Construction World April 2017

Debonding of plaster is often noticed as a hollow sound when the surface is tapped. Pictured: debonding from an off-shutter concrete surface.

Plaster popping as a result of expansion of ash bricks.

While grinning may be unsightly, it is unlikely to lead to further cracking. The choice is to live with it, or to remove and replace the plaster. Application of an undercoat or a spatterdash coat before plastering will help to avoid grinning. Expansion This includes swelling, softening, layer cracking and spalling of the plaster. It is usually caused by the inclusion of

proprietary gypsum-based products in the mix. Under moist conditions, the sulphate from the gypsum reacts with the portland cement paste and forms compounds of increased volume which disrupt the plaster. The only remedy for expansion-induced disruption due to gypsum in the mix is to remove and replace the plaster. Popping Popouts are conical fragments that break

to qualify their foremen and artisans in LSFB, in preparation for a building project comprising five three-storey blocks of flats and offices. The students of Regional Works Unit KwaZulu-Natal – under the command of Capt S. Mashigo – who enrolled for the course included, amongst others, plumbers, electricians, and project managers. Col E Jacobs coordinated arrangements for the course from the SANDF’s side, while the SASFA members who supplied support for the course and made it possible were Saint-Gobain, Martin and Associates, and Simpson Strong-tie. Bosch Tools illustrated its wide range of equipment suitable for use in the LSFB industry. out of the surface of the plaster leaving holes that vary in size. These are caused by the presence of contaminant particles in the mix which, reacting with the moisture in the mix, expand and cause cavities in the plaster. Contaminants are usually seeds, other organic material, or particles of dead burnt lime. Once the cause of the popout has been removed, the hole can be filled with a proprietary filler and painted over. 

SASFA director John Barnard says that the successful training programmes undertaken by SASFA have been key in the promotion and growth of light steel frame building (LSFB) in Southern Africa. “Education is the foundation for getting the advantages of a new method understood as well as for protecting and enhancing quality of building through the growth phases and beyond,” says Barnard. The latest to come on board is the SANDF to whom, on their request, SASFA presented a 5-day training course for LSFB contractors at the Old Fort Rd Military Base in Durban. The intention of the course was BABCOCK 1/2

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CONSTRUCTION WORLD APRIL 2017