Impacts Of Diatomite On Performance Of Inorganic Thermal Insulation Mortar

Inorganic thermal insulation mortar is an innovative thermal insulation material of buildings, which develops in recent years. It is preferable by builders because of its well performance in fireproofing, mechanical property, durability and easy to construct.Our country is rich in diatomaceous earth and it is widely distributed in our country land. But with the mining of primary ore, a large scale of middle and low grade DE is abandoned, stacking in the air, not being well used. After some activation treatment(e.g. grinding, calcination, etc.) to the middle and low grade DE, the surface area can be increased effectively and DE can be well activated. Adding activated DE instead of a part of cement into thermal insulation mortar, which will make DE has a secondary reaction of hydration with cement hydration products, hence it can be used as the active admixture.In this project, I made the activation treatment to the middle and low grade DE, and then added it instead of cement with the same quality into the thermal insulation mortar, the main idea is to explore the effects diatomaceous earth with different treatment progress and mixing amounts will have on the performance of inorganic thermal insulation mortar. Details are as follows:(1) Making activation treatment on DE by grinding and calcination, using the methods of scanning electron microscope、XRD phase analysis、BET to compare the surface area、pore analysis、laser particle size analysis to do the univariate analysis of the impact of grinding time, calcination time, calcination temperature have on the physical and chemical properties of DE, the results show that with the grinding time of 5min, the calcination temperature of 650℃, calcination time of 2h, the activation level of DE is highest.(2) The activation experiment result indicates, activated DE has hydration activity. This paper explores the impact of the replacement with same amount on a scale of 10%~50% on thermal insulation mortar from mechanical properties, thermal properties and durability. With the increasing of the adding amount of DE, thermal insulation mornar’s mechanical property performs better then gets worse. At the point of 10%, it performs best. The durability performs similar. While when grinding diatomite for 5 minutes the thermal property shows a decreasing trend to the increasing amount of added DE. But change the grinding time to 10 min the thermal conductivity shows better then gets worse. At the point of 10%, it performs best.(3) This paper studies the influence of calcination temperature on thermal insulation mortar’ properties. When the calcination temperature increases, its mechanical property increases first and then decreases. The optimum calcination temperature is 650℃. With the increasing of calcination temperature, the thermal conductivity、water resistance and freezing resistance all go up first and then go down. At the temperature of 650℃, the thermal conductivity and the softening coefficient are the largest, the loss of freeze-thaw quality and pressure are the smallest.(4) In this project, I did the research about calcination time’s impact on the properties of thermal insulation mortar. The results show that when the calcination time is longer, its mechanical property performs better, its softening coefficient gets larger, its freezing resistance is optimized, its thermal conductivity is increasing as well.(5) In this project, I also analyzed what the influence grinding time has on the properties of thermal insulation mortar. The results indicate that, increasing the grinding time, the compression resistance and flexural strength decrease, thermal conductivity goes up at first and then go down. When the grinding time is 15 min, it has the minimum thermal conductivity, its water resistance and freezing resistance get worse.(6) Last, I did the microstructure analysis about thermal insulation mortar with different mixing amount of DE through a scanning electron microscope. Observed that without mixing DE, the internal structure of mortar shows a little loose. When the proportion of DE is 10%, the hydration product increase, the internal porosity reduces significantly, the particles of mortar packs more tightly. When the proportion of DE is 50%, the internal hydration product decrease, the hydration degree of its surface is low, and DE is mainly acting as fillers now.(7)Diatomite show hydration characteristics when it is in inorganic thermal insulation mortar. In the process of slurry condensation sclerosis DE can react with cement hydrates turn to the secondary reaction of hydration. As the diatomite particles appears small, it is able to fill in the tiny pores of mortar to improve the pore structure. The result shows that add the right amount of diatomite in inorganic thermal insulation mortar can improve the mechanical properties、durability and reduce the heat conductivity of thermal insulation mortar. The activation of diatomite is a rational activity of mixed material.