风积沙混凝土力学性能及孔隙特征

为了解决中国西北地区天然河砂分布不均及资源短缺的问题,利用库布齐沙漠风积沙替代部分天然河砂作为细骨料配制风积沙混凝土,通过立方体抗压强度、劈裂抗拉强度与核磁共振孔隙等因素对风积沙混凝土进行试验研究.结果表明:随着风积沙掺量增加,混凝土立方体抗压强度与劈裂抗拉强度均呈先增高后降低的趋势,且风积沙掺量分别为20%,30%与40%的混凝土可满足设计强度要求;随着养护龄期增加,风积沙掺量为30%的混凝土强度值增长幅度最大.风积沙混凝土核磁共振T₂图谱共有3个特征峰,随着养护龄期增加,混凝土中大孔隙都向着小孔隙方向发展;随着风积沙掺量增加,孔隙度呈先降低后增高的趋势,且凝胶孔与毛细孔呈先增加后减少的趋势.该研究可以为风积沙混凝土在中国干旱半干旱地区水利工程中应用推广提供理论依据.

Mechanical properties and pore characteristics of aeolian sand concrete

In order to solve the problem of uneven distribution of natural river sand and resource shor-tage in northwestern of China, aeolian sand concrete was prepared by using the aeolian sand of Kubuqi Desert to replace part of natural river sand as fine aggregate. The experimental study on aeolian sand concrete was carried out through the cube compressive strength, splitting tensile strength and nuclear magnetic resonance porosity. The research results show that with the increase of the aeolian sand content, the early cubic compressive strength value and the splittling tensile strength value of the aeolian sand concrete both first increase and then decrease. The aeolian sand content with 20%, 30% and 40% concrete can meet the design strength requirements. With the increase of the curing age, the cubic compressive strength and splitting tensile strength of each group of aeolian sand concrete specimens increase differently, and the strength value of concrete with 30% aeolian sand has the largest increase. The T2 spectrum of aeolian sand concrete has three characteristic peaks. With the increase of curing age, the large pores in the concrete develop towards small pores. As the amount of aeolian sand increases, the porosity first decreases and then increases. The gel pores and pores show a tendency to increase first and then decrease. This research can provide a theoretical basis for the application and promotion of aeolian sand concrete in water conservancy projects in arid and semi-arid areas in China.