Construction and demolition waste as recycled aggregate for environmentally friendly concrete paving

Abstract

Recycled aggregates (RA) from construction and demolition waste (CDW) instead of natural aggregates (NA) were analysed in the manufacture of new eco-friendly concrete. Fine (FRA) and coarse (CRA) recycled aggregates were used in different percentages as substitutes of natural sand and gravel, respectively. The results revealed that the use of RA in percentages of up to 50 wt.% is feasible. Additionally, RA were used to produce paving blocks in accordance with industrial requirements. Thus, values of water absorption lesser than 6.0% and tensile strength upper than 3.6 MPa were obtained, which are similar to those of a reference sample and within the limit values established by the regulations. These results were achieved by reducing the incorporation of cement, thereby saving production costs and minimizing environmental impact.

Recycled Aggregates from Construction and Demolition Waste in the Manufacture of Urban Pavements

“…Recycled sand (RS) and gravel (RG) were provided by an integrated CDW treatment plant of the Murcia region. These types of RAs with physical and mechanical properties similar to those of NAs used in the present study are quite easy and cheap to obtain following the separation method reported in previous studies [ 25 ]. This methodology (crushing, grinding, sieving, and removal of impurities) eliminates the most fragile materials, concentrating those that are more resistant and suitable to be applied in concrete manufacture.…”

“…[ 26 , 27 , 28 ]. According to similar studies [ 25 , 29 , 30 , 31 ] the partial saturation (around 50% of the complete saturation) of the superficial pores guaranteed an appropriate consistency and workability with a minimum loss in the resistance of the final concrete. Additionally, this method reduces water absorption during the cementation process, keeping the process water-free until the cement hydration [ 10 , 30 , 31 ].…”

“…The chemical and mineralogical composition of the raw materials used in this study has been fully discussed in a previous paper [ 25 ]. Briefly, the major constituent element of recycled aggregates is silicon (78.4 and 73.0 wt.% SiO 2 in RG and RS, respectively).…”

“…Furthermore, the results of BD obtained under compacted conditions of natural constituents (NS and NG) and recycled aggregates (RS and RG) were similar and around 1600 kg m −3 . Similarly, the specific gravity (SG) was slightly higher in the natural aggregates (NS and NG, 2450 and 2650 kg m −3 , respectively) in comparison to recycled aggregates (RS and RG, 2280 and 2390 kg m −3 , respectively) because the density of natural constituents is higher than that of recycled aggregates [ 10 , 16 , 25 ]. Moreover, the recycled aggregates, RS and RG, met the requirements established in the EN 12620 standard [ 33 ], which specifies the required properties of natural, mechanically processed, recycled, or mixtures of aggregates to be used in concrete manufacture and requires aggregates with SG greater than 2000 kg m −3 ( Table 2 ).…”

Recycling Construction and Demolition Residues in Clay Bricks

“…Research on the recycling of CDR into ceramic materials is extremely scarce. There are few studies on the technological behavior of CDR in ceramic materials, with the exception of a few studies on lightweight aggregates [29,30] and some papers on clay-based building ceramics [31][32][33][34][35][36][37][38][39][40]. In general, these studies concluded that CDRs can be used as major ingredients, but that its processing indications are contradictory (e.g., relevant variation of the firing sintering temperatures).…”