Field Repair of Damaged Cement Linings

Cement lining will withstand normal handling; nevertheless, pipe or fittings may be found at times to have damaged linings which need to be repaired before placing in service. AWWA C104, EN545, and ISO 4179 provide that damaged lining may be repaired, and the following repair procedure is recommended:

1. Cut out the damaged lining to the metal. Square the edges.

2. Thoroughly wet the cut-out area and adjoining lining.

3. With the damaged area cleaned and the adjoining lining wet, spread the mortar (see recommended mix below) evenly over the area to be patched. After the lining has become firm and adheres well to the surface, finish it with a wet 80mm or 100mm paint brush or similar soft-bristle brush.

4. The repaired lining should be kept moist by placing a wet burlap over the required area of the pipe or fitting for at least 24 hours.

RECOMMENDED CEMENT MIX

Cement mix by volume: Three parts Portland Cement; Two parts clean sand; necessary water for slump of 125mm to 200mm. The sand should be free of clay and screened through a No. 20 Screen.

PRECAUTIONS

1. Mortar for lining should not be used after it has been mixed for more than one hour.

2. Too rapid a loss of moisture from fresh linings due to hot weather or high wind will prevent proper cure, resulting in the lining being soft and powdery. To prevent this loss of moisture, (a) do not line hot castings and (b) close the ends of the castings with wet burlap.

3. Fresh linings which become frozen will not be serviceable. Avoid lining in freezing weather.