Development of alkali activated crushed rock for environmentally sustainable roadway rehabilitation

Abstract

For roadway rehabilitation, in-situ pavement recycling with cement stabilisation is considered as an economical and sustainable solution. However, it cannot be sustainable due to substantial consumption of ordinary Portland cement as the primary stabiliser. The production of cement releases a large amount of CO2 into the environment. Recently, an alkali-activated material (AAM) has been promoted as a green construction material with no cement usage resulting in sustainable material for roadway rehabilitation. Therefore, this study aimed to introduce the use of alkali-activated crushed rock (AACR). Crushed rock (CR) was used as a prime material and a precursor incorporation with a designed liquid alkali activator for AACR synthesis. Four CR categories were studies including to powder CR, standard CR, ideal grading CR, and possible grading CR. Results show that a designed liquid alkali activator derived from this study can be used to synthesise AACR with all types of CR. AACR, with the possible grading CR, gives UCS exceeding the requirement of the chemically stabilized road base material. Outcomes of this study could overcome the limitation in sourcing a capable AAM precursor for such low strength as current possible precursors for AAM synthesis are almost impractical for mass AAM production.