Use of High Volumes of Fly Ash to Improve ECC Mechanical Properties and Material Greenness

Abstract

Environmental sustainability considerations are taken into account in this report on high-performance fiber-reinforced cementitious composite (HPFRCC) development. Featuring high tensile ductility with high volumes of fly ash (HVFA) replacement of cement (up to 85% by weight), unique HPFRCC members are engineered cementitious composites (ECC). While the material design process sees application of micromechanics in many of its aspects, this study emphasizes how fly ash content alters material microstructure and mechanical properties. While they incorporate high recycled fly ash volumes, HVFA ECCs are shown in experimental results to be able to retain an approximately 2 to 3% long-term tensile ductility. Significantly, there is reduction in both free drying shrinkage and crack width with a fly ash amount increase, though which HVFA ECC structures' long term durability may benefit. That HVFA ECCs' fiber/matrix interface frictional bond increase is responsible for tight crack width is indicated through micromechanics analysis. Use of industrial waste stream material instead of cement reduces environmental impact and achieves more saturated multiple cracking, meaning a robustness improvement is shown in HVFA ECCs.