COMPOSITE BINDERS WITH USE CLINKER KILNS DUST

Abstract

The article deals with the features of obtaining a composite binder containing cement kilns dust, blast furnace slag and Portland cement, in which increased complex activation of blast-furnace granulated slag is achieved, due to the increased content of alkalis in cement dust, as well as the effects of hydroxide and calcium sulphate, contained in the cement. The influence of composition, fineness of grinding and content of chemical additives on the degree of hydration and strength of astringent low water requirements was studied. The optimal relationships between the components of the binder and the required fineness of the grinding are established, which ensure the strength characteristics and the curing speed. The influence of chemical additives of superplasticizers of naphthalene formaldehyde and polycarboxylate types, which provide low water consumption of binding agent and high fineness of its grinding, is studied. Using the method of mathematical design of the experiment, equations for the regression of strength in compressive and bending in different compensations were obtained, which allow predicting strength, taking into account the composition and features of the technology for obtaining the binder. The analysis of the obtained equations is carried out. The effects of the investigated factors are established. With the use of mathematical models, the optimal binder composition, the necessary fineness of grinding and the content of the superplasticizer are adopted. It is established that the dust of cement production clinker kilns can be used as an activating component of composite binder, which include Portland cement, dust, blast-furnace granular slag and additive-superplasticizer. At optimum values of the composite mineral admixture content and the dust-slag ratio, the binder grinding for a specific surface of 450-500 m²/kg allows, with the use of a naphthalene formaldehyde superplasticizer, to provide the strength of binders 50-60 MPa, and polycarboxylate superplasticizer up to 70 MPa.