矿物掺合料对混凝土增强机理的研究

Strengthening Mechanism of Mineral Admixtures to Concrete

研究了细磨的粉煤灰、矿渣对混凝土的增强作用,利用SEM分析其增强机理。结果表明:与纯水泥混凝土相比,单掺20%细磨粉煤灰1 d和3 d强度略低,28 d和56 d强度有较大增长;单掺20%细磨矿渣后,1 d强度略低,其余3个龄期强度均有提高。当细磨的矿渣和粉煤灰按1 1的比例混掺后4个龄期的强度均有所提高,说明混掺增强效果最好。SEM分析表明,强度的提高是由于细粉的微填充作用和积极参与水泥水化反应而使混凝土的致密程度提高并使水泥石与集料间的过渡层性能改善所致。

The strengthening effect and mechanism of finely ground slag, flyash and their combination were investigated by means of scanning electron microscope （SEM）. Test results show that compared with pure cement concrete, incorporation of only 20% flyash for 1 d or 3 d causes a reduction of earlier strength, but the later strength for 28 d or 56 d increases significantly ; incorporation of only 20% slag for 1 d leads to decrease of strength, but the strength at the other 3 periods all increases. Incorporation of the combination of flyash and slag at the ratio of 1 ： 1 can increase the compressive strength of concrete at all ages, implying its strengthening effect is the best. From the SEM analysis it can be found that the strengthening effect of those mineral admixtures is because of a denser microstructure being formed due to the micro-filler effect and actively taking part in the cement hydration process. Another reason of strength ening effect is because the transition zone has been improved by incorporating the combination of flyash and slag.