Rapid screening tests for supplementary cementitious materials: past and future

Abstract

Rapid screening tests for supplementary cementitious materials (SCMs) have been in use for over 150 years. Over the years a multitude of methods have been put forward to predict the strength development of SCM blended mortars and concrete. This paper summarizes and rationalizes the main approaches and then applies them to a selection of materials that cover a broad range of SCMs, both pozzolanic and hydraulic. Included are siliceous fly ash, blast furnace slag, natural pozzolan, metakaolin and an inert quartz filler. The selected test methods are the Chapelle test, the Frattini test, active silica and alumina extractions, a dissolution rate test, and a new calorimetry-based test. The results are compared, interpreted and discussed in view of their aim of predicting the compressive strength development. Finally, a new test method is proposed that relates the cumulative heat of the SCM reaction in a simplified model system to the compressive strength development in standardized mortars. The new method is practical, repeatable and applicable to a wide range of SCMs (both pozzolanic and hydraulic), it furthermore reduces the experiment duration by a factor of 10 and correlates well to the compressive strength development of blended cement mortar bars.

A nearly self-sufficient framework for modelling reactive-transport processes in concrete

“…In recent years, several attempts have been made to standardize the SCM reactivity tests [87][88][89][90][91]. These tests are limited for use as a standard for quantifying fly ash reactivity and do not provide a simple numerical result for the maximum reactivity of the pozzolan [89]. Recently, a method for determining SCM reactivity has been proposed to overcome this issue [84].…”

Assessing, Understanding and Unlocking Supplementary Cementitious Materials

“…Properties that are commonly followed are Ca(OH) 2 consumption, bound water, sample volume, heat flow and solution composition. A common flaw of these methods is that correlation with compressive strength development is not necessarily straightforward for a wide range of SCMs [24]. Recent efforts have therefore focused on establishing more relevant, reliable tests that deliver an assessment of the SCM contribution to strength development rapidly.…”

Evaluation of Ash Pozzolanic Activity by Means of the Strength Activity Index Test, Frattini Test and DTA/TG Analysis

“…However, global supplies of SCMs are limited compared to the amount of clinker produced, while a very high proportion of suitable SCMs is already used in blended cements [2]. Furthermore, variability in SCM properties and quality is far larger than that of Portland cement [3]. Therefore, most recent research has focussed on the exploration of alternative SCMs and their performance in building materials [1].…”

“…Many different methods involving various chemical or physical tests can be used for the assessment of SCM pozzolanic activity [2,3,[14][15][16][17][18][19]. Pozzolanic activity is characterised by two parameters: the maximum amount of lime with which the pozzolan can chemically bind, and the rate at which such a reaction takes place [20].…”