The confused world of sulfate attack on concrete

http://cec.sut.ac.th/download/published/CBM-micro.pdf

Analysis of strength development in cement-stabilized silty clay from microstructural considerations

Application of experimental design and optimization to PFC model calibration in uniaxial compression simulation

Sulfate attack on alkali-activated slag concrete

The recent modifications in the cement manufacturing technology and the extensive use of mineral admixtures have introduced changes in the chemical and mineralogical composition of the present-day cements. These changes may significantly affect the durability of concrete, particularly the sulfate attack. Due to these modifications, the need for understanding the mechanisms of sulfate attack through laboratory and field exposure studies becomes all the more important. This paper reviews the studies conducted at King Fahd University of Petroleum and Minerals (KFUPM) to assess sulfate attack on plain and blended cements exposed to aggressive environments in the laboratory and the field. Based on this review, the mechanisms of sulfate attack are discussed. The effect of cation type associated with the sulfate anions on concrete deterioration due to sulfate attack and the role of chloride ions on sulfate attack in plain and blended cements are also elucidated.

Attack on plain and blended cements exposed to aggressive sulfate environments

Effects of confining pressure and temperature on mixed-mode (I–II) fracture toughness of a limestone rock

This investigation is carried out: (1) To study the effect of magnesium‐sodium sulfate environment on the performance of two plain and three blended cements; and (2) to elucidate the sulfate attack mechanisms on these cements in the mixed magnesium and sodium sulfate environment. After two years of exposure, deterioration is observed in all cements. However, the deterioration is more pronounced in blast‐furnace‐slag (BFS) and silica‐fume (SF) cements. Deterioration in these cements significantly exceeds that observed in plain and fly‐ash‐(FA‐) blended cements. XRD and SEM analyses indicate that the greater deterioration in BFS‐ and SF‐blended cements may be attributable to the depletion of the hydrated calcium hydroxide as a result of pozzolanic reaction. In the absence of Ca(OH)2, magnesium ions react more directly and extensively with the cementitious calcium silicate hydrate to generate gypsum and noncementitious magnesium silicate hydrate resulting in aggravated deterioration.

Magnesium-sodium sulfate attack in plain and blended cements

Knowledge of the swell potential of expansive soil at the outset of an investigation can be helpful in avoiding possible damage to the structure. A review is presented of several methods that have been proposed to identify swell potential and test techniques, which are used to quantify the amount of swell. A site investigation was conducted to obtain hand-carved block specimens from a fresh excavation site near Al-Qatif, Eastern Province of Saudi Arabia. Laboratory tests were used to determine geotechnical and physicochemical properties and mineralogical composition. The results of a range of laboratory tests, including oedometer types, filter paper, triaxial, and new stainless steel tank apparatus, showed the problems associated with investigating swell behavior of soils. A field swelling test was conducted, and results are compared with laboratory tests to establish guidelines for estimation of swell potential.

Determination of swell potential of Al-Qatif Clay

This investigation was carried out to elucidate the role of chloride ions in sulphate attack in plain and blended cements. Paste and mortar specimens made with Type I and Type I cements as well as with Type I cement blended with fly ash, silica fume and blastfurnace slag (BFS) were exposed to four sulphate and/or chloride environments for a period of two years. The performance of these cements was evaluated through visual inspection and measurement of reduction in compressive strength. X-ray diffraction and scanning electron microscopic techniques were used to study the sulphate attack mechanisms in plain and blended cements in both the presence and the absence of chloride ions. Results indicate that sulphate deterioration in plain cements was mitigated by the presence of chloride ions, whereas in blended cements, particularly those made with silica fume and BFS, the beneficial effect of chloride was only marginal. This is attributed to the Mg-oriented sulphate attack which was more operative in blended c...

Sahel N. Abduljauwad

Papers

Effects of confining pressure and temperature on mixed-mode (I–II) fracture toughness of a limestone rock

Magnesium-sodium sulfate attack in plain and blended cements

Determination of swell potential of Al-Qatif Clay

Influence of chloride ions on sulphate deterioration in plain and blended cements

Expansive characteristics of gypsiferous/anhydritic soil formations