Performance of granular road base and sub-base layers containing recycled concrete aggregate in different ratios

ABSTRACT

In this study, the usability and performance properties of recycled concrete aggregates (RCA) as granular road base (GRB) and granular road subbase (GRSB) material were investigated. A natural aggregate and the RCAs obtained from concretes with three different compressive strength and mixtures created by adding the RCAs to NA at the ratios of 25, 50 and 75% were used. Physical properties, modified Proctor, resilient modulus, permanent deformation, California bearing ratio (CBR), and permeability tests were carried out on all mixtures. Resilient modulus values (M_r) were obtained using three different resilient modulus models. The highest M_r value among pure RCAs was observed for RCA2 (average of 200 MPa). For the mixture samples, the highest M_r values were obtained in the mixtures containing RCA1 (average of 250 MPa). The minimum of permanent deformation value (ϵ_p) for the mixtures was obtained when the ratio of the RCA1 in the mixtures was 50% (ϵ_p = 0.238%). The obtained CBR values were not related to the M_r values, and the highest CBR values were found for the pure RCAs (average of 126%). High permeability coefficient values (average of 9.973×10⁻⁶ m/s) were obtained for the RCAs. As a result, it was more appropriate to blend the RCAs with the natural material rather than to use them in pure form. In general, it was appropriate to use 50% of RCAs in the mixtures. It was observed that if concrete compressive strength is as high as in RCA1 (18.5 MPa), RCA can be used even in the mixture at a ratio of 75%.

KEYWORDS:

• Recycled concrete aggregate
• resilient modulus
• permanent deformation
• granular road base
• granular road subbase

Acknowledgement

This paper is in the scope of ‘Experimental Investigation of the Usability of Recycled Concrete Aggregate in Road Superstructure’ Master's Thesis (Toka 2019) and ‘Investigation of the Usability of Recycled Concrete Aggregate Obtained from Urban Transformation Applications in Road Base and Subbase Layer’ the Scientific and Technological Research Council of Turkey (TUBITAK) project (Grant Number: 217M969). This study was supported and funded by TUBITAK.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) : [Grant Number 217M969].