Influence of Combined Expansive Agent and Internal Curing Water of Super Absorbent Polymer on Concrete Shrinkage
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摘要: 为调控混凝土早期收缩开裂,探究膨胀剂和高吸水树脂内养护剂组合对混凝土早期收缩的调控规律及对力学强度的影响,本研究以膨胀剂和内养护水均占胶凝材料总质量的0、3%、6%、9%组合掺入的混凝土作为对象,测试了早期自由变形、抗压和劈裂抗拉强度以及干燥失水率。结果表明:随着膨胀剂和内养护水组合掺量的增加,前3 d龄期内的混凝土自由变形曲线由"W "型逐渐向" L"型演变,混凝土28 d内自收缩和干燥收缩均被调控下降,直至掺量9%组密封养护下产生1 310×10-6的明显膨胀;但各组的净干燥收缩仍不能根除,同时28 d龄期的力学强度逐渐降低。混凝土3~28 d内净干燥收缩和干燥失水率基本呈线性相关。基于试验结果,确定6%组合掺量在本研究中相对较优。Abstract: In order to regulate the early shrinkage and cracking of the concrete, the influence of combined expansive agent and internal curing water of super absorbent polymer (SAP) on the regulation laws of early shrinkage and mechanical strength of concrete were investigated in this study. Specifically, this study analyzed the concrete in which the expansive agent and internal curing water with a combined dosage accounting for 0%, 3%, 6%, and 9% of the total mass of the binding material are added. In addition, the study tested the early free deformation, compressive strength, splitting tensile strength, and drying-induced water loss rate. The results show that as the combined dosage of the expansive agent and internal curing water increases, the free deformation curve of concrete in the first three days gradually evolves from W-shaped to L-shaped, and the concrete autogenous and drying shrinkage decreases gradually in 28 days until an expansion up to 1 310×10-6 is noticed in the group with a combined dosage of 9% under sealed curing condition. However, the net drying shrinkage of all groups cannot be eliminated, and the mechanical strength of the concrete decreases gradually in 28 days. Furthermore, the drying-induced water loss rate is linearly correlated to the net drying shrinkage of concrete from three days to 28 days. According to experimental results, the group with a combined dosage of 6% is optimal in this study.
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Key words:
- concrete /
- shrinkage /
- expansive agent /
- internal curing /
- SAP /
- combined control
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