Quality control and quality assurance in concrete repair works are essential to regain lost strength in concrete due to cracks or other damages. Concrete repairs are required when structural members get damaged.
The reason for damages can be over-stressing, poor construction practices, environmental exposures, chemical attacks or the age of concrete member etc.
Quality assurance is a method for the proper monitoring and evaluation of different aspects of repair work to make sure that standards of quality are met. Quality control is inspection and tests set to confirm that the materials used and repair technique meet project specification.
The concrete repair involves replacing, restoring or renewing of old or damaged concrete from existing structural member. The need for repair can vary from time to time depending on structural requirement or type of damages in the structural member.
Quality Control and Quality Assurance of Concrete Repair
Concrete Repair Procedure
Concrete repair involves several steps which are presented below. It is highly crucial to consider quality control and quality assurance in each step in order to achieve successful concrete repair.
- Determining the cause of damage
- Evaluation of damage to identify need and method of concrete repair
- Preparation of damaged structural member
- Application of repair method selected
- Curing of repaired concrete member.
As listed above, the damages in concrete structures need to be carefully evaluated and repaired, each step involved need to be carefully performed.
Inadequate workmanship, procedures or materials in concrete repairs may result in poor repair and may fail during occupancy involving significant cost.
Proper attention to and implementation of each step in the repair process is critical to successful application of repair technique.
Materials for Concrete Repairs
The first step is ensuring that the contractor is using approved materials. The selection of repair materials for concrete should be of high quality and as per the specifications requirements as per the need and type of repair method selected.
Testing of repair materials should be done to ensure its quality and suitability for the given repair method. Any materials procured from vendors should have its manufacturers test certificate and should be used only as per manufacturer's specifications and approved methods.
Suitability of materials for type of damage should be ensured as this may lead to high cost and failure of repair, if the materials used are unsuitable. Care should be taken during mixing, proportioning, handling and placement of repair materials to ensure good concrete repair quality control.
Workmanship in Concrete Repairs
Quality and durability of concrete repairs depend on the workmanship during repair process. The aim of repair is to provide strength and durability of structural member comparable to its original or designed strength.
For this, the workmen involved in repair process should have sufficient knowledge, skills and training to perform the concrete repair work. Work carried out should be done in a way that the repaired concrete is well bonded with existing concrete and durability requirement is met.
All the process should be carefully supervised by experienced personnel. Well trained, competent workmen are particularly essential when epoxy, polyurethane, or other resinous materials are used in repair of concrete.
Concrete Repair Procedures
Selection of right procedures for concrete repair is essential to ensure repair quality control and techniques are carefully performed. Wrong or poor repair procedure and workmanship may lead to ineffective concrete repairs.
Repairs can be on old concrete surface or new concrete just after stripping of formwork. For new concrete surface, the repairs are easy and bond between repair concrete existing concrete surfaces will be same as the original construction work.
One of the common problems that leads to premature failure of repairs is improper curing, especially cementitious materials which cause early cracking.
Recommended curing method is to leave the forms in place when using form-and-pour applications, ponding for small repairs, continuous moist curing, and curing membranes.