Construction World July 2018

PRODUCTS & SERVICES

Perrie says the development of high-tech computer modelling systems – coupled with advances in concrete technology and waterproofing – have elevated roof design and construction far beyond previous limitations. “In cities, if designed accordingly at the inception phase, flat concrete roofs can allow for additional storeys to be added to structures as the need arises, or as funds become available. This increased densification can optimise the use of well-located urban land and existing services. “There is also increased pressure to provide ‘green spaces’ in CBDs where space is at a premium. In this regard, a flat concrete roof presents an innovative opportunity to offset the carbon footprint of a building by re-introducing potentially lost green space at roof level in the form of a roof garden. At the same time, thermal insulation will also be improved significantly inside the building. “Latest innovations in waterproofing systems and products, coupled with increased public awareness of their environmental benefits, have resulted in roof gardens gaining in popularity and evolving into a variety of permutations. The functional practicality of water-wise gardens – even food gardens – on concrete roofs provides additional socio-economic benefits in the affordable housing market.” Perrie says for housing in both urban and rural locations, there has been a rapid growth in the specification and application of concrete roof tiles. “There is a timeless aesthetic appeal in concrete roof tiles, and the installation process is relatively simple. It requires no additional finish, is labour-intensive, and has low maintenance requirements. The roof pitch enhances interior thermal comfort by encouraging the convectional flow of hot and cold air caused by natural ventilation. “Whether specifying in-situ or precast concrete for roofs, the material presents the means to create shelter that is at the same time both impressive and sustainable by harnessing concrete’s natural qualities of sculptural flexibility, durability, affordability and thermal mass in conjunction with best practices and quality construction techniques,” he adds.  Concrete is increasingly becoming the roof covering material of choice for a wide variety of practical reasons, says Bryan Perrie, Managing Director of The Concrete Institute (TCI). Concrete roofs for rural and urban environments

The advantages of precast concrete wingwall units

Precast wingwall units offer the client a faster installation time, reduced material usage and no site-mix concrete or reinforcing on site resulting in project cost efficiencies. The natural flow path of water upstream of a construction is wider than the culvert or pipe structure. Therefore, transition sections are required to receive and direct the flow of this upstream water through the culvert/pipe, this is also true of the downstream end of the culvert/pipe where the flow of water is to be returned to the natural width of the stream. Where water velocities reach up to 4 m/s and above, the precast concrete wingwall unit is the most effective structure to use for the effective transfer of this water. In stormwater applications the primary focus is to direct water into a flow path that results in the least amount of turbulence which optimises the hydraulic capacity of the conduit. The wingwall portion directs the water, whilst the wingwall, floor slab and toe provides protection for the embankment and surrounds against scouring and possible collapse. Rocla’s precast concrete wingwall units offer: • Fast and easy installation • Reduction in quantity of materials required • No waste and no clean up required • No formwork • Making remotely located sites simpler to manage • Concrete strength is guaranteed • Quantity and positioning of designed reinforcing is guaranteed • No curing of concrete or formwork stripping required – saving time • Units capable of fitting a wide range of pipe diameters and culvert sections • Lifting anchors cast into the structure “We believe that the time and cost savings associated with the utilisation of precast concrete wingwall units can be enormous for infrastructure-related projects. The full range of wingwalls can be manufactured at all Rocla factories nationwide, optimising transportation costs. Rocla is well known for its manufacturing capabilities and quality standards in addition to its technical team available to assist with technical support required by the customer,” said Justin Kretzmar, Rocla’s Sales Engineer. Rocla has been supplying precast concrete products to most of the major infrastructure projects in South Africa, Mozambique, Namibia and Botswana. Rocla’s entire product offering is manufactured to the ISO 9001:2008 standard at various plants throughout South Africa, Namibia and Botswana.  Precast concrete products offer many known advantages and Rocla’s precast concrete wingwall units are no exception. Wingwall units are used at both the inlet and outlet of a pipe system in both culvert and stormwater applications.

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CONSTRUCTION WORLD JULY 2018