During construction projects, the main challenges for concrete coring contractors are: poor finishing, poor design, poor quantity and location of cores and the impediment to recycling concrete. It is important to note that the LEs and SMEs need to develop an agreement on these issues to ensure successful implementation of concrete cutting projects.
No good agreement between LEs and SMEs on the main challenges to concrete recycling in construction projects
Currently, the construction industry is undergoing rapid growth with increased demand for infrastructure projects. This is accompanied by rapid growth in population and rising living standards. Concrete is one of the most used construction materials. Nevertheless, recycling of concrete waste is still a challenge.
Increasing costs, lack of national programs, and lack of comprehensive rules are some of the main challenges of concrete recycling in construction projects. These challenges can be grouped into economic and technical categories.
There is a lack of technical knowledge about concrete recycling. This may be due to the fact that construction firms are not aware of environmental standards. Also, companies are underinformed about new materials and equipment that may become useful to the construction industry.
There are also challenges associated with the lack of proper record keeping for concrete removed from a construction site. Lastly, lack of space for additional rubbish containers is an issue.
Quantity and location of cores
Obtaining and selecting the right quantity and location of cores for concrete testing is a crucial step in the process of determining a concrete’s strength. A core is a hollow core of concrete that is usually cut off for testing.
For strength testing, a core must have a diameter of 50 mm or more and a length of at least twice the diameter. Cores that are cut off must also have rebar perpendicular to the axis of the core.
The core hole must be smooth and straight and have minimal impingement into the subgrade. It must also have a cap that is as thin as possible. It should be capped with a mixture of high alumina cement mortar and sulfur sand. This cap should not be blown off before the concrete is tested.
Impediment to recycling concrete
Using recycled concrete in a construction project is a good way to offset emissions from the cement sector. Good quality concrete can replace as much as twenty to thirty percent of the aggregate in a new concrete mix.
Using recycled concrete in a construction project can reduce construction waste in dedicated landfills. Local governments can work together on a regional scale to manage concrete waste. Several recycling services charge for processing construction waste. In some industrial regions, contractors have reported financial benefits resulting from avoiding landfill tipping costs.
The study aims to highlight the complexities of recycling concrete in a construction project, and to identify the efficiencies and shortcomings of the recycling process. The study utilized a well-defined methodology involving a survey of industry practitioners, a review of the literature on the subject, and an unstructured, semi-structured interview to obtain information.
Flawed design causes concrete to fail
During the construction of a concrete structure, many problems can arise. One of the most common problems is faulty design. This can cause a variety of different types of concrete damage. A faulty design can also lead to corrosion of reinforcement.
In general, there are four main types of concrete failures. The first is a cracking or spalling process. This type of concrete damage is more common in colder climates. This is a result of expansive pressure, which breaks off the top surface of the concrete. This can also lead to water ponding and leakage through cracks.
The second type is shrinkage cracking. This happens when the surface of the concrete is rapidly dried. The process can also lead to random cracks. This type of damage can be caused by incorrect mix design, improper placement, or insufficient finishing.
Among the many challenges that concrete coring contractors face is the task of finishing the concrete properly. There are many ways to finish concrete properly, but a few common errors can result in poor quality concrete.
Some common finishing mistakes include using the wrong raw materials, a poor mix, and a wrong ratio of materials. These errors can result in slabs that are weak, cracking, or not fully cured. They also can lead to premature scaling of the surface of the concrete.
Incorrect finishing can also lead to air or water entrapment in the concrete. When air and water entrapment occurs, the concrete slab will become weak and may crack. This can be an especially dangerous problem when a slab has a lower strength than its underlying concrete. Fortunately, there are several techniques to offset this problem, including spray on evaporation retarders and foggers.