轻砂内养护剂的协同膨胀效应对微膨胀混凝土变形性能的影响

Effect of Synergistic Expansion of Light Sand Internal Curing Agent on Deformation Performance of Micro-expansion Concrete

为了减少地铁装配式地下车站叠合式墙板现浇混凝土结构的裂缝产生,采用膨胀剂与内养护剂复掺技术,设计了基准组、单掺膨胀剂、复掺膨胀剂和轻砂内养护剂或SAP的4组C40混凝土,通过混凝土限制膨胀率、自收缩和干燥收缩等变形性能以及大平板抗裂试验,研究了轻砂内养护剂的协同膨胀效应对微膨胀混凝土变形性能的影响.结果表明:轻砂内养护剂具有强度高、吸水率大、密度大、能均匀分布于混凝土中的特点,掺轻砂内养护剂的补偿收缩混凝土14 d限制膨胀率比不掺内养护剂组增大72%,60 d的自收缩变形仍处于膨胀状态且膨胀率达153×10^(-6),抗裂性显著提高,且综合性能明显优于SAP内养护剂.本文提出内养护剂对膨胀混凝土具有协同膨胀效应.

In order to reduce the occurrence of cracks in the cast-in-situ concrete structure of the laminated wall panel in the subway assembly underground station,the expansion agent and the internal curing agent compound technology were adopted.Four groups of C40 concrete with benchmark group,single-mixed expansion agent,com⁃bined expansion agent,and light sand internal curing agent or SAP were designed.Through the concrete limited ex⁃pansion rate,auto-shrinkage and drying shrinkage and other deformation properties and large slab crack resistance test,the influence of the cooperative expansion effect of light sand internal curing agent on the deformation perfor⁃mance of micro-expansion concrete was studied.The results show that the light sand internal curing agent has the characteristics of high strength,high water absorption,high density,and can be evenly distributed in the concrete.The 14 day limited expansion rate of the shrinkage-compensating concrete mixed with light sand internal curing agent is increased by 72%compared with the group without the internal curing agent.The 60 day self-shrinkage is still in the expanded state,the expansion rate is 153×10^(-6),the crack resistance is significantly improved,and the overall performance is significantly better than that of the SAP internal curing agent.The synergistic expansion effect of internal curing agents on expansive concrete is proposed for the first time.