發(fā)布時(shí)間：2018-08-14 11:57

【摘要】：堿-激發(fā)膠凝材料具有早強(qiáng)高強(qiáng)、低水化熱、耐酸堿腐蝕性好、抗氯離子腐蝕性強(qiáng)和抗?jié)B抗凍性良好等特性，但也存在著諸如快凝、收縮大、易產(chǎn)生裂縫和可能潛在堿骨料反應(yīng)危害等問題。其中由于收縮導(dǎo)致的混凝土開裂會影響耐久性，這也成為制約其應(yīng)用和發(fā)展最主要的原因。堿-激發(fā)膠凝材料的水化和收縮性能受到膠凝組分的特性和激發(fā)劑的種類與摻量等多種因素的共同影響。而粉煤灰的加入對其水化發(fā)展歷程和收縮變形特性都有很大影響。配比設(shè)計(jì)良好的堿-激發(fā)礦渣/粉煤灰水泥能在保證強(qiáng)度的同時(shí)降低費(fèi)用并提高成型質(zhì)量，但是目前對其水化和收縮特性的研究還不夠系統(tǒng)。 本文旨在針對Me2O MeO Me2O3 SiO2 H2O和Me2O Me2O3 SiO2 H2O兩個(gè)體系研究水玻璃模數(shù)、礦渣摻量和溫度對堿-激發(fā)礦渣/粉煤灰水泥水化放熱特性的影響，并對其進(jìn)行動(dòng)力學(xué)分析和表征；同時(shí)研究自收縮和干燥收縮的影響因素及其影響規(guī)律，探究最佳的減縮方式。 研究結(jié)果表明：堿-激發(fā)礦渣/粉煤灰水泥在不同水化階段的水化放熱速率不同。水化初期礦渣和粉煤灰中的鈣硅離子逐漸溶出，水玻璃則水解生成NaOH和Si(OH)4。當(dāng)反應(yīng)進(jìn)行到0.5~6h時(shí)，第一個(gè)水化放熱峰出現(xiàn)，溫度越高，水化初期和第一個(gè)峰的出峰時(shí)間跨度越短。繼續(xù)水化到1~12h，可能出現(xiàn)第二個(gè)水化放熱峰。在相同的水化溫度下，堿-激發(fā)礦渣/粉煤灰水泥的水化放熱速率隨著礦渣摻量的增多和水玻璃模數(shù)的增加而逐漸加快。水化動(dòng)力學(xué)計(jì)算得出其表觀活化能也隨著配比的不同而呈現(xiàn)一定的變化規(guī)律。 NaOH激發(fā)的礦渣/粉煤灰水泥自收縮相對較小，水玻璃激發(fā)的則較大，且在水玻璃模數(shù)為0.5~1.5范圍內(nèi)，隨著水玻璃模數(shù)的增加，自收縮隨之減小，變化速率也逐漸減慢。而在相同的水玻璃模數(shù)下，，自收縮隨著礦渣摻量的減少而減小。 堿-激發(fā)礦渣/粉煤灰水泥的干燥收縮率隨著礦渣摻量的增加而減小，隨著水玻璃模數(shù)的增大而增大。指數(shù)函數(shù)式的回歸方程對干縮隨齡期變化的曲線的擬合較好，能有效預(yù)測不同齡期的干燥收縮率。隨著礦渣摻量的減少，堿-激發(fā)礦渣/粉煤灰水泥56天內(nèi)的質(zhì)量損失不斷增大。NaOH激發(fā)的礦渣/粉煤灰水泥的干縮值和質(zhì)量損失呈線性關(guān)系，且礦渣摻量越大，直線的斜率越大。摻氧化烯醇類的減縮劑對減少堿-激發(fā)礦渣/粉煤灰水泥砂漿干燥收縮的效果明顯，而氧化鎂膨脹劑的減縮效果稍差。
[Abstract]:Alkali-activated cementing materials have the characteristics of early strength and high strength, low heat of hydration, good corrosion resistance to acid and alkali, strong corrosion resistance to chloride ions and good resistance to seepage and freezing, but they also have such characteristics as fast solidification and large shrinkage. It is easy to produce cracks and potential alkali-aggregate reaction hazards and so on. The cracking of concrete caused by shrinkage will affect the durability, which is the main reason that restricts its application and development. The hydration and shrinkage properties of alkali-activated cementitious materials are influenced by many factors, such as the properties of the gelling components and the types and contents of the activators. The addition of fly ash has great influence on hydration development and shrinkage deformation. The alkali-activated slag / fly ash cement with good proportioning design can reduce the cost and improve the molding quality while ensuring the strength, but the research on its hydration and shrinkage characteristics is not systematic. The purpose of this paper is to study the effects of water glass modulus, slag content and temperature on the hydration heat release characteristics of alkali-activated slag / fly ash cement in Me2O / MeO / Me2O3 / SiO2 and Me2O Me2O3 / SiO2 / H _ 2O systems, and to analyze and characterize their kinetics. At the same time, the influencing factors and the law of autogenous shrinkage and drying shrinkage were studied, and the best way of reducing shrinkage was explored. The results show that the hydration heat release rate of alkali-activated slag / fly ash cement is different in different hydration stages. In the early stage of hydration, calcium and silicon ions in slag and fly ash were gradually dissolved, while water glass was hydrolyzed to form NaOH and Si (OH) _ 4. The first hydration exothermic peak appeared when the reaction was carried out for 6 h, and the higher the temperature, the shorter the time span between the initial hydration stage and the first peak. A second hydration exothermic peak may occur when hydration continues to 1: 12 h. At the same hydration temperature, the hydration heat release rate of alkali-activated slag / fly ash cement is accelerated with the increase of slag content and the increase of water glass modulus. The kinetic calculation of hydration shows that the apparent activation energy also changes with the different ratio. The autogenous shrinkage of slag / fly ash cement excited by NaOH is relatively small, and that of water glass is larger. With the increase of the sodium silicate modulus, the self-shrinkage decreases and the rate of change slows down gradually in the range of 0.5 ~ 1.5 of sodium silicate modulus. At the same water glass modulus, the self-shrinkage decreases with the decrease of slag content. The drying shrinkage of alkali-activated slag / fly ash cement decreases with the increase of slag content and increases with the increase of water glass modulus. The regression equation of exponential function fits the curve of dry shrinkage with age and can effectively predict the drying shrinkage of different ages. With the decrease of slag content, the mass loss of alkali-activated slag / fly ash cement increases continuously within 56 days. The dry shrinkage value of slag / fly ash cement stimulated by NaOH is linearly related to the mass loss, and the bigger the slag content is, the bigger the straight line slope is. The shrinkage reducing agent mixed with oxidized enol has obvious effect on reducing drying shrinkage of alkali-activated slag / fly ash cement mortar, but the effect of magnesium oxide expansion agent is a little poor.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TQ172.1

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