高流态地质聚合物混凝土的高应变率动态压缩变形特性

以矿渣、粉煤灰为原材料,以NaOH、Na₂CO₃为碱激发剂,制备了强度等级为C30的高流态地质聚合物混凝土（highly-fluidized geopolymer concrete,HFGC）,运用波形整形技术改进了?100mm SHPB实验装置,通过参数控制保证应力均匀和恒应变率加载,对HFGC开展了动态压缩实验,分析了HFGC在冲击压缩荷载下的变形特性。HFGC属于应变率敏感材料和脆性材料,高应变率作用下,HFGC的典型应力应变曲线包括压实挤密阶段、弹性阶段和软化、屈服阶段。在10~100s-1的应变率范围内,HFGC的峰值应变ε_c随应变率的变化表现出明显的冲击韧化效应,ε_c随应变率的升高先增大后减小,满足二次函数关系ε_c＝-1.2×10-6+1.6×10-4+0.001 7,变形特性变化的临界应变率为66.7s-1。HFGC的动态弹性模量均低于其在准静态下的弹性模量。

Deformation behaviors of highly-fluidized geopolymer concrete during dynamic compression at high strain rates

Thehighly-fluidizedgeopolymerconcrete(HFGC)withthestrengthgradeofC30waspreparedbyusingslagandflyashasraw materialaswellasNaOHandNa2CO3asalkaliactivator.DynamiccompressiontestswerecarriedoutforthepreparedHFGCspecimensbyusingthe100- mm-diametersplitHopkinsonpressurebar( SHPB)apparatusimprovedbythepulse-shapingtechnique. Andinthedynamiccompressiontests,thedynamicstressequilibriumandthenearlyconstantstrain rateloadingwereachievedbycontrollingthetechniqueparameters.Basedontheabovetests,thedeformationbehaviorsoftheHFGCundertheimpactloadingswereanalyzed. TheHFGCbelongsto brittleandstrain-ratesensitivematerials.Thetypicalstress-straincurveoftheHFGCconcludescompactionstage, elasticstage,softeningandyieldingstageathighstrainrates.Inthestrainraterange from10to100s-1,thevariationoftheHFGC’speakstrainwithstainrateembodiesobviousimpact toughening,thepeakstrainincreasesfirstlyandthendecreaseswithrisingstainrate.Andtheoverall changeaccordswiththequadraticfunctionεc=-1.2×10-6ε·2+1.6×10-4ε· +0.0017,andthecritical strainrateofdeformationbehaviorsis66.7s-1.ThedynamicelasticmodulioftheHFGCarelower thanthequasi-staticones.