本文關(guān)鍵詞： 超高性能混凝土 大流動性 體積穩(wěn)定性 微觀結(jié)構(gòu)　出處：《哈爾濱工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：超高性能混凝土(UHPC)是近年來各國學(xué)者研究的熱點(diǎn)問題。但由于其工藝復(fù)雜,無法現(xiàn)場澆筑施工,收縮較大等因素嚴(yán)重影響其實(shí)際應(yīng)用。本文在基本配合比優(yōu)化設(shè)計(jì)的基礎(chǔ)上,通過復(fù)摻高性能減水劑與消泡劑制備出大流動性、力學(xué)性能優(yōu)良的超高性能混凝土材料,并研究了膨脹劑與減縮劑對超高性能混凝土體積穩(wěn)定性的影響規(guī)律。研究結(jié)果表明:隨著砂膠比增大,超高性能混凝土流動度降低,抗壓強(qiáng)度先增大后降低;當(dāng)硅灰摻量為所用水泥量的25%時,UHPC的抗壓強(qiáng)度較高;摻入適量粉煤灰可以在一定程度上提高UHPC砂漿流動度,但對強(qiáng)度影響不大;石英粉的摻入會很大程度上降低UHPC砂漿流動度,但對強(qiáng)度有促進(jìn)作用。最終得到常溫養(yǎng)護(hù)下超高性能混凝土的基本配合比為:水泥:硅灰:石英砂(粗):石英砂(細(xì)):水=1:0.25:0.6125:0.4785:0.2125。消泡劑的摻入能有效降低UHPC新拌砂漿的含氣量,平均降幅可達(dá)到50%;并且能夠有效地提高其抗壓強(qiáng)度,最大可提高20%;充分振動的情況下,相同消泡劑摻量的高水膠比UHPC砂漿的含氣量較低水膠比降低60%左右,抗壓強(qiáng)度最高可提高50%;對于高水膠比的超高性能混凝土來說,消除氣泡比降低水膠比對強(qiáng)度的改善效果更加顯著。減縮劑的引入對UHPC的收縮起到很好的抑制作用,但對強(qiáng)度影響較大,會使其自收縮降低39.9%,干燥收縮降低47.3%;膨脹劑的引入對UHPC收縮的抑制效果并不明顯,但對其強(qiáng)度不會有太大影響,會使其自收縮降低16%,干燥收縮降低29.5%。消泡劑的引入會在很大程度上降低UHPC內(nèi)部的大孔含量,增加微小孔的含量,對優(yōu)化孔結(jié)構(gòu)與孔徑分布,從而顯著提高超高性能混凝土強(qiáng)度。
[Abstract]:UHPC) is a hot issue studied by scholars all over the world in recent years. However, due to its complex technology, it can not be used in situ, and its practical application is seriously affected by large shrinkage. This paper is based on the optimization design of basic mix ratio. High performance concrete materials with high fluidity and excellent mechanical properties were prepared by mixing high performance water reducing agent and defoaming agent. The effect of expansion agent and shrinkage reducer on the volume stability of UHPC is studied. The results show that with the increase of the ratio of sand and binder, the flow degree of UHPC decreases, and the compressive strength increases first and then decreases. When the content of silica fume is 25% of the cement used, the compressive strength of UHPC is higher, the fluidity of UHPC mortar can be improved to some extent by adding proper amount of fly ash, and the fluidity of UHPC mortar will be greatly reduced by the addition of quartz powder. But it can promote the strength. Finally, the basic mix ratio of UHPC under normal temperature curing is obtained as follows: cement: silica fume: quartz sand (coarse: quartz sand: water: 1: 0.25: 0. 125: 0. 4785: 0. 2125). The addition of defoamer can effectively reduce the gas content of UHPC freshly mixed mortar. The average drop can reach 50%, and the compressive strength of the mortar can be increased by 20%. Under the condition of full vibration, the air content of UHPC mortar with the same amount of defoamer is about 60% lower than that of UHPC mortar. The maximum compressive strength can be increased by 50%. For the super high performance concrete with high water-binder ratio, the effect of eliminating bubbles is more remarkable than reducing the strength of water-binder ratio. The introduction of reducing agent has a good effect on the shrinkage of UHPC. However, the effect on the strength is greater, which will reduce the autogenous shrinkage by 39.9% and the dry shrinkage by 47.3%. The inhibition effect of the expansion agent on the shrinkage of UHPC is not obvious, but it will not have much effect on its strength. The defoamer can reduce the content of macropore in UHPC to a great extent, increase the content of micropore, optimize the pore structure and pore size distribution, and increase the strength of UHPC.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU528

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