TC 238-SCM: hydration and microstructure of concrete with SCMs

Abstract

This paper is the work of working group 2 of the RILEM TC 238-SCM. Its purpose is to review methods to estimate the degree of reaction of supplementary cementitious materials in blended (or composite) cement pastes. We do not consider explicitly the wider issues of the influence of SCMs on hydration kinetics, nor the measurement of degree of reaction in alkali activated materials. The paper categorises the techniques into direct methods and indirect methods. Direct methods attempt to measure directly the amount of SCM remaining at a certain time, such as selective dissolution, microscopy combined with image analysis, and NMR. Indirect methods infer the amount of SCM reacted by back calculation from some other measured quantity, such as calcium hydroxide consumption. The paper first discusses the different techniques, how they operate and the advantages and limitations along with more details of case studies on different SCMs. In the second part we summarise the most suitable approaches for each SCM, and the paper finishes with conclusions and perspectives for future work.

The Interfacial Transition Zone in Alkali-Activated Slag Mortars

“…The reproducible contrast of BSE images makes them well suited to use in achieving this aim. Scrivener et al (1986) have shown that the amount of unreacted cement measured by BSE and image analysis corresponds well with independent measures of hydration, and this has also been demonstrated to be highly effective for determination of the extent of reaction of supplementary cementitious materials in blends containing PC (Wong et al, 2006;Scrivener et al, 2015). However, the situation is likely to be different for the study of porosity, which is usually present in discrete regions that are much smaller than the anhydrous cement (or slag) particles.…”

Towards more sustainable construction–application of superabsorbent polymers in cementitious matrices with reduced carbon footprint

“…High performance concrete (lower w/b ratio), for example, is very prone to early age cracking induced by self-desiccation and autogenous deformation [13,15]. High content of GGBS also leads to increased chemical shrinkage due to its filler effect and greater hydration degree [1,4,5]. Thus, SAPs showed themselves as a great shrinkage reducer in GGBS-PC matrices (Fig.…”

“…Its ability to slow down cementitious reactions and induce a filler effect leads to a denser CH-laden interfacial zone and formation of finer capillaries, in particular, those in the mesopore range [1,2,6,36]. Fig.…”

“…It is widely accepted fact that Supplementary Cementitious Materials (SCM) reduce energy and CO 2 emissions from cement production, improve material's performance as well as reduce wastes from other industries [1][2][3]. Ground granulated blastfurnace slag (GGBS), a by-product of iron industry, is one of the most popular SCMs.…”

Influence of Temperature and Added Lime on the Glassy Phase Dissolution in Low-calcium Fly ash Binary Blend

“…The degree of reaction of fly ash in fly ash cement blended system are determined using methods like the selective acid dissolution Glasser 1987, 1998;Sakai et al 2005;Ohsawa et al1985;Suprenant and Papadopoulos 1991;Li et al1985;Fernández-Jiménez et al 2006;Haha et al 2010;Scrivener et al 2015), NMR analysis (Brunet et al 2010), backscattered electron imaging (Deschner et al 2013;Feng et al 2004) SCM with energy dispersive spectroscopy (EDS) (Durdziński et al 2015a) and mass balance (Deschner et al 2012). Among all the methods, selective dissolution is the most widely used method to determine the reaction of fly ash.…”