Effect of Cement Fineness on Recycled Aggregate Concrete Compressive Strength at Elevated Temperatures

Abstract

Cement of different fineness CEMΙΙ42.5Ν and CEMΙΙ32.5Ν (EN 197-1) are used, to make concretes with aggregates that had been originated from recycled concrete standard cubic specimens of three different characteristic strengths. Specimen had been produced, during approximately one year, in order to control the production quality of a ready mixed concrete industry. As a consequence, recycled aggregates are of different ages and different compressive strength, such as those which could be taken from a recycling centre. Characteristic cubic strength of origin concrete was 15 or 20 or 25 MPa, and new concretes were made either with all their aggregates recycled or with virgin sand and recycled coarse aggregates. Compressive strength at 200C and at temperatures up to 5500C was estimated, by both destructive and non destructive methods. Results were compared to those obtained from concretes made with virgin siliceous aggregates. Curves of compressive strength versus non-destructive tests before as well as after heating to high temperatures are given.