A building’s quality and resilience are not only affected by the materials used to construct it. Workmanship and building techniques also determine how well a structure will be completed. Poor concrete construction methods will result in a badly-built structure. Construction mistakes are made when contractors are not trained properly or when they are negligent.
Poor construction methods can also be the result of inadequate supervision from project managers or inadequate quality control. The lead supervisor on any construction site must check the workmanship and inspect the quality of the building on a daily basis. Here are the common construction errors that supervisors need to look for.
Common concrete construction mistakes
1. Inadequate concrete curing
The curing process is vital when it comes to the quality and strength of a concrete structure. Concrete needs to be kept hydrated for about 28 days after pouring to ensure that it cures sufficiently. The main cause of poor curing is not keeping the concrete wet during this time. This negatively affects the strength of the concrete and can cause it to shrink, resulting in cracks and a brittle structure.
2. Poor concrete compaction
Even if you use the highest-quality cement and building materials, poor concrete compaction will lead to a bad structure. Concrete compaction is important because it removes air bubbles and creates a solid, dense and well-bonded structure. Propper ramming and vibration is needed to ensure that all the trapped air inside the wet concrete is removed.
3. Concrete segregation
This construction mistake is the result of poor mixing of cement, water and aggregates. If the aggregates and mortar mix are not properly mixed, the concrete can segregate. Segregation can also occur when concrete is dropped from a height. Contractors need to use chutes or pipes to transport mixed concrete down into a building basement. A concrete mix with a high volume of aggregates, or over-compaction, can also cause aggregates to sink in the concrete mix, leading to segregation.
4. Incorrect placement of steel rebar
The placement of steel rebar within a concrete structure is vital. It forms the inner skeleton of the structure and provides extra strength and reinforcement. Incorrect placement of steel rebar can lead to a weakened structure. If this rebar is exposed, it can also lead to rust and corrosion – especially in coastal regions. In the worst-case scenario, steel rebar that is badly placed can lead to a sudden collapse of the structure.
5. Concrete leakage in bad formwork
Concrete leakage is a common mistake that takes place when concrete is being placed and compacted in formwork. The formwork needs to be airtight and properly sealed. If the joints in the formwork are not tight, the wet concrete will seep through the gaps and the water inside the concrete will leak out. This will result in a hardened concrete with a high cement to water ratio. The concrete will be weaker, more brittle and prone to cracking and chipping.
6. Incorrect construction joints
This point leads on from the last – construction joints need to be created with proper preparation and execution in line with the original architect drawings. Before making joints between new concrete and old concrete, the surface of the old structure needs to be washed and prepared properly. This will ensure a proper bond between the two structures. If the construction joints are not good, a number of issues can arise, including moisture penetration, concrete staining, cracking, disconnection and compromised structural integrity.
7. Concrete with high water content
Experience is important when it comes to concrete mixing. Sometimes, inexperienced contractors do not use the right amount of cement, water and aggregates in a concrete mix. The most common of these mistakes is using too much water. A high water content will make the concrete slump and decrease its workability. Too much water will also affect the final strength of the mix.
These are common mistakes that can be made on construction sites by inexperienced builders or through poor supervision. Project managers need to inspect the building process and completed jobs on a daily basis to ensure that these mistakes are not being made. These mistakes can determine the final quality of a building so they need to be avoided.
LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.
LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.
At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.
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