This method is used to repair holes whose depth is at least approximately equal to the surface dimension, i.e. for narrow slots cut to repair any holes and cracks. This method is not used for shallow pits; To fill patches where reinforcement is exposed or holes that protrude through and through a wall or beam.
Dry pack method of concrete surface repair
- The hole should be thoroughly cleaned and free of broken pieces of aggregate, washed and dried before actual operation.
- A thin layer of cement grout is applied to the surface. The mixture for bonding grout is a mixture of cement and fine sand in a 1:1 ratio and has a thick cream-like consistency.
- Next, the dry pack material is poured over before the bonding grout dries. The packing material consists of a mixture of 1 part cement and 2 parts sand by volume or weight.
- The water requirement for mixing is such that a mortar is produced which, when used, will clump together when molded into a ball, and will not expel water but leave hands moist. If less water is added to it then it will not make a sound solid pack. If more water is added then excessive shrinkage occurs and the material becomes loose.
- The dry pack material should not be filled in one go, but should be filled in layers and compacted appropriately with a compacted thickness of about 1 cm.
- Each layer is finished by scraping so that the bond for the next layer is secured and compacted over its entire surface using a hardwood stick and hammer. The size of such a stick is about 20 to 30 cm long and does not exceed 2.5 cm in diameter. Wood sticks will not polish the surface of each layer and thus a better bonding surface is formed. The last layer is finished to match the surroundings.
- For better results and when water tightness is necessary, the holes on the sides of the surface should be sharp and square, but the inner corners of the holes should be rounded. The hole for the dry pack should have a depth of at least 2.5 cm.