Search

Highlights • The fracture behaviors of SFGC are influenced by the material parameters. • The Bažant and Becq-Giraduon model predicts well the fracture energy of SFGC. • The characteristic length of SFGC is higher than the prediction for PCC. • The SFGC beam with M s = 2.0 exhibits more ductility behavior. Abstract Slag/fly ash (FA)-based geopolymer cured in ambient temperature as a green alternative to Portland cement is attracting increasing attentions. The fracture properties of slag/FA-based geopolymer concrete (SFGC) was studied by conducting three-point bending (TPB) tests on precut beams. The effects of material parameters including the alkali concentration, the modulus of alkali activator, the slag/FA mass ratio and the liquid/binder ratio on the fracture properties of SFGC were assessed. The results exhibit that the fracture behaviors of SFGC are influenced significantly by the material parameters. The fracture energy and the ultimate load of TPB tests of SFGC beams increase with the increase of the alkali concentration, the modulus of alkali activator as well as the slag/FA ratio while decrease with the increase of liquid/binder ratio. The Bažant and Becq-Giraduon model predicts well whereas the CEB-FIP model underestimates the fracture energy of SFGC beams. Besides, the characteristic length of SFGC decreases with the increase of compressive strength regardless of the mix proportion, and is higher than the prediction for Portland cement concrete (PCC) given the similar compressive strength, suggesting that SFGC might be more ductile. In addition, the relationships between compressive strength, splitting tensile strength, elastic modulus and material parameters of SFGC specimens are also discussed. [ABSTRACT FROM AUTHOR]

In order to enhance the CO 2 curing efficiency of concrete block prepared with recycled aggregates, several material characteristics of the concrete block including moisture content, bulk density, aggregate to cement ratio, recycled aggregate content and types of binders, were studied experimentally to assess their effects on the CO 2 curing process. The results indicated that, during 2 h of CO 2 curing period, the moisture content and aggregate to cement ratio of the prepared blocks had significant effects on the CO 2 curing degree and the compressive strength. Appropriate pre-drying of the block specimens before CO 2 curing enabled the maximum curing degree, and the compressive strength attained was comparable or superior to that of the 6 h steam cured blocks. The bulk density and recycled aggregate content of the prepared blocks would also influence the CO 2 curing degree, but their effects on compressive strength were more complex. It was confirmed that the presence of recycled aggregate in the concrete blocks can promote the CO 2 curing efficiency. [ABSTRACT FROM AUTHOR]