Construction World April 2015

PENALTIES FOR POOR CURING The South African building and civil engineering industries have for years not employed correct or adequate methods of curing concrete – sacrificing strength, permeability and durability in the process, says Bryan Perrie, managing director of The Concrete Institute.

concrete in various environments; • Project specifications do not clearly state the specific curing action required for concrete on a given project; • The cost of curing is not billed separately in most tender documents; • Insufficient support at all personnel levels for training and education, such as offered by The Concrete Institute’s School of Concrete Technology, exacerbates the situation. “This training is vital for all employees involved in the design, construction, and management of concrete projects,” Perrie stresses; • The misconception that cube • The increasing emphasis on ‘fast track’ construction methods in which concrete is enclosed in shutters for very short periods of time, followed by exposure to drying conditions. Perrie says the need to develop a more“respon- sible” approach to concrete curing cannot be over-emphasised. “A pro-active approach is essential to address the present lack of educa- tion and control of concrete curing, particu- larly in the South African environment with its excessive heat, dry climates, considerable compressive strength sufficiently indicates the durability of concrete in a structure; and

Perrie says the fact that curing is important is well-known in the construction sector, yet current curing

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Incorrect curing methods still prevail in the South African construction industry, says The Concrete Institute. wind speeds, all of which lead to a rapid loss of moisture from freshly cast concrete, often resulting in plastic cracking on the exposed concrete surfaces.” He also believes that curing should be listed as separate cost in the Bill of Quantities or be listed as a fixed, prime cost in the tender docu- ments, with penalties imposed for inadequate curing. “It is also necessary for national Codes of Practice and specifications to provide more details and guidance on concrete curing,” Perrie adds.

practice still remains generally inadequate. “Perhaps the time has come to consider intro- ducing penalties for incorrect curing to change the apathy that prevails in the building and civil engineering sectors,” he suggests. “Correct curing means maintenance of adequatemoisture and temperature conditions to encourage cement hydration. This is of fundamental importance in the development of the physical properties of concrete necessary to ensure its performance in service. Proper- ties such as strength and durability, as well as permeability, depend on the extent and quality of curing of concrete during the first few days after casting. Curing, in fact, is the final – and vital – step in the production of good quality concrete,” Perrie states. He says some of the major factors that contribute to the poor state of curing in South Africa, include: • National specifications and codes of practice contain only vague stipulations regarding the curing methods required for the different applications of Ottermann believes this project has been resoundingly successful and has saved PPC a lot of money. “Load shifting is an important part of reducing the likelihood of load shedding and, although each single contribution seems as if it is just a drop in the ocean, everyone needs to do their part. I encourage everyone to participate and shift as much load as possible,” implores Ottermann. “By doing so, it is only going to make us all more resilient once we come out of this crisis. If this power crisis is going to last five years, then we all need to do as much as we possibly can to become as efficient as we can. This will help reduce the occurrences of load shedding tremendously because Eskom’s systems are under immense strain in peak times. By cutting our peak time use, we can allow that electricity to be distributed elsewhere.” Being well versed in matters of energy consumption around the world, Egmont firmly believes that industry in South Africa is actually on the leading edge of the energy fight – more out of necessity than anything else.

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CONSTRUCTION WORLD APRIL 2015