Properties and hydration behavior of blended clinker and portland-sediment cement pastes

In recent years, an increase of the interest in the use of secondary raw materials (sediment, sludge…) in construction has been observed.  This paper aims to contribute to the use of dredging sediments in the cement industry. Despite the literature on this subject, the available data on the aspects and phenomena related to the hydration process of such mixtures are incomplete. This paper aims to specify the calorimetric curves of hydration of mixtures made, from the sediment trapped at the site of Lyvet in the Brittany region of France. The mixtures are made ??using in one hand clinker and in the other hand Portland cement. Pastes with 8%, 16% and 33% of clinker or Portland cement substituted by sediment are used to determine the hydraulic properties of mixtures. The physico-chemical characterization of materials is made by different techniques to determine the chemical composition and physical properties. X-ray diffraction is used to determine the mineralogical compositions of samples before and after treatment. A  Tian-Calvet microcalorimeter is used to explore hydration behavior of the blended Sediment-Portland cement pastes. The addition of untreated sediment to both clinker or Portland cement increase the dormant period duration. On the contrary, this period becomes shorter when the sediment is thermally treated. The results show that 8% of treated sediment improve hydration of blended Sediment-Portland cement pastes. Mechanical properties of blended sediment-cements are also investigated. After 28 days of curing in water, the mortar containing 8% of treated sediment exhibits a compressive strength equal to 93.7% of the one of the reference mortar, maintaining it in the same cement class (52.5)

Report of RILEM TC 281-CCC: insights into factors affecting the carbonation rate of concrete with SCMs revealed from data mining and machine learning approaches

© The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.The RILEM TC 281–CCC ‘‘Carbonation of concrete with supplementary cementitious materials’’ conducted a study on the effects of supplementary cementitious materials (SCMs) on the carbonation rate of blended cement concretes and mortars. In this context, a comprehensive database has been established, consisting of 1044 concrete and mortar mixes with their associated carbonation depth data over time. The dataset comprises mix designs with a large variety of binders with up to 94% SCMs, collected from the literature as well as unpublished testing reports. The data includes chemical composition and physical properties of the raw materials, mix-designs, compressive strengths, curing and carbonation testing conditions. Natural carbonation was recorded for several years in many cases with both indoor and outdoor results. The database has been analysed to investigate the effects of binder composition and mix design, curing and preconditioning, and relative humidity on the carbonation rate. Furthermore, the accuracy of accelerated carbonation testing as well as possible correlations between compressive strength and carbonation resistance were evaluated. One approach to summerise the physical and chemical resistance in one parameter is the ratio of water content to content of carbonatable CaO (w/CaOreactive ratio). The analysis revealed that the w/CaOreactive ratio is a decisive factor for carbonation resistance, while curing and exposure conditions also influence carbonation. Under natural exposure conditions, the carbonation data exhibit significant variations. Nevertheless, probabilistic inference suggests that both accelerated and natural carbonation processes follow a square-root-of-time behavior, though accelerated and natural carbonation cannot be converted into each other without corrections. Additionally, a machine learning technique was employed to assess the influence of parameters governing the carbonation progress in concretes.Peer reviewe

Metakaolin

peer reviewedMetakaolin (MK) is known to be a highly pozzolanic material that can be used in concrete. MK is usually produced by heating kaolin-containing clays, within the temperature range of about 600–900 ℃. This chapter summarizes the utilization of metakaolin in relevant worldwide standards, mainly in Europe and North America. The health, safety and environmental sustainability concerns on using metakaolin as a supplementary cementitious material are also addressed in this chapter. It is reported that MK incorporation has benefits on both early-age and long-term properties. On the other hand, this chapter also reports that the results of heat of hydration and rate of reaction in metakaolin-blended concrete are controversial and need further investigation. Overall, the optimum level of cement replacement by MK is around 10–20%, which provides concrete the maximum strength. Metakaolin appears to have an excellent potential as a supplementary cementitious material in structures made of high-performance concrete, because it controls deleterious expansion due to alkali-silica reaction in concrete (depending on the nature of the aggregate), and reduces the ingress of chloride by improving the microstructure and chloride binding behavior. © RILEM 2018

