风积沙混凝土轴心受压力学性能研究

Study on Axial Compression Performance of Aeolian Sand Concrete

风积沙混凝土的力学性能是表征风积沙混凝土性能优劣的重要指标,国内外学者对风积沙混凝土的立方体抗压强度、劈裂抗拉强度及微观作用机制进行了广泛研究。关于混凝土轴心受压力学性能研究成果较少,而混凝土棱柱体受压更加接近于工程实际。因此,试验设计风积沙(替代率为0~40%)和粉煤灰(替代率为10%~20%)内掺替代等质量的河砂及水泥,制备了10组风积沙-粉煤灰混凝土,进行60 d风积沙-粉煤灰混凝土轴心抗压试验,开展风积沙-粉煤灰混凝土轴心受压破坏形貌、微观结构、应力-应变关系、轴心抗压强度、峰值应变、弹性模量、泊松比等内容的试验研究。结果表明:弹性阶段各掺量风积沙混凝土应力-应变曲线基本趋于一致,进入弹塑性阶段后,风积沙混凝土较基准混凝土应力增长较快,混凝土脆性增加。轴心抗压强度、弹性模量及泊松比随风积沙掺量增加呈现先增大后减小的变化趋势,随粉煤灰掺量增加在降低。最后,对过镇海经典模型上升段本构参数A进行二次演化,建立了本构参数与轴心抗压强度和风积沙掺量之间的演化模型,得出风积沙混凝土应力-应变上升段本构方程,其计算模型对风积沙混凝土的研究应用具有一定借鉴。

Mechanical properties of aeolian sand concrete,are important indicators to characterize the performance of aeolian sand concrete.Domestic and foreign scholars have extensively studied the cubic compressive strength,splitting tensile strength and microscopic mechanism of aeolian sand concrete,but there are few researches on the mechanical properties of concrete under axial compression,while the compression of concrete prism is closer to the engineering practice.Therefore,10 groups of aeolian sand-fly ash concrete were prepared by mixing aeolian sand(replacement rate was 0~40%)and fly ash(replacement rate was 10%~20%)with river sand and cement of equivalent quality.The 60-day-old aeolian sand-fly ash concrete axial compression test was carried out,and the axial compression failure morphology,microstructure,stress-strain relationship,axial compressive strength,peak strain,elastic modulus and Poisson’s ratio of the aeolian sand-fly ash concrete were tested.It was found that the stress-strain curves of aeolian sand concrete with different amounts of aeolian sand in the elastic stage are basically consistent.After entering the elastic-plastic stage,the stress of aeolian sand concrete increases faster than that of the reference concrete,and the brittleness of concrete increases.The axial compressive strength,elastic modulus and Poisson’s ratio showed a trend of increasing first and then decreasing with the increase of aeolian sand content,and decreased with the increase of fly ash content.Finally,the constitutive parameter A of the rising section of Guo Zhenhai’s classic model was subjected to secondary evolution,and an evolution model between the constitutive parameter and axial compressive strength and aeolian sand content was established.The constitutive equation of the stress-strain rising section of aeolian sand concrete was obtained.The calculation model had certain reference for the research and application of aeolian sand concrete.