养护对泡沫混凝土收缩及抗裂性能的影响

发布时间：2018-02-21 16:36

  本文关键词： 泡沫混凝土 温度 相对湿度 早期收缩 约束开裂　出处：《合肥工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,泡沫混凝土得到了越来越广泛的应用。但在实际应用中暴露出的收缩开裂问题亟需解决。对普通混凝土,养护能够抑制的收缩及开裂问题;但对泡沫混凝土,相关的研究却很少。探讨养护对泡沫混凝土收缩开裂影响十分必要。本文以不同的温湿度条件为控制变量,对泡沫混凝土体积变形与开裂规律进行系统的试验研究。采用非接触式收缩变形测定仪测定浇注成型至3d龄期泡沫混凝土的早期收缩变形曲线,对3d龄期内泡沫混凝土的变形特征进行阶段性分析；采用比长仪对28d龄期泡沫混凝土的干燥收缩进行测量；使用椭圆环形约束试验,研究不同环境条件下泡沫混凝土的收缩开裂特征。采用多因素方差分析的统计方法对实验数据进行了分析。试验结果表明：25℃条件下3d龄期泡沫混凝土变形特征呈收缩、膨胀交替变化的变形特点,高温65℃条件下的混凝土自收缩变形曲线分为4个阶段,并且早期呈膨胀变形状态。初凝后的变形做为有效变形可以用来代表泡沫混凝土的早期收缩。泡沫混凝土的有效变形起始时间随温度的升高而提前。当养护温度由25℃升至65℃时,水灰比为0.5的泡沫混凝土的有效变形起始时间为5.5-12.5h。环境温度与湿度对泡沫混凝土干燥收缩变形影响显著。当温度变化从25℃-65℃时,泡沫混凝土28d龄期收缩的变化范围为1588×10-6-1850×10-6；水灰比越小,其收缩相比越小。环境温度固定时,各组泡沫混凝土RH15%条件下的收缩明显大于RH75%条件下的收缩。随着水灰比和温度的升高,湿度差异对泡沫混凝土干燥收缩影响作用减弱；高温作用同时增加了椭圆环开裂的风险,表现在初始开裂时间的提前以及最大裂缝宽度的增大,减小水灰比有利于抵抗泡沫混凝土开裂。
[Abstract]:In recent years, foam concrete has been more and more widely used. However, the problem of shrinkage cracking exposed in practical application needs to be solved. For ordinary concrete, curing can restrain shrinkage and cracking; but for foam concrete, It is necessary to study the effect of curing on shrinkage cracking of foamed concrete. In this paper, different temperature and humidity conditions are used as control variables. The volume deformation and cracking of foamed concrete were studied systematically. The early shrinkage and deformation curves of foamed concrete from pouring to 3 d age were measured by non-contact shrinkage deformation tester. The deformation characteristics of foamed concrete in 3D age were analyzed in stages; the drying shrinkage of foamed concrete at 28 d age was measured by using a specific length meter; and the elliptical annular confinement test was used. The shrinkage and cracking characteristics of foamed concrete under different environmental conditions were studied. The experimental data were analyzed by using the statistical method of multifactor variance analysis. The experimental results showed that the deformation characteristics of foamed concrete at 3 d age showed shrinkage at 25 鈩，

本文编号：1522347