SAP对碱激发泡沫混凝土自收缩与热力学性能的影响OA

Alkali-activated foam concrete(AAFC)possesses multiple advantages,including low density,high strength,and excellent thermal insulation.However,its inherent susceptibility to shrinkage cracking remains a critical drawback that hinders widespread practical application.This study systematically investigated the effects of the morphology and water absorption/release behavior of superabsorbent polymer(SAP)on the workability,autogenous shrinkage,compressive strength,and thermal conductivity of AAFC using ground granulated blast-furnace slag as the primary binder.The underlying mechanisms were elucidated through thermogravimetric analysis(TG),scanning electron microscopy(SEM),low-field 1H nuclear magnetic resonance(1H NMR),and capillary pressure measurements.The results demonstrate that the addition polyacrylate SAP(SAP-A),characterized by a high-water absorption capacity and irregular morphology,significantly increases the yield stress and plastic viscosity of the paste,markedly raises the proportion of pores larger than 500 μm in diameter,and ultimately leads to a 30.5%reduction in the 28 d compressive strength of AAFC compared to the control group without SAP.In contrast,the incorporation of acrylic acid-acrylamide copolymer SAP(SAP-M),which exhibits a moderate water absorption capacity and spherical structure,facilitates uniform dispersion of bubbles.This optimizes the pore structure,thereby enabling the steady development of strength while reducing the thermal conductivity of AAFC to 0.089 W/(m·K).Furthermore,SAP-M rapidly releases its absorbed water after final setting,achieving a 32.6 percentage point higher cumulative water release at 3 d compared to SAP-A.This behavior effectively alleviates the development of capillary pressure and enhances the autogenous shrinkage mitigation efficiency by 28.7%.