Effect of Various Fly Ash and Ground Granulated Blast Furnace Slag Content on Concrete Properties: Experiments and Modelling

Abstract

Concrete is known as the most globally used construction material, but it releases a huge amount of greenhouse gases due to cement production. Recently, Supplementary Cementitious Materials (SCMs) such as fly ash and Ground Granulated Blast Furnace Slag (GGBFS) have been widely used in concrete to reduce the cement content. However, SCMs can alter the mechanical properties and time-dependent behaviors of concrete and the early age mechanical properties of concrete significantly affect the concrete cracking in the engineering field. Therefore, evaluation of the development of the mechanical properties of SCMs-based concrete is vital. In this paper, the time development of mechanical properties of concrete mixes with various fly ash and GGBFS was experimentally investigated. Four different cement replacement levels including 0%, 20%, 30%, and 40% by fly ash and GGBFS as well as ternary binders were considered. Compressive strength, splitting tensile strength, flexural strength, and elastic modulus of concrete were measured until 28 days. Three additional concrete mixes with ternary binders were also cast to investigate the early-age autogenous shrinkage development until 28 days. In addition, prediction models in existing standards were used and compared to experimental results. The comparison results showed that the prediction models overestimated the compressive strength but underestimated the splitting tensile strength development and autogenous shrinkage. As a result, a model capturing the effect of fly ash and GGBFS on the development of compressive and splitting tensile strength is proposed to improve the prediction accuracy for current standards and empirical models.

Eco-Friendly Geopolymer Composites Prepared from Agro-Industrial Wastes: A State-of-the-Art Review

“…Beyond 800 • C, recrystallization of amorphous silica to tridymite and cristobalite occurred, and more prism-shaped particles were observed in the micrograph of calcined SBA samples. In addition, the microstructural properties of RH-SiO 2 , as displayed in Figure 9, revealed that the particles contained porous, angular, cellular, and irregular shapes and textures [112,113]. The reactive amorphous silica can have a cellular structure; the samples that were cellular and porous contained greater surface area, thereby having greater water-absorption features.…”

“…Figure 9. Residual ashes' SEM micrographs (a) FA[113], (b) GGBFS[113], (c) SBA[93], (d) RH-SiO₂, (e) POA[97] and (f) SA[116] Figure9. Residual ashes' SEM micrographs.…”

Based on the CT Image Rebuilding the Micromechanics Hierarchical Model of Concrete

“…Concrete is a composite material consisting of water, cement, and coarse aggregates. e special properties of the composite material determine its macroscopic mechanical properties [1]. e destruction process involves the interaction of various scales, from the microscopic to the macroscopic [2,3] .…”

Modeling blended cement concrete tensile creep for standard ring test application

“…SCMs have been widely used in concrete to reduce cement content (consequently decreasing CO 2 emission) and improve the mechanical and durability performance of concrete 29 . In addition, SCMs are mainly industrial by‐products, so more economical than cement.…”

“…9,[26][27][28] SCMs have been widely used in concrete to reduce cement content (consequently decreasing CO 2 emission) and improve the mechanical and durability performance of concrete. 29 In addition, SCMs are mainly industrial byproducts, so more economical than cement. However, SCMs also have drawbacks, such as decreasing the early age strength development and impacting the viscoelastic properties like tensile creep.…”