本文選題：鈣礬石 + 合成條件��； 參考：《中國(guó)建筑材料科學(xué)研究總院》2017年碩士論文

【摘要】：鈣礬石是硫鋁酸鹽水泥水化的主要產(chǎn)物,決定著硫鋁酸鹽水泥的性能,且在硅酸鹽水泥混凝土中其影響也非常重要。鈣礬石的形成條件決定了其形貌,其形成時(shí)間影響著水泥和混凝土的性能。鈣礬石形成和形貌的研究,對(duì)水泥混凝土性能的改善具有重要的意義。本文采用鋁酸三鈣和二水石膏、硫鋁酸鈣和二水石膏、氫氧化鈣和硫酸鋁三組原材料,在溶液中合成了純的鈣礬石。采用電子掃描電鏡(SEM)、X射線衍射(XRD)、熱分析(TG-DSC)、紅外光譜(IR)等測(cè)試技術(shù),研究了合成時(shí)間、原材料、合成溫度、p H值、不同摻量的硼酸、碳酸鋰、聚羧酸減水劑等對(duì)鈣礬石形成和形貌的影響。1.不同原材料合成的鈣礬石形貌顯著不同且長(zhǎng)寬比差異顯著,以C3A和二水石膏為原材料合成的鈣礬石尺寸遠(yuǎn)小于其他兩組原材料合成的鈣礬石,長(zhǎng)寬比約為其他兩組長(zhǎng)寬比的1/10;在100℃合成溫度下,鈣礬石不能穩(wěn)定存在,在較短的時(shí)間后就會(huì)轉(zhuǎn)化為單硫型水化硫鋁酸鈣;隨著液相p H值的增加,鈣礬石的長(zhǎng)寬比逐漸減小,且鈣礬石形貌由長(zhǎng)桿狀向細(xì)小的針狀轉(zhuǎn)變。溶液中鈣礬石的形成機(jī)理為:既可直接生成鈣礬石,又可先形成單硫型水化硫鋁酸鈣,而后單硫型水化硫鋁酸鈣和SO42 、Ca2+反應(yīng)形成鈣礬石。2.硼酸能夠抑制鈣礬石的生長(zhǎng),隨著硼酸摻量的增加,鈣礬石的長(zhǎng)寬比逐漸減小,尺寸變短,當(dāng)硼酸摻量提高到10%、20%時(shí),出現(xiàn)了較多的扁柱狀的鈣礬石;碳酸鋰通過吸附在鈣礬石晶體的側(cè)面,抑制鈣礬石晶體寬度的生長(zhǎng),碳酸鋰可以加快鈣礬石的形成速度;聚羧酸減水劑對(duì)鈣礬石晶體寬度上的生長(zhǎng)起到抑制作用,使得鈣礬石晶體變長(zhǎng)變細(xì),長(zhǎng)寬比明顯增加,但對(duì)鈣礬石成核起到促進(jìn)作用。3.提出了鈣礬石形貌調(diào)控的方案。通過摻加碳酸鋰和聚羧酸減水劑均可獲得長(zhǎng)桿狀鈣礬石;調(diào)節(jié)p H值為12.5以上時(shí),可以獲得細(xì)針狀鈣礬石;摻加硼酸可以獲得短柱狀鈣礬石;硼酸與聚羧酸減水劑復(fù)合摻加,可以獲得又短又細(xì)的鈣礬石。
[Abstract]:Ettringite is the main product of sulphoaluminate cement hydration, which determines the performance of sulphoaluminate cement, and its influence in Portland cement concrete is also very important. The morphology of ettringite is determined by the formation conditions of ettringite, and the formation time of ettringite affects the properties of cement and concrete. The formation and morphology of ettringite are of great significance to the improvement of cement concrete performance. In this paper, pure ettringite was synthesized in solution from three groups of raw materials such as tricalcium aluminate and gypsum dihydrate, calcium sulphoaluminate and gypsum dihydrate, calcium hydroxide and aluminum sulfate. The synthesis time, raw materials, synthesis temperature, boric acid and lithium carbonate were studied by means of electron scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal analysis (TG-DSCN) and IR (IR). Effects of polycarboxylic acid superplasticizer on the formation and morphology of ettringite. The morphology and aspect ratio of ettringite synthesized from different raw materials are significantly different. The size of ettringite synthesized from C3A and gypsum dihydrate is much smaller than that from other two groups of raw materials. The aspect ratio is about 1 / 10 of the other two groups. Ettringite can not exist stably at 100 鈩，

本文編號(hào)：1797076