水下自护混凝土与钢筋握裹力试验研究

随着水下自护混凝土技术的推广和应用，其关键工艺参数水下保护剂浓度对水下自护钢筋混凝土结构性能的影响成为关注的热点。基于水下自护技术，在常用工作浓度范围内，对水下自护混凝土的素混凝土力学性能、混凝土与钢筋握裹力、微观孔隙结构开展了试验研究。试验结果表明：在不同水下保护剂浓度下，水下自护素混凝土抗压强度水陆强度比均超过80%；混凝土与钢筋握裹力水陆强度比约在40%～65%，水下保护剂浓度越高，混凝土与钢筋握裹力水陆强度比越低；混凝土基质区域孔隙率和混凝土与钢筋握裹力存在负相关关系；水下保护剂能够有效提升水下自护混凝土的力学性能，但水下保护剂浓度的提升会对混凝土与钢筋握裹力强度造成不利影响。因此，合理选择水下保护剂浓度并增加钢筋用量是提升水下自护钢筋混凝土工程的可靠性的重要举措。

Experimental study on the bond strength between self-protected underwater concrete and steel bars

Self-protected underwater concrete (SPUC) is widely used in concrete projects, as the key parameter of SPUC, the concentration of underwater protective agent (UPA) has a significant impact on the structural performance of SPUC, which has become the research focus nowadays. Based on SPUC technique, experimental studies on the mechanical properties of plain SPUC, the bond strength between SPUC and steel bars, and the microstructure of SPUC pores under the commonly used working concentrations were conducted. The results showed that the water-to-ground strength ratio of plain SPUC compressive strength was over 80% at different concentrations of UPA; the water-to-ground strength ratio of the bond strength between SPUC and steel bars was about 40%-65%, and the higher the concentration of UPA, the lower the water-to-ground strength ratio of the bond strength between SPUC and steel bars. In addition, the porosity of the concrete matrix region is negatively correlated with the bond strength between SPUC and steel bars. UPA can effectively improve the mechanical properties of SPUC; however, the increase in the concentration of UPA will cause adverse effects on the bond strength between SPUC and steel bars. Therefore, the rational selection of the concentration of UPA and the increase in the amount of reinforcing steel bars are crucial measures for enhancing the reliability of self-protected reinforced underwater concrete projects.