scholarly journals Recent developments in reactivity testing of supplementary cementitious materials

2021 ◽  
Vol 6 ◽  
pp. 131-139
Author(s):  
Prannoy Suraneni
Keyword(s):  
Heat Release ◽  
Calcium Hydroxide ◽  
Bound Water ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Concrete Durability ◽  
Index Test ◽  
Bulk Resistivity ◽  
Amorphous Content ◽  
Two Parameters

Identification and rapid characterization of novel supplementary cementitious materials (SCMs) is a critical need, driven by shortfalls in conventional SCMs. In this study, we present a discussion of recently developed reactivity tests – the R3 test, the modified R3 test, the lime strength test, and the bulk resistivity index test. These tests measure reactivity parameters such as heat release, bound water, calcium hydroxide consumption, strength, and bulk resistivity. All tests can screen inert from reactive materials. To additionally differentiate pozzolanic and latent hydraulic materials, two parameters, for example, calcium hydroxide consumption and heat release, are needed. The influences of SCM bulk chemistry, amorphous content, and fineness on measured reactivity are outlined. Reactivity test outputs can predict strength and durability of cement paste/mortar/concrete; however, caution must be exercised as these properties are influenced by a variety of other factors independent of reactivity. Thoughts are provided on using reactivity tests to screen materials for concrete durability.

scholarly journals Reactivity Assessment of Modified Ferro Silicate Slag by R3 Method

2021 ◽  
Vol 11 (1) ◽  
pp. 366
Author(s):  
Pithchai Pandian Sivakumar ◽  
Stijn Matthys ◽  
Nele De Belie ◽  
Elke Gruyaert
Keyword(s):  
Heat Release ◽  
Water Content ◽  
Bound Water ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Reaction Products ◽  
Silicate Slag ◽  
Hydration Mechanism ◽  
Novel Method ◽  
Bound Water Content

Traditional methods to track the reactivity of supplementary cementitious materials (SCMs) and their contribution to the hydration mechanism mostly use Portland Cement (PC) as an activator. Alternatively, a novel method to assess the reactivity of SCMs called R3 was recently presented. This novel method uses lab grade chemicals such as portlandite (CH), K2SO4, KOH, and CaCO3 to activate the SCM by resembling the pH of the alkaline pore solution created by PC. By using this method, the reactivity of the SCM can be easily quantified from measured heat release, bound water content, and CH consumption. The primary objective of the current study is to apply the novel methodology to analyze the reactivity of Modified Ferro Silicate (MFS) Cu slag benchmarked against siliceous fly ash (FA), ground granulated blast-furnace slag (GGBFS), and inert quartz filler. GGBFS showed the highest cumulative heat release and bound water content due to its latent hydraulic behavior. Determination with XRD analysis of the major phase of the R3 model MFS slag paste showed the participation of Fe in the hydration mechanism by forming Fe-AFm. R3 paste with GGBFS showed the presence of hydrotalcite/Al-AFm, whereas FA showed the presence of ettringite (AFt) as their crystalline reaction products. The experiments also indicate that the MFS slag acts as a reactive pozzolanic material with an acceptable performance in heat release, bound water content, and CH consumption, and can be used as SCM to make concrete. With the possibility of using MFS slag as SCM to replace part of PC, sustainability and circular economy can be fairly well achieved.

scholarly journals Mechanically activated mine tailings for use as supplementary cementitious materials

2021 ◽  
Vol 6 ◽  
pp. 61-69
Author(s):  
Sivakumar Ramanathan ◽  
Priyadarshini Perumal ◽  
Mirja Illikainen ◽  
Prannoy Suraneni
Keyword(s):  
Mine Tailings ◽  
Isothermal Calorimetry ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strong Correlations ◽  
Negative Effects ◽  
Cement Pastes ◽  
Amorphous Content ◽  
Milling Duration ◽  
Median Particle

Two mine tailings are evaluated for their potential as supplementary cementitious materials. The mine tailings were milled using two different methods – ball milling for 30 minutes and disc milling for durations ranging from 1 to 15 minutes. The modified R3 test was carried out on the mine tailings to quantify their reactivity. The reactivity of the disc milled tailings is greater than those of the ball milled tailings. Strong correlations are obtained between milling duration, median particle size, amorphous content, dissolved aluminum and silicon, and reactivity of the mine tailings. The milling energy results in an increase in the fineness and the amorphous content, which do not appreciably increase beyond a disc milling duration of 8 minutes. The reactivity increases significantly beyond a certain threshold fineness and amorphous content. Cementitious pastes were prepared at 30% supplementary cementitious materials replacement level at a water-to-cementitious materials ratio of 0.40. No negative effects of the mine tailings were observed at early ages in cement pastes based on isothermal calorimetry and thermogravimetric analysis, demonstrating the potential for these materials to be used as supplementary cementitious materials.

