Construction World January 2021

ROADS & BRIDGES

ROADS INFRASTRUCTURE FOR THE ICONICMALL OF TEMBISA

The iconic double-level Mall of Tembisa, developed by McCormick Property Development, was completed in November. The Mall of Tembisa is located on greenfield land, south of the Olifantsfontein Road (R562), with the Kaalspruit creating the eastern boundary of the property, between the townships of Tembisa and Clayville.

T his 45 000 m² gross leasable area (GLA) regional shopping centre is situated in the under-serviced north-western quadrant of Tembisa in Ekurhuleni Metropolitan Municipality. The Mall is part of a mixed-use development project being undertaken in conjunction with KJA Developments (specialists in low-cost housing) and comprise commercial, retail and high-density residential components. Philip Booyens, Director of SCIP Engineering Group provides an insight into the development of the road infrastructure for the new mall. Booyens explains: “SCIP Engineering Group were appointed as the civil and structural engineers for the project. Specifically looking at the roads, we were responsible for all road, stormwater and the geometric designs”. Techworld Consulting Engineers, assisted with the configuration of the traffic circles and the intersection layout, in particular the design of the signals of the main intersection at Aluminium Drive. Pavement specialists Leo Consult assisted with undertaking a condition assessment of the existing Olifantsfontein Road surface. A ECI SprayPave manufactures bituminous binders, emulsions, primes and pre-coats for road construction. In response to an ongoing bitumen shortage in South Africa, the company acquired a multistage bitumen converter from Technix Industries in New Zealand in 2015, only the second to be commissioned worldwide. The technology enables AECI SprayPave to achieve predictable and repeatable conversion of penetration grade bitumen available from South African refineries to grades that are both lower in penetration and higher in softening point than the feedstock bitumen. “We are very excited to be able to add 10/20 bitumen, which is currently in short supply, to our offering,” says AECI SprayPave director Eddie Jansen van Vuuren. “The 10/20 bitumen product conforms to the penetration grade bitumen specification.” 10/20 bitumen is commonly used in the production of high modulus asphalt (EME), which is well suited to high trafficked roads likely to suffer significant fatigue and stress. Currently this grade of bitumen is only supplied by one South

Bulk earthworks commenced in April 2019, piling started in June 2019 and the main building contractor began with foundation excavations during July 2019. Due to the COVID-19 shutdown, road construction only started in May 2020. Road infrastructure Booyens discusses the road infrastructure requirements for the Mall of Thembisa. “The development comprises of two Gautrans provincial intersections for access from Olifantsfontein Road (R562, planned K27), consisting of the extension of Aluminium Drive as a full signalised intersection and new partial access. The 550 m lengthening of Aluminium Drive starts as a divided four-lane road narrowing to a two-lane road with 35 m diameter traffic circles. Furthermore, a 700 m two-lane ring road must be constructed to connect the new partial intersection with Aluminium Drive. Pedestrian movement will be accommodated by the construction of various paved sidewalks that link up with the new taxi and bus loading zones on Olifantsfontein

AECI SprayPave is now able to offer the asphalt industry scarce 10/20 penetration grade bitumen using unique technology that enables the production of specialist bitumen products. ANSWERS TOHIGHGRADE BITUMEN SHORTAGE

African refinery. Other local refineries have not been able to produce 10/20 bitumen due to higher demand for other “normal” grades and difficulty in meeting the required specifications. Unforeseen breakdowns and scheduled shutdowns at refineries add to the problem, Jonathan Bell, AECI SprayPave’s Cape Town technical manager, points out. The multistage bitumen converter uses pressure, heat and air to precisely convert bituminous refinery feedstocks into high grade bitumen. The softness, penetration index and physical properties of the bitumen can be changed to meet exact design specifications. The controlled processes in a bitumen converter make it possible to rearrange chemical structures to create asphaltenes. The gentle process and highly efficient addition of air and therefore oxygen (air rectification), preserve the highly polar aromatic/resin fraction and minimise coke build-up. In addition to the 10/20 product, the current bitumen line-up offered by AECI SprayPave includes 70/100, 50/70 and 35/50. “The converter has enabled us to deliver SABS certified 50/70

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