CEMENT & CONCRETE Variety of finishes There are also unlimited possibilities for finishes, which can be designed in a range of attractive colours and a multitude of textures. The finishes are incorporated into the concrete during the construction stage, rather than applied later as a separate operation. The use of concrete as the ultimate finish means no other finishing activities – such as painting, tiling or coating – are required, saving energy and materials at the construction stage, with lower future maintenance costs. Additionally, concrete finishes do not emit any toxic or volatile products into the environment and have no detrimental effects on the community during their entire lifespan.
Life-cycle cost Due to its durability, various analyses show that the whole-life cost of many projects is lower when concrete is used as the major construction material. Then, at the end of the usage phase, concrete can easily be recycled and crushed to produce building aggregate. South Africa has not yet fully exploited the recyclability of concrete.
Countering moisture loss and shrinkage 1 P roFilm 19 will prevent concrete cracking in hot and windy conditions 2 R apid evaporation of surface moisture from concrete can cause map cracking and plastic shrinkage 3 T he film formed by ProFilm 19 is active while the concrete remains plastic
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Structural integrity The structural design and construction of concrete elements in buildings (including in situ reinforced concrete, precast concrete, tilt-up, hybrid construction and post-tensioned concrete elements) has been fully appreciated and acknowledged by architects, structural engineers and contractors for many years. Well-constructed concrete can last well over a century. For example, the Pantheon in Rome, built around AD 126, is still in use and has a coffered dome that – almost 1 900 years after it was built – remains the world’s largest unreinforced concrete dome.
Conclusion Concrete offers many other benefits, including – to name just a few – sound insulation, fire resistance, light reflectance, and more durable roads that require far lower maintenance and fewer pothole repairs. Concrete structures are also beautiful and enhance the aesthetic appeal of any town or city. In fact, this age-old material is the cornerstone for providing the infrastructure that can lead South Africa to a sustainable future. The Auditorio de Tenerife in the Canary Islands, designed by renowned Spanish architect Santiago Calatrava, spectacularly shows the creative scope concrete offers the designer
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ne of the dangers of working in low-humidity conditions – even inside heated buildings during cold weather – is the rapid evaporation of surface moisture from the concrete. This can cause map cracking and plastic shrinkage, where cracks can penetrate to the full depth of a concrete slab. According to the American Concrete Institute (ACI), plastic shrinkage cracking is likely to occur whenever the evaporation rate is more than 1 kg/m2/hour. The ACI highlights that this rate of evaporation can be readily caused by many combinations of air temperature, relative humidity, concrete temperature and wind velocity. As an evaporation reducer, Chryso ProFilm 19 prevents this cracking by protecting fresh concrete from the effects of excessive moisture loss in rapid drying conditions. Furthermore, it can achieve this result without increasing the bleed.
Mono-molecular film By spraying this evaporation-reducing product on to fresh concrete surfaces, the user creates a continuous mono-molecular film, which inhibits the rapid loss of bleed water. This film lasts for as long as the concrete remains plastic, even where floating and trowelling operations must be conducted to create the required surface finish. The effectiveness of the mono-molecular film means there is no need for water spraying on the surface of the concrete in order to slow the evaporation process. It can be used on a range of horizontal concrete pours where the evaporation rate may exceed the bleeding rate of concrete. These applications include industrial floors, roads, bridge decks, slabs, patios, driveways and sidewalks.
IMIESA March 2021
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