發(fā)布時(shí)間：2018-10-10 18:36

【摘要】：高性能混凝土具有比普通混凝土更優(yōu)越的性能,但是在火災(zāi)作用下,內(nèi)部致密的結(jié)構(gòu)以及較低的滲透率使其更易發(fā)生爆裂,而蒸汽壓是引起高性能混凝土爆裂的主要原因之一。但由于蒸汽壓力試驗(yàn)比較復(fù)雜,目前可供參考的試驗(yàn)數(shù)據(jù)較少。探索高性能混凝土高溫下的蒸汽壓力以及微結(jié)構(gòu)變化,為蒸汽壓力理論提供試驗(yàn)依據(jù),對(duì)抑制高性能混凝土高溫爆裂具有重要意義。本文依托國家自然科學(xué)基金(51478290),對(duì)不摻纖維與摻聚丙烯纖維C60高性能混凝土高溫蒸汽壓力及微結(jié)構(gòu)變化進(jìn)行試驗(yàn)研究,主要內(nèi)容如下:一、通過對(duì)不同溫度作用后高性能混凝土的劈裂抗拉強(qiáng)度的測試,對(duì)劈裂抗拉強(qiáng)度損失情況與溫度的變化規(guī)律進(jìn)行研究,表明高性能混凝土劈裂抗拉強(qiáng)度隨著溫度的升高呈下降趨勢,400℃之前聚丙烯纖維混凝土劈裂抗拉強(qiáng)度高于不摻纖維混凝土劈裂抗拉強(qiáng)度,500℃與600℃分別為不摻纖維與摻纖維試件的閾值溫度,劈裂抗拉強(qiáng)度損失率分別為57.88%與63.71%。二、對(duì)高溫電阻爐加熱下的不加鋼筋高性能混凝土小板(不摻纖維與摻0.1%、0.2%、0.3%聚丙烯纖維),以及加鋼筋的高性能混凝土小板(不摻纖維與摻0.2%聚丙烯纖維)的內(nèi)部不同測點(diǎn)的蒸汽壓力隨時(shí)間以及測點(diǎn)溫度的變化規(guī)律進(jìn)行研究,表明摻聚丙烯纖維可以顯著降低蒸汽壓力,且0.2%為聚丙烯纖維最佳摻量。三、對(duì)明火與荷載耦合下的加鋼筋的高性能混凝土大板(不摻纖維與摻0.2%聚丙烯纖維)內(nèi)部不同測點(diǎn)位置的蒸汽壓力隨時(shí)間以及測點(diǎn)溫度的變化規(guī)律進(jìn)行研究,表明在明火與荷載耦合下,摻入聚丙烯纖維同樣抑制了混凝土內(nèi)部蒸汽壓力,且50 mm測點(diǎn)處蒸汽壓力值較大。四、對(duì)高溫電阻爐、明火與荷載耦合下同一測點(diǎn)處的蒸汽壓力進(jìn)行對(duì)比,表明在明火與荷載耦合下蒸汽壓力增大,聚丙烯纖維對(duì)蒸汽壓力抑制作用降低。并利用薄壁球理論,將蒸汽壓力與劈裂抗拉強(qiáng)度建立了聯(lián)系,計(jì)算得出了不摻纖維試件可能出現(xiàn)的爆裂位置,驗(yàn)證了摻聚丙烯纖維試件未出現(xiàn)爆裂的事實(shí)。五、探討溫度對(duì)高性能混凝土內(nèi)部微觀結(jié)構(gòu)的影響。利用掃描電鏡設(shè)備對(duì)不摻纖維與摻0.2%聚丙烯纖維混凝土不同溫度下的漿體、界面過渡區(qū)、孔隙結(jié)構(gòu)以及高溫后的聚丙烯纖維通道的微觀圖像進(jìn)行了觀察與定性分析,表明常溫與155℃下高性能混凝土較為密實(shí),300℃與500℃后劣化嚴(yán)重;利用IPP軟件進(jìn)行定量分析,表明高性能混凝土內(nèi)部孔隙面積比呈先降低再增加的趨勢,300℃后聚丙烯纖維試件孔隙面積比低于不摻纖維試件孔隙面積比;并將不同溫度下的孔隙面積比與蒸汽壓力進(jìn)行了曲線擬合。本文旨在研究溫度對(duì)高性能混凝土蒸汽壓力與微觀結(jié)構(gòu)的影響,為解釋高性能混凝土爆裂的蒸汽壓力理論及聚丙烯纖維抑制高溫爆裂的研究提供依據(jù)。
[Abstract]:High performance concrete (HPC) has better performance than ordinary concrete, but under the action of fire, the internal compact structure and low permeability make it more prone to burst, and steam pressure is one of the main causes of high performance concrete bursting. However, due to the complexity of steam pressure test, there are few experimental data available for reference at present. To explore the steam pressure and microstructure change of high performance concrete at high temperature provides experimental basis for steam pressure theory and is of great significance to restrain high temperature crack of high performance concrete. Based on the National Natural Science Foundation (51478290), this paper studies the high temperature steam pressure and microstructure change of high performance concrete without fiber and polypropylene fiber C60. The main contents are as follows: 1. By testing the splitting tensile strength of high performance concrete under different temperature, the loss of splitting tensile strength and the variation of temperature are studied. The results show that the splitting tensile strength of high performance concrete decreases with the increase of temperature. The splitting tensile strength of polypropylene fiber reinforced concrete is higher than that of non-doped fiber concrete before 400 鈩，

本文編號(hào)：2262822