ASSESSMENT OF THE MECHANICAL AND ENVIRONMENTAL PROPERTIES OF CONCRETES WITH HIGH LEVELS OF LIME FILLER AND FLY ASH

Abstract

This study evaluated the possibility of producing high strength concrete (HSC) by replacing Portland cement (PC) with high levels of limestone filler (LF) in binary mixtures and ternary mixtures of PC, LF and fly ash (FA) in contents varying from 50 % to 80 %, with the objective of reducing CO2 emissions during manufacture. Parameters evaluated were axial compression strength, CO2 emissions of the constituent materials and cost per m³ of concrete with focus on reductions in environmental impact. Results indicated the possibility of producing HSC with high LF and FA contents, reduced water/binder content (w/b = 0.25) and workability of 100 mm ± 20 mm through particle packaging and the use of a superplasticizer additive. The resulting concrete had axial compression strength of 51.8 MPa at 91 days with 77 kgco2/m3 of concrete for a mixture with 80 % of PC replaced with 70 % LF and 10 % FA. These amounts corresponded to the use of only 97 kg/m3 of PC (87 kg/m3 of clinker) and 104 L/m3 of water. Thus, it was demonstrated to be possible to obtain a HSC with fck of up to 80 MPa and low CO2 emissions.

Keywords

• Sustainability; High strength concrete; Limestone filler; Fly ash; high strength concrete.