Case 1
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Cause of Defects
The nonalignment of construction joints could form gaps between panels, permitting water penetration. Inadequate provision to accommodate anticipated differential movements could lead to cracking
and, in turn, water seepage through these crack lines.
Basement water seepage – courtesy of DryProof
Waterstops and drainage details are common devices in controlling water seepage through construction joints in basements. Proper installation of waterproofing details at these joints to achieve optimum watertightness could be achieved by the following:
(a) Internal waterstops can be secured by using wires to hold them in place.
(b) External waterstops are tied to the formwork of concrete works.
(c) Flanges of waterstops should be tied to the reinforcement steel at an interval of 300 mm along the flanges.
(d) Bulb of the waterstop should be placed directly onto the midpoint of the joint for efficient expansion actions.
(e) Individual sections must be properly jointed by special junction pieces.
- The porosity of concrete, coupled with crack lines, allows the ingress of water, and, when re-surfaced, may result in the formation of efflorescence (deposit of salt) and/or calthemite (deposit of calcium carbonate).
- This is exacerbated by the formation of cracks due to the weak tensile strength of concrete against stresses resulting from shrinkage, differential settlements, etc.
