Search

What are the reasons of occurrence of dusting and scaling of concrete surface?

Dusting refers to the formation of loose powder arising from the disintegration of concrete surface. For dusty concrete surface, they can be easily scratched by nails. The cause of dusting can be related to finishing works carried out before completion of concrete bleeding. The working back of bleeding water to concrete surface produces a low strength layer with high water cement ratio. It may also arise owing to inadequate curing and inadequate protection of freshly placed concrete against rain, wind and snow.

Continue Reading »

What is the significance of isolation joints?

Isolation joints isolate slabs or concrete structure from other parts of structure. The presence of isolation joints allows independent vertical or horizontal movement between adjoining parts of the structure.

Continue Reading »

What is the difference between plastic shrinkage cracks and crazing cracks?

Plastic shrinkage cracks are caused by a rapid loss of water from concrete surface before setting of concrete such that the rate of evaporation of surface water is higher than the rate of replacement of upward rising water. Tensile force is developed at concrete surface which forms plastic shrinkage cracks when the concrete starts to stiffen. Plastic shrinkage cracks appear to be parallel to each other with spacing of about 300mm to 1m. The cracks are shallow and generally do not intersect the perimeter of concrete slab.

Continue Reading »

What is the difference between curing compound and sealing compound?

Curing compound is primarily used for reducing the loss of moisture from freshly-placed concrete and it is applied once after concrete finishing is completed.

Continue Reading »

Is curing compound suitable for all concrete?

For concrete structures with low water-cement ratio (i.e. less than 0.4), it may not be suitable to use curing compound for curing. When hydration takes place, the relative humidity of interior concrete drops which leads to self-desiccation and drying-out.

Continue Reading »