Abstract:To achieve the resource utilization of sludge solid waste and improve the thermal performance of building materials, alkali-modified sludge biochar was used as the shaping base for paraffin. Paraffin/alkali-modified sludge biochar shape-stabilized phase change materials were prepared by vacuum adsorption method, and were partially substituted for cement to obtain low-carbon phase change energy storage mortar. The research shows that the proportion of paraffin/alkali-modified sludge biochar composite is a key factor in regulating the mechanical properties and thermal properties of the phase change mortar. The mechanical properties of the mortar decrease with the increase in the proportion, and are positively correlated with the apparent density of the mortar; the heat storage capacity and thermal conductivity both gradually increase with the increase in the proportion, and the thermal conductivity is negatively correlated with the apparent density. When the proportion of the shaped phase change material is 15%, the comprehensive performance of the phase change mortar is the best, with a compressive strength of 34.5 MPa, the latent heat of phase change and specific heat capacity increasing to 5.07 J·g-1 and 1.41 kJ·(kg·℃)-1 respectively, and the thermal conductivity decreasing to 0.7311 W·(m·K)-1. After 100 freeze-thaw cycles, the mechanical strength and heat storage performance of the mortar do not show significant attenuation. This developed phase change energy storage mortar meets the structural requirements and has good thermal insulation and durability, and is suitable for building energy conservation.
