregation decreases. However, when the viscosity exceeds 180 mPa.s, using a viscosity-modifying admixture becomes a good solution to prevent segregation in EPS-C mixtures. Therefore, the optimal viscosity range for the binder paste to ensure the concrete mixture does not segregate is between 50 and 180 mPa.s.