Effect of airborne particle on SO2–calcite reaction

Böke, Hasan; Göktürk, E. H.; Caner-Saltık, Emine N.; Demırcı, Şahınde

doi:10.1016/s0169-4332(98)00468-1

Cited by 61 publications

(39 citation statements)

References 25 publications

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“…Some previous work showed crystal shapes belonging to calcium sulphate crystals [8,20] and other studies presented calcium sulphite hemihydrate crystals with rough spherical and platelet forms [42,43]. In the present study, it seems that the addition of surfactant molecules (water-repelling admixtures) to the mortar favoured the formation of agglomerates of acicular calcium sulphite hemihydrate crystals.…”

Section: Mortars With Water-repelling Agentssupporting

confidence: 61%

Ageing of lime mortars with admixtures: Durability and strength assessment

Izaguirre

Lanas²,

Álvarez

2010

Cement and Concrete Research

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Lime-based mortars modified with admixtures were prepared and subjected to different environments such as outdoor and indoor exposures, climatic chamber, SO 2 -chamber, and freezing-thawing cycles. The influence that the different admixtures (water repellents, water retainers, polypropylene fibre and a viscosity modifier) had on the pore size distribution of the hardened specimens was assessed and related to the water absorption capacity, and hence to the durability. Ageing resistance and mechanical strengths improved when additives reduced the water intake and increased the aircontent. High dosages of water repellents were necessary to enhance the durability, sodium oleate being the most effective additive to endure freezing processes. Also the low tested dosage of fibre, a water retainer (guar gum derivative), and a starch proved to be useful. SO 2 deposition caused the formation of calcium sulphite hemihydrate as the main degradation product. A very small amount of calcium sulphate dihydrate was observed. A crystal habit composed of acicular agglomerates of calcium sulphite hemihydrate was detected in SO 2 deposition on calcareous materials.3

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Section: Mortars With Water-repelling Agentssupporting

confidence: 61%

Ageing of lime mortars with admixtures: Durability and strength assessment

Izaguirre

Lanas²,

Álvarez

2010

Cement and Concrete Research

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“…In a study by Elfving et al [3], SO 2 -calcite reaction is described as proceeding in a water film when con-densation is favourable on calcite surface. Sulphation mechanism under these conditions can be explained by successive stages of gas -liquid -solid interfacial reactions [4] as follows: diffusion of the SO 2 from the gas phase into aqueous phase present on marble surface, dissolution of SO 2 in aqueous phase, dissolution of calcite in aqueous phase, precipitation of calcium sulphite hemihydrate in aqueous phase, partial dissolution of calcium sulphite hemihydrate in aqueous phase, formation of gypsum by oxidation of sulphite ions present in aqueous phase.…”

Section: Resultsmentioning

confidence: 99%

“…The results were used to quantify the calcium sulphite hemihydrate and gypsum formed on marble surfaces. For this purpose, a calibration curve was prepared by plotting the absorbance ratio of gypsum to calcium sulphite hemihydrate as a function of their concentration ratio [4]. Using the calibration curve and corresponding weight increase results, the amount of calcium sulphite hemihydrate and gypsum were accurately calculated.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Effect of some surfactants on SO2–marble reaction

2002

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In the polluted atmosphere, sulphur dioxide (SO 2 ) reacts with calcite (CaCO 3 ) in marble producing calcium sulphite hemihydrate (CaSO 3 Á0.5 H 2 O) and gypsum (CaSO 4 Á2H 2 O). Gypsum develops crust at rain-sheltered surfaces and then, being more soluble, accelerates erosion at areas exposed to rain. Eventually, all these lead to significant deformations in the appearance and structure of marble surfaces. Clearly, some precautions must be taken to stop or at least to slow down this deterioration process which destroys our cultural heritage. In this study, we have investigated the possibilities of preventing the SO 2 -marble reaction by using water-soluble surfactants: Abil Quat 3270 and Tween 20. Experiments for measuring their effects have been carried out at conditions simulating the dry deposition of SO 2 . Infrared spectrometry and scanning electron microscopy were used to analyze the mineralogical composition and morphology of the reaction products. The extent of sulphation reaction was calculated by determining calcium sulphite hemihydrate and gypsum quantitatively by an IR approach and also by weight increases observed during the progress of SO 2 -marble reaction. A 10% decrease is observed in the total sulphation with both surfactant applications. The results have been discussed in relation to the possible stages of sulphation reaction and surface reactions of calcite. D

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“…Industrialization and heavy urbanization increased the use of fossil fuel that resulted in the increase of sulphur dioxide (SO 2 ) concentration in the atmosphere. Sulphur dioxide, the main pollutant affecting the marble structure, reacts with marble composed of calcite crystals (CaCO 3 ) and converts it into calcium sulphite hemi-hydrate (CaSO 3 ·1/2H 2 O) [1][2][3]. Calcium sulphite hemi-hydrate is not a stable product and rapidly oxidized to gypsum (CaSO 4 ·2H 2 O) by the oxygen in the presence of water [1,2].…”

Section: Introductionmentioning

confidence: 99%