Construction World January 2015

PROJECTS AND CONTRACTS

MULTICELL ROADS Edendale township, situated in the southwest outskirts of Pietermaritzburg, KZN, is a large area dominated by steep hills and valleys. It was here that Kaytech’s Multi-Cell was chosen to solve a resurfacing problem for two of the township’s dilapidated roads. Kaytech’s Paul Lombard was on site to offer specialist supervision.

Most of the roads used by the local people to access their homes are constructed of gravel, often so poorly maintained that no gravel is

paving for road or canal construction. Multi-Cell provides a high cell wall/infill interlock as well as high tensile strength and seam strength. It is usually supplied in standard 5 m x 10 m panels but, to accom- modate the narrower, single-track roads on this project, Kaytech specially manufac- tured 4 m x 10 m panels. Livestock and stray animals walking through the wet mix before it was properly cured posed a problem for the contractor, but this was rectified by manually filling the footprints with concrete once the concrete had set. Environmental impact This project and others like it in Unit H of Edendale demonstrate the potential of using concrete-filled geocells for upgrading and improving road networks into previously inaccessible steep environments. Multi-Cell is rot-proof and resistant to most low-con- centration chemicals and ultra violet light, thus it is sustainable, requiring minimal maintenance. It is lightweight and has low packaged volume in relation to the installa- tion area, posing a low transportation carbon footprint in comparison to alternative solu- tions. Being flexible, Multi-Cell conforms to existing environmental surfaces, thereby reducing many of the costs inherent in using steel as concrete reinforcement. Local impact The Multi-Cell system proved to be the most economical technical solution for this Eden- dale roads project, providing an ideal oppor- tunity for labour intensive construction (LIC) techniques. It was the first Multi-Cell project undertaken by the contractor, Okuhlekwethu Developments, who installed the product according to Kaytech’s installation guide- lines. The patented Tension Frame makes the Multi-cell quick and easy to install, thus unskilled labour was employed by simply following Kaytech’s installation guidelines and receiving on-site training by a foreman. 24 members of the local community were employed and trained to install the Multi- Cell system in accordance with the Govern- ment’s policy on the LIC and Extended Public Works Program (EPWP) programme. The local labourers employed were

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evident. Following heavy rainfall, the in-situ clay material is exposed, especially on the steeper gradients, which are rendered inac- cessible to most vehicles. Innovation Paving these roads was not economically viable due to the steep gradients and the prohibitive costs of asphalt paving. Engi- neers from the KZN Department of Transport (DOT) made the decision to resurface two steep road sections using Kaytech’s Multi- Cell 100 mm filled with ready-mix concrete. This solution was possible because the roads here are trafficked mostly by light motor vehicles and pedestrians. Since the Multi-Cell system had been successfully installed on a section of a District Road at Vulindlela (adjacent to Edendale) in 2006 and at Unit H in Edendale in 2007, the DOT engineers were confident in specifying the system in this case. Although Multi-Cell has been around for some time, it has not been used extensively for road resur- facing. Other more popular uses include effective erosion protection treatment for hydraulic structures, as well as slope protec- tion and load support. However, it is proving to be an innovative alternative to reinforced concrete roads, negating the excessive cost of steel reinforcing. Working within tight budget constraints and the limitations of an existing 20 m fixed road reserve, the regrading of the 28% incline and widening of the sharp horizontal curves was particularly chal- lenging. After conducting a feasibility study and having considered other options, a 600 m section at 19% design grade was constructed using Multi-Cell geocells infilled with 25 MPa concrete. Multi-Cell is a honeycombed, cellular structure manufactured from strips of a coated slit film. This woven polypro- pylene tape is stitched together to form three-dimensional diamond shaped cells. It is used as an in-situ shuttering to cast continuous, interlocking concrete

Application is simple: a section of geocell road being filled with concrete.

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Local labour was used to fill the Multi-Cell road

The completed road ready for foot traffic and small vehicles.

given DOT standards and kitted out in PPE gumboots, gloves, and reflective vests in compliance with Health & Safety standards. No health and safety issues were reported on this project.

CONSTRUCTION WORLD JANUARY 2015