【摘要】：由于鎂工業(yè)近年來發(fā)展迅速,鎂渣排放量急劇增加,導(dǎo)致環(huán)境污染問題日益嚴(yán)重,同時(shí)限制了鎂工業(yè)的進(jìn)一步發(fā)展;為追求混凝土的高強(qiáng)度以及高流動(dòng)性,往往在混凝土中大量摻加外加劑和摻合料,這就導(dǎo)致混凝土收縮問題日益嚴(yán)重;鎂渣的化學(xué)成分與水泥相近,有一定的水化活性,所含MgO具有膨脹性,將鎂渣作為混凝土摻合料,能提高混凝土的強(qiáng)度,對(duì)混凝土的自生收縮有潛在的補(bǔ)償,且可以降低工程成本,減少環(huán)境污染,因此該課題具有較高的研究意義,研究得到國(guó)家自然科學(xué)基金項(xiàng)目的支持。以C30鎂渣混凝土為研究對(duì)象,設(shè)計(jì)單因素試驗(yàn)方案和正交試驗(yàn)方案;采用趨勢(shì)分析、極差分析、方差分析等數(shù)據(jù)分析方法,分析各礦物摻合料對(duì)鎂渣混凝土自生收縮的作用規(guī)律,揭示鎂渣對(duì)混凝土自生收縮的作用機(jī)理,并建立混凝土自生收縮率隨齡期以及各礦物摻合料摻量變化的關(guān)系模型,研究得出如下結(jié)論:(1)隨鎂渣摻量的增加混凝土的自生收縮逐漸減少,鎂渣摻量越高鎂渣對(duì)自生收縮的抑制效應(yīng)越大。鎂渣可以提高混凝土的抗壓強(qiáng)度,但隨著鎂渣摻量水平的增加,鎂渣對(duì)抗壓強(qiáng)度的增強(qiáng)效應(yīng)逐漸降低。(2)摻入粉煤灰對(duì)混凝土的自生收縮有抑制作用,隨著粉煤灰摻量的增加,混凝土自生收縮大致呈線性降低�；炷� 28d抗壓強(qiáng)度隨著粉煤灰摻量的增加而降低,28d抗壓強(qiáng)度與粉煤灰摻量大致呈線性關(guān)系。(3)摻入礦粉會(huì)使混凝土的自生收縮率增大,在測(cè)量齡期的前三天,礦粉對(duì)混凝土的自生收縮表現(xiàn)為抑制作用,之后,礦粉會(huì)促進(jìn)混凝土自生收縮的發(fā)展,礦粉可以提高混凝土強(qiáng)度,兩者大致呈線性關(guān)系。(4)各礦物摻合料對(duì)混凝土自生收縮作用的重要性次序依次為:鎂渣摻量粉煤灰取代率礦粉取代率。(5)混凝土自生收縮率隨齡期的變化趨勢(shì)符合雙曲線關(guān)系,建立的雙曲線關(guān)系顯著性高,相關(guān)性好,能準(zhǔn)確預(yù)測(cè)不同齡期的混凝土自生收縮值。
[Abstract]:Due to the rapid development of magnesium industry in recent years, the discharge of magnesium slag increases rapidly, which leads to the increasingly serious environmental pollution problem and restricts the further development of magnesium industry. In order to pursue the high strength and high fluidity of concrete, a large number of admixtures and admixtures are often added to the concrete, which leads to the increasingly serious shrinkage problem of concrete. The chemical composition of magnesium slag is similar to that of cement, and it has certain hydration activity. The MgO contained in magnesium slag has expansibility. If magnesium slag is used as admixture of concrete, the strength of concrete can be improved and the autogenous shrinkage of concrete can be compensated. And it can reduce the project cost and reduce the environmental pollution, so the research is of high significance, and the research is supported by the National Natural Science Foundation of China. Taking C30 magnesium slag concrete as the research object, the single factor test scheme and the orthogonal test scheme are designed. By means of trend analysis, range analysis and variance analysis, the effect of mineral admixtures on the autogenous shrinkage of magnesium slag concrete is analyzed, and the mechanism of the effect of magnesium slag on the autogenous shrinkage of concrete is revealed. The relationship model of the autogenous shrinkage rate of concrete with age and the amount of mineral admixture is established. The conclusions are as follows: (1) the autogenous shrinkage of concrete decreases with the increase of magnesium slag content. The higher the content of magnesium slag, the greater the inhibition effect of magnesium slag on autogenous shrinkage. Magnesium slag can improve the compressive strength of concrete, but with the increase of the content of magnesium slag, the enhancement effect of magnesium slag on compressive strength decreases gradually. (2) the addition of fly ash can inhibit the autogenous shrinkage of concrete. With the increase of fly ash content, the autogenous shrinkage of concrete decreases linearly. The compressive strength of concrete decreases with the increase of the amount of fly ash, and the compressive strength of 28 days has a linear relationship with the content of fly ash. (3) the autogenous shrinkage of concrete increases with the addition of mineral powder, which is three days before the measuring age. After that, the mineral powder can promote the development of the concrete autogenous shrinkage, and the mineral powder can improve the strength of concrete. (4) the order of importance of mineral admixtures to the autogenous shrinkage of concrete is as follows: the replacement rate of mineral powder with magnesium slag and fly ash. (5) the rate of autogenous shrinkage of concrete with age. The trend of change accords with the hyperbolic relation, The hyperbolic relation is significant and the correlation is good. It can accurately predict the autogenous shrinkage of concrete at different ages.
【學(xué)位授予單位】：寧夏大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU528

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