Concrete Surface loses its aesthetic appearance (mainly concrete floors) with time due to the formation of cracks, distress, and other undesirable problem. This is due to the causes of continuous utility, exposure to undesirable fluids or environment traffics and loads. Conventional policy employs the complete removal of distressed concrete and lay a new one. But now the innovative ideas have been put forward to repair and resurface the old and existing concrete to a newer finish.
Considerations in Concrete Resurfacing
Before carrying out resurfacing, there are certain considerations and specifications the surface should hold. These considerations are more concerned within the internal of the concrete material. They are:
- The concrete structure must have adequate thickness to carry out the service
- The joints in the concrete, both longitudinal and transverse must transfer the load coming over it smoothly. This must not have any undesirable effect on the smoothness of the surface
- Adequate over must be provided so that extreme exposure conditions are resisted. This can help in the reduction of crack formation.
- The thickness employed for resurfacing and the steel spacing will decide the aggregate size that has to be employed in the area.
- Based on the conditions of temperature, loads and sound problems appropriate and durable aggregates have to be employed.
- The shoulder material infiltration must be reduced by employing concrete shoulders.
Need For Resurfacing
There are two reasons for employing resurfacing of concrete. They are:
- Functional Deficiency
- Structural Deficiency
Many old concrete surface or pavements will have both the deficiencies. The AASHTO design guide does not specifically provide any guidelines for both the deficiency.
Material used in the Resurfacing of Plain Cement Concrete (PCC)
Based on the deficiency and the need, different materials are employed in different regions.
- Materials used in the interface
- Materials used in the resurfacing layer
- Materials used to cure the resurfacing layer
- Materials used to seal the joints and cracks formed in the resurfacing layer
Materials Used in the Interface - Interface Materials
The interface materials can be used in order to:
- Enhance the bond between the underlying pavement and the resurfacing: This will ensure both the units to behave monolithically under load and during its performance
- Separate the overlay and the old pavement: Here there very small bond or no bond between the elements. These perform independently.
Based on the above category, we have
Bonded Resurfacing: The material used to have bonded interface is PCC slurry or grout. A mixture of portland cement and water will give the material. This will have a water cement ratio, not more that 0.62.
Unbonded Resurfacing: Areas where the underlying pavement is not in a situation to contribute its side to behave monolithically, a unbonded resurfacing is provided. This is because a bond between both the elements will result in reflective cracking and other distress which is due to the underlying weak pavement layer. The most commonly used material is polyethylene, liquid asphalts, and different types of asphalt -aggregate mixtures.
Special Concretes Used For Resurfacing
In order to get high durability, strength, and performance, special concretes are employed for resurfacing. Commonly used ones are:
- Fiber- Reinforced Concrete
- Modified Concretes