Ozhyshchenko O. Rapid-hardening dry construction mixtures based on ettringite matrix

The subject of the research is rapid-hardening multicomponent dry mixes based on ettringite matrix. The objective of the thesis is the development of rapid-hardening multicomponent dry mixes based on ettringite matrix and studying of their properties. The research methods: viscosimetry; conductometry; infrared spectrometry; differential thermal analysis; thermogravimetric analysis; X-ray diffraction analysis; extent of proper shrinkage deformation was determined by the indicating gage; processing of the research materials was accomplished by the methods of the correlated and regression statistical analyses. Theoretical and practical results: multicomponent dry construction mixes were formed, the use of which permits increasing of construction efficiency by obtaining high strength properties of concrete and mortar (18 МРа at eight hours age) at early stage of hardening; factors influencing high early strength of mortars were experimentally and analytically defined. Novelty of the research: for the first time the parametres were determined (correlation of matrix and modifying agents, fineness of grinding of aluminous cement and portlandcement, a sort of calcium sulphate used, quantity of modifying agents, time and speed of outsettling of new hydrate formations), which condition high early compression strength of mortars of dry construction mixes based on ettringite matrix; the research technique was improved and for the first time mathematical model of predicting the strength properties of mortars of dry construction mixes based on ettringite matrix depending on their composition, percentage of ingredients, chemical and mineralogical composition of ettringite matrix, was proposed; the influence of the conditions of hardening and exploitation (normal humidity, air-dry conditions, aqueous environment) on the properties (compression strength, proper deformation) of mortars based on ettringite matrix was determined. Implementation extent: a lot of dry construction mix was produced which was applied at the construction object for jointing of monolithic and prefabricated concrete elements, elimination of delaminating of a brick wall by the injection method; theoretical calculation of the affordability of construction of the nine-storey building makes 371,000 UAH which is 102,7 UAH for 1 м3 of concrete. Application sphere: repair and construction works where early strength of the material is required.