Studies have shown encouraging results for use of recycled and local materials in construction projects.
A research project was awarded by the Qatar National Research Fund (QNRF) to the Ministry of Municipality and Environment (MME) on the implementation of recycled materials in construction.
The project commenced in 2018 for a three years duration and was led by Dr. Eng. Muhammad bin Saif Al Kuwari, from MME; Dr. Khaled Hassan, Managing Director of Infrastructure Research and Development (IRD) at the Qatar Science and Technology Park; Dr. Ian Sims, an international expert in geology from the UK; Dr. Murray Reid, an expert in geotechnical and ground engineering from the UK, and in partnership with the Public Works Authority (Ashghal).
The project aims to promote use of recycled and local materials in government projects in line with the Ashghal Recycling Roadmap and the government strategy of sustainable development.
The project identified main solid waste streams in Qatar for potential use in construction and investigated advanced technologies for recycling that could be effectively applied to Qatar. Wadi gravel is one of the main resources identified for use as aggregate in construction.
The material is produced as a by-product from the sand washing plants, as over-size materials that could provide high quality aggregate provided appropriate processing procedures are applied. The project demonstrated that processing Wadi gravel using advanced crushing, screening and washing is essential to minimise the gypsum deposits adhering to the particles to acceptable levels for use in construction.
Wadi gravel is available in various sand deposits in the southern region of Qatar; mainly the areas of Al Kharaij, Al Kharara and Mekaines, with the latter deposit containing 4.5 million tonnes alone. Advanced testing of physical, chemical, mechanical and petrographic analysis was conducted of the processed Wadi gravel in specialised laboratories in the UK, the Road Department and the Ashghal Research & Development Centre within the Ashghal Quality and Safety Department.
The results showed excellent performance and compliance with national and international specifications for use in concrete and drainage applications as a replacement to imported gabbro with positive impacts on cost and environment.
As part of the project implementation, the team worked closely with Ashghal's Road Department in implementing Wadi gravel as a pipe bedding material in trench soakaways, with estimated quantity of 27 tons in one of the infrastructure projects in Umm Salal. Monitoring performance of Wadi gravel after 18 months in service showed encouraging results for wider use in infrastructure projects.
The project team also worked with experts and consultants from Ashghal on investigating the use of reclaimed asphalt pavement (RAP) in road construction. The technique is based on milling old roads and recycling the RAP materials in new asphalt mixtures, with conservative use of gabbro and bitumen.
RAP recycling has positive impacts on cost and the environment, with the potential use of 100 percent materials to improve aggregate supply chain and accelerate project completion. The performance of RAP asphalt was monitored in five Ashghal projects in Doha, Al Wakra, Old Airport, and Izghawa areas, with positive and encouraging results after exposure to traffic and weather conditions.
The project team is delighted with the outcomes of the recycling implementation project that supports the Qatar National Vision 2030 and the Qatar Second National Development Strategy 2018-2022 of achieving environmental sustainability and optimising the use of local resources towards self-reliance.