The form of construction where concrete is casted in a re-usable mould and then cured in a controlled environment (precast plant) is called precast concrete. The casted structural member is then transported to the construction site and then erected. Structural members such as concrete frame, concrete wall and concrete floors etc. can be constructed using precast concrete.
Advantages of Precast Concrete
There are many advantages of precast concrete. They are discussed below.
- Saves Construction Time: Precast Concrete construction saves time, the risk of project delay is also less. The precast concrete casting can be carried on simultaneously with other works on site such as earthwork, survey, etc. and thus saves time.
- Quality Assurance: The key factors which regulate the quality of construction such as curing, temperature, mix design, formwork, etc. can be monitored for Precast Concrete. So, improved quality construction can be performed.
- Usage of Prestressed Concrete: By using pre-stressed precast, structural materials of high strength and load-bearing capacity can be achieved, which can result in greater clear span, reduced size of the cross-section of structural members, etc.
- Cost-effective: The simplified construction process reduces the time, increases the productivity, quality and safety and thus the cost is reduced.
- Durability: Precast Concrete structure has a longer service time period and minimal maintenance. The high-density Precast Concrete is more durable to acid attack, corrosion, impact, reduces surface voids and resists the accumulation of dust.
- Aesthetics: As the structures are prefabricated in a controlled factory environment, several combinations of colors and textures can be used. A wide range of shapes and sizes are available to choose from with smooth finishing and thus the aesthetical value of products are increased.
- Safe Construction Platform: No raw materials have to be stocked in site for Precast Concrete construction. It reduces the requirement of traditional formworks and props, wastage, workers, etc. and thus provides a safe working platform.
Disadvantages of Precast Concrete
There are some disadvantages to precast concrete. They are discussed below.
- High Initial Investment: For installing a Precast Concrete plant, heavy and sophisticated machines are necessary which requires a high initial investment. A large scale of precast construction projects must be available to ensure sufficient profit.
- Transportation Issue: The construction site can be at a distant location from the Precast Concrete plant. In that case, the precast members must be carried to the site using trailers. In many cases, the reduced costs of Precast Concrete is compensated by the transportation cost.
- Handling Difficulties: Proper care and precaution have to be taken for handling precast concrete. Usually, precast members are heavy and large which makes it difficult to handle without damage. Generally, portable or tower cranes are used to handle precast members.
- Modification: Limitation In case of precast structures, it is difficult to modify the structure. For example, if a structural wall is to be dismantled for modification it will impact the overall stability of the structure.
- Sensitive Connection Works: Assembling of the precast members is one of the key points for ensuring strong structural behavior. Connections between several structural members must be supervised and done properly to ensure the intended behavior of the connection such as simple, semi-rigid or rigid connections. Besides this, faulty connections may lead to water leakage and fail sound insulation.