Report of RILEM TC 267-TRM phase 3: validation of the R3 reactivity test across a wide range of materials

RILEM TC 267 TRM– “Tests for Reactivity of Supplementary Cementitious Materials” recommends the Rapid Reliable Relevant (R3) test as a method for determining the chemical reactivity of supplementary cementitious materials (SCMs) in Portland cement blends. In this paper, the R3 test was applied to 52 materials from a wide range of conventional and alternative SCMs with the aim to validate such test. An excellent correlation was found between the cumulative heat release and the bound water determined following the R3 test method. Comparison of the R3 test results to mortar compressive strength development showed that all conventional SCMs (e.g. blast furnace slag and fly ashes) followed the same trend, with the notable exception of very reactive calcined kaolinitic clays. It is discussed, through an in-depth statistical regression analysis of the R3 reactivity test results and the 28 days relative compressive strengths, how reactivity threshold values for classification of the chemical reactivity of SCMs could be proposed based on the R3 test results

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

Report of RILEM TC 267-TRM phase 2: optimization and testing of the robustness of the R3 reactivity tests for supplementary cementitious materials

The results of phase 1 of an interlaboratory test, coordinated by the RILEM TC 267-TRM “Tests for Reactivity of Supplementary Cementitious Materials” showed that the R3 (rapid, relevant, reliable) test method, by measurement of heat release or bound water, provided the most reliable and relevant determination of the chemical reactivity of supplementary cementitious materials (SCMs), compared to other test methods. The phase 2 work, described in this paper aimed to improve the robustness of the test procedure and to develop precision statements for the consolidated test procedure. The effect of the pre-mixing and mixing conditions, and the impact of the mix design on the test method robustness were assessed and fixed for optimal conditions to carry out the R3 heat release test. The effect of the drying step was evaluated to define the R3 bound water test procedure in more detail. Finally, the robustness of the consolidated final test methods was determined by an interlaboratory study to define the precision statements

Zootherapeutics utilized by residents of the community Poço Dantas, Crato-CE, Brazil

<p>Abstract</p> <p>Background</p> <p>Animals have been used as a source of medicine in Brazil since ancient times, and have played a significant role in healing practices. Specifically in Northeast Brazil, zootherapy is a very common practice, and together with medicinal plants, it plays an important role as a therapeutic alternative. In the state of Ceara, no works have been carried out on rural communities with regard to use of zootherapeutics, even though the practice of zootherapy is common in this region. Therefore, the aim of this study was to analyze the use of medicinal animals in a rural community (Poco Dantas) in the municipality of Crato, Ceara, Brazil.</p> <p>Methods</p> <p>The field survey was carried out from October 2008 to January 2009 by conducting interviews using structured questionnaires with 72 people (33 men and 39 women), who provided information on animal species used as remedies, body parts used to prepare the remedies, and ailments for which the remedies were prescribed. We calculated the informant consensus factor (ICF) to determine the consensus over which species are effective for particular ailments, as well as the species use value (UV) to determine the extent of utilization of each species.</p> <p>Results</p> <p>A total of 29 species, distributed in 17 families were categorized as having some medicinal property. The taxa most represented were: mammals (9), insects (7), reptiles and birds (4). <it>Progne chalybea</it>, a species not previously recorded as being of medicinal use, was cited in the present work, where it is utilized in the treatment of alcoholism. The animals are used in the treatment of 34 diseases or symptoms, where sore throat, inflammations and cough are the ailments with the greatest number of citations.</p> <p>Conclusion</p> <p>The data show that zootherapy represents an important therapeutic alternative for the inhabitants of the community. New studies on medicinal fauna should be conducted with the aim of determining the exploitation level of the species utilized, promoting sustainable development of medicinal species that are eventually threatened, and preserving and disseminating the knowledge developed by traditional individuals of the community.</p