Reclaimed Concrete Material

Reclaimed concrete material (RCM) is sometimes referred to as recycled concrete pavement (RCP), or crushed concrete [ 159-162]. It consists of high-quality, well-graded aggregates, bonded by a hardened cementitious paste. The aggregates comprise approximately 60-75% of the total volume of concrete. RCM is generated through the demolition of Portland cement concrete elements of roads, runways, and structures during road reconstruction, utility excavations, or demolition operations. 

In many metropolitan areas, the RCM source is from existing Portland cement concrete curb, sidewalk and driveway sections that may or may not be lightly reinforced. The RCM is usually removed with a backhoe or pay loader and is loaded into dump trucks for removal from the site. The RCM excavation may include 10-30% sub-base soil material and asphalt pavement. Therefore, the RCM is not pure Portland cement concrete, but a mixture of concrete, soil, and small quantities of bituminous concrete [159-161]. 

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To produce a granular base or subbase aggregate, RAP must be crushed, screened, and blended with conventional granular aggregate, or sometimes-reclaimed concrete material... 

As for the reclaimed concrete, after removing the steel, when properly crushed and screened, it can be used as aggregate replacement in hot mix production, as a granular base or sub-base or as an embankment or fill material. 

As can be seen in Table 3.24, the energy consumption for the construction of a concrete layer is higher than that of the asphalt layer with virgin materials. Similarly, when 20% reclaimed material is used, the energy consumed for an asphalt base layer is less than that for an asphalt base layer with virgin materials. The processes that use unheated aggregate and cold applied binders utilise the least amount of energy per tonne. 

The reclaimed material from old concrete slabs (crushed and screened concrete particles) can be used as aggregate for (a) production of concrete, (b) stabilised or non-stabilised base and sub-base material, (c) construction of embankments or drainage filters, (d) construction of shoulders and (e) production of asphalts for base and binder courses. 

Stroup-Gardiner M. and T. Wattenberg-Komas. 2013. Recycled Materials and Byproducts in Highway Applications Volume 6 Reclaimed Asphalt Pavement, Recycled Concrete Aggregate, and Construction Demolition Waste. NCHRP Synthesis 435. Washington, DC TRB, National Academy of Science. 

Dry landfill disposal of fly ash and bottom ash from Power Plants has been widely used for years without problems. The possibilities of using the freshly produced or reclaimed material have been extensively studied and a significant portion of fly ash is used for road works, cement manufacture or concrete additives... 

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