Spongy concrete is often a common issue in concrete structure projects. In addition to affecting aesthetics, spongy concrete can also pose potential safety hazards. This is because the factors causing spongy concrete not only reduce the dimensions of the concrete but also affect the overall strength of the structure.
Here are the factors that contribute to spongy concrete.
Errors in the Mixing Process
The first step is to ensure that the mixture of cement, sand, gravel, and water is well-blended. Make sure there are no dry lumps, as these can weaken the concrete.
Too Watery Concrete Mix
This is a frequent issue due to a lack of awareness of its consequences. A watery concrete mix can cause cement water to seep into the gaps of the mold, resulting in spongy concrete due to insufficient volume.
Rebar Installation
Rebar installation must align with the design drawings, both in terms of dimensions and spacing between the rebars. If the rebars are placed too closely together, the concrete cannot flow properly into the gaps and will be trapped on the surface. Additionally, the thickness of the concrete cover needs to be checked. If the cover is too thin, the concrete may erode easily and become spongy. This can be avoided by placing a sufficient layer of concrete beneath the rebar, especially in horizontal structures like beams and slabs.
Dirty Formwork
The condition of the formwork must be inspected. If using used formwork, ensure it is clean and suitable. Dirty formwork can result in spongy concrete.
Incomplete Compaction Process
Compaction of the concrete must be done thoroughly. For smaller pours, a rubber or wooden mallet can be used to tap the surface of the formwork. For larger pours, specialized equipment should be employed.
Formwork Removed Too Early
It’s important to allow enough time for the formwork to remain in place. Ensure the concrete is fully cured before removing the formwork. Premature removal of the formwork can cause the concrete to peel, and the quality will degrade because uncured concrete is more vulnerable to surrounding vibrations.
If spongy concrete occurs, it must be repaired to ensure the structure functions properly. If your concrete structure is spongy, grouting is the solution. Grouting involves filling gaps using special materials, injecting or filling grouting material into the gaps, or closing cracks in the spongy concrete. There are various types of grouting materials used to fix spongy concrete.
However, if the repair costs are too high, it might be better to demolish and redo the work, considering both the cost and time required for rework.
For more information on solutions for spongy concrete and consultation regarding grouting products, visit www.consolindonesia.com.
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CONSOL, THE BEST!
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