轻质骨料对泡沫混凝土性能的影响及其内养护机制

为降低泡沫混凝土干燥收缩,采用轻质骨料(页岩陶粒及粉煤灰陶粒)制备泡沫混凝土,研究了轻质骨料对泡沫混凝土抗压强度、干燥收缩、内部湿度及孔结构等的影响,并分析了轻质骨料的内养护机制。结果表明,轻质骨料能够调节泡沫混凝土的内部湿度,约束基体的变形,降低泡沫混凝土的干燥收缩。而轻质骨料也会在泡沫混凝土中引入缺陷,导致其强度降低。轻质骨料中大于100 nm的墨水瓶孔是内养护效果的控制因素,大于100 nm的墨水瓶孔数量越多,轻质骨料释水能力越强,内养护效果越好,制备的泡沫混凝土干燥收缩越小。

Effects of Lightweight Aggregates on Properties of Foamed Concrete and Internal Curing Mechanism

In order to mitigate the drying shrinkage of foamed concrete, lightweight aggregates (shale ceramsite and fly ash ceramsite) were used to prepare foamed concrete. Effects of lightweight aggregates on the compressive strength, drying shrinkage, internal humidity and pore structure of foamed concrete were studied, and the internal curing mechanism of lightweight aggregates was analyzed. Experimental results reveal that lightweight aggregates can adjust the internal humidity of foamed concrete, restrict the deformation of the matrix, and decrease the drying shrinkage of foamed concrete. However, lightweight aggregates can also introduce defects in foamed concrete, resulting in the decrease of compressive strength. The ink-bottle pores larger than 100 nm in lightweight aggregates are the control factor of efficient internal curing. The lightweight aggregates with more ink-bottle pores larger than 100 nm tend to possess stronger water release capacity and better effect of internal curing, thus resulting in lower drying shrinkage of foamed concrete.