Matthew Deloney

What is Dry Pack Mortar?

Drypack mortar is a stiff sand-cement mortar that is typically used to repair small areas that are deeper than they are wide.

According to the Bureau of Reclamation's Guide to Concrete Repair, dry pack mortar contains (by dry volume or weight) one part cement, 2 1/2 parts sand, and enough water to produce a mortar that will just stick together while being molded into a ball with the hands.

The ball should neither slump when placed on a flat surface, nor crumble due to lack of moisture. Place dry pack mortar immediately after mixing it. Compact the mortar in the hole by striking a hardwood dowel or stick with a hammer. The sticks are usually about eight to 12 inches long and no more than one inch in diameter.

Use a wooden stick instead of a metal one because metal tends to polish the surface of the mortar, making bonding less certain and filling less uniform. Place and pack the mortar in layers to a compacted thickness of about 3/8 inch.

Direct the tamping at a slight angle toward the sides of the hole to ensure maximum compaction in these areas. Overfill the hole slightly, then place the flat side of a hardwood piece against the hole and strike it several times with a hammer. If necessary, a few light strokes with a rag may improve its appearance.

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Mixture Proportion

It is reported that one part of cement to four part of sand, preferably sharp clean sand, is adequate. However, mix proportions like one to two and half, and one to five or even six are reported.

With regard to quantity of water, it depends on the moisture content of used sand. if moisture of sand is low, greater quantity of water would be needed compare with case where moisture content is high.

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Applications of Dry Pack Mortar

1. Used to prepare ordinary thick mortar beds, as shown in Fig.4.


2. Employed to level concrete surfaces up to 51 mm thick


3. Used for floating shower bases, as illustrated in Fig.5.


4. It can be directly bonded or used as a detached floating mortar bed over a cleavage membrane or waterproofing membrane


5. Use in both residential and commercial applications in dry and wet areas


6. Dry pack mortar is used to fill deep holes in a concrete wall. As the dry pack mortar components are mixed, it should be placed in layers of 10mm and then compacted with hammer, stick, or hardwood dowel. It is recommended to employ metal stick to compact dry pack mortar rather than wooden stick. This is because metal stick yields better compaction and ensure greater bond. Additionally, it is advised to apply direct tamping at an angle to the sides of the hole to ensure good compaction at the sides of the hole.

Advantages of Dry Pack Mortar

1. Used for Interior and Exterior applications


2. Jobsite mixing of sand and cement is no longer needed


3. It can be tamped, compacted, and sloped easily


4. It guarantees a consistent mix on large jobs

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