论文部分内容阅读
利用高吸水树脂(SAP)作为内养护剂抑制水泥基材料的早期收缩开裂已受到广泛研究,然而,掺加SAP制备的内养护水泥基材料自加水24 h内的早期变形行为往往被忽略。由于从塑性到硬化阶段的早期变形较为剧烈,导致在此阶段内的自收缩零点选取对测试结果影响较大。研究了掺加3种不同种类的SAP浆体的全过程收缩变形、毛细管压力及水化放热速率,结果表明,泌水回吸等因素导致的膨胀变形先于SAP引起的膨胀变形出现,SAP的释水历程变化会导致更多的膨胀变形出现。采用维卡仪测试的初凝时间与早期密封条件下的变形速率稳定发展时刻对应较好,毛细管压力发展速率最大时刻与凝结及内应力平衡时刻相对应,更适合作为自收缩测试零点。
The use of superabsorbent polymer (SAP) as an internal curing agent to suppress the early shrinkage cracking of cement-based materials has been extensively studied. However, the early deformation behavior of the internally cured cement-based materials prepared by adding SAP within 24 h has often been neglected. Since the early deformation from plasticity to hardening stage is more severe, the selection of self-shrinking zero point in this stage has a great influence on the test results. The shrinkage deformation, capillary pressure and heat of hydration of three different kinds of SAP slurries were studied. The results show that the swelling deformation caused by factors such as bleeding and recovery is earlier than that caused by SAP. SAP The change of the water release process will lead to more expansion and deformation. The initial setting time with the Vicat apparatus is corresponding to the steady development moment of the deformation rate under the early sealing condition. The maximum moment of the capillary pressure development corresponds to the time of equilibrium of the condensation and internal stress, which is more suitable for the self-shrinking test zero point.