Viability of Recycled Concrete Waste as Construction Material for a Sustainable Environment

A major source of environmental burden in construction industries is concrete waste because its generation and accumulation start from the time fresh concrete are produced on-site or off-site till its hardens. This made concrete the largest portion of solid waste stream by weight in the construction industries. Recycling of these waste materials into new form as well as appropriate reuse could therefore conserve natural resources, reduce the space required for land filling and the cost of transportation. This paper assesses the viability of reusing aggregates obtained from concrete waste collected from four different construction sites by comparing compressive strength of concrete made with the recycled concrete waste aggregate with concrete made with natural fresh aggregate as control specimens using an aggregate size not greater than 25mm. A total of 60 cubes of size 150mm x 150mm were cast and cured for different maturity age of 7, 14, 21 and 28 days before crushing.  Laboratory results revealed that there was little variation in strength as the cubes matures. Average compressive strength of concrete made with recycled concrete waste aggregates obtained from two of the site were 22.8 N/mm2 and 24.3 N/mm2 and these were almost the same with the control test cubes with average compressive strength of 24.4 N/mm2. However, test cubes obtained from the other two sites had concrete strength lower than 20 N/mm2. Hence, concrete produced with recycled concrete waste aggregate though exhibiting lower compressive strength could be used for walkways and kerbs production in road construction, backfilling, and in concrete production for light load bearing structural components so as to achieve a sustainable environment and conserve natural resources

Viability of Recycled Concrete Waste as Construction Material for a Sustainable Environment

A major source of environmental burden in construction industries is concrete waste because its generation and accumulation start from the time fresh concrete are produced on-site or off-site till its hardens. This made concrete the largest portion of solid waste stream by weight in the construction industries. Recycling of these waste materials into new form as well as appropriate reuse could therefore conserve natural resources, reduce the space required for land filling and the cost of transportation. This paper assesses the viability of reusing aggregates obtained from concrete waste collected from four different construction sites by comparing compressive strength of concrete made with the recycled concrete waste aggregate with concrete made with natural fresh aggregate as control specimens using an aggregate size not greater than 25mm. A total of 60 cubes of size 150mm x 150mm were cast and cured for different maturity age of 7, 14, 21 and 28 days before crushing.  Laboratory results revealed that there was little variation in strength as the cubes matures. Average compressive strength of concrete made with recycled concrete waste aggregates obtained from two of the site were 22.8 N/mm2 and 24.3 N/mm2 and these were almost the same with the control test cubes with average compressive strength of 24.4 N/mm2. However, test cubes obtained from the other two sites had concrete strength lower than 20 N/mm2. Hence, concrete produced with recycled concrete waste aggregate though exhibiting lower compressive strength could be used for walkways and kerbs production in road construction, backfilling, and in concrete production for light load bearing structural components so as to achieve a sustainable environment and conserve natural resources

Comparative Analyses of Circularity Practices in Civil and Construction Engineering Between UK and Nigeria

The circular economy in the civil and construction engineering sectors is gaining momentum globally. The inadequate waste management system, especially in emerging nations, is quite concerning. Various waste sources such as construction and demolition (C&D), industrial wastes as well as agricultural wastes such as cassava peel, rice husk, and coconut fibre have been utilized in developing construction products. This study adopts the UK (United Kingdom) and Nigeria as two cases with critical analyses of the status quo and recommendations for promoting circularity. The existing studies on the circular use of waste construction products were comprehensively reviewed by mapping them against the Technology Readiness Level (TRL). The study addressed three research questions: (1) the existing locally available wastes used in civil and construction industries in the two studied countries, (2) the effects of these wastes on the properties of new construction products, and (3) visions to enhance circular use of wastes on civil and construction engineering practices. It is found that both countries have abundant industrial, agricultural, and demolition wastes that are potential materials for circularity in construction. While the TRL of utilizing these wastes is at an advanced stage in the UK, there is still a need for more concerted efforts to bring those wastes in Nigeria to a higher TRL. This study contributes to the existing body of knowledge by mapping the three aforementioned questions between the two studied countries, shedding light on continuous work in enhancing circular practices across the global civil and construction sectors