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Recycled Materials as Substitutes for Virgin Aggregates in Road Construction: I. Hydraulic and Mechanical Characteristics
Author(s) -
Kang Dong-Hee,
Gupta Satish C.,
Ranaivoson Andry Z.,
Siekmeier John,
Roberson Ruth
Publication year - 2011
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2010.0295
Subject(s) - asphalt , aggregate (composite) , materials science , leaching (pedology) , hydraulic conductivity , fly ash , cohesion (chemistry) , porosity , environmental science , composite material , geotechnical engineering , geology , chemistry , soil science , organic chemistry , soil water
Waste generation in household, industry, and highway reconstruction has spurred recycling nationwide. One of the venues for use of recycled materials is in road construction. This study evaluated the suitability of 17 mixtures of four recycled materials with aggregates as a replacement of 100% virgin aggregates in base and subbase layers of roads. Recycled materials tested were recycled asphalt pavement (RAP), recycled concrete material (RCM), fly ash (FA), and foundry sand (FS). Properties characterized were water retention, hydraulic conductivity, resilient modulus (M R ), shear strength, and leaching characteristics. In this paper, we discuss the hydraulic and mechanical characteristics of these mixtures. The shapes of the water retention curves of recycled mixtures were nearly similar whereas the saturated hydraulic conductivities of these mixtures were higher than that of 100% aggregates. This suggested that the drainage characteristics of these particular recycled materials mixtures with aggregates will be similar or better than that of 100% aggregates. Generally, addition of RAP, RCM, and FA+RAP to aggregates increased M R values but addition of FS (fine material) to aggregate decreased the M R values. These results suggest that the stiffness of these particular RAP, RCM, and FA mixtures of aggregates will be similar or better than that of 100% aggregates. Addition of RAP, RCM, and FA+RAP to aggregates generally increased the cohesion values whereas friction angles mostly varied within a narrow range (38–49°). Addition of FS to aggregates, however, did not improve the shear strength of the mixtures. Based on these results, we concluded that FA, RAP, and RCM mixtures will be good substitutes for virgin aggregates in base and subbase layers of roads.