Time-dependent water vapor desorption isotherm model of hardened cement paste

Rymeš, Jiří; Maruyama, Ippei; Aili, Abudushalamu

doi:10.1016/j.cemconres.2021.106612

Cited by 7 publications

(2 citation statements)

References 60 publications

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“…Based on the plotted desorption isotherms, it was observed that in the case of the tested composites, desorption was irreversible. The graphs of the desorption isotherms clearly showed a decrease at RH=35%, which was confirmed by tests [26], [27] carried out on cement slurry. The authors attributed this rapid loss of water over a narrow range of relative humidity to the cavitation of water condensed in the pores of the CSH gel surrounded by narrow interlayer constrictions.…”

Section: Figure 3 the Relationship Between Thermal Conductivity And T...supporting

confidence: 61%

Preliminary Studies on a Lightweight Porous Cement-Based Composite – Gel Concrete

Strzałkowski,

Stolarska

2023

J. Phys.: Conf. Ser.

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This paper presents some preliminary results of research on light, highly porous cement composites – gel concretes. A material based on Portland cement was tested, the very high porosity of which (over 60%) was obtained by direct gelatinization of starch in a liquid cement slurry. A composite based solely on cement and concretes produced with the addition of metakaolin or zeolite was tested. The basic properties of the concretes obtained in this way were determined, i.e., the volume density in a dry state, the thermal properties, and the compressive strength. In the case of the thermal properties, tests were performed on specimens dried to constant mass, while the test itself was carried out at an average temperature of 10°C. The tests employed an Isomet 2114 apparatus, which uses a non-stationary heat flow technique. The thermal conductivity coefficients and the volumetric specific heat were determined. The compressive strength tests were carried out on cubic specimens with a side of 4 cm after 28 days of curing by air-drying. Four specimens of each type of composite were tested. For composites based solely on Portland cement, the sorption properties of the material were also tested. For this purpose, the method of dynamic water vapor sorption (DVS) was used. As a result, graphs of the sorption and desorption of individual composites of different densities were obtained. Preliminary qualitative tests were also carried out using an electron microscope. The use of the starch gelatinization process directly in the cement slurry made it possible to obtain a very homogeneous material, in which the initial, temporary structure was starch gel, around which, after exceeding the setting time of the cement, the target cement-based structure was formed – gel concrete. The tested materials are innovative, having excellent thermal properties, comparable mechanical properties to lightweight concretes of the same densities, and is formed using an easily available, relatively cheap admixture in the form of starch. They can be used to produce small masonry elements, such as blocks for external walls or other typical prefabricated lightweight concrete elements.

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Section: Figure 3 the Relationship Between Thermal Conductivity And T...supporting

confidence: 61%

Preliminary Studies on a Lightweight Porous Cement-Based Composite – Gel Concrete

Strzałkowski,

Stolarska

2023

J. Phys.: Conf. Ser.

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“…The reaction was carried out at room temperature (20–40 °C) for a duration of 3 h. Outstanding PCE demonstrated a notable water-reducing ratio of 33.1%, along with effective slump retention and dispersion capabilities. Rymeš et al [ 55 , 56 ] similarly employed this initiation system in their patents to synthesize PCE at room temperature. This method offers several advantages, including the absence of an external heat source requirement, a high solid content of PCE, and cost-effectiveness in transportation.…”

Section: Synthesis Of Pcementioning

confidence: 99%

Synthesis and Modification of Polycarboxylate Superplasticizers—A Review

Xia,

Shi,

Xiang

et al. 2024

Materials

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The molecular-scale structural changes in polycarboxylic superplasticizer (PCE) can influence dispersion and water retention. Polycarboxylate superplasticizer, synthesized using different methods, may alter dispersion and water-reducing effects. The synthesis of PCE involves creating a novel macromolecular monomer with a controllable molecular mass, adjustable lipophilic, and hydrophilic moieties, as outlined in this study. This article reviews processes for synthesizing polycarboxylates and identifies the optimal method through orthogonal experiments to produce a modified polycarboxylate superplasticizer (PCE-P). The study investigated the effects of different PCE types and concentrations on the surface tension, fluidity, and ζ potential of cement paste. PCE-P, synthesized at room temperature, showed comparable performances in initial hydration and conversion rate in cement to PCE synthesized at high temperatures. PCE-P exhibited an increased slump but had a wider molecular weight distribution and longer main and side chains, leading to a 24.04% decrease in surface tension, indicating a good dispersibility.

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Moisture transport properties of concrete with SCMs – descriptions, test methods and some applications

Nilsson

2023

ce papers

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Moisture transport properties of concrete are rarely determined, simply because it is difficult and time‐consuming. Most studies in literature are limited to cement paste and mortar. Translation of these properties to concrete are not straight‐forward. Recently, however, a few measurements are done, also on concretes with supplementary cementitious materials.An overview is given on various ways of theoretically describing the moisture transport properties of concrete, with different “moisture transport coefficients” and their interrelations. Methods of determining those properties are shown and their advantages and drawbacks are discussed. Available data in literature are summarized and compared. A recently developed test method, the tin‐can method, is described. New results are shown for concretes with SCMs. The method's possibilities to be used for short‐term tests of aging concrete are discussed.A few important applications where the moisture transport properties are decisive are presented: applying moisture‐sensitive flooring materials on concrete floor slabs and carbonation‐initiated reinforcement corrosion under varying climatic conditions.

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Time-dependent water vapor desorption isotherm model of hardened cement paste

Cited by 7 publications

References 60 publications

Preliminary Studies on a Lightweight Porous Cement-Based Composite – Gel Concrete

Preliminary Studies on a Lightweight Porous Cement-Based Composite – Gel Concrete

Synthesis and Modification of Polycarboxylate Superplasticizers—A Review

Moisture transport properties of concrete with SCMs – descriptions, test methods and some applications

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