2.12 : 石積み壁のモルタル目地の劣化

A masonry wall, when exposed to rainwater, often collects water in the mortar-filled joints of the wall.

The water collected in the joints, when subjected to repeated expansion upon freezing and subsequent melting upon thawing, develops cracks in the mortar binding the masonry units.

Eventually, the mortar in the joints splits and flakes off, making the masonry units loose and creating pathways for water to penetrate the wall through the joints.

This is avoided by thoroughly filling the masonry joints with water-resistant mortar and tightly compacting it when the masonry is laid.

Masonry walls exposed to severe climatic conditions can experience considerable deterioration of the mortar joints.

In such conditions, repointing is done, which involves raking and cutting out the deteriorated mortar to a uniform depth.

This is followed by removing the debris in the joints and wetting the area to be repointed.

Finally, the joint is filled with fresh mortar, which is then finished using a joint tool, making it resistant to water penetration.