Civil Engineering September 2022 | Vol 30 No 8

4 September 2022 Civil Engineering On the cover R umdel Construction is tackling a 4.6 km stretch of highway from the Lynnfield Park to Ashburton interchanges as part of the South African National Roads Agency Limited (SANRAL) multi-billion-rand N3 upgrade between Pietermaritzburg and Durban. It is one of the largest contracts yet undertaken by Rumdel and demonstrates the company’s depth of expertise and experience. The result will be five lanes heading south to Durban and four lanes going north to Pietermaritzburg, as well as the revamp of two important bridges: Lynnfield and Mpushini. According to Rumdel site agent Andrew Robinson, site mobilisation began in January 2021 and the first ground was broken three months later in April. Currently in phase one of a three-phase contract, the project focus has been on the temporary widening of the southbound carriageway. “In the first phase of work, north- bound traffic is being accommodated on the wider southbound route. Once the traffic is able to travel contraflow, we will be able to rebuild the northbound road in its entirety – extending its carrying capacity,” says Robinson All traffic can then be rerouted onto this new highway while the southbound lanes – including the temporary works – receive the same overhaul treatment. HEAVY DUTY ROADS The design of the pavement layer itself marks an interesting departure from conventional road design. The continuous reinforced concrete pavement (CRCP) method is being applied, which will in- volve considerable quantities of readymix concrete from AfriSam. Robinson explains that the CRCP layer for the whole project will require 40 000 m 3 of 35 MPa concrete, or about 80% of all the readymix that AfriSam will supply. According to AfriSam regional sales man- ager Randall Chetty, AfriSam had already supplied some 4 000 m 3 by mid-2022 from its Umlaas Road readymix plant just 2 km from site. CRCP designs are known for their long-term performance and cost effective- ness, and are suitable when heavy traffic volumes amount to tens of millions of load repetitions over its service life. He notes that CRCP is also beneficial where ground conditions are poor, as is the case along parts of the contract route. LAYERS OF STRENGTH “The continuous concrete provides a 230 mm sub-layer including reinforcing, which is covered with a 40 mm bitumen- rubber asphalt gap-graded (BRAGG) as- phalt layer. Under these layers is 100 mm Rumdel, AfriSam forge ahead on major high-spec N3 contract Exciting upgrades on the busy N3 highway promise to streamline logistics on this vital economic artery, and Rumdel Construction is working closely with construction materials leader AfriSam to pave the way. Rumdel Construction is tackling a 4.6 km stretch of highway from the Lynnfield Park to Ashburton interchanges