Modeling materials flow of waste concrete from construction and demolition wastes in Taiwan

Material flows of concrete from construction and demolition (C&D) waste in Taiwan have grown considerably over the last two
decades, Hsiao et al. (2001). This increased flow puts pressure on limited national disposal capacity and has indirectly caused
ecological damage to domestic riparian zones used as sources of natural aggregate. Using existing statistics and literature sources
for C&D waste generation in Taiwan we have developed a dynamic model of domestic material flows of concrete waste and employ
statistical analyses to obtain projections of future material flows. Our major findings are: (1) Taiwan’s rate of waste concrete
generation in 2001 for the residential and commercial construction industry was approximately 2.4 Million Metric Tons (MMT)
per year, averaging 0.11 metric tons of waste concrete generated annually by each Taiwanese; (2) Around the year 2009, the
national rate will more than triple to exceed the spike in C&D concrete waste generation that occurred after the Chi Chi earthquake
9/21/99, 8.5 MMT. (3) Aside from pilot-scale development of waste concrete utilization technology, nationwide recycling rates
remain negligible. Without resource recovery, the volume of C&D waste generation by 2009 is projected to occupy nearly 7% of
all existing and planned domestic landfill capacity. A target is established to raise resource recovery rates for waste concrete to
50% by 2005 and a 100% nationwide recycling rate by 2009.