Coal ash activated excitant and high-content high-calcium fly-ash cement

Abstract

The invention discloses coal ash activated excitant and high-content high-calcium fly-ash cement. The coal ash activated excitant consists of slaked lime, sodium hydroxide and sodium sulfate. The high-content high-calcium fly-ash cement comprises silicate cement clinker, dihydrate gypsum, silica fume, coal ash and the coal ash activated excitant. The activity of coal ash is excited through physical grinding and compounding with chemical reagents, the high-content high-calcium fly-ash cement of which the fly ash content is 50-75% can be prepared, various properties of the high-content high-calcium fly-ash cement can meet the requirements specified in GB175-2007 Common Portland Cement, and therefore the cement is applicable to industrial application; and large-scale resource utilization of wastes can be achieved. The influence of lots of coal ash piling up on the environment and damage to soil caused by toxic heavy metals can be effectively reduced, and the land resource can be saved.

Description

technical field [0001] The invention relates to a fly ash active stimulator and a large-volume high-calcium fly ash cement, belonging to the technical field of resource utilization of building materials and solid waste. Background technique [0002] Fly ash is fine-grained dust collected after pulverized coal is burned in boilers in coal-fired power plants. In view of my country's energy characteristics of "rich in coal, poor in oil, and low in gas", coal has become the most important primary energy source. As coal production and the number of coal-fired power plants increased rapidly, so did fly ash production. In 2013, the national output of fly ash reached 460 million tons, accounting for 14.8% of the total industrial solid waste. A large amount of stockpiling of fly ash not only occupies a large amount of land, but also has a serious impact on the environment, such as air pollution caused by flying dust, and damage to soil caused by toxic heavy metals in fly ash. [0...

AI Technical Summary

Problems solved by technology

[0004] Although fly ash can undergo pozzolanic reaction, but the reaction speed is slow, which leads to a significant decrease in the early strength of the fly ash system

GB175-2007 "General Portland Cement" stipulates that the amount of fly ash in fly ash Portland cement is 20%-40%, but in actual industrial production, it rarely reaches 40%, and the amount is too high will significantly reduce the strength of the system

This is due to: on the one hand, the calcium content in fly ash is low, which cannot fully provide the calcium required for the formation of gelled products; on the other hand, fly ash has much poorer reactivity than cement clinker. The reaction rate is very slow in the absence of external stimulation

At present, the cement industry mostly grinds fly ash and clinker together, but the grindability of the two is different. When grinding at the same time, the activation effect of fly ash by mechanical force is limited, and the reactivity is also limited.

In addition, although some scholars have studied the chemical excitation of fly ash, the selection of the activator is not reasonable enough, and the excitation effect of the activator is not significant.

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