Influence of buckwheat hulls on the mineral composition and strength development of easily fusible clay body

Abstract

In order to replace the traditional burning-out additive, sawdust, with another, but not less effective, substituent, the influence of buckwheat hulls and their ash on the development of the mineral composition and the physical-mechanical properties of a ceramic body from hydromicous easily fusible clay was studied. By X-ray diffraction, simultaneous thermal analysis, dilatometry and optical microscopy, it has been established that the composition of the newly formed phases depends on the nature and amount of burning-out additives. Buckwheat hulls, like sawdust, reduce the vitreous phase formation temperature in the samples by ~100 °C and accelerate the breakdown of clay mineral structures. As a result, anorthite starts to crystallize at temperature lower by ~60 °C and increases its amount in the ceramic body. Buckwheat hull ash promotes the formation of leucite. These changes in mineralogical composition, among other factors, affect the increase in the compressive strength of the ceramic body. Buckwheat hulls can be used successfully in the production of porous ceramic products because the technological process does not change, and the values of compression strength are close or even better than the values of the ceramic body without additives.