INFLUENCE OF THE CHARACTERISTICS OF THE ORIGINAL CONCRETE ON THE PROPERTIES OF PORTLAND CEMENT USING RECYCLED CONCRETE AS A MINERAL ADDITIVE
DOI:
https://doi.org/10.31713/budres.v0i46.05Abstract
The article investigated the possibility of using the dispersed fraction obtained during grinding of concrete scrap as a mineral additive to Portland cement. The influence of the characteristics of recycled concrete (composition and strength of the original concrete, mineralogical and granulometric composition) on the technical properties of Portland cement was studied. In the research, specially made concrete samples were used, which differed in the content of Portland cement, mineral additives and, accordingly, in strength. The samples were crushed in a jaw crusher. A dispersed fraction less than 1.25 mm in size was used as a mineral additive to cement. The granulometric and chemical-mineralogical composition of the obtained fraction was determined. The laboratory ball mill produced cements that differed in the type of recycled concrete required and its amount (15 and 30% of the clinker mass). For the received cements, a complex of laboratory tests was carried out in accordance with the current regulatory documents. The possibility of replacing granulated blast furnace slag in the production of II and III types of Portland cement with the fine fraction obtained during grinding of recycled concrete has been established. It is shown that the replacement of blast furnace slag with a dispersed fraction of recycled concrete in the amount of 15% causes a slight decrease in the strength of cement-sand beams, about 1-5%. Replacing 30% of clinker with recycled concrete causes an average strength reduction of 12 to 45%. According to the main indicators, the received cements meet the requirements of the standards and are characterized by a slight decrease in strength with an equivalent replacement of blast furnace slag. The strength of the original concrete affects the ability of cement to grind. The use of recycled concrete of lower strength causes an increase in the fineness of cement grinding.
