Effects of several retarders on setting time and strength of building gypsum

Zhang, Yuanyuan; Yang, Jian; Cao, Xiangyang

doi:10.1016/j.conbuildmat.2019.117927

Cited by 51 publications

(17 citation statements)

References 2 publications

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“…On the other hand, the consistent retarding effect of citric acid was seen both in the initial and final setting. That behavior has been observed before in gypsum plaster (Badens et al, 1999;Lanzón and García-Ruiz, 2012;Zhang et al, 2020), a material in which citric acid is used as an established retarder. In this case, the retardation is caused by the inhibition of hemihydrate dissolution (Lanzón and García-Ruiz, 2012).…”

Section: Discussionsupporting

confidence: 67%

Self-Desiccation of a Vernacular CSA Binder

Martins

Çiçek

Brumaud

et al. 2022

Construction Technologies and Architecture

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The fast precipitation of ettringite in conventional Calcium Sulfo Aluminate (CSA) cement causes rapid stiffening of the cement paste and is directly associated with short setting times and self-desiccation. To extend the time during which those types of cement remain workable, retarding admixtures can be used. However, retarders may affect the amounts and types of hydration products formed and as a consequence the ability of hydrated cement to chemically bind water. This work investigates the influence of two natural-based admixtures on the self-desiccation ability of a vernacular CSA ternary binder used as earth stabilization. Vicat measurements were used to study the efficiency of citric acid and sucrose as retarding admixtures on the setting time of stabilized earth. A quantitative study of the self-desiccation ability of the binder was performed on dried binder pastes using thermogravimetric analysis (TGA). Results show that both admixtures have a significant impact on the setting time of the binder. Furthermore, TGA showed that the self-desiccation ability of this vernacular CSA binder is significantly reduced when citric acid at high dosages is used, both at early hydration and after 14 days. On the contrary, the use of sucrose does not affect the water chemically bound at an early age but can maximize bound water after 14 days of hydration.

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Section: Discussionsupporting

confidence: 67%

Self-Desiccation of a Vernacular CSA Binder

Martins

Çiçek

Brumaud

et al. 2022

Construction Technologies and Architecture

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“…It is interesting to note the shape of crystals in IB2 i.e., short thick crystals and plate like crystals (Figure 6c,d). The modification of CsD crystal shape and size can be due to the modification of reaction conditions in the presence of sodium bicarbonate addition [28] or/and to an oriented growth of crystals due to selective adsorption of retarding addition [24].…”

Section: Resultsmentioning

confidence: 99%

“… [23,24];• Compressive or/and flexural strengths were assessed on paste specimens (cubes-20 × 20 × 20 mm and cuboids-40 × 40 × 160 mm) hardened for 7 days in air; the cuboid specimens were dried at 40 ± 2 • C up to constant mass before the test; minimum 3 flexural strength values and minimum 6 compressive strength values were considered for the calculation of average values of flexural and compressive strengths; the mixing procedure for paste preparation, the curing conditions (air, RH = 50 ± 5%, 23 ± 2 • C) and the procedure for mechanical testing are described in SR EN 13279-2:2014[25];• Geometrical density was assessed on cubes (20 × 20 × 20 mm) and was calculated as mass to volume ratio based on minimum 5 values (assessed on specimens cured in similar conditions); • Open porosity was measured on fractured specimens, using the liquid saturation method under vacuum[26]; the working liquid was xylene (ρ = 0.866 g/mL).•Thermal conductivity was assessed according to European Standard EN 12667[27] on boards (300 × 300 × 20 mm) hardened for 7 days in air (RH = 50 ± 5%, 23 ± 2 • C). Before testing the specimens were dried at 40 • C up to constant mass.…”

mentioning

confidence: 99%

Lightweight Gypsum Materials with Potential Use for Thermal Insulations

et al. 2020

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This article presents the influence of three additions i.e., hydroxyethyl methyl cellulose (HEMC), sodium bicarbonate and flue gas desulfurization (FGD) gypsum on the porosity of gypsum-based materials. The specific microstructure for a material with good thermal insulation properties i.e., numerous closed pores distributed in the binding matrix, was achieved using HEMC (0.3 wt.%) and sodium bicarbonate (0.5–2 wt.%). The addition of HEMC to the gypsum binder determines, as expected, an increase of the porosity due to its ability to stabilize entrained air. In the case of a sodium bicarbonate addition, the pores are formed in the binding matrix due to the entrapment of the gas (CO2) generated by its reaction. Sodium bicarbonate addition delays the setting of gypsum binder therefore in this study FGD gypsum (waste produced in the desulfurization process of combustion gases generated in power plants) was also added to the mixture to mitigate this negative effect. The decrease of geometrical density (up to 13%, in correlation with the additive nature and dosage) correlated with the increase of the porosity, determines, as expected, the decrease of flexural and compressive strengths (33–75%), but improves the thermal properties i.e., decreases the thermal conductivity (9–18%).

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“…However, its relative abundance, ease of working on site, and low cost compared to other conglomerates continue to favor its direct use today [ 5 ]. In addition, this traditional application generally requires increasingly scarce qualified labor [ 6 ]; for this reason, current research lines tend to reduce the limitations of gypsum as a construction material, which implies increasing its mechanical resistance, promoting industrialization through new construction systems, reducing the weight of precast to reduce building loads, and advancing the understanding of setting times [ 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

Low-Cost Sensors for Determining the Variation in Interior Moisture Content in Gypsum Composite Materials

et al. 2020

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Non-destructive testing can be used to determine some of the most relevant physical properties of building materials. In this work, two low-cost measuring devices were developed capable of determining the variation in real-time of the percentage of humidity that is produced in the construction of gypsum and plaster during the hardening process. For this, an Arduino resistive sensor and a capacitive sensor of our design were used. The results show how it is possible to determine the variations in mixing water content during the seven days of curing established by the UNE-EN 13279-2 standard as well relate to the mechanical resistance of the test specimens with the same percentage of humidity. Additionally, the study was completed with the determination of the formation of the dihydrate compound linked to this setting process in the test specimens by conducting X-ray diffraction and thermogravimetric analysis tests at different ages of the samples.

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Effects of several retarders on setting time and strength of building gypsum

Cited by 51 publications

References 2 publications

Self-Desiccation of a Vernacular CSA Binder

Self-Desiccation of a Vernacular CSA Binder

Lightweight Gypsum Materials with Potential Use for Thermal Insulations

Low-Cost Sensors for Determining the Variation in Interior Moisture Content in Gypsum Composite Materials

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