Life Cycle Assessment Of Cost,Energy And Carbon Emission For Pavement Preventive Maintenance

Pavements are one of the highest assets and represent massive investment.With the vast amount of resources dedicated to pavements and its constant public scrutiny,it is imperative that the serviceability of pavements be maintained in an efficient and effective manner to get the most out of these investments.Highway agencies worldwide have become increasingly concerned with the environmental consequences and sustainability of their preservation treatments.The need to design and provide a sustainable maintenance service is becoming a priority and this comes hand in hand with the intentions to reduce the impacts caused by the road sector to the environment.This paper presents a life cycle cost and assessment technique to measure the cost effectiveness,embodied energy and carbon emissions of four preventive maintenance treatments for use on Zambian roads: Thin Hot Mix Asphalt,Chip + Fog Seal,Microsurfacing and Mill and Fill.These treatments could either be applied separately or in combination during the preventive maintenance of road pavements.The analyses were carried out through a thorough literature review,a questionnaire survey and performance analyses trends.Results shows that chip + fog seal,micro-surfacing are the best alternatives with an LCC of 30-40% lower,embodied energy which is 3-4 times lower,and carbon emission which is 3-6 times less than the three least performing alternatives which are full depth reconstruction,mill and fill and a combination of thin overlay and mill and fill.Additionally,a sensitivity analysis was conducted to show the variability of altering the discount rate and the construction costs on the Net Present Value.Results showed an indirectly proportional relationship between the discount rate and NPV while a direct proportional relationship was exhibited with the increase or decrease of construction costs on the NPV.In light of the results,an expertly defined LCC and LCA system for pavement preservation treatments is the only way forward to combat the impending energy crisis and climate change impacts of road construction.It is also recommended that agencies also include elements of user costs like accident,work zone and environmental for better probabilistic LCC as part of their decision making process.