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Sulfate Attack and Mechanical Load



Author(s):
Paper category: Bibliography
Book title: Publications on Durability of Reinforced Concrete Structures under Combined Mechanical Loads and Environmental Actions: An Annotated Bibliography
Editor(s): Yao Yan, Wang Ling, Wittmann Folker
Print ISBN: 978-3-942052-03-0
Publisher: Aedificatio Publishers
Pages: 59 - 69
Total Pages: 11
Language: English


Abstract: 
Sulfate attack can be divided external or internal. In the 1980s, German researchers reported internal sulfate attack in heatcured concrete products. The typical manifestation of distress is the presence of voids around the coarse aggregate, indicating expansion of the cement paste. For external Sulfate attack, due to penetration of sulfates in solution, in groundwater for example, into the concrete from outside. This is the more common type and typically occurs where water containing dissolved sulfate penetrates the concrete.

Sulfate attack against cement concrete comprise a complex process involving the movement of sulfate ions through the pores by different transportation mechanisms. For example, the interaction of aggressive solution with some compounds of cement paste to form some expansive compounds leads to cracking, strength loss, and softening of concrete. The most common minerals produced by sulfate attack are gypsum (CaSO₄·2H₂O) and ettringite (3CaO·Al₂O₃·3CaSO₄·31H₂O). Thaumasite product, the third mineral produced by sulfate attack, has been increasingly found in cement-based materials exposed to sulfate ambient. Thaumasite is a calcium silicate carbonate sulfate hydrate (CaSiO₃·CaCO₃·CaSO₄·15H₂O), which can be found occurring alongside ettringite, gypsum, or on its own.
Sulfate attack is one of the most aggressive environmental deteriorations that affect the long-term durability of concrete structures and can cause huge economic loss. For concrete in marine environment, drying-wetting cycles can accelerate the deterioration of concrete such as in the environment like splash and tidal zone. Furthermore, concrete in marine environment endures multifarious loading all the time. Many researches dealt with studies of durability of concretes under simultaneous long-term mechanical load and sulfate attack. Generally, durability of concretes was assessed by means of creep and creep recovery, compressive strength measurements and analysis of phase content in cement paste. Results of these studies indicate a significant effect of stress level, kind of aggregate as well as interaction of both factors on concrete performance in sulfate solution. The occurrence of physico-mechanical changes due to the magnitude of stress and chemical changes connected with the kind of aggregate affect the rate of sulfate corrosion. Selected papers are included in this annotated bibliography.


Online publication: 2014
Publication Type: full_text
Public price (Euros): 0.00