Reservoir sediment as a secondary raw material in concrete production

This paper summarizes the physical and chemical properties of sediments dredged from the small water reservoir Klusov (Slovakia) and their potential use as a secondary raw material in concrete production. The effects of the sediment addition on the concrete technological properties (compressive and flexural strength, freeze–thaw resistance) have been determined. Concrete specimens were pressed and cured for 2, 7, 28 and 365 days. Results show that progress of compressive strength of concrete mixture, prepared from 20 wt% natural aggregate replacement by coarse-grained sediments, was similar to the control concrete mixture. Specimens containing fine-grained sediment as a cement replacement, at a 40:60 sediment/cement weight ratio, achieved compressive strength values below 35 % in comparison to that of the previous mixtures. The flexural strengths of concrete specimen prepared as a natural aggregate replacement were higher when compared to the reference mixture at all ages of hardening and have achieved a value of 6.59 MPa after 365 days of curing. Flexural strengths of the other samples were at about 4.0 MPa. All tested concrete specimens resistant to freeze–thaw attack achieved frost resistance coefficient values above 0.85 according to the standard requirements. The weight loss values after 50 cycles of freeze–thaw testing were in range from 1.33 to 2.5 % and hence the standard requirement of maximum 5 % weight loss was also fulfilled. The results of the frost resistance coefficient and the weight loss after 50 cycles of freeze–thaw testing show that the tested concrete specimens meet the standard requirements for frost-resistant concrete class XF2.