Suitability of Reclaimed Asphalt Concrete as a Cold Mix Surfacing Material for Low Volume Roads
Chrispus Sifuma Ndinyo1, Zachary Abiero Gariy2, Stephen M.Mulei3
1Chrispus Sifuma Ndinyo, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
2Prof. Zachary Abiero Gariy, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
3Mr. Stephen M. Mulei, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
Manuscript received on November 25, 2013. | Revised Manuscript received on December 18, 2013. | Manuscript published on December 30, 2013. | PP: 354-360 | Volume-3, Issue-2, December 2013. | Retrieval Number: B2488123213/2013©BEIESP
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: Increase in the number of high volume roads constructed to bitumen standards in the past five years in Kenya has led to a strain in the supply of scarce natural resource aggregates. Some of the existing roads have undergone reconstruction which involved removal of top asphalt concrete surfacing layer to accommodate new layers underneath. The disposal of the old asphalt concrete surfacing layer in the open spaces has led to environmental degradation. Lack of sufficient funds has led to low volume roads being left in a deplorable state. The main objective of the study was to evaluate the suitability of a mix of reclaimed asphalt concrete, virgin aggregates and a cationic emulsion as a surfacing material for the construction of low volume roads. The research involved laboratory investigations and a design process. Reclaimed asphalt concrete, virgin aggregates and a cationic emulsion were evaluated to determine their engineering properties. A combined aggregate gradation for reclaimed asphalt concrete aggregates and virgin aggregates was determined which was used in the determination of the percent emulsion demand for the combined aggregates based on the suggested empirical formula and there after designing an optimal mix according to the modified Marshall mix design method. The optimal gradation envelope from the combined aggregates coupled with emulsion demand that provided a specimen with the desired workability and posing no evidence of surface flushing or bleeding was taken as an ideal mix. The ideal mix provided an optimal stability value of 6900N and a residual binder of 5.2%. The study indicates that the stability values obtained for the designed cold mix were greater than the minimum specified of 3336N for medium traffic surfacing (Asphalt Institute Design Manual, 1994).Cost of producing a unit of reclaimed asphalt concrete cold mix was Kenya shillings 8,445 cheaper than the production costs of conventional asphalt concrete cold mixes in Kenya. The study concludes that reclaimed asphalt concrete cold mix is a suitable surfacing material for the construction of low volume roads. It’s therefore recommended as an economical and environmentally friendly surfacing material.
Keywords: Cost, conventional, Environmental, Modified, optimal.