A low absorption rate and a small thermal conductivity coefficient are the main targets in the preparation of traditional coarse lightweight aggregate (LWA). Fine LWA is generally used as internal curing materials and crushed from coarse LWA. Large pores or low water absorption will reduce the effectiveness of internal curing. In this study, a waste-based fine LWA with high water absorption (≥20%) has been made of bauxite tailings, silica fume, and paper sludge. The pore structure formation of fine LWA was analyzed. Time-dependent water absorption, water desorption, and pore structure of fine LWA were tested. Their effects on the early-aged hydration, autogenous shrinkage, pore structure, and compressive strength of high-strength mortars were studied. The results showed that different from the isolated and large pore structure of the expanded shale, fine LWA had a connected and fine pore structure of 200–2000 nm. It could absorb about 30.6% water by mass and quickly reaches saturation, and more than 95% of water absorbed was released at 97% relative humidity (RH). Fine LWA had a good water retention capacity and did not result in the delay of the main hydration. The capillary pore size of 20–50 nm increased and the total porosity reduced due to the increased degree of hydration. Compared to the high-strength mortars with the same mixing water content, fine LWA reduced the autogenous shrinkage of mortars by up to 88% and increased the strength of mortars by up to 2.5%.

低吸收率和小导热系数是传统粗轻骨料（LWA）制备的主要目标。细LWA一般用作内固化材料，由粗LWA粉碎而成。气孔大或吸水率低会降低内固化效果。在本研究中，以铝土矿尾矿、硅灰和造纸污泥为原料，制备了一种具有高吸水率（≥20%）的废物基精细 LWA 。分析了精细LWA的孔结构形成。测试了精细 LWA 的随时间变化的吸水率、水解吸率和孔隙结构。它们对早期水化、自收缩、孔隙结构和抗压强度研究了高强度砂浆。结果表明，与膨胀页岩的孤立大孔结构不同，细LWA具有200~2000 nm的连通细孔结构。它可以按质量吸收约30.6%的水并迅速达到饱和，在97%的相对湿度（RH）下释放95%以上的水。Fine LWA具有良好的保水能力，不会导致主水化延迟。由于水化程度的增加，20-50 nm 的毛细管孔径增加，总孔隙率降低。与相同拌合含水量的高强砂浆相比，细LWA降低砂浆自收缩率达88%，提高砂浆强度达2.5%。