Case 2

Remedial (see also Remedial)

Removal of fungus

The leaking water source should be sealed. Suitable sealant or water-repellent can be applied to increase the water-tightness of the joints. Once the water source is sealed, remove fungus with a soft brush and bleach. Flush with clean water and allow to dry thoroughly. If necessary, repaint the surface with a suitable paint.

Remedial for water seepage

Use of water plug

Remove the defective paint from the affected area in order to expose cracks. First chisel a V-shape along the visible cracks. Pack the hydraulic plug into the groove. It will expand when it comes into contact with water and hence, seal off the leakage. The plug is strengthened with a layer of flexible cementitious waterproofing membrane.

Use of Water repellent

Apply the chemical on the slab that is above the beam. It will react with moisture and and seal up the cracks in the concrete. The passage of moisture will be sealed up. However this method is not feasible for large cracks.

Injection of capillary cemetitious compound

This method is useful if there is wet area directly above the defect. It requires minimal hacking and the chemical will penetrate deeply into the capillry pores of the concrete, sealing the pores and cracks by crystallization permanently. The active chemcials in the slurry react with the free lime and moisture in the substrate. It will seal up the water passage.

Spores need 3 things to grow into moulds:
(1) Nutrient – food for spores in an indoor environment is organic matter, often cellulose
(2) Moisture – moisture is required to begin the decaying process caused by the mould
(3) Time – mould growth begins between 24 hours and 10 days from the provision of the growing condition.