Use of Algerian Natural Mineral Deposit as Supplementary Cementitious Materials

2018 ◽  
Vol 34 ◽  
pp. 48-58 ◽  
Author(s):  
Karima Arroudj ◽  
Saida Dorbani ◽  
Mohamed Nadjib Oudjit ◽  
Arezki Tagnit-Hamou
Keyword(s):  
Mechanical Strength ◽  
Calcium Hydroxide ◽  
Cement Paste ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Heat Of Hydration ◽  
Cement Industry ◽  
Supplementary Cementitious Materials ◽  
Natural Mineral ◽  
Different Ages

Much of the current research on concrete engineering has been focused on including siliceous additions as supplementary cementitious materials (SCMs). Silica reacts with Calcium hydroxide release during cement hydration, and produces more C-S-H. The latter contributes to increase compactness, mechanical strengths and sustainability of concrete. This paper explores the hydration characteristics of cement paste based on various natural mineral additions, that are very abundant in Algeria and present a high silica content (ground natural pozzolana “PZ” and ground dune sand “DS”). For this purpose, several analyses were carried out on modified cement pastes and mortars. TheseSCMswere introduced by replacement levels of 15, 20 and 25 by weight of cement. We first, studied the effect of these SCMs on the heat of hydration and mechanical strength of mortars at different ages. The evolution of hydration of modified paste was studied, by using Thermal analysis (TG/TDA) at different ages, to analyze the Calcium Hydroxide (CH) content of the modified pastes. It is shown that the CH content of the mixes including SCMs is lower than that of the plain cement paste, indicating that silica reacts with the cement paste through a pozzolanic reaction. Increased pozzolanic activity results in higher amounts of Calcium Silicate Hydrate in the paste, which in turn results in higher compressive strength for modified cement mortars. Due to its crystalline morphology, the ground DS particles present a partial pozzolanic effect, compared to PZ which is semi-crystalline. Modified mortars by 20% DS can be the optimal composition. It presents satisfactory results: good mechanical strength and low heat of hydration. It can lead to an economic and sustainable concrete. Ground DS is very abounded in Africa and free of any impurities and can be a good alternativeSCMsin cement industry.

scholarly journals The Relationship between Cementitious Composition and Properties of Ultrahigh Strength Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Dehui Wang ◽  
Zhiwen Zhang
Keyword(s):  
Fly Ash ◽  
Calcium Hydroxide ◽  
Silica Fume ◽  
Design Method ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Concrete ◽  
Ultrahigh Strength ◽  
Acceleration Period ◽  
The Relationship

It is well known that supplementary cementitious materials (SCMs) have obvious effects on the properties of concrete. In order to understand the relationship between cementitious materials and properties of ultrahigh strength concrete (UHSC), the cementitious compositions of UHSC were designed by the simple-centroid design method. The effects of cementitious compositions on the properties of UHSC were investigated. It was found that the incorporation of silica fume (SF) improved the flowability and strength of UHSC, but it decreased the time of acceleration period, calcium hydroxide (CH) content, and porosity of UHSC at a certain content. The incorporation of fly ash (FA) increased the flowability, time of acceleration period, and porosity of UHSC, but it decreased the strength and CH content of UHSC. The relationships between cement, silica fume, and fly ash and the properties of UHSC were calculated based on the simple-centroid design method.

scholarly journals A Mass Balance Approach for Thermogravimetric Analysis in Pozzolanic Reactivity R3 Test and Effect of Drying Methods

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5859
Author(s):  
Kira Weise ◽  
Neven Ukrainczyk ◽  
Eduardus Koenders
Keyword(s):  
Thermogravimetric Analysis ◽  
Mass Balance ◽  
Calcium Hydroxide ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Supplementary Cementitious Materials ◽  
Drying Methods ◽  
Calorimetric Measurement ◽  
Balance Approach ◽  
Mass Balance Approach

The reactivity of supplementary cementitious materials (SCMs) is a key issue in the sustainability of cement-based materials. In this study, the effect of drying with isopropanol and acetone as well as the interpretation of thermogravimetric data on the results of an R3 test for evaluation of the SCM pozzolanic reaction were investigated. R3 samples consisting of calcium hydroxide, potassium hydroxide, potassium sulphate, water, and SCM were prepared. Besides silica fume, three different types of calcined clays were investigated as SCMs. These were a relatively pure metakaolin, a quartz-rich metakaolin, and a mixed calcined clay, where the amount of other types of clays was two times higher than the kaolinite content. Thermogravimetric analysis (TGA) was carried out on seven-day-old samples dried with isopropanol and acetone to stop the reaction processes. Additional calorimetric measurement of the R3 samples was carried out for evaluation of the reaction kinetics. Results show that drying with isopropanol is more suitable for analysis of R3 samples compared to acetone. The use of acetone results in increased carbonation and TGA mass losses until 40 (isothermal drying for 30 min) and 105 °C (ramp heating), indicating that parts of the acetone remain in the sample, causing problems in the interpretation of TGA data. A mass balance approach was proposed to calculate calcium hydroxide consumption from TGA data, while also considering the amount of carbonates in the sample and TGA data corrections of original SCMs. With this approach, an improvement of the linear correlation of TGA results and heat release from calorimetric measurement was achieved.

Quantification of supplementary cementitious content in blended Portland cement using an iterative Rietveld–PONKCS technique

2017 ◽  
Vol 50 (2) ◽  
pp. 498-507 ◽  
Author(s):  
Yuri P. Stetsko ◽  
Natallia Shanahan ◽  
Harvey Deford ◽  
A. Zayed
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Binary Systems ◽  
Accurate Determination ◽  
Ternary Systems ◽  
Cementitious Materials ◽  
Iterative Refinement ◽  
Supplementary Cementitious Materials ◽  
Amorphous Content ◽  
Wide Range

An iterative Rietveld–PONKCS (partial or no known crystal structure) technique has been developed for precise and accurate determination of the weight percentages of predominantly amorphous supplementary cementitious materials (SCMs) contained in Portland cement–SCM blends. This technique involves the iterative refinement of the SCM amorphous phase (SCMAP) content, with the separation of the refinement of the SCMAP shape parameters from background refinement. The technique also includes an internal and external standard refinement of both the calibration SCM and the cement–SCM blend. This approach enables the separation of the contributions of the SCMs and the cement to the amorphous content of the cement–SCM blend. The technique has been successfully applied to binary systems of cement–slag and cement–fly ash, and ternary blends of cement–fly ash–slag, over a wide range of cement replacement levels. In the ternary systems, the proposed technique was successfully able to separate the individual amorphous contributions of slag and fly ash to the total amorphous content of the system. The approach was also implemented on a pair of commercially available binary blended cements containing 30% slag and 30% fly ash, respectively.

scholarly journals Calcium oxychloride formation in pastes containing supplementary cementitious materials: Thoughts on the role of cement and supplementary cementitious materials reactivity

2016 ◽  
Vol 1 ◽  
pp. 24 ◽  
Author(s):  
Prannoy Suraneni ◽  
Vahid Jafari Azad ◽  
Burkan O. Isgor ◽  
William Jason Weiss
Keyword(s):  
Calcium Hydroxide ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Concrete Pavements ◽  
Scanning Calorimetry ◽  
Supplementary Cementitious Material ◽  
Deicing Salts ◽  
Constituent Material ◽  
Local Saturation

Over the last decade many concrete pavements in North America have begun to show excessive damage at the joints. This damage appears to be due to two primary causes: classic freeze-thaw damage due to local saturation caused by the pooling of water at the joints, and formation of an expansive phase known as calcium oxychloride due to a reaction between chloride-based deicing salts and calcium hydroxide in concrete. This letter explores the formation of calcium oxychloride in cementitious matrices based on constituent materials and mixture compositions. Low temperature differential scanning calorimetry and thermogravimetric analysis were used to quantify the amount of calcium oxychloride and calcium hydroxide, respectively. Thermodynamic modeling was used to predict calcium hydroxide contents from the constituent material compositions. It is shown that calcium oxychloride contents are well correlated with calcium hydroxide contents in cementitious pastes. Supplementary cementitious materials, such as fly ash and slag, can reduce calcium oxychloride formation by reducing the amount of calcium hydroxide. Complexities in the determination of reactivity of supplementary cementitious materials based on their replacement level and different water-to-cement ratios are discussed. Although it is clear that supplementary cementitious materials are beneficial in reducing calcium oxychloride formation, additional analysis tools are needed to more accurately quantify the specific mechanisms (such as dilution, pozzolanic or hydraulic reaction, changes in cement hydration) that result in the beneficial aspects of each supplementary cementitious material.

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