钢渣和含钢渣的复合矿物掺合料对混凝土性能的影响
发布时间：2019-04-30 05:54
【摘要】：钢渣是炼钢过程中的副产品，其排放量约为钢产量的10~15%，大量钢渣的堆放和闲置不仅占用大量的耕地，而且钢渣中所含有的重金属离子和碱金属离子还会渗入土壤中，造成地下水污染。因而开展钢渣综合利用的研究是一个非常有意义的课题。 钢渣中含C3S、C2S等具有水硬性的组分，因而钢渣具有一定的活性，是一种潜在的混凝土的矿物掺合料。本文主要针对钢渣的安定性问题和含钢渣的复合胶凝材料配制的混凝土的力学性能及耐久性开展了研究，得出了以下结论： （1）不同钢渣的安定性有较大的差异，钢渣的安定性与其游离氧化钙的含量之间有密切的联系。游离氧化钙在压蒸条件下和标准养护条件下反应所生成的Ca(OH)2均与水泥水化生成的Ca(OH)2有所差异，游离氧化钙生成的Ca(OH)2具有更大的比表面积或体积，容易引发混凝土的膨胀。钢渣的安定性不良是否会引发混凝土微结构的破坏取决于多个因素，包括：钢渣中游离氧化钙的含量、钢渣占胶凝材料总量的比例、混凝土的强度等级等。 （2）在保持水胶比不变的条件下，随着钢渣掺量增大，混凝土的很多性能降低；水胶比较低时，钢渣对混凝土性能的不利影响的程度相对较小。在28d抗压强度基本相同的情况下，钢渣混凝土的早期强度低于纯水泥混凝土，但后期强度略高于纯水泥混凝土；钢渣混凝土的渗透性、干燥收缩性能及抗碳化性能与纯水泥混凝土相差不大。 （3）当钢渣与矿渣的比例为3:7时，钢铁渣粉混凝土的流动性、强度、弹性模量与矿渣混凝土相近，钢铁渣粉混凝土比矿渣混凝土的绝热温升低、自生收缩和干燥收缩小、抗冻性好。当钢渣与矿渣的比例为4:6时，，钢铁渣粉混凝土的早期强度和28d强度低于矿渣混凝土。 （4）在钢渣中掺入少量的硅灰即可以显著提高钢渣的性能（强度和抗氯离子渗透性）。当硅灰的含量达到15%时，钢渣-硅灰复合矿物掺合料的性能可以接近或超过矿渣。钢渣 超细粉煤灰复合矿物掺合料对混凝土强度的影响与矿渣接近，尽管降低混凝土28d渗透性的作用不及矿渣，但对混凝土90d渗透性的影响与矿渣接近。
[Abstract]:Steel slag is a by-product of the steelmaking process, and its discharge is about 10% of the steel output. The stacking and idle use of a large amount of steel slag not only occupies a large amount of farmland, but also contains heavy metal ions and alkali metal ions in the steel slag, which will also infiltrate into the soil. Cause groundwater pollution. Therefore, the research on the comprehensive utilization of steel slag is a very meaningful subject. Steel slag contains C _ 3s, C _ 2S and other hydraulic components, so steel slag has certain activity and is a potential mineral admixture of concrete. In this paper, the stability of steel slag and the mechanical properties and durability of concrete made of composite cementitious material containing steel slag are studied. The following conclusions are drawn: (1) the stability of different steel slag is different greatly, and the mechanical properties and durability of concrete made of composite cementitious material containing steel slag are different. There is a close relationship between the stability of steel slag and the content of free calcium oxide. The Ca (OH)-2 produced by the reaction of free calcium oxide under autoclave and standard curing conditions is different from that of Ca (OH)-2 formed by hydration of cement. The Ca (OH)-2 produced by free calcium oxide has a larger specific surface area or volume. It is easy to cause the expansion of concrete. The failure of steel slag to cause the failure of concrete microstructure depends on many factors, such as the content of free calcium oxide in steel slag, the ratio of steel slag to total cementitious material, the strength grade of concrete and so on. (2) under the condition of keeping the ratio of water to binder constant, the performance of concrete decreases with the increase of steel slag content, and the degree of adverse effect of steel slag on concrete performance is relatively small when the ratio of water to binder is low. Under the same compressive strength of 28 days, the early strength of steel slag concrete is lower than that of pure cement concrete, but the later strength of steel slag concrete is slightly higher than that of pure cement concrete. The permeability, drying shrinkage and carbonation resistance of steel slag concrete are similar to those of pure cement concrete. (3) when the ratio of steel slag to slag is 3: 7, the fluidity, strength and elastic modulus of steel slag powder concrete are similar to that of slag concrete, and the adiabatic temperature rise of steel slag powder concrete is lower than that of slag concrete, and the autogenous shrinkage and drying shrinkage are reduced. The freezing resistance is good. When the ratio of steel slag to slag is 4: 6, the early strength and 28 d strength of steel slag powder concrete are lower than that of slag concrete. (4) adding a small amount of silica fume into steel slag can significantly improve the performance (strength and resistance to chloride ion penetration) of steel slag. When the content of silica fume is up to 15%, the properties of steel slag-silica fume composite mineral admixture can be close to or higher than that of slag. The effect of steel slag / ultra-fine fly ash composite mineral admixture on the strength of concrete is close to that of slag. Although the effect of reducing the permeability of concrete for 28 days is less than that of slag, the effect on the permeability of concrete for 90 days is similar to that of slag.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528
本文编号：2468532
[Abstract]:Steel slag is a by-product of the steelmaking process, and its discharge is about 10% of the steel output. The stacking and idle use of a large amount of steel slag not only occupies a large amount of farmland, but also contains heavy metal ions and alkali metal ions in the steel slag, which will also infiltrate into the soil. Cause groundwater pollution. Therefore, the research on the comprehensive utilization of steel slag is a very meaningful subject. Steel slag contains C _ 3s, C _ 2S and other hydraulic components, so steel slag has certain activity and is a potential mineral admixture of concrete. In this paper, the stability of steel slag and the mechanical properties and durability of concrete made of composite cementitious material containing steel slag are studied. The following conclusions are drawn: (1) the stability of different steel slag is different greatly, and the mechanical properties and durability of concrete made of composite cementitious material containing steel slag are different. There is a close relationship between the stability of steel slag and the content of free calcium oxide. The Ca (OH)-2 produced by the reaction of free calcium oxide under autoclave and standard curing conditions is different from that of Ca (OH)-2 formed by hydration of cement. The Ca (OH)-2 produced by free calcium oxide has a larger specific surface area or volume. It is easy to cause the expansion of concrete. The failure of steel slag to cause the failure of concrete microstructure depends on many factors, such as the content of free calcium oxide in steel slag, the ratio of steel slag to total cementitious material, the strength grade of concrete and so on. (2) under the condition of keeping the ratio of water to binder constant, the performance of concrete decreases with the increase of steel slag content, and the degree of adverse effect of steel slag on concrete performance is relatively small when the ratio of water to binder is low. Under the same compressive strength of 28 days, the early strength of steel slag concrete is lower than that of pure cement concrete, but the later strength of steel slag concrete is slightly higher than that of pure cement concrete. The permeability, drying shrinkage and carbonation resistance of steel slag concrete are similar to those of pure cement concrete. (3) when the ratio of steel slag to slag is 3: 7, the fluidity, strength and elastic modulus of steel slag powder concrete are similar to that of slag concrete, and the adiabatic temperature rise of steel slag powder concrete is lower than that of slag concrete, and the autogenous shrinkage and drying shrinkage are reduced. The freezing resistance is good. When the ratio of steel slag to slag is 4: 6, the early strength and 28 d strength of steel slag powder concrete are lower than that of slag concrete. (4) adding a small amount of silica fume into steel slag can significantly improve the performance (strength and resistance to chloride ion penetration) of steel slag. When the content of silica fume is up to 15%, the properties of steel slag-silica fume composite mineral admixture can be close to or higher than that of slag. The effect of steel slag / ultra-fine fly ash composite mineral admixture on the strength of concrete is close to that of slag. Although the effect of reducing the permeability of concrete for 28 days is less than that of slag, the effect on the permeability of concrete for 90 days is similar to that of slag.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528
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