Development of mobile crusher for recycled aggregate production

Owing to the comprehensive building redevelopment programme in Hong Kong, there is a huge volume of concrete waste generated that will soon exhaust all the available landfill areas. As such, Recycled Aggregate (RA) is advocated. However, recycled aggregate has been confined only to lower-grade concrete applications, such as pavements, roadwork and sub-base. The major reason is the variable behavior of RA resulted from different concrete waste sources collected for centralised crushing in a centralised recycling plant. This paper proposes the adoption of a mobile crusher for RA production which can: 1) reclaim RA from known sources; 2) maintain consistency of RA properties; 3) alleviate the traffic congestion in delivering concrete waste to a central crushing plant; 4) save in traveling time of discharging trucks; and 5) remove the requirement on the minimum boulder size to be handled by a centralised plant. In this paper, ten samples of recycled aggregate (Samples 1 to 10) had been obtained from ten demolition sites while Sample 11 was collected from Tuen Mun Area 38, the centralised recycling plant. They were compared with the performance of virgin aggregate (Sample 12). From the experimental results, one of the samples (Sample 6), akin to Sample 12 (virgin aggregate), was found to be suitable for all types of construction applications while some samples (Samples 2 and 9) were not suitable for recycled aggregate concrete of any grades of application. This concludes that recycled aggregate from different sources should preferably be separately crushed by mobile crushers rather than processed centrally which will lower the overall quality of recycled aggregate and confine their applications.