Reactivity tests for supplementary cementitious materials: RILEM TC 267-TRM phase 1

A primary aim of RILEM TC 267-TRM: “Tests for Reactivity of Supplementary Cementitious Materials (SCMs)” is to compare and evaluate the performance of conventional and novel SCM reactivity test methods across a wide range of SCMs. To this purpose, a round robin campaign was organized to investigate 10 different tests for reactivity and 11 SCMs covering the main classes of materials in use, such as granulated blast furnace slag, fly ash, natural pozzolan and calcined clays. The methods were evaluated based on the correlation to the 28 days relative compressive strength of standard mortar bars containing 30% of SCM as cement replacement and the interlaboratory reproducibility of the test results. It was found that only a few test methods showed acceptable correlation to the 28 days relative strength over the whole range of SCMs. The methods that showed the best reproducibility and gave good correlations used the R3 model system of the SCM and Ca(OH)2, supplemented with alkali sulfate/carbonate. The use of this simplified model system isolates the reaction of the SCM and the reactivity can be easily quantified from the heat release or bound water content. Later age (90 days) strength results also correlated well with the results of the IS 1727 (Indian standard) reactivity test, an accelerated strength test using an SCM/Ca(OH)2-based model system. The current standardized tests did not show acceptable correlations across all SCMs, although they performed better when latently hydraulic materials (blast furnace slag) were excluded. However, the Frattini test, Chapelle and modified Chapelle test showed poor interlaboratory reproducibility, demonstrating experimental difficulties. The TC 267-TRM will pursue the development of test protocols based on the R3 model systems. Acceleration and improvement of the reproducibility of the IS 1727 test will be attempted as well

Effects of SNF and LS superplasticizer on cement paste using electrical measurement

27-33A non-contact electrical resistivity measurement is used to study the effects of sulfonated naphthalene formaldehyde condensates (SNF) and lignosulphonate (LS) superplasticizers on cement paste. Other experiments like fluidity test and test of the amount of superplasticizer adsorbed on cement particles are also carried out. Results show that SNF superplasticizer has different effects on the resistivity of cement pastes comparing with LS superplasticizer. The plot of initial resistivity versus SNF dosage can be divided into 4 zones. Each zone reflects the characteristics of SNF as a superplasticizer of cement paste, respectively. The curves of the resistivity developing with time; ρ(t), and their derivatives; dρ(t)/dt(t), have distinct changes when the dosages of SNF and LS superplasticizer are high. Electrical method is potentially a very useful method in concrete designing

RILEM TC-238 SCM recommendation on hydration stoppage by solvent exchange for the study of hydrate assemblages

© 2018, RILEM. This recommendation is an outcome of the work carried out by a working group within the RILEM Technical Committee 238-SCM “Supplementary Cementitious Materials”. The working group studied the effect of supplementary cementitious materials on the pore solution, the microstructure and the hydration product assemblage of hardened Portland cements blended with common supplementary cementitious materials. The recommendation reflects the results of a round robin test programme on common hydration stoppage methods in 10 participating laboratories. Among four different methods tested, solvent exchange by isopropyl alcohol (isopropanol) gave the best results in terms of preservation of the cement hydrate assemblage and overall reproducibility of the results [1]. The current protocol is developed based on best laboratory practices of the participating laboratories and literature reports [2–4]. The presented hydration stoppage protocol is recommended for the study of Portland cement-based hydrate assemblages by common material characterization techniques such as thermogravimetry and X-ray powder diffraction.status: publishe

Report of TC 238-SCM: hydration stoppage methods for phase assemblage studies of blended cements-results of a round robin test

International audienc

AQP1 ablation mimicks M2 functional differentiation induced in WT macrophages by IL4/IL13: A- CD206 redistribution into ruffles. (A) Confocal images.

<p><i>Aqp1</i>^<i>+/+</i> and <i>Aqp1</i>^-/- macrophages were maintained for 24h in serum-containing medium without supplements (to keep macrophages in undifferentiated M0 state; upper row), or with LPS (to orient towards M1 phenotype; middle row) or IL4/IL13 (to orient towards M2 phenotype; lower row). Cells were fixed/permeabilized and double-immunolabelled for CD206 (green) and F4/80 (red) by reference to nuclei (Topro-3; blue). Representative of 2 independent experiments. Insets of M0 (<i>Aqp1</i>^<i>-/-</i>; panel b) and M2 macrophages (<i>Aqp1</i>^<i>+/+</i> and <i>Aqp1</i>^-/-; panels e and f) show strong recruitment of CD206 (green) into ruffles, contrasting with preferential perinuclear localization in WT M0 and M1 macrophages (panels a and c). Scale bars, 5μm. <b>(B) Morphometry: redistribution of CD206 in ruffles.</b> From left to right, analysis was performed on 54, 35, 30, 31, 10 and 7 cells, pooled from 2 independent experiments. NS, not significantly different; ***, p<0.001.</p

Report of TC 238-SCM: hydration stoppage methods for phase assemblage studies of blended cements—results of a round robin test

For many microstructural studies it is necessary to “stop” cement hydration—to remove free water. This paper describes the results of a round robin test on the impact of hydration stoppage methods on the composition of hydrated cements. A regular and a fly ash blended Portland cement hydrated for 90 days were selected. Ten laboratories participated in the round robin test. Four common hydration stoppage methods were studied: (1) oven drying at 105 °C, (2) solvent exchange by isopropanol, (3) vacuum drying and (4) freeze drying. After the stoppage of hydration powder samples were studied by thermogravimetry (TG) and X-ray diffraction (XRD). Bound water and Ca(OH)2 content were determined based on the TG data. Portlandite and ettringite content were quantified by Rietveld analysis of the XRD data. The goal was to establish interlaboratory reproducibility and to identify the best available protocols for research and standardization purposes. Based on the results of the round robin test three recommendations are made. (1) Oven drying at 105 °C is not recommended. This dehydrates, alters and decomposes calcium aluminate hydrates significantly more than other methods and often produced carbonation artefacts. (2) Isopropanol exchange is the most appropriate hydration stoppage method for the study of the complete hydrate assemblage of cements, including calcium aluminate hydrates such as ettringite and AFm phases. (3) For quantification of portlandite (Ca(OH)2) all tested hydration stoppage protocols are satisfactory, with the exception of oven drying.status: publishe