Construction World June 2019

PRECAST CONCRETE PRODUCTS

Helping PCMs keep pace, REDUCE ENERGY THIS WINTER The winter months hold a number of challenges for precast concrete manufacturers (PCMs). Using the appropriate

admixtures can assist with maintaining the rate of production, while holding down energy costs.

CHRYSO ® Alpha Block S550 prioritises strength and is used in precast products such as lintels.

“M aintaining mould turnaround times and associated productivity achieved during the summer can be difficult for PCMs in winter, as the lower ambient temperatures will slow down cement hydration,” says Hannes Engelbrecht, general manager for inland sales and marketing at CHRYSO Southern Africa. “However, raising these temperatures sufficiently can push up energy costs dramatically – a factor which is now further complicated by more frequent load shedding across the country.” Engelbrecht emphasises that early strength development is vital for PCM operations, as this determines how soon a product can be stripped from its mould, freeing up the mould for the next production cycle. While steam can be an economical accelerator and is widely used by the larger producers of heavy precast items such as pipes and culverts, many producers do not have access to this method of heating. “Our CHRYSO ® range of admixtures for dry cast concrete offers an economical solution for precast products from blocks, paving stones and roof tiles to kerbs, pipes and hollow core slabs,” he says. “With all our admixture solutions engineered through an innovative, hi-tech approach, our new products use latest generation molecules for unprecedented performance.” Engelbrecht also highlights that winter can heighten the challenge of efflorescence in precast products and this is an industry issue that affects especially those producers in the brick, block and paving segment. While minor efflorescence occurs all year round – depending on factors like humidity and the type of cement used – it can be aggravated by drops in temperature. A popular solution for paving is using CHRYSO ® Alpha Color 100, which is an efflorescence inhibitor, has proven to be an economical product with a low dosage rate. A new product has recently been launched which is focused on the reduction of efflorescence in both roof tiles and paving. The CHRYSO ® Alpha Block range includes compaction agents that improve hydration and placement of the concrete. While CHRYSO ® Alpha Block S600 delivers best on cost and compaction, CHRYSO ® Alpha Block S550 prioritises compressive strength and appearance

CHRYSO ® admixtures ensure early strength in precast products such as kerbs.

and CHRYSO ® Alpha Block S515 is suited to difficult materials. Working alongside these products is the CHRYSO ® Dem WB mould release product for the protection of wooden pallets. For paving stones, CHRYSO ® offers dual-purpose products which enhance compaction while at the same time are water repellent. Combined with specific solutions for mould release, acceleration and aesthetics, the range improves quality and reliability of paving stones. There is less risk of efflorescence, a lower reject rate, higher colour intensity and improved abrasion resistance. Kerb applications benefit from the CHRYSO ® Alpha K range of compaction agents, which deliver better swipe and surface finish, as well as higher compressive strength. In this application, CHRYSO ® Alpha Colour 600, the high-performance efflorescence reducer, will enhance colour and resist water penetration. Specifically pioneered for the manufacture of pipes and elements such as hollow core slabs, the CHRYSO ® Alpha T range gives the product greater element strength and surface finish. It also reduces the risk of both cracking and efflorescence. The range includes synthetic macro and micro fibres which are used to either fully or partially replace the steel mesh reinforcement used to reduce shrinkage cracking. CHRYSO ® admixture products for roof tiles help customers optimise raw material costs, while improving the curing cycle time by ensuring early strengths, fewer breakages and less efflorescence. Another CHRYSO ® roof tile solution is the unique delayed mould

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CONSTRUCTION WORLD JUNE 2019