本文關(guān)鍵詞： 泡沫混凝土 溫度 相對濕度 早期收縮 約束開裂　出處：《合肥工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來,泡沫混凝土得到了越來越廣泛的應(yīng)用。但在實(shí)際應(yīng)用中暴露出的收縮開裂問題亟需解決。對普通混凝土,養(yǎng)護(hù)能夠抑制的收縮及開裂問題;但對泡沫混凝土,相關(guān)的研究卻很少。探討?zhàn)B護(hù)對泡沫混凝土收縮開裂影響十分必要。本文以不同的溫濕度條件為控制變量,對泡沫混凝土體積變形與開裂規(guī)律進(jìn)行系統(tǒng)的試驗(yàn)研究。采用非接觸式收縮變形測定儀測定澆注成型至3d齡期泡沫混凝土的早期收縮變形曲線,對3d齡期內(nèi)泡沫混凝土的變形特征進(jìn)行階段性分析；采用比長儀對28d齡期泡沫混凝土的干燥收縮進(jìn)行測量；使用橢圓環(huán)形約束試驗(yàn),研究不同環(huán)境條件下泡沫混凝土的收縮開裂特征。采用多因素方差分析的統(tǒng)計方法對實(shí)驗(yàn)數(shù)據(jù)進(jìn)行了分析。試驗(yàn)結(jié)果表明：25℃條件下3d齡期泡沫混凝土變形特征呈收縮、膨脹交替變化的變形特點(diǎn),高溫65℃條件下的混凝土自收縮變形曲線分為4個階段,并且早期呈膨脹變形狀態(tài)。初凝后的變形做為有效變形可以用來代表泡沫混凝土的早期收縮。泡沫混凝土的有效變形起始時間隨溫度的升高而提前。當(dāng)養(yǎng)護(hù)溫度由25℃升至65℃時,水灰比為0.5的泡沫混凝土的有效變形起始時間為5.5-12.5h。環(huán)境溫度與濕度對泡沫混凝土干燥收縮變形影響顯著。當(dāng)溫度變化從25℃-65℃時,泡沫混凝土28d齡期收縮的變化范圍為1588×10-6-1850×10-6；水灰比越小,其收縮相比越小。環(huán)境溫度固定時,各組泡沫混凝土RH15%條件下的收縮明顯大于RH75%條件下的收縮。隨著水灰比和溫度的升高,濕度差異對泡沫混凝土干燥收縮影響作用減弱；高溫作用同時增加了橢圓環(huán)開裂的風(fēng)險,表現(xiàn)在初始開裂時間的提前以及最大裂縫寬度的增大,減小水灰比有利于抵抗泡沫混凝土開裂。
[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，

本文編號：1522347