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.

KEYWORDS:

• Alkali-activated crushed rock
• alkali-activated material
• crushed rock
• liquid alkali activator
• unconfined compressive strength

Acknowledgments

The first author wishes to express gratitude to the Thailand Research Fund (TRF) scheme ‘TRF Research Career Development Grant (2016-2018)’ for the financial support of this project (RSA5980070). The last author would like to acknowledge the financial support of the Thailand Research Fund (TRF) under the TRF Distinguished Research Professor grant number DPG6180002. The research team of the Civil Engineering Department in Chiang Mai University, Khon Kaen University, and Burapha University, Thailand, are also gratefully acknowledged for providing overview guidance and valuable input to this