The Constructor STEPS FOR CONCRETE DAMAGE REPAIRS IN STRUCTURES

Repair of concrete is needed time to time as the structure gets old due to several reasons. We will discuss the steps involved in the process of repair of concrete structures.

Following are the steps involved in the repair of damaged concrete:

1. Determination of cause of Concrete defects:

The first and important step for repairing a damaged concrete structure is to identify the causes responsible for the damage. Because, if the cause of the damage to concrete structure is not identified or misidentified, then the same damage can repeat even if the repairing work have been done. Based on the causes of concrete damage, the nature of the cause can be identified. If the cause of damage is repetitive in nature then the structural repair will have to consider the effect of the cause, but if the cause is one time event, then that can be neglected.

2. Evaluation of extent of concrete damage:

Evaluation of the extent of damage to concrete helps to understand severity of damage and its effect on the life and serviceability of the structure. This activity includes prediction of how quickly the damage is occurring and what progression of the damage is likely. Knowing the extent of the damage to concrete, decision can be made weather the damage can be repaired or the structural members have to be replaced. It also helps to take precautionary measures to stop the damage in future for the known cause of the damage. The main difference in severity lies in the fact that proper maintenance can reduce or eliminate damage caused to the structural members.

The most common technique used to determine the extent of damage is sounding the damaged and surrounding undamaged concrete with a hammer. If performed by experienced personnel, this simple technique, when combined with a close visual inspection, will provide the needed information in many instances of concrete damage. In sounding suspected delaminated or disbonded concrete, it should be remembered that deep delaminations or delaminations that contain only minute separation may not always sound drummy or hollow. The presence of such delaminations can be detected by placing a hand close to the location of hammer blows or by closely observing sand particles on the surface close to the hammer blows. If the hand feels vibration in the concrete, or if the sand particles are seen to bounce however slightly due to the hammer blows, the concrete is delaminated.

Strength of concrete can also be determined while evaluation of the extend of damage by hammer blows. High strength of concrete gives distinct ring from a hammer blow and hammer rebounds smartly. Low strength of concrete rebounds with dull thud and little rebound of the hammer.

Non- destructive testing of concrete can also be done to evaluate the extent of damage of concrete structures and also to get its strength. More details about NDT Tests on concrete.

3. Evaluate the Need for Concrete Repair:

Repair of concrete structural members required cost and time. So, it should be evaluated whether the structure needs the repair or can serve its intended purpose. Not all damaged concrete requires immediate repair. Repairs should be carried out immediately on concrete if the damage affects the safety and serviceability of structure. Also, if the damage has reached to the stage or progressing at a rate that soon the structure will become unserviceable, then repair should be carried out. Most concrete damage, however, progresses slowly, and several options are usually available if the deterioration is detected early. With early detection, it may be possible to arrest the rate of deterioration using maintenance procedures. Even if repair is required, early detection of damage will allow orderly budgeting of funds to pay the costs of repair.

4. Select the Concrete Repair Method:

There is a tendency to attempt selection of repair methods/materials too early in the repair process. This should be guarded against. With insufficient information, it is very difficult to make proper, economical, and successful selections. Once the above three steps of the repair process have been completed, or upon completion of a detailed condition survey, the selection of proper repair methods and materials usually becomes very easy. These steps define the types of conditions the repair must resist, the available repair construction time period, and when repairs must be accomplished. This information, in combination with data on the volume and area of concrete to be repaired, will usually determine which standard repair materials should be used. Also, this information will determine when the standard repair materials cannot be expected to perform well and when nonstandard materials should be considered.

5. Prepare the Old Concrete for Repair:

Preparation of the old concrete for application of the repair material is of primary importance in the accomplishment of durable repairs. The very best of repair materials will give unsatisfactory performance if applied to weakened or deteriorated old concrete. The repair material must able to bond to sound concrete. It is essential that all of the unsound or deteriorated concrete be removed before new repair materials are applied. Saw cutting of perimeter, removal of concrete, preparation of reinforcement, maintenance of prepared damaged area should be carried out before application of concrete repair.

6. Apply the Suitable Repair Method:

There are many different standard concrete repair methods and materials available based on type of damage. More details about these will be discussed in future post. Suitable methods and materials should be used based on types of concrete damage.

7. Cure the Concrete Repair Properly:

Concrete damage when applied with repair materials, it requires proper curing to gain the required strength and durability. Curing is usually the final step of the repair process, followed only by cleanup and demobilization. It should be noted that if the proper curing has not been done to the concrete repair works, then the concrete will not gain required strength and all the cost and time invested to the repair work goes waste. So, special attention is required for the curing the concrete repair.