on their strengthening surface was removed using sandblaster and washed with high pressure water.
The bonding sides of the concrete blocks are then sandblasted with a hand grinder to provide appropriate rough surfaces for bonding, and any debris, grease, laitance
, and loose material at the surface are cleaned with acetone using a cotton cloth.
Surface preparation for all types of cementitious surfaces is covered under this standard, which should be free of surface contaminants including laitance
, loose concrete and dust.
The surface was cleaned by using air pressure to avoid any dust on the surface, as the substrates must be sound, dry, clean and free from laitance
, ice, standing water, grease, oils, old surface treatments or coatings and all loosely adhering particles.
Concrete may be covered with dirt, membrane-curing compounds (waxes, oils, or acrylic polymers), moisture, or laitance
(a fine, loose, dusty layer).
For bonding the FRP sheets, the weak laitance
were removed by wire brushing and the dusts were cleaned properly.
Shook: Permacast cement liners are structural by themselves and they adhere well to existing masonry and concrete substrates after pressure washing to remove laitance
For the uniaxial tensile testing, each cement concrete cylinder fabricated (100 mm tall and [empty set] 100 mm) was subjected to treatment with a primer after removing laitance
on top of the cylinder specimen.
Second, the weak layer of fine cement particles found at the surface of concrete, called "laitance
," must be removed to expose sound substrate.
It was also found that satisfactory adhesion strength could be obtained by removing laitance
on the concrete surface and controlling the water content of the surface.
After maintaining for more than 28 d, the laitance
was cut off, and the ends of the mortar were polished.