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The built environment consumes a lot of energy and material. A huge demand of about 40 billion tonnes of aggregates is demanded for construction purpose. The cost of material accounts for more than 60% of the total project cost. However, 10% of construction material end up as demolition wastes yearly. Aggregate is a beneficial building component in construction. There is much need to develop ways to ensure it is utilized properly as construction and demolition waste contribute a large percent to landfills. This review of literature examined the generation of construction and demolition waste generated in developed countries, waste characterization, and utilization in pavement construction. Additionally, environmental, economic and social benefits of the reuse of this waste was espoused. The result of the review revealed that The initial construction material quality, scale of the project, contract and construction mode used affect the amount and quality of CDW. CDW are bulky and not suitable for composting and incineration. Ultimately, the utilization of this waste would reduce the amount of raw material used in construction leading to conservation. Also, there would be reduction in the energy cost associated with mining (quarrying), extraction and transportation of natural aggregates in track with the conservation of natural resources and the construction of cost-effective pavements.

Sustainable transport system must be supported by resilient infrastructure such as bridges. Bridge is an essential transportation structure that offers unique solutions for road and rail traffic to cross rivers, gorges and difficult ground conditions or for reducing conflict points in transportation system by carrying one mode of traffic over the other. Due to its pronounced economic importance to the society, bridge design aspects must go beyond the physical bridge structures and must cover all the factors that impact on the safe operation throughout its serviceable life span. The environment and the obstacle it crosses, the soil which carries it, the self-weight, imposed dead weights and the moving live loads must be adequately taken care of. The considerable conflicting factors of the site’s soil characteristics, river hydrology, ecosystem environmental impact, aesthetics, historical and archaeological impacts, permanent and transient loads, construction technologies and construction materials bring together a vast expertise of professionals. These sizeable factors must be well managed and harnessed by the vast team of experts involved to guarantee a positive outcome. The vast decay of Nigerian transport system is visible in all complimenting infrastructure including bridges. Cases of bridge collapse abound in Nigeria within the last decade. This research studies the failure trends of bridges in Nigeria and forty-five documented cases are considered for the research. Structural health monitoring approaches were combined with statistical measures to assess the causes and to proffer solutions to the failure trend. Poor maintenance, torrential rainfall/flooding, terrorist attacks, faulty design, poor materials and construction quality and truck overloading were found to be the major causes of bridge failures in Nigeria.

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This research developed a mathematical model and optimization of materials for the development of metakaolin self-compacting concrete. This is in a bid to reduce the overall material quantity and cost towards sustainable infrastructural construction. To achieve the aim of this research, Response Surface Analysis (RSM) was used. Kaolinitic clay was De-hydroxylated at 750°C to form metakaolin. This was used as a partial replacement for cement at 0%, 5%, 10%, 15%, 20% and 25% weight of Portland limestone cement. Both strength and rheology properties of the developed metakaolin self-compacting concrete were assessed. To this end, slump flow, L-Box test and V-funnel test were carried out alongside the compressive strength using relevant standard. The result of the research revealed that at 15% addition of metakaolin the slump flow, passing ability and filling ability was unsatisfactory according to EFNARC standard. From the numerical optimization of the compressive strength, the maximum predicted compressive strength of 44.35 N/mm 2 was obtained. At a low value of metakaolin addition (5-15%), the compressive strength increased as the age of the concrete increased from 3-150 days. The age with the optimum mechanical strength formation was 110 days with metakaolin addition of 52.73 kg. The result of this research provide a database for Engineers, Researchers and Construction workers on the optimum metakaolin required to achieve satisfactory mechanical strength in metakaolin self-compacting concrete.