Analysis of the Causes of  Poor Bond between Mortar and Brick

1. Low-strength grade mortar, such as cement mortar, due to poor cement mortar workability, it is difficult to squeeze the mortar during masonry. After the operator scrapes the mortar with a shovel or tile cutter, the bottom ash will generate cavities and the mortar will not be full.

2. Use dry bricks to make the wall dehydrate early and reduce the strength of the mortar, and the adhesion with the bricks is reduced, while the dust on the surface of the dry bricks acts as a barrier, which weakens the adhesion between the bricks and the mortar layer.

3.The masonry method is used for masonry. Sometimes the masonry speed cannot keep up because the masonry is too long. The water in the mortar is absorbed by the bottom brick, so that the brick layer on the masonry and the mortar lose their adhesion.

4.In order to eliminate the seam scraping process when laying clean water walls, a large shrinkage ashing method was adopted to make the shrinkage depth of the masonry bricks more than 20mm, which reduced the fullness of the mortar and increased the jointing workload.

Preventive measures

1.Improving the workability of the mortar is the key to ensuring the fullness of the mortar joint mortar and improving the bond strength. The choice of mortar raw materials is important. Sand cement should be within the shelf life, thickener cellulose ether and redispersible powder to improve the adhesion of mortar should be selected from regular enterprises.

2.Improve masonry methods. It is not advisable to adopt the method of laying bricks or laying bricks, and the "three-one bricklaying method" should be promoted, that is, using a large shovel, a brick, a shovel, and a squeeze method.

3.When using the grouting method, the length of the grouting must be controlled. In general, the temperature should not exceed 750mm, and when the temperature exceeds 30 ° C during construction, it should not exceed 500mm.

4.Never use it on brick walls. The bricks should be wet 1 to 2 days before masonry, so that the moisture content of sintered ordinary bricks and porous bricks can reach 10% to 15% during masonry; the moisture content of lime sand bricks and fly ash bricks can reach 8% to 12%.

5.During winter construction, the brick surface should also be properly wet under positive temperature conditions before laying. When it is impossible to pour bricks under negative temperature, the consistency of mortar should be appropriately increased. For the 9-degree earthquake-proof fortification area, masonry cannot be carried out when bricks cannot be burned in the severe winter.

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