Magnesium sulfate attack on portland cement paste-I. Microstructural analysis

Bonen, David; Cohen, Menashi D.

doi:10.1016/0008-8846(92)90147-n

Cited by 164 publications

(62 citation statements)

References 5 publications

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“…SMC component materials were also subjected to extensive geochemical tests (Poole et al, 1994;Wakeley et al, 1994b). The geochemical research showed that strength loss of cementitious solids in brines with strong concentrations of magnesium occurred by loss of calcium from cement hydration products, and not by direct replacement of calcium by magnesium, as has been reported elsewhere (Oberste-Padtberg, 1985;Bonen and Cohen, 1992).…”

Section: I Previous Wipp Research At the Wessupporting

confidence: 69%

Variability in properties of Salado Mass Concrete

Wakeley¹,

Harrington²,

Hansen³

1995

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Section: I Previous Wipp Research At the Wessupporting

confidence: 69%

Variability in properties of Salado Mass Concrete

Wakeley¹,

Harrington²,

Hansen³

1995

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“…Increase of C 3 S in cement causes enhancement of CH formation in hardened cement paste, which in turn reduces the sulphate resistance of cement (13). In the case of magnesium sulphate attack, the first stage is the reaction between sulphate ions and CH followed by the production of brucite (magnesium hydroxide) and gypsum (8,15). Brucite deposits on the exposed surface and creates a temporary protective layer against the diffusion of sulphate ions.…”

Section: Sulphate Attack Overviewmentioning

confidence: 99%

“…With degradation of this layer due to the continuation of sulphate attack and decrease in concentration of CH because of its reaction with sulphate ions, deterioration of CSH begins resulting in the formation of gypsum, brucite, and silica gel. With more protraction of sulphate ion attack, magnesium silicate hydrate is formed (11,12,15,16).…”

Section: Sulphate Attack Overviewmentioning

confidence: 99%

A composite cement of high magnesium sulphate resistance

2018

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This study investigates the magnesium sulphate resistance of chemically activated phosphorus slag-based composite cement (CAPSCC). Enough mortar specimens were prepared from phosphorus slag (80 wt.%), type II Portland cement (14 wt.%), and compound chemical activator (6 wt.%) and were exposed to 5% magnesium sulphate solution after being cured. Mortar specimens of both type II and V Portland cements (PC2 and PC5) were also prepared and used for comparison purpose. According to the test results, after 12 months of exposure, PC2, PC5 and CAPSCC exhibited 43.5, 35.2 and 25.2% reduction in compressive strength, 0.136, 0.110, and 0.026% expansion in length, and 0.91, 2.2, and 1.78% change in weight, respectively. Complementary studies by X-ray diffractometry and scanning electron microscopy revealed that CAPSCC has a very low potential for the formation of sulphate attack products, especially ettringite. The results confirm a high magnesium sulphate resistance for CAPSCC compared to PC2 and PC5. RESUMEN:Cemento compuesto de alta resistencia al sulfato de magnesio. Este trabajo aborda el estudio de la resistencia al sulfato de magnesio de un cemento compuesto con base de escoria de fósforo activada química-mente (CAPSCC). Se prepararon muestras de mortero a partir de escoria de fósforo (80% en peso), cemento Portland tipo II (14% en peso) y activador químico (6% en peso) y tras el curado, se expusieron a una solución de sulfato de magnesio al 5%. También se prepararon morteros de cementos Portland de tipo II y V (PC2 y PC5) que se usaron con fines comparativos. De acuerdo a los resultados obtenidos, después de 12 meses de exposición, PC2, PC5 y CAPSCC mostraron un 43.5, 35.2 y 25.2% de reducción en la resistencia a la compresión, 0.136, 0.110, y 0.026% de expansión en longitud, y 0.91, 2.2 y 1.78% de cambio en peso, respectivamente. Estudios complementarios por difracción de rayos X y microscopía electrónica de barrido revelaron que los cementos CAPSCC tienen un potencial muy bajo para la formación de productos de ataque de sulfato, especialmente etringita. Los resultados confirman una alta resistencia al sulfato de magnesio para CAPSCC en comparación con PC2 y PC5

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“…Recently D Bonen et al [2] found that cements with low initial magnesia contents may react with Mg-containing ground waters, which results in the formation of Mg(OH) 2 and M-S-H gel(s) with Mg/Si ratio in the rang of 4:1-1:1 after years. Gollop and Taylor [3,4] characterized this product as a poorly crystallized serpentine, approximately M 3 S 2 H 2 .…”

Section: Introductionmentioning

confidence: 98%

Reaction products of MgO and microsilica cementitious materials at different temperatures

Wei

Zhang

et al. 2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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The paste was prepared by mixing MgO, microsilica and H 2 O in the presence of water reducer at different reaction ratios and temperatures, and characterized by XRD, DTA, TGA, IR, and solid-state 29Si NMR. The experimental results showed that, besides Mg(OH) 2 , magnesium silicate hydrate (M-S-H) was formed at a low temperature such as 25 and 50 ℃. At a high temperature of 100 ℃, Mg(OH) 2 can be further transformed into M-S-H completely, for instance, within ca. 1 month in an excess of microsilica. The average composition and structure of M-S-H was mainly related to the reaction mixture and curing temperature and was discussed in detail.

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Magnesium sulfate attack on portland cement paste-I. Microstructural analysis

Cited by 164 publications

References 5 publications

Variability in properties of Salado Mass Concrete

Variability in properties of Salado Mass Concrete

A composite cement of high magnesium sulphate resistance

Reaction products of MgO and microsilica cementitious materials at different temperatures

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