The failure of buildings and structures can often be attributed to poor concrete construction methods and workmanship. This is often the result of negligence and inadequate quality control at the construction site. The primary causes of poor construction methods are generally related to three factors: poor workmanship, inadequate supervision, and inadequate quality control.
Poor workmanship refers to the lack of skill or care taken by the workers involved in the construction process. This can be the result of a variety of factors, including insufficient training, lack of experience, or simply a lack of attention to detail. When workmanship is poor, the final product may not meet the required specifications and may be more prone to failure.
Inadequate supervision is another major factor that can lead to poor construction methods. Without proper oversight, workers may cut corners, skip important steps, or use substandard materials. In some cases, supervisors may not have the necessary expertise or training to recognize when work is being done improperly.
Finally, inadequate quality control can also contribute to poor construction methods. This can occur when the quality control procedures in place are not followed or are insufficient to catch defects in the construction process. When quality control is lacking, errors or defects may go unnoticed until it is too late, leading to failure of the structure.
In summary, poor concrete construction methods and workmanship can result from a range of factors, including poor workmanship, inadequate supervision, and inadequate quality control. Addressing these factors can help to prevent failures and ensure that buildings and structures are constructed to the required standards.
Common Concrete Construction Mistakes at Site
BS 8110 is a British Standard for the design and construction of reinforced and prestressed concrete structures. The standard identifies some poor construction methods that should be avoided as they can have detrimental effects on the quality and durability of the concrete structures.
These poor construction methods include using excessive water in the concrete mix, inadequate compaction of the concrete, insufficient curing of the concrete, and inadequate cover for reinforcement. When excessive water is added to the concrete mix, it results in weaker and more porous concrete, which can lead to cracks and reduced durability. Inadequate compaction of the concrete can result in voids or honeycombing, which can weaken the concrete structure and increase the risk of moisture penetration. Insufficient curing of the concrete can also result in reduced strength and durability, as the concrete needs sufficient time to gain its strength. Finally, inadequate cover for reinforcement can lead to corrosion and weakening of the reinforcement, which can ultimately lead to structural failure.
Therefore, it is important to avoid these poor construction practices in order to ensure the quality and durability of concrete structures. Proper mix design, compaction, curing, and reinforcement cover are essential for achieving long-lasting and safe concrete structures. Compliance with BS 8110 ensures that the best construction practices are followed and high-quality concrete structures are produced.
1. Incorrect placement of steel
Proper guidance and drawing are essential when placing steel reinforcement for any structure. Inaccurate placement of the steel can result in insufficient cover for the structure, which can then lead to corrosion of the reinforcement. This problem is particularly severe for structures situated near water bodies.
If the steel is placed incorrectly, other than what is required, the area may be unable to withstand a mass load. This can result in the sudden failure or collapse of the structure. Therefore, it is crucial to follow proper guidelines and adhere to the specified drawing when placing steel reinforcement. Doing so can help to prevent potential hazards and ensure the longevity of the structure.
2. Inadequate cover to reinforcement
Improper placement of steel in concrete can have negative consequences such as increased moisture penetration, corrosion of reinforcement, and cracking and spalling of the concrete. When steel is not placed correctly, it can cause moisture to seep into the concrete, which can lead to further deterioration of the structure. This moisture can also cause the steel reinforcement to corrode, which weakens the entire structure.
Moreover, if the steel is placed too close to the surface of the concrete, it can cause cracking and spalling of the concrete. This occurs when the steel expands and contracts with temperature changes, creating pressure against the concrete. If the concrete is not strong enough, it can crack and break apart, which can lead to significant structural damage. Ultimately, proper placement of steel in concrete is crucial for ensuring the durability and longevity of the structure.
3. Grout leakage
During the process of concrete placement and compaction, it has been observed that issues can arise when the formwork used is not properly constructed. One crucial aspect of constructing good formwork is to ensure that it is air tight and free from any leaks. When the joints of the formwork are not tightly fit, there is a risk of water leaking from the grout. This can have significant consequences on the final product, as the leakage of water can result in the concrete hardening with a reduced amount of cement and fine aggregates. Furthermore, the concrete will contain a large number of air voids and pores, which can also negatively impact its quality. Therefore, it is essential to construct formwork that is tightly sealed and free from any leaks to ensure the production of high-quality concrete.
4. Incorrect Construction Joints
Construction joints are an essential part of any concrete structure, and it is crucial to make them with proper preparation and compaction to ensure their durability and longevity. When making a joint with old concrete, it is essential to prepare the surface properly. The surface must be washed, cleaned, and a thin layer of fresh concrete should be placed before the new concrete is poured continuously.
Failing to prepare the joint surface adequately can result in moisture penetration, which may lead to concrete staining and affect the integrity of the structure. Therefore, it is critical to take the necessary precautions and ensure that the joint is in good condition before pouring new concrete to prevent any unwanted consequences.
Overall, proper preparation and compaction of construction joints are crucial in maintaining the strength and durability of concrete structures. Therefore, it is important to follow the necessary procedures to ensure that the joints are in good condition and can withstand any external forces or environmental conditions.
5. Poor compaction
When it comes to creating a concrete structure, the quality of the concrete mix and the compaction work are both critical factors to consider. Even if the mix is of excellent quality, poor compaction work can result in a low-grade concrete structure.
To prevent the formation of honeycombed and porous concrete, it is crucial to properly ram or vibrate the fresh concrete to compact it thoroughly. A lack of proper compaction can create a porous and weak structure that is vulnerable to damage and deterioration over time.
On the other hand, a good compaction process will result in dense and impermeable concrete that is more resistant to damage and wear. By ensuring that the concrete is thoroughly and properly compacted, builders can create high-quality, durable structures that will stand the test of time.
Fig.1: Honey Combed Hardened Concrete
6. Segregation of Concrete
Segregation in concrete refers to the separation of aggregates from the mortar mix, which can occur due to various reasons. One common cause of segregation is when the concrete is placed or dropped from a great height. To avoid this, chutes or pipes should be used to transfer the concrete to its intended location.
Another factor that can lead to segregation is the use of a concrete mix with a high amount of aggregate, which is also known as a “harsh mix.” This type of mix is more prone to segregation as the aggregates tend to settle and separate from the mortar. Therefore, it is important to carefully select the appropriate mix design for the specific application to minimize the risk of segregation.
Fig.2.Concrete Segregation
When concrete is compacted excessively by either vibration or ramming, it can cause the aggregate to sink. This can lead to structural issues and reduce the overall durability of the concrete. Therefore, it is important to avoid over-compaction and ensure that the concrete is properly placed.
In an attempt to address issues with workability, some may opt to use plasticizers in excess. However, this can lead to a phenomenon known as segregation, where the different components of the concrete separate from one another. When a concrete mix is plagued with segregation, it can create an uneven and porous surface in the finished structure.
To ensure the structural integrity of concrete, it is crucial to handle it with care during the placement process. Avoiding over-compaction and being mindful of the appropriate amount of plasticizers will help to prevent issues such as sinking aggregate and segregation. By taking these precautions, the resulting concrete will be stronger, more durable, and provide a smooth and even surface for the intended structure.
7. Poor curing
In order to ensure that concrete is fully hydrated, it is important to provide it with good curing. Even if the concrete has been mixed with the appropriate amount of water, poor curing methods will not be able to make up for any water that has been lost due to evaporation. If the concrete has not been adequately hydrated, its strength will be negatively impacted. Furthermore, if the concrete loses too much moisture, it may begin to shrink and crack, which can be detrimental to its overall integrity. Therefore, it is essential to ensure that concrete is properly cured in order to achieve optimal hydration and prevent any potential issues related to shrinkage or cracking.
8. Use of High Water Content
Using excessive amounts of water to achieve the desired workability of concrete can have negative consequences on its strength and durability. When too much water is added to the mix, the resulting concrete will have lower strength and increased porosity and permeability. This increased porosity and permeability can lead to corrosion of the reinforcement used in the concrete structure. Therefore, it is important to maintain a proper water-cement ratio in the concrete mix to avoid these problems. By using the correct amount of water, the resulting concrete will have better strength, reduced porosity, and improved durability. Overall, it is strongly recommended to be cautious with the amount of water used in concrete mixes to ensure that the resulting concrete is of the highest possible quality.