How to repair concrete with Dry Pack Mortar Method
The purpose of dry pack mortar is to repair the concrete surfaces with cracks or holes of depth greater than or equal to the minimum dimension of the repair area. The holes usually discovered on concrete surfaces are cone bolt holes, she bolt holes, holes formed with ties etc.
Dry pack mortar should not be used for shallow cracks, fully extended holes i.e., from one side to other side, space behind reinforcement etc.
Dry pack method involves the following steps for executing repairing work to concrete.
1. Arrangement of Hole Inner Surface
2. Arrangement of Dry Pack Mortar
3. Using Dry Pack Mortar
4. Curing of Dry Pack Repair Area
1. Preparation of Hole Inner Surface
a. Prior to use dry pack mortar, the surface or hole to be repaired should be cleansed, washed and dried perfectly. Also they should not contain any damaged pieces of aggregates.
b. The inside surface of hole should have been rough to create superior bond. If the surface is smooth, it should be roughened with tapered reamer or star drill.
c. Usually, there exist three methods to develop the inside surface area of holes for maintaining superior bond with dry pack mortar.
Method – 1
a. Bonding grout is used to brush the inside surface of hole. Bonding grout is made of cement and fine sand in the proportion 1:1.
b. Now, the dry pack mortar is applied prior to bonding mortar becomes dry to make superior bond among mortar and surface.
c. When bonding grout is used, ensure that no free surface water exists in the hole so that the hole remains fully dry.
Method – 2
a. By applying wet rags or burlap, the hole is pre-soaked all night with and permitted to dry.
b. When the hole is partly dried or comprises of some amount of surface water, then spray dry cement on to the surface with small brush.
c. The cement will consume free water and develops a layer on the surface. Extra cement still in dry form is eliminated with jet of air so that dry pack can be applied on the surface.
Method – 3
a. Under this method, superior bond among dry pack mortar and surface is formed with epoxy bond resins
b. Epoxy resin is blended and used on the surface with brush.
c. Ensure that the concrete temperature should not exceed at the time of using epoxy or else it may burn or dry up the epoxy promptly.
d. As soon as epoxy is used, instantly use the dry pack mortar prior to epoxy gets dried out.
e. Epoxy bond resin can resist the hydration of water to adjacent concrete surface.
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