Influence of Cement Type and Water-to-Cement Ratio on the Formation of Thaumasite

Zhang, Ailian; Zhang, Linchun

doi:10.1155/2017/7643960

Cited by 2 publications

(2 citation statements)

References 15 publications

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“…Increased quantity as a result of use of high w/c ratio also affects the flow or rheology of the mixture, as well as cohesion between paste and aggregate. High w/c increases the voids and reduces the cohesion in the mortar matrix, and as a result, it reduces the overall strength of the mortar [39].…”

Section: Compressive Strengthmentioning

confidence: 99%

Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

Marangu

M’thiruaine

Bediako

2020

Journal of Chemistry

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In the presence of significant quantities of carbon dioxide (CO2) and elevated temperatures in the atmosphere due to climate change, cement-based materials are susceptible to carbonation. Blended cements are more prone to carbonation attack than Portland cement. There is a need to evaluate the carbonation resistance of blended cements in a carbonation-prone environment. This paper presents experimental findings obtained from an evaluation of carbonation resistance tests on Rice Husk Ash- (RHA-) blended cement. The blended cement was made by intergrinding of Portland Cement (PC) and RHA to make the test cement (PC-RHA). The RHA dosage in the PC-RHA was varied from 0 to 30% by mass of PC. Pozzolanicity, standard consistency, and setting time tests were conducted on PC-RHA. Mortar prisms measuring 160 mm × 40 mm x 40 mm were separately cast at a water/cement ratio ( w / c ) of 0.50 and 0.60 and cured in water for 2, 7, 14, 28, and 90 days. Compressive strength tests were conducted on the mortar prisms at each of the testing ages. The prepared mortars were also subjected to accelerated carbonation tests in two Relative Humidity (RH) curing regimes, one maintained at an RH greater than 90% and the other between 50–60%. Carbonation resistance of the mixtures was evaluated in terms of the changes in carbonation depth using a phenolphthalein test at the age of 7, 14, 28, and 56 days of curing in a continuous flow of CO2. Compressive strength measurements were also taken during each of the carbonation testing ages. For comparison, similar tests were conducted using commercial PC. The results showed that PC-RHA was pozzolanic while PC was nonpozzolanic. Higher water demand and longer setting times were observed in PC-RHA than in PC. Moreover, there was increased strength development in water-cured samples with increased curing duration. Carbonation results indicated that there was a marked increase in carbonation depth with increased dosage of RHA in PC-RHA binders, increased duration of exposure to CO2, and decreased RH (RH between 50–60%). PC-RHA binders exhibited lower carbonation resistance than PC. In conclusion, for mortars at any w / c ratio, carbonation resistance decreased with increase in RHA dosage and increased w / c ratio.

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Section: Compressive Strengthmentioning

confidence: 99%

Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

Marangu

M’thiruaine

Bediako

2020

Journal of Chemistry

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“…The effects of the mixing solution with varied phosphate and water amounts on the characteristics of the CAP have not been openly reported, despite the significance of water contents in the properties of cementitious systems. Numbers of studies on the water contents can be found for the other cement systems [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Influence of mixing solution on characteristics of calcium aluminate cement modified with sodium polyphosphate

Irisawa

García-Lodeiro

Kinoshita

2020

Cement and Concrete Research

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This study investigated characteristics of a calcium aluminate cement modified with a phosphate (CAP) by changing an amount and concentration of mixing solution with sodium polyphosphate. When the amount of mixing solution was increased with a constant amount of sodium polyphosphate, an enhanced consumption of monocalcium aluminate was observed compared with gehlenite in calcium aluminate cement. Formation of gibbsite, Al(OH)3, was also increased as a hydration product in the CAP and a reduction of water in the amorphous gel phase. When the amount of mixing solution was increased with a constant concentration of sodium polyphosphate, the enhanced consumption of monocalcium aluminate was not observed. Neither gibbsite nor any other crystalline hydration products were identified in this series. In addition, unreacted sodium polyphosphate remained in the system. The increased formation of gibbsite and the possible reduction of water from the amorphous gel phase appears to contribute to the improvement of the microstructure in the products.

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Influence of Cement Type and Water-to-Cement Ratio on the Formation of Thaumasite

Cited by 2 publications

References 15 publications

Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

Influence of mixing solution on characteristics of calcium aluminate cement modified with sodium polyphosphate

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