Gel/Space Ratio Evolution in Ternary Composite System Consisting of Portland Cement, Silica Fume, and Fly Ash

Abstract

In cement-based pastes, the relationship between the complex phase assemblage and mechanical properties is usually described by the “gel/space ratio” descriptor. The gel/space ratio is defined as the volume ratio of the gel to the available space in the composite system, and it has been widely studied in the cement unary system. This work determines the gel/space ratio in the cement-silica fume-fly ash ternary system (C-SF-FA system) by measuring the reaction degrees of the cement, SF, and FA. The effects that the supplementary cementitious material (SCM) replacements exert on the evolution of the gel/space ratio are discussed both theoretically and practically. The relationship between the gel/space ratio and compressive strength is then explored, and the relationship disparities for different mix proportions are analyzed in detail. The results demonstrate that the SCM replacements promote the gel/space ratio evolution only when the SCM reaction degree is higher than a certain value, which is calculated and defined as the critical reaction degree (CRD). The effects of the SCM replacements can be predicted based on the CRD, and the theological predictions agree with the test results quite well. At low gel/space ratios, disparities in the relationship between the gel/space ratio and the compressive strength are caused by porosity, which has also been studied in cement unary systems. The ratio of cement-produced gel to SCM-produced gel (GC to GSCM ratio) is introduced for use in analyzing high gel/space ratios, in which it plays a major role in creating relationship disparities.

Performance evaluation of sustainable high strength mortars incorporating high volume waste glass as binder

“…In consideration of environmental protection, it is an efficient method to apply the waste glass in building materials. In previous studies, waste glass exhibits a potential to be an ingredient in concrete, for example, waste glass fractions not only can be used as aggregates [1] [2], but also supplementary cementitious materials as GGBS or coal fly ash [3]- [6].…”

Influence of Silica Fume Addition in the Long-Term Performance of Sustainable Cement Grouts for Micropiles Exposed to a Sulphate Aggressive Medium

“…In relation to silica fume, research indicates that this addition improves the microstructure and properties of cement-based materials [ 11 , 12 , 13 , 14 ], such as their permeability, and recommend its use for several applications. However, at least in Spain, there are several fields of civil engineering where silica fume is not used.…”

Analysis of Early Performance of Cement Paste by Low Field NMR

“…The saturated gel volume can be calculated by the degree of hydration and the specific volume of saturated gel. The pure cement paste gel/space ratio X is calculated as follows: where νsg and νc are the specific volumes of saturated gel and cement, respectively; νsg = 0.67 and νc = 0.32, according to the literature [20,21]; w/c is the water-to-cement ratio; αc is the reaction degree of the cement. Therefore, the relationship between gel/space ratio X of cement paste and the hydration degree of cement can be expressed as: It can be seen from Figure 3 that the initial setting time of the cement paste occurs when the gel/space ratio is 0.09 ± 0.02, and the final setting time appears when the gel/space ratio is 0.15 ± 0.02.…”

“…where ν sg and ν c are the specific volumes of saturated gel and cement, respectively; ν sg = 0.67 and ν c = 0.32, according to the literature [20,21]; w/c is the water-to-cement ratio; α c is the reaction degree of the cement. Therefore, the relationship between gel/space ratio X of cement paste and the hydration degree of cement can be expressed as:…”