1 The protected ambient temperature is very wet
2. Surface pulverization caused by "alkali impurities"
3. When the density of the green body is low, the porosity increases, and the carbon dioxide in the air can be more easily dispersed into the green body, causing the damage to occur.
4.the amount of water added to the construction function can be better, but the initial strength and density of the body have certain side effects, together with the increase in water will inevitably add hydration response, simpler to make the appearance of the external surface powder.
1. Low Cement Refractory Castable Surface Pulverization Caused by Alkali Impurities
In the formulation of refractory castables, the primary refractory materials, cement and sodium salt admixtures all contain soluble sodium. In low grade refractory raw materials, the content of alkali metal impurities tends to be relatively high, and the admixture also introduces sodium ions. With the addition of cement, the alkalinity of the system increases, and the hydration mineral deposits formed together are relatively large, and a series of repercussions occur in the presence of these soluble alkalis.
The soluble alkali in the low cement refractory castable will be hydrolyzed, and the carbon dioxide will react with the carbon dioxide in the air, and the cement will hydrate, and the two will continue to reverberate. Continuous differentiation of calcification. Only when there is cement hydration product, the above reaction will be cycled, the product will continue to differentiate, and the castable body will be damaged from the outside to the inside. The presence of soluble alkali in the castable, the solubility of CO2 added, is an important condition for rapid response. The greater the alkalinity of the system, the more hydrated mineral deposits, the more favorable the reaction is.
2. Protection Ambient Temperature Humidity Low Cement Refractory Castable
Which usually the protection temperature is 15 ~ 20 ° C, large precast block, in order to protect the strength of the addition, will enter the low temperature kiln for 30 ~ 35 ° C protection, after investigation, Advances in the protection temperature can enhance the strength and service life of the green body, and the phenomenon of powdering on the outer surface of the blank is also reduced accordingly. It can be seen that the protection of the body temperature and humidity is a serious factor in the damage. In general, the greater the humidity, the easier it is to wet the pores in the castable body. Under wet conditions, the dissociation of the soluble alkali in the castable is simpler and the response is smoother.
3.Influence of Density of Green Body of Low Cement Refractory Castable
The density of the green body is also an important factor that causes the external powdering of the castable. When the density of the green body is low, the porosity increases, and the carbon dioxide in the air can be more simply After being dispersed into the body, the damage resounds, causing the body to be powdered from the outside to the inside.
4. Impact of Construction Water Addition in Low Cement Refractory Castavble
The initial strength and construction function of the low cement refractory castables are closely related to the amount of water added to the construction. The application of water addition can be better, but there are certain side effects on the initial strength and density of the green body. It is inevitable to add hydration reaction when adding more water together, and it is easier to make the surface of the in vitro surface powder. It is difficult to reach the functional requirements of the construction by manipulating the amount of water added, so the amount of water added to the construction is also an influential factor of the damage.
