摘要
煤矸石作为水泥混合材具有很高的经济价值和社会价值,.目前煤矸石在这方面的应用还处于粗放式,而且存在着许多问题(配成水泥需水量大,强度低等),使得综合利用率不高,因此如何合理有效的处理煤矸石是当务之急。
本文针对自燃煤矸石水泥需水量大和强度低的问题,主要做了以下研究：通过改变自燃煤矸石细度与掺量降低自燃煤矸石体系的需水性；利用灰色关联对自燃煤矸石粒径分布与体系需水量的关系进行分析；研究自燃煤矸石粉磨时间对自燃煤矸石水泥强度的影响；通过复掺煅烧白云石、硅灰、矿渣和粉煤灰对自燃煤矸石水泥强度进行优化。主要结果如下：
采用对自燃煤矸石粉磨时间的不同得出自燃煤矸石作为混合材对水泥体系需水性的研究。研究表明：随着自燃煤矸石细度的增加,水泥标准稠度用水量先呈现下降趋势,但随着细度继续增加,水泥标准稠度用水量呈现持续增长的趋势。
采用灰色关联分析的方法分析了自燃煤矸石粒径分布对水泥体系需水量的影响。结果表明：不论水泥细度大小,粒径范围在5.0～10.0μm的自燃煤矸石将增加水泥的需水量,而适当增加10.0～40.0μm范围的自燃煤矸石颗粒,将有利于降低水泥体系需水量。
采用矿渣、钢渣与自燃煤矸石复合后,矿渣-自燃煤矸石水泥体系需水量和钢渣-自燃煤矸石水泥体系需水量都低于单掺自燃煤矸石水泥,且矿渣对自燃煤矸石水泥需水性优化效果较好。
采用柠檬酸法和水化法对煅烧白云石的活性进行了研究,我们得出白云石经过750℃煅烧,保温2.5 h后的活性最好。
采用水泥胶砂实验强度方法对复掺750℃煅烧白云石改性自燃煤矸石进行研究。结果表明：水泥体系早期强度有所增加,后期强度全部低于单掺自燃煤矸石。
在复掺750℃煅烧白云石的条件下通过引入硅灰,各组强度都有不同程度的增加,与单掺自燃煤矸石的体系相比早期强度增加不太明显,后期强度增加明显。当煅烧白云石掺量为8 wt%时,28天强度比单掺自燃煤矸石的体系强度增加近8 MPa,而90天强度增加11 MPa。微观分析显示水泥浆体结构致密,水化产物较多。
矿渣对自燃煤矸石的复合效应优于粉煤灰对自燃煤矸石的复合效应,体系强度都随着矿渣和粉煤灰掺量的增加而增加。当矿渣的掺量在10 wt%时,28天强度比单掺自燃煤矸石的体系强度要高近10 MPa,60天、90天平均增加近7MPa。当粉煤灰的掺量在10 wt%时,28天强度比单掺自燃煤矸石的体系强度要高近7 MPa,而60天、90天平均增加仅为3.5 MPa。
The research on coal gangue as the cement admixture has high economic value and social significance. At present, the utilization of coal gangue in this field is in extensive style, and has a lot of problem, such as the greater water requirement and lower strength, and the comprehensive utilization of the coal gangue was low. So the utilization of coal gangue in reasonable and effective is urgent affairs.
This paper researched on the coal gangue as the cement admixture aiming at the problem on the utilization. The water requirement of spontaneous combusted gangue cement was decreased by changing the fineness and mixing amount of coal gangue; the relationship of water requirement and particle size distribution for coal gangue was studied; and the effect of grinding time of coal gangue on strength of spontaneous combusted gangue cement was researched; at last, strength of spontaneous combusted gangue cement was optimized by adding calcined dolomite, silica fume, slag. The main results were as follows:
In this paper, the auxiliary gelling was modified by 750℃calcined dolomite, silica, slag and fly ash. The influence of SCG for admixture in cement on the water demand was studied, we can determined the optimum fineness and optimizational measures of SCG. The influence of different calcination temperature and soaking time on dolomite activity was studied by citric acid way and hydration way, we can find the best calcined system for dolomite. The supporting gel modification mechanism was studied by cement mortar strength, XRD, SEM. The main results were as follows:
The influence of different grinding time for SCG on the water demand was studied. The experiment indicates that when the fineness of SCG increased, the water requirement decreased. When the fineness of SCG increased more, the water requirement of cementitious system will trend to increase significantly.
The influence of particle size distribution of SCG on the water demand of cement system by gray relational analysis was studied. The results showed that no matter the fineness of cement, the particle size of SCG ranging from 5.0μm to 10μm will increase the water demand of cement system, and it will help reduce the water demand of cement system when the particle size of SCG appropriated to increase the range of 10～40μm.
When compounding slag and steel slag into coal gangue respectively, the water requirement of steel slag gangue cement system was higher than slag gangue cement, but all were lower than only having coal gangue.
The influence of calcining technology on the activity of light- burned dolomite was studied. The experimental results showed that the best technological parameters of calcining process were as follows:calcinations temperature was 750℃, holding time was 2.5h.
Compound doped with 750℃calcined dolomite to modify the SCG for mixed materials by means of cement mortar test was studied. The experimental results showed that calcined dolomite contributed to increase the early strength of cement systems, but post- strength was all lower than the only doped SCG
Through the introduction of silica fume, each group has different levels to increase strength, early strength was not significantly increased when compared with only doped SCG. When calcined dolomite content of 8 wt%, the 28- day strength was 8 MPa bigger than the strength of uni doped SCG, and the 90- day strength was 11 MPa bigger than the strength of uni doped SCG.
For spontaneous combustion gangue, the compound effect of slag was equal than fly ash, and the strength of cement system will increase with the content of slag and fly ash increased. When content of the slag is 10 wt%, the 28- day strength was 10 MPa bigger than the strength of uni doped SCG,60- day and 90- day on average was nearly 7 MPa. When the content of fly ash is 10 wt%, the 28- day strength was 7 MPa bigger than the strength of uni doped SCG,60- day and 90- day on average was only 3.5 MPa.
引文
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