Waterproofing and Repairing of Sinking Column for 90 Circular Road


Repairing of sinking column leading with water damage to various walls and columns for 90 Circular Road. Project was conducted in a joint exercise between the tenant, owner, BCA and structural PE to strengthen the crack lines and repair water damage.

Many areas such as South Bridge road , Chinatown and Neil road are built on marine clay as bedrock. There is high water hydrostatic pressure leading to water seepage. Also, as the buildings are heritage and considered to to be pre-war era, owners are required to abide by URA conservation guidelines.

Areas with water seepage damage were repaired using crystalline waterproofing cement with vapour permeability and ability to seal tiny pores on contact with water. We used mineral paint from PuHua Singapore. It is a natural paint with high water vapour permeability on walls. This is different from synthetic paint which is less efficient in allowing the walls to breathe.

For the cracked lines on the main column and other smaller columns. After opening up, we noted deep cracks going right into the depth of the column. With the guidance of a structural professional engineer, we embedded 16mm rebars with 6mm BRC mesh and anchored to the existing concrete with Hilti500. Then we apply non shrink cement, patched up and painted over with PuHua mineral paint for added water vapour permeability.

Before Improvement Work

During and After Improvement Works