常用无机盐对混凝土界面过渡区性能及孔结构的影响研究

发布时间：2018-03-27 12:43

本文选题：混凝土　切入点：无机盐　出处：《哈尔滨工业大学》2017年硕士论文

【摘要】：无机盐外加剂由于它的经济适用性经常被用于混凝土工程中,起到早强、防冻、速凝等作用。当无机盐加入后可参与到水泥水化反应中,会对水泥石早期及后期内部结构产生一定的影响。本文主要对单掺无机盐(NaCl、Ca(NO_2)_2、Ca(NO_3)_2、Na_2SO_4、NaNO_2)、粉煤灰与无机盐混掺下混凝土的界面过渡区性能、孔结构及气孔结构进行测试与观察。利用显微硬度仪观察掺加无机盐后的混凝土界面过渡区的显微硬度及厚度情况,比较发现Na Cl、Ca(NO_3)_2的加入会使显微硬度有所增加;Ca(NO_2)_2和NaNO_2会使显微硬度降低;低掺量Na_2SO_4对显微硬度影响不大,高掺量会使显微硬度明显下降。NaCl、Ca(NO_2)_2、NaNO_2的掺入对界面厚度影响不大,Ca(NO_3)_2、Na_2SO_4会使界面区厚度有所增大。掺入粉煤灰后会使界面区的显微硬度值有所降低;除了Na_2SO_4与粉煤灰混掺后会使界面厚度减小,其它无机盐与粉煤灰混掺均会使界面厚度增加。利用氮吸附仪及压汞仪测试无机盐掺加后孔结构的变化情况,发现NaCl、Na_2SO_4的加入会对早期孔结构有细化作用,Ca(NO_2)_2及Ca(NO_3)_2会对早期孔结构有粗化效果;无机盐的掺入均会使后期的孔结构发展变缓。掺入粉煤灰后无机盐对早期孔结构无明显作用,28d龄期后,NaCl的加入有效的减少了最可几孔的数量,NaNO_2及Ca(NO_2)_2的加入也有上述的作用。其它无机盐加入后会使最可几孔数量及孔径减小,而且Ca(NO_3)_2的加入还使最可几孔孔径增大。采用显微镜观察硬化非引气混凝土的气孔结构,发现除Na_2SO_4能增大含气量外,其它无机盐的加入均对混凝土的含气量有或多或少的降低作用;NaCl对气孔平均半径影响不大,Ca(NO_2)_2、Ca(NO_3)_2及Na_2SO_4的掺入会使气孔平均半径增大;NaNO_2的掺入会使气孔半径有所降低;NaCl、Ca(NO_2)_2、Ca(NO_3)_2、Na_2SO_4的掺入会不同程度的增大气泡间距系数,NaNO_2的加入会降低气泡间距系数。当粉煤灰掺入时,Ca(NO_2)_2、Ca(NO_3)_2、Na_2SO_4及NaNO_2四种无机盐随着粉煤灰掺量的增加各个含气量都有所增加,NaCl的含气量呈现先降低后增大的变化;随着粉煤灰掺量的增加气孔平均半径与气泡间距系数都在不断的减小。
[Abstract]:Inorganic salt admixtures are often used in concrete engineering because of their economic applicability, which play a role of early strength, anti-freezing, quick setting, etc. When inorganic salts are added, they can participate in the hydration reaction of cement. This paper mainly deals with the interfacial transition zone performance of concrete mixed with inorganic salt, NaClCl-CaNO2 + + 2CaNO3 / 2CaNO3 / 2 / Na2SO4 / NaNO2, and the interfacial transition zone of concrete mixed with fly-ash and inorganic salt, which has a certain effect on the internal structure of cement stone in its early and late stages. The main purpose of this paper is to study the properties of the interfacial transition zone of concrete mixed with inorganic salt and fly ash. The pore structure and pore structure were tested and observed. The microhardness and thickness of the transition zone of concrete interface after adding inorganic salt were observed by microhardness tester. It was found that the addition of NaCl-CaNo3 / s _ 2 would increase the microhardness, and that the microhardness would be decreased with the addition of Na_2SO_4 and NaNO_2, while the microhardness would not be affected by the addition of low content of Na_2SO_4. The microhardness of the interface decreases obviously with the addition of high dosage. The addition of NaCl-CaNO-2S _ 2S _ 2 has little effect on the interface thickness. The thickness of the interface area is increased by the addition of fly ash, and the microhardness value of the interface region is decreased after the addition of fly ash. In addition to Na_2SO_4 and fly ash mixing, the interfacial thickness will decrease, but other inorganic salts and fly ash will increase the interfacial thickness. The pore structure changes after adding inorganic salt are measured by nitrogen adsorption instrument and mercury injection meter. It is found that the addition of NaCl-Na _ 2SO _ 4 can refine the early pore structure and that Ca(NO_3)_2 can coarsening the early pore structure. The addition of inorganic salt can slow down the development of pore structure in the later stage. The addition of inorganic salt has no obvious effect on the early pore structure after the addition of fly ash, and the addition of nano _ 2 and Ca(NO_2)_2 can effectively reduce the number of the most available pores after 28 days of age. The addition of other inorganic salts will reduce the number and pore size of the most probable pores, The pore structure of hardened non-air-entraining concrete was observed by microscope, and it was found that the pore structure of hardened non-air-entraining concrete could be increased with the addition of Ca(NO_3)_2, except that Na_2SO_4 could increase the gas content. The addition of other inorganic salts has a more or less effect on the air content of concrete. The effect of NaCl on the mean pore radius is not significant. The addition of Na_2SO_4 and the incorporation of Na_2SO_4 can increase the mean radius of the pore. The addition of NANO2 will reduce the radius of the pore. The addition of NaNO2 will decrease the bubble spacing coefficient. When the fly ash is added, the gas content of each of the four inorganic salts, Na2SO4 and NaNO_2, will increase with the increase of fly ash content, and the gas content of NaCl will increase with the increase of fly ash content, and the gas content of each inorganic salt will be increased with the increase of fly ash content, and the gas content of NaCl will be increased by the addition of NaNO2. When the fly ash is mixed in, the gas content of each inorganic salt will increase with the addition of fly ash. The quantity decreased first and then increased. With the increase of fly ash content, the mean radius of pores and the coefficient of bubble spacing are decreasing.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.042

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