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Any material or geometric property change that has an impact on structural performance is known as structural deterioration. Although this phenomenon is gradual, if it is not evaluated and fixed in a timely manner, it will have a severe impact on the structure and, in some historical occasions, may result in collapse. Deterioration has a variety of...
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Context 1
... sulphate-containing salts such as alkali-earth (calcium, magnesium) and alkali (sodium, potassium) sulphates, which are chemically reactive with concrete components, cause sulphate attack. Sulphate attack on concrete can take several forms, depending on the chemical type of sulphate and the exposure of the concrete to the environment. (See Fig. 1) Sulphate sources might be internal or external. Internal sources are less common, but they appear with materials used in concrete, such as hydraulic cements, fly ash, aggregate, and admixtures. External sources are more common, typically soils and ground water have high-sulphate content, as well as pollution from the atmosphere or ...
Context 2
... the standard considered the source of sulphate attack from a concrete constituent: aggregate. Sulphate in aggregate (A.7.5) and Alkali-aggregate reaction (A.8.2) (British Standards Institution, 2019). ...
Citations
... It is known that the presence of sulphate salts in cement paste causes increased formation of Ettrengite at high rates that negatively affects the hardened cement paste due to a large volume increase in the hardened cement paste [33]. Similarly saline water also affects the workability, strength and durability of cementitious structures [34]. ...
Cement production consumes huge energy and creates environmental pollution. Cracks present in the cement-based concretes, deteriorate the structural longevity and requires costly repair. An eco-friendly and energy-efficient geopolymeric material is developed by incorporating modified bacterium cells, assuming that the developed material will be a cement-alternatives in construction industries in near future. Transformed Bacillus subtilis cells is incorporated to the alkali-activated fly ash only (100%) for making the geo-polymeric material. The mortar samples prepared by geopolymeric material are cured under various conditions to achieve the best possible energy-efficient curing process. Simulated cracks on mortars are developed by applying 50% (half) of predetermined breaking load for studying the self-healing phenomenon. Artificial cracks on mortars are created by introducing steel bar for studying crack-repairing activity. Mechanical strengths (compressive, tensile and flexural), water permeability, sulfate and chloride resistant activities along with the crack-repairing and the self-healing efficacy of the samples are characterized. Higher mechanical strengths and better longevity in terms of decreased water and chloride ions permeability and increased sulfate resistant activity are noted in the bacterium amended mortars. Ambient temperature modified heat curing process reveals the best possible energy-efficient curing condition. Images and micro-structures analyses show that several new phases (e.g., silicate, mullite, albite and alite etc.) are developed within the bacteria-amended mortars. Eco-friendliness of the bacterium is confirmed by toxicity study against rats models and human cell lines. We hypothesize that the developed geo-polymeric material is a suitable cement alternative in construction industries as well as an eco-friendly and energy efficient material.
Several incidents of early deterioration of reinforced concrete structures have been reported in recent years. Consequently, the critical demand to incorporate durability in the structural design and construction approach has emerged. As a result, durability design provisions in many countries’ standards have gotten increasingly stringent. In the absence of clear standard guidelines for design engineers, insufficient design and failures or an expensive over-design to provide for the worst-case scenario may occur. This paper compares and critically reviews the durability design requirements and provisions in the Eurocode, British standards, and ISO standards and proposes improvements that will contribute to the development of the coming generation of these documents. The review revealed similarities in the durability design approach, exposure conditions, and design requirements in the Eurocode code and British standard, whereas the ISO 13823 approach is different. The studied documents’ durability provisions are comprehensive, detailed, and well-defined. Nevertheless, several provisions require to be revised to avoid misinterpretation by the code practitioners and to ensure an economically conservative durable design.
