Yan Hao, Liu Qing, Han Fengxia, Liu Shan, Han Tong, He Bowen
College of Civil Engineering and Architecture, Xinjiang University, Urumqi 830017, China.
Key Laboratory of Building Structure and Seismic Resistance of Xinjiang, Urumqi 830017, China.
Materials (Basel). 2023 Sep 25;16(19):6393. doi: 10.3390/ma16196393.
Aeolian sand (AS) and recycled coarse aggregate (RCA) can be reasonably utilized as green materials for concrete modification. The paucity of natural sand and gravel in the construction industry is anticipated to be remedied by the use of these two eco-friendly concrete ingredients. This is incredibly important for environmental protection. Study on the damage law of self-compacting concrete with the addition of AS and RCA (ARSCC) under severely cold conditions is of great significance for the promotion and implementation of this material. In this study, 12 groups of ARSCC specimens were prepared for freeze-thaw cycle experiments, with AS substitution rates of 0, 20%, 40%, and 60% as well as RCA replacement rates of 0, 25%, and 50%. Then, the degradation mechanism of ARSCC freeze-thaw damage was discussed from both macroscopic and microscopic perspectives via mass loss rate (W), relative dynamic modulus of elasticity (P), bubble spacing factor, and SEM analysis. Finally, the response surface method was utilized to determine the damage variable. A freeze-thaw damage model for ARSCC was developed based on the Weibull distribution and Grey theories. The results showed that the P could reflect the evolution law of the internal structure of ARSCC. Appropriate addition of AS to fill the large, harmful pores in RCA would inhibit freeze-thaw damage of ARSCC. The optimum substitution rates of AS and RCA were determined to be 20-40% and 25-50%, respectively. In addition, the values obtained from theoretical damage modeling and experiments were in good agreement. The acquired damage model had the potential to predict ARSCC damage under freeze-thaw cycles.
风积砂（AS）和再生粗骨料（RCA）可作为混凝土改性的绿色材料得到合理利用。预计通过使用这两种环保型混凝土成分，可弥补建筑行业天然砂石的短缺。这对环境保护极为重要。研究在严寒条件下添加AS和RCA的自密实混凝土（ARSCC）的损伤规律，对该材料的推广应用具有重要意义。本研究制备了12组ARSCC试件进行冻融循环试验，AS替代率分别为0、20%、40%和60%，RCA替代率分别为0、25%和50%。然后，通过质量损失率（W）、相对动弹模量（P）、气泡间距系数和扫描电镜分析，从宏观和微观角度探讨了ARSCC冻融损伤的劣化机理。最后，利用响应面法确定损伤变量。基于威布尔分布和灰色理论建立了ARSCC的冻融损伤模型。结果表明，P能反映ARSCC内部结构的演化规律。适当添加AS填充RCA中的大尺寸有害孔隙，可抑制ARSCC的冻融损伤。确定AS和RCA的最佳替代率分别为20 - 40%和25 - 50%。此外，理论损伤建模与试验得到的值吻合良好。所建立的损伤模型具有预测ARSCC冻融循环损伤的潜力。
