Influence of type and maximum aggregate size on some properties of high-strength concrete made of pozzolana cement in respect of binder and carbon dioxide intensity indexes

• Influence of type and size of aggregate and pozzolana cement on HSC was determined.
• 0/8 mm aggregate with cement at 700 instead of 600 kg/m3 improved strength by 8.5%.
• In case of 0/16 mm aggregate there was no need to increase cement amount to 700 kg/m3.
• Basalt or granite of 0/16 mm size and 600 kg/m3 of cement curbed HSC carbon footprint.

In compliance with up-to-date concrete technology requirements combining technological and ecological aspects, the paper describes the effect of the type and maximum aggregate size and cement content on some properties of high strength concrete. The following kinds of coarse aggregate were used to produce concrete: natural mineral (gravel) and crushed (granite and basalt) aggregates and pozzolana cement – ingredient classified as ecological binder. The concretes contained a highly effective superplasticiser and microsilica. Air content in concrete mixes, water absorption and concrete compressive strength after various periods of hardening were examined. Certain calculations (based on compressive strength results) on values of intensity indexes of cement used and carbon dioxide, treating them as a key for evaluation of eco-efficiency of concrete, were performed. Using pozzolana cement with simultaneous use of a highly effective superplasticiser and microsilica made it possible to obtain high strength concrete, made of mineral natural and crushed aggregates. More encouraging strength tests results were achieved for concrete of crushed aggregates, particularly granite. It was discovered that using aggregate with a maximum particle size less than 8 mm instead of aggregate with particles measuring up to 16 mm with a simultaneous increase in the cement content led to a greater rise in concrete strength. The smallest indexes of binder and carbon dioxide intensity were obtained as a result of use of granite and basalt aggregate, with a maximum particle size up to 16 mm.