严寒与寒冷地区塑钢纤维轻骨料混凝土抗冻耐久性研究

The frost resistance durability of plastics-steel fiber reinforced lightweight aggregate concrete in sever and cold zones is the main in this project. Based on the theory of damage mechanics and structure reliability theory, the durability degradation and life prediction of plastics-steel fiber reinforced lightweight aggregate concrete are systematically investigated in freezing and thawing environment by the combination of engineering structure test technique and modern structural analysis theory, macroscopic experimental phenomena and microscopic structure analysis. Taken the fly ash haydite lightweight aggregate as object, the prewetting time of lightweight aggregate is determined by means of the strength and frost-resistance test of plastics-steel fiber reinforced lightweight aggregate concrete. The range of reasonable dosage of plastics-steel fiber in lightweight aggregate concrete is obtained combined with the requirement of engineering structure. The strength degradation plastics-steel fiber reinforced lightweight aggregate concrete and bond behaviour degradation of reinforcement after freeze-thaw damage are investigated on basis of experimental study and theoretical analysis. Then the freeze-thaw damage model on plastics-steel fiber reinforced lightweight aggregate concrete structure is established. Finally, durability failure criterion of the structure is established and durability life prediction method of plastics-steel fiber reinforced lightweight aggregate concrete is proposed in the freeze-thaw environment. The project aimed at the durability cutting-edge of concrete structures, which is great significance to promote the interdisciplinary and development of structural engineering and new materials engineering and to guarantee the sustainable and steady development of the national economy.

本项目围绕严寒与寒冷地区塑钢纤维轻骨料混凝土的抗冻耐久性问题展开，采用工程结构试验技术及现代结构分析理论、宏观试验现象与微观结构分析相结合的研究方法，以损伤力学理论和结构可靠度理论为基础，对冻融环境下塑钢纤维轻骨料混凝土结构的耐久性退化规律与寿命预测进行全面系统地研究。以粉煤灰陶粒轻骨料为对象，根据塑钢纤维轻骨料混凝土强度和抗冻性试验确定了轻骨料预湿时间，结合工程结构要求确定了塑钢纤维在轻骨料混凝土中的合理掺量范围。通过试验研究和理论分析，得出塑钢纤维轻骨料混凝土遭受冻融损伤后混凝土的强度性能退化规律以及钢筋的粘结性能退化规律，建立塑钢纤维轻骨料混凝土结构冻融损伤模型，确立结构耐久性破坏准则，提出冻融环境下塑钢纤维轻骨料混凝土耐久性寿命预测方法。本项目瞄准混凝土结构耐久性研究前沿，对于推动结构工程与新型建筑材料学科交叉及发展，保证国民经济可持续稳定发展具有重要意义。

本项目围绕严寒与寒冷地区塑钢纤维轻骨料混凝土的抗冻耐久性问题展开。根据陶粒常压预湿和加压预湿两种方式下塑钢纤维轻骨料混凝土宏观上工作性、强度、抗冻性试验确定了轻骨料预湿时间，综合塑钢纤维掺入对轻骨料混凝土抗压性能、劈拉性能、抗折性能、弯曲韧性及抗冲击性等各项力学性能指标给出塑钢纤维轻骨料混凝土用于工程结构时塑钢纤维的合理掺量范围。.利用中心拉拔试验研究塑钢纤维掺入量、钢筋直径、混凝土保护层厚度等材料参数和锚固参数对钢筋与塑钢纤维轻骨料混凝土之间粘结性能的影响，对比各影响因素下的粘结滑移曲线（τ-s），分析粘结应力沿锚固长度的分布，统计回归出粘结锚固极限强度公式以及特征滑移值，提出塑钢纤维轻骨料混凝土中变形钢筋的锚固长度计算公式。.通过试验研究和理论分析，得出塑钢纤维轻骨料混凝土遭受冻融损伤后混凝土的强度性能退化规律以及与钢筋的粘结性能退化规律，引入粘结韧性、粘结应力不均匀系数ζ等指标参数来研究冻融环境对塑钢纤维轻骨料混凝土与钢筋之间的粘结性能影响。以此为基础，建立塑钢纤维轻骨料混凝土结构冻融损伤模型，预测了冻融环境下塑钢纤维轻骨料混凝土的耐久性寿命，提出遭受冻融后钢筋与塑钢纤维轻骨料混凝土粘结强度的计算表达式。.冻融环境下塑钢纤维轻骨料混凝土结构的抗冻耐久性研究为我国严寒与寒冷条件下塑钢纤维轻骨料混凝土的耐久性设计提供了有益的参考，对于推动结构工程与新型建筑材料学科交叉及发展，保证国民经济可持续稳定发展具有重要意义。