How to Repair Cracks in RCC Slab
The cracks in the reinforcement concrete slabs (RCC slabs) refer to those openings or fissures which have been developed in the concrete structure. The cracks in the RCC slabs have varied in size and severity. It is necessary to understand the types and causes of the cracks to determine the methods for repairing the cracks in the RCC slabs.
Structural cracks
Structural cracks of the RCC slabs refer to those cracks which can impact the structural integrity and load-bearing capacity of the RCC slabs.
Horizontal Cracks
These horizontal cracks have been found on the beam-column junction of the RCC slab which occurs due to insufficient reinforcement.
Diagonal Cracks
This type of crack has been observed along with the height of the reinforced concrete slab which impacts the slab’s integrity.
Splitting Cracks
This type of cracks are short and parallel which occurs when the column has inadequate steel reinforcement.
Corrosion Cracks
These types of structural cracks have appeared near the reinforcement lines on the columns.
Flexural Cracks
The flexural cracks have occurred due to the flexing or bending of the RCC slabs which has been found near the load-bearing areas.
Overloaded Slab Cracks
This type of structural crack has occurred in the case the excessive weight has been placed on the RCC slab during snowfall or heavy rain.
Non-structural cracks
The non-structural cracks of the RCC slabs are narrower which only affects the surface layer of the RCC slab.
Temperature-related cracks
The variations in the temperature lead to thermal expansion and slab contraction which results in cracks in the RCC slabs.
Premature drying cracks
This can be of two types including crusting cracks and crazing cracks, in which, crusting cracks occur during stamping whereas the crazing cracks occur while the top loses the moisture quickly.
Reasons behind the occurrence of cracks in the RCC slabs
Improper structural design of the RCC slabs
The errors in the design stage of the RCC slab lead to the development of cracks in the RCC slabs. The lower reinforcement ratio leads to a lower capacity of the RCC slabs which leads to creating cracks at smaller loads.
Poor quality of the concrete of the RCC slabs
The cracks also developed in the RCC slabs while compromising the quality of the concrete of the RCC slabs. The poor quality of the concrete of the RCC slabs reduces the strength of the concrete. This can also caused by inadequate mixing of the concrete, incorrect water to the cement ratio or improper placement of the concrete.
Wrong selection of the materials
The right material selection including aggregate is important to reduce the risks of the initiation of the cracks in the RCC slabs. In the case of using alkali-aggregate in the concrete of the RCC slabs leads to the crack development in the RCC slabs.
Improper curing process
There is shrinkage in the concrete and initiation of the cracks if the curing process is improper. Improper curing leads to reduced concrete strength which leads to cracks in the RCC slabs.
Effect of excessive load
The RCC slabs have been designed to resist specific loads. If the loads have exceeded the permissible loads, the excessive loads can lead to the development of cracks in the RCC slabs. Overlaodsingleads to the bend of the RCC slabs beyond the capacity of those slabs which leads to structural issues and cracks.
Insufficiency thickness of the RCC slabs
The thickness of the RCC slabs helps to determine how long the slabs can prevent the cracks. It needs to be ensured that there is a span between the supporting beams and the expected loads during the design phase of the RCC slabs. Thus, the cracks in the RCC slabs can be kept at bay.
Environmental factors
In harsh environmental conditions including coastal areas, sulfate attacks on the RCC slabs have occurred.
Methods of repairing cracks in the RCC slabs
There are some common methods of repairing cracks in the RCC slabs which include:
Routing and Sealing process
This method can be used to detect wider cracks in the RCC slabs. Cracks have been widening into V-shape and polymer-based sealants filled the cracks in this method.
Grouting method
This repairing method can be used in case RCC slab cracks have to occur due to void or settlement beneath the RCC slab. In this repairing method, the voids are filled and the RCC slabs have been stabilized.
Epoxy Injection
In this crack-repairing method, epoxy resin has been injected into the RCC slab cracks to bond and seal those cracks. This repairing method is effective for both structural and non-structural types of cracks.
Epoxy Injection
In this crack-repairing method, epoxy resin has been injected into the RCC slab cracks to bond and seal those cracks. This repairing method is effective for both structural and non-structural types of cracks.
Stitching method
In this repairing method, holes have been drilled across the RCC slab cracks and staples or metal rods have been inserted along with epoxy which helps to hold the crack of the RCC slab together.
To learn more, watch the following video tutorial.
Video Source: Emecole Metro LLC
Reinforcement of the Carbon Fiber
The Carbon Fiber sheet has been bonded to the surface of the RCC slab over cracks of the RCC slabs which helps to provide strength as well as prevent further chances of cracks.
Overlay or Resurfacing method
A new layer polymer-modified overlay has been applied in the RCC slab which helps to cover and reinforce the existing cracks of the RCC slabs.
Concrete Patching method
The damaged concrete has been removed and replaced with fresh concrete or suitable repair mortar if there are small cracks in the RCC slabs.
Installation of the Concrete Joint
The concrete joints have been created at specific intervals which help to redirect the cracks to the predetermined locations thus helping to reduce the visibility and impact of the slab cracks.
Use of Caulking and Sealants
In the case of the non-structural cracks, sealants or caulking can be used which helps to fill and seal the RCC slab cracks as well as helps to prevent water infiltration.
