Optimization of mechanical properties and water absorption behavior of building gypsum by ternary matrix mixture

Abstract

• The optimization analysis of a ternary matrix mixture of building gypsum. • Multifactor experiments were performed using the Box–Behnken design approach. • The effects of different multifactor were analyzed using response surface methodology. Building gypsum has the disadvantages of low strength and poor water resistance, which limits its wide use. In this paper, the mechanical properties and water absorption behavior of building gypsum by ternary matrix mixture (including cement, fly ash and lime) were optimized. Three maximum levels under the influence of different factors (including cement, fly ash and lime) were initially obtained through single-factor experimental analysis. Next, multifactor experiments were performed using the Box–Behnken design approach. The effects of different multifactor were analyzed using response surface methodology, and relevant prediction models were established and verified. Subsequently, the effects of different factors were verified through optimization mechanism analysis, including thermogravimetric analysis, X-ray diffraction, and scanning electron microscope. The results indicated that the maximum compressive strength and water absorption values were observed at a single-factor impact (including cement, fly ash, and lime) content of 20 %. Prediction models of the compressive strength and water absorption were established, and the proposed models exhibited a high degree of fitness. In addition, the optimum content ratios for the compressive strength and water absorption were cement: fly ash: lime = 10 %: 20 %: 14.86 % and 20 %: 20 %: 14.29 %, respectively. Furthermore, the optimal group exhibited a high intensity, the total weight loss decreased by 35 %. at high temperatures, and a homogeneous structure and distributed crystalline network of gypsum crystals were formed.