Complex evaluation of the mechanical and fracture properties of cementitious materials with different water-cement ratio

Abstract

This paper is aimed at the development of the physical, mechanical and fracture characteristics of cementitious materials during ageing. Three mortars which differed only in the water-cement ratio (w/c) were prepared for manufacturing of the test specimens intended for the experiments. All mortars were prepared using the standardized quartzite sand with the particle grain size distribution of 0−2 mm CEN 196-1, CEM I 42.5 R Portland cement (cement plant Mokrá, Czech Republic) and water. The reference w/c was set to the value of 0.5. To produce two other mortars, this ratio was reduced by approx. 5 and 30 %. This resulted in w/c ratio 0.47 and 0.35 respectively. All test specimens were not protected intentionally from drying during the whole time of measurement and were stored in laboratory at ambient temperature of 21 ± 2 °C and relative humidity of 60 ± 10 %. The results of the shrinkage, elastic, fracture and strength parameters determined within the time interval from 3 days to 2 years of ageing are summarized and discussed in the paper. The results of performed experiments were partially published within the conference DYN-WIND'17. This paper focuses especially on the evaluation of the results obtained after 2 years of specimens ageing and also provides a complex discussion of the results gathered during the whole time of ageing. The results show a crucial impact of the w/c on the final values of mechanical and fracture characteristics. The early-age and long-term characteristics were substantially influenced by the poor curing conditions.