地聚物免烧结人造骨料混凝土的力学性能试验研究

Research on mechanical properties of geopolymer cold-bonded artificial aggregate concrete

以偏高岭土、粉煤灰和硅灰作为前驱体制备了两种地聚物免烧结人造骨料,进一步制备了135个人造骨料混凝土试件并对其性能进行研究。观察和研究了试件的破坏形态、抗压抗拉强度、应力-应变全过程曲线及各特征点参数,并对其微观形貌进行分析。结果表明:偏高岭土-粉煤灰-硅灰三元地聚物骨料具有最高的筒压强度(21.1 MPa)和比强度(11.6 MPa·cm^(3)/g)以及致密的微观结构,其配制的混凝土立方体抗压强度为65.53~97.34 MPa,轴心抗压强度为50.03~78.60 MPa,劈裂抗拉强度为4.12~5.94 MPa。提出了基于骨料强度修正的人造骨料混凝土Bolomey强度式。相比胶水比,骨料强度对混凝土强度的统计学意义影响更显著。随着骨料强度的提高,混凝土的峰值应力、峰值应变和初始弹性模量增加,脆性破坏特征更明显。地聚物免烧结骨料在混凝土中的力学性能表现远优于商用烧结黏土骨料。

Two kinds of geopolymer cold-bonded artificial aggregates using metakaolin(MK),fly ash(FA),and silica fume(SF)powder as the precursor were first prepared.135 artificial aggregate concrete specimens were further prepared and their properties were evaluated.The failure patterns,compressive strength,tensile strength,peak stress,peak strain,elastic modulus,and stress-strain curve were investigated,combining micromorphology analyses.Results from the tests showed that the MK-FA-SF ternary blend geopolymer aggregate had the highest bulk crushing strength(21.1 MPa)and specific strength(11.6 MPa·cm^(3)/g)as well as a denser micromorphology.The cubic compressive strength,axial compressive strength,splitting tensile strength of its resulting concrete was in range of 65.53~97.34 MPa,50.03~78.60 MPa,4.12~5.94 MPa,respectively.The Bolomey formula of artificial aggregate concrete strength based on the corrected aggregate strength was proposed.The aggregate strength had a more statistically significant effect on the concrete strength than the binder-to-water ratio.With the aggregate strength increased,the peak stress,peak strain,as well as elastic modulus of concrete increased,and the brittle failure characteristics were more obvious.The mechanical properties of concrete obtained from geopolymer cold-bonded aggregate in this research were far superior to the concrete prepared from commercial expanded clay aggregate.