【摘要】：高強混凝土結(jié)構(gòu)耐火性問題已經(jīng)成為當(dāng)今工程界普遍關(guān)注的問題。已有研究表明，在高強混凝土中摻加聚丙烯細纖維，纖維高溫熔化后形成的泄壓通道，可以緩解爆裂的發(fā)生，提高結(jié)構(gòu)耐火性能。與聚丙烯細纖維相比，工程中廣泛應(yīng)用的聚丙烯粗纖維具有相同的材質(zhì)和熔點，直徑卻相對較大，高溫熔化后形成的泄壓通道有所區(qū)別，可能會對高強混凝土高溫火災(zāi)后性能產(chǎn)生不同影響。因此，研究聚丙烯粗纖維對高強混凝土高溫后性能的影響十分必要。 本文通過改變聚丙烯纖維的摻量，制備了五組不同配合比的高強混凝土試件，試件尺寸為40mm×40mm×160mm，采用箱式電阻爐進行高溫試驗（目標(biāo)溫度分別為200℃、400℃、600℃和800℃）。通過研究不同纖維摻量高強混凝土試件高溫后的抗壓強度和抗折強度的變化規(guī)律，分析了聚丙烯粗纖維對高強混凝土高溫后力學(xué)性能的影響。結(jié)果表明：摻加聚丙烯粗纖維有利于提高高強混凝土高溫后的殘余抗壓強度，但會對殘余抗折強度產(chǎn)生不利影響，，聚丙烯粗、細纖維混雜協(xié)同作用可使不利影響降至最低。通過對基體質(zhì)量損失率和吸水率的測定，探討了聚丙烯粗纖維對高強混凝土高溫后孔結(jié)構(gòu)的影響，發(fā)現(xiàn)：與聚丙烯細纖維相比，聚丙烯粗纖維熔化后形成的泄壓通道更為粗化，使得高強混凝土的基體質(zhì)量損失率及吸水率更大；過高摻量的聚丙烯粗纖維，將使泄壓通道過于粗化，混凝土的總孔隙率明顯增大。結(jié)合超聲波無損檢測技術(shù)，對不同纖維摻量高強混凝土的高溫損傷進行了探測，建立了聚丙烯纖維高強混凝土的損傷度隨受火溫度變化的數(shù)學(xué)模型，工程中可以依據(jù)該模型，推定結(jié)構(gòu)的實際受火溫度。 本文將會對高強混凝土結(jié)構(gòu)耐火性設(shè)計和正確進行災(zāi)后損傷評估具有一定的指導(dǎo)意義。
[Abstract]:The fire resistance of high-strength concrete structures has become a common concern in the engineering field. It has been shown that adding polypropylene fine fiber to high strength concrete can reduce the explosion and improve the fire resistance of the structure by reducing the pressure channel formed by melting the fiber at high temperature. Compared with the polypropylene fine fiber, the coarse polypropylene fiber widely used in engineering has the same material and melting point, but the diameter is relatively large, and the pressure relief channel formed after melting at high temperature is different. It may have different effects on the performance of high strength concrete after high temperature fire. Therefore, it is necessary to study the effect of polypropylene fiber on the properties of high-strength concrete after high temperature. In this paper, five groups of high strength concrete specimens with different blending ratio were prepared by changing the content of polypropylene fiber. The size of the specimens was 40mm 脳 40mm 脳 160 mm. The high temperature test was carried out in a box resistance furnace (the target temperature was 200 鈩

本文編號：2341643