How can you protect concrete from chemical exposure in structural engineering?

To protect concrete from chemical exposure: Select Resistant Mix: Use chemical-resistant concrete mixes with additives like silica fume or fly ash to enhance durability. Coatings: Apply chemical-resistant coatings, such as epoxy or polyurethane, to the concrete surface for added protection. Seal Joints: Seal joints and cracks to prevent chemicals from seeping into the concrete. Proper Curing: Ensure appropriate concrete curing to minimise porosity and enhance resistance. Chemical Containment: Implement secondary containment systems to prevent spills from reaching the concrete. Example: In industrial settings where acids are used, like battery manufacturing plants, epoxy-coated concrete floors are employed to resist chemical corrosion.

Em meus trabalhos costumo indicar para uma melhor prote??o para o concreto estrutural o uso de argamassa polimérica, sempre atento ao tipo e tempo de exposi??o das substancias químicas e indico o uso de selante para impedir a penetra??o do produto nos poros do concreto.

Look out for deleterious material in concrete aggregate, its not only the crushing strength to look out for, but reactive aggregate (e.g. crushed greywacke-type sandstone, microcrystalline quartz or chalcedony found in ?int and chert) Be wary of high alkaline cements as these can combine with certain types of silica in the aggregate when moisture is present. This reaction produces an alkali-silica gel that can absorb water and expand to cause cracking and disruption of the concrete. Mild cases of ASR may be managed by using a combination of external coatings, restriction of the supply of moisture, and regular monitoring of the structure. More severe cases may require the introduction of secondary supports/demolition & member replacement.

One way to improve the durability and resistance of concrete against aggressive chemicals is to use low-permeability concrete. This involves incorporating materials and admixtures that can reduce the permeability of concrete and prevent the ingress of such chemicals. Some of the ways to achieve this include using high-quality aggregates, supplementary cementitious materials such as fly ash or silica fume, and maintaining a low water-to-cement ratio (w/c). By doing so, the concrete's durability and resistance to chemical attack can be significantly improved.

Shield concrete from chemical exposure by applying protective coatings and sealants. These coatings act as a barrier, preventing harmful substances from penetrating the concrete surface. Choose coatings specifically designed to resist chemical corrosion and ensure periodic maintenance to uphold their effectiveness over the lifespan of the structure.

Siloxane sealers are effective in safeguarding concrete from environmental contaminants. They penetrate deeply into the concrete's pores, providing excellent resistance to chloride ion penetration. Although they may not offer the same level of chemical resistance as epoxy or polyurethane coatings, they are still efficient for this purpose. Polyaspartic coatings are high-performance coatings that offer superior chemical resistance, UV stability, and abrasion resistance. They are used in industrial and commercial settings where rapid turnaround times and long-term durability are required. Polyaspartic coatings are versatile and can be applied in a wide range of temperatures, making them suitable for both indoor and outdoor applications.

Besides having specified for the correct type of cement (CEM 1 normal, CEM 2 or CEM 3 slow setting) for the intended use for the building structure whilst also having procured non-reactive aggregates and having ascertained that there is no possibility of sulphate or chloride attack what about the presence of moisture. Has this been adequately detailed for the concrete structure not to be subjected to continuous wetting, which over a number of years will initiate deterioration to the proper functioning of reinforced or prestressed concrete, thus being subjected to a process known as carbonation. This simply placed, also referred to as the cancer of concrete, can reduce the design life of the structure to much less than the codified 50 years

A prime example of adhering to best practices and guidelines in structural engineering is the evolution of methods used in the UAE for reinforced concrete structures protection over the past 20 years. One of the early popular applications focused on the use of epoxy-coated steel bars. This practice continued until a major drawback was discovered: even minor scratches on the steel bars led to a significant loss of protection efficiency. These scratches caused concentrated corrosion in the coated steel bars, far exceeding what would have occurred if the bars were uncoated. Consequently, the use of epoxy-coated steel bars was superseded by emerging methods such as cathodic protection and silica fume admixtures.

Use of suitable cement according to environmental conditions Use of cathodic protection system Using a suitable additive to concrete and reducing the amount of water in cement

It's important to choose cementitious materials that have properties that enhance chemical resistance when selecting them for use in construction projects. Some good options include sulfate-resistant cement, slag cement, or high-alumina cement. These materials can resist chemical degradation caused by aggressive agents such as sulfate attack or alkali-silica reaction (ASR). In addition, it's important to select aggregates that are resistant to chemical damage and compatible with the surrounding environment. Dense and non-porous aggregates such as granite or basalt are ideal options as they are less likely to deteriorate and provide enhanced durability in aggressive environments.