Deformation behaviors of highly-fluidized geopolymer concrete during dynamic compression at high strain rates
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摘要: 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Ø100mm 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εc随应变率的变化表现出明显的冲击韧化效应，εc随应变率的升高先增大后减小，满足二次函数关系εc＝-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。 -
关键词:
- 固体力学 /
- 变形特性 /
- 动态压缩实验 /
- 高流态地质聚合物混凝土 /
- 波形整形技术
Abstract: The highly-fluidized geopolymer concrete(HFGC)with the strength grade of C30was prepared by using slag and fly ash as raw material as well as NaOH and Na2CO3as alkali activator.Dynamic compression tests were carried out for the prepared HFGC specimens by using the 100-mm-diameter split Hopkinson pressure bar (SHPB)apparatus improved by the pulse-shaping technique.And in the dynamic compression tests, the dynamic stress equilibrium and the nearly constant strain rate loading were achieved by controlling the technique parameters.Based on the above tests, the deformation behaviors of the HFGC under the impact loadings were analyzed.The HFGC belongs to brittle and strain-rate sensitive materials.The typical stress-strain curve of the HFGC concludes compaction stage, elastic stage, softening and yielding stage at high strain rates.In the strain rate range from 10to 100s-1, the variation of the HFGC's peak strain with stain rate embodies obvious impact toughening, the peak strain increases firstly and then decreases with rising stain rate.And the overall change accords with the quadratic functionεc=-1.2×10-6+1.6×10-4 +0.001 7, and the critical strain rate of deformation behaviors is 66.7s-1.The dynamic elastic moduli of the HFGC are lower than the quasi-static ones. -
图 3 不同应变率下HFGC试样的应力应变曲线
Figure 3. Stress-strain curves of HFGC specimens at different strain rates
图 4 高应变率下HFGC试样典型的应力应变曲线
Figure 4. Typical stress-strain curve of HFGC specimens at high strain rate
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