Browsing by Author "Heyns, Migael Gabriel"
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- ItemDevelopment of a green concrete road barrier prototype in South Africa(Stellenbosch : Stellenbosch University, 2022-11) Heyns, Migael Gabriel; Sinclair, Marion; Combrinck, Riaan; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: This study investigated the development of a Green concrete median or roadside barrier prototype. The study focussed on the development and testing of a Green concrete barrier, to determine if the creation and implementation of the barrier are feasible and if it would adhere to all the safety requirements of roadside barriers. The Green concrete alternative cannot be applied if road users’ safety is not ensured. Therefore, the main goal of the study was to identify the most suitable median barrier profile and mix design for a Green concrete barrier. The secondary aim was to determine if there is a demand for this product and if the implementation of this barrier would be feasible from the perspective of South Africa’s Transport sector. Thirdly, to perform impact tests on the Green concrete alternatives to indicate if the barrier would adhere to the standards set in EN 1317. For median barriers, the optimal profile was determined to be the F-shape barrier and for bridge parapets and road restraint systems, the vertical face and single-slope barriers were the best alternatives. The glass aggregate (GA) and limestone calcined clay (LC²) concrete mixes were determined to be the mixes with the best mechanical performances relative to the Reference mix. The cost-benefit analysis of the Green concrete alternatives concluded that the LC² mix was the most cost-effective. The environmental impact assessment considered the Global Warming Potential (GWP) of the LC² mix, with the net saving determined to be 72.24 kg 𝐶𝑂2/m³. The LC² barrier had a 6.8% reduction in cost per barrier, which was determined to be R152.6 for each six-metre barrier. From these results, the most suitable mix was determined to be the LC² mix. The mix performed adequately in the mechanical tests and showed it was environmentally beneficial with a reduction in cost for each barrier. The industry experts believed the implementation of the barrier would be a good alternative to the standard barrier and fully supported the implementation of the barrier if it had a similar price as the standard barrier, with the quality of the barrier not being compromised. However, some experts believed the State-Owned Entity’s regulations and the reluctance of authorities to implement and promote change to a tried and tested practice would hinder the implementation of the barrier. The small-scale impact tests for this study were the high loading rate flexural strength test and the Charpy impact test. Both tests showed that there is no indication that the Green alternatives (excluding the R8 mix), acted differently than the standard concrete mix. The tests show that the Green alternatives have similar or even improved results under high loading rates. The concrete specimens also have similar failure patterns, with no significant splintering or disintegration under the loading conditions. Therefore, these tests indicate that a Green concrete barrier would perform similarly in the EN 1317 crash tests to the standard concrete barrier. However, it is still recommended that the final Green concrete barrier be tested according to EN 1317, before it is implemented on a wide scale.