Construction World June 2022

vibrator control systems and a longitudinal levell ing beam behind the finishing machine or so-called “supersmoother”; • Properly installed guide wires for controll ing the machine or the use of modern wireless guidance; and • New types of evenness measurement set up immediately behind the paver to allow correct construction. “It should be remembered that an important property of concrete pavements is that the longitudinal evenness obtained after construction is retained for many years. “There is no doubt that concrete pavements are the logical and sustainable solution for South Africa. One only has to look at the thousands of potholes on our road networks at the moment to see how concrete could have prevented such a costly and dangerous situation. Concrete pavements are the natural choice for projects where performance, value, longevity, social responsibil ity and concern for the environment are paramount,” Perrie adds. 

susceptible to cracking, curl ing and faulting; • Narrow sealed construction joints to overcome the problems previously encountered with joint performance; and • Dowels in the transverse joints and cement-bound bases to ensure excellent load transfer and the prevention of faulting at the joints. “Continuously reinforced concrete pavements – which have no transverse joints – are often chosen for freeways and primary roads. The shrinkage of the concrete is absorbed by a pattern of fine microcracks that has no impact whatsoever on the pavements’ evenness or ride comfort.” Furthermore, smooth concrete pavements can now be built thanks to: • Optimised concrete mixes offering constant workabil ity and prepared in modern computer controlled batching and mixing plants often establ ished on site; • New generations of sl ipform pavers equipped with automatic

reduce the curing time to just three days and, in certain cases, to only 24 hours. This technique is used in several countries on busy traffic routes and has been used on a number of projects in South Africa as well .” When it comes to riding comfort, Perrie bel ieves that the situation is now totally different to early concrete pavements which did not offer top qual ity riding comfort because of the length of slabs and width of joints and faulting at the joints, or damage to supporting erosion-prone layers. He says for over 40 years now these problems have been dealt with by using designs that implement new and superior measures in jointed pavements such as: • Shorter slabs with 4,5 m

“It should be remembered that an important property of concrete pavements is that the longitudinal evenness obtained after construction is retained for many years.”

maximum length to make concrete pavements less

35 CONSTRUCTION WORLD JUNE 2022