Effect of sludge ceramsite particle grade on static and dynamic mechanical properties of alkali-activated slag lightweight concrete at early age

Sewage sludge (SS) produced in water supply and drainage plants is a kind of solid waste with pollution and high water content. SS mixed with fly ash and other materials to make sludge ce-ramide (SC) can be used as light environmental protection building materials. Alkali-activated lightweight concrete (ASLC) is prepared by mixing SC with alkali-activated slag mortar with low carbon emission, which has lightweight and early strength characteristics. Using the split Hop-kinson pressure bar test system, the dynamic and static uniaxial compressive tests of ASLC at an early age were carried out. The influence of aggregate particle gradation on the mechanical prop-erties of ASLC was comprehensively evaluated from static compressive strength and dynamic peak stress. Experiments show that small-size SC has better mechanical properties and lower air content. SEM test shows that the paste has closely meshed with SC, which proves that SC has good compatibility with alkali-activated slag material. The air content of ASLC was quantified by mesopore characterization. The results show that the increase in SC size will increase the air con -tent of the specimen and weaken the compressive performance of ASLC.