Formation and carbonation of C-S-H in water

Suzuki, Kazuyuki; Nishikawa, Tadahiro; Ito, Suketaka

doi:10.1016/0008-8846(85)90032-8

Cited by 122 publications

(53 citation statements)

References 15 publications

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“…Formation of C-S-H depletes portlandite and the low C/S ratio enables the entrapment of alkalis, both of which reducing the amount of hydroxyl ions available to participate in the alkali-silica reaction. In their work done on poor portlandite materials (Suzuki et al 1985) indicate that the lower the molar ratio C/S is, the greater the volume of meso and macro pores is created after carbonation. Chen et al (2006) come to the same conclusion.…”

Section: Nitrogen Adsorption and Water Adsorptionmentioning

confidence: 99%

Effects of Carbonation on the Microstructure of Cement Materials: Influence of Measuring Methods and of Types of Cement

Phạm

Prince

2014

Int J Concr Struct Mater

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The objective of this work was to examine the influence of carbonation on the microstructure of cement materials. Different materials, which were CEM I mortar and paste, CEM II mortar and paste, were carbonated at 20°C, 65 % relative humidity and 20 % of CO 2 concentration. The specific surface area and pore size distribution were determined from two methods: nitrogen adsorption and water adsorption. The results showed that: (1) nitrogen adsorption and water adsorption do not cover the same porous domains and thus, we observed conflicts in the results obtained by these two techniques; (2) the CEM II based materials seemed to be more sensible to a creation of mesoporosity after carbonation than the CEM I based materials. The results of this study also helped to explain why observations in the literature diverge greatly on the influence of carbonation on specific surface area.

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Section: Nitrogen Adsorption and Water Adsorptionmentioning

confidence: 99%

Effects of Carbonation on the Microstructure of Cement Materials: Influence of Measuring Methods and of Types of Cement

Phạm

Prince

2014

Int J Concr Struct Mater

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“…These studies showed that the aluminate competes with Ca for the free silicates and the formation of CSH gel was observed [45,49]. Because the chemistry of Sr and Ca are similar Sr may be consumed in a similar manner to Ca in the formation of an analogous gel phase.…”

Section: Encapsulation Of Sr In Na Based Geopolymersmentioning

confidence: 96%

Encapsulation of Cs/Sr contaminated clinoptilolite in geopolymers produced from metakaolin

Kuenzel

Cisneros

Neville

et al. 2015

Journal of Nuclear Materials

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“…The strong band centered at 1485 cm -1 can be ascribed to C-O stretching vibrations in carbonates. Finally, the broad band from 1096 to 1152 cm -1 occurred due to S-O stretching vibrations in sulfates [6][7].…”

Section: ) Samples Cured In Water For 28 Days At 20°c Before Leachingmentioning

confidence: 99%

“…According to the equilibrium concentrations of calcium hydroxide (the limit concentration of lime), hydration products will gradually dissolve or decompose when the concrete cement is in long-term contact with "soft" water (i.e. water containing less or no soluble calcium and magnesium compounds) [4][5][6][7]. This is the dissolution part of leaching.…”

Section: Introductionmentioning

confidence: 99%

Effects of Mineral Admixture on the Carbonic Acid Leaching Resistance of Cement-Based Materials

Dong¹

2017

Ceramics - Silikaty

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In order to reveal the degradation process and deterioration mechanism of cement-based materials, this paper analyzes the effects of carbonic acid leaching on the mechanical strength of mortars, as well as relative mass loss, microstructure, and composition of various cement pastes. The results indicate that cement pastes containing less than 20 % fly ash have higher carbonic acid leaching resistance than cement pastes without fly ash. However, after carbonic acid leaching, the compressive strength of the samples with fly ash is lower than that of the cement pastes without fly ash. The leaching resistance is good for samples cured at an early age before leaching. Carbonic acid leaching proceeds from the paste surface to the interior. The incorporation of an appropriate amount of slag powder helps to increase the density of the paste. Due to the pozzolanic activity of fly ash at late-stage leaching, a mixture of fly ash (≤ 20 %) and slag powder (≤ 20 %) INTRODUCTIONWater with high contents of carbonic acid is commonly found on the sites of hydroelectric projects [1]. Most of these projects are situated in wet, hot and rainy environments [2]. There is usually luxuriant vegetation along the riverbank, with large amounts of humus accumulated both along the bank and at the bottom of the river [3]. When the permeability of the soil layer is bad anaerobic bacteria are present, and organic fertilizers in the soil will be resolved and produce abundant amounts of CO 2 under the actions of these bacteria. According to the equilibrium concentrations of calcium hydroxide (the limit concentration of lime), hydration products will gradually dissolve or decompose when the concrete cement is in long-term contact with "soft" water (i.e. water containing less or no soluble calcium and magnesium compounds) [4][5][6][7]. This is the dissolution part of leaching. Portland cement hydration products are alkaline substances, which are soluble in water to some extent. They do not dissolve in water and are stable only if the lime content in the liquid phase is above the respective limit concentration of the hydration products. On the contrary, when the lime content in the liquid phase is below the limit concentration of hydration products, the hydration products will decompose and release lime, resulting in a change of high-calcium hydration products into low-calcium hydration products [8]. Calcium hydroxide, which has the largest limit concentration of lime in hydration products, will be the first to dissolve out when the cement comes into contact with "soft" water. The water around the cement is easily saturated by the calcium hydroxide, which in the case of non-pressurized static water will discontinue dissolution. In this case, the dissolution is limited to the surface layer, which has little effect on the concrete [9][10]. From the aforesaid it is clear that the degree of dissolution leaching is related to the "hardness" of the water, the density of the concrete, and the environmental conditions.Researchers have attached great impo...

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Formation and carbonation of C-S-H in water

Cited by 122 publications

References 15 publications

Effects of Carbonation on the Microstructure of Cement Materials: Influence of Measuring Methods and of Types of Cement

Effects of Carbonation on the Microstructure of Cement Materials: Influence of Measuring Methods and of Types of Cement

Encapsulation of Cs/Sr contaminated clinoptilolite in geopolymers produced from metakaolin

Effects of Mineral Admixture on the Carbonic Acid Leaching Resistance of Cement-Based Materials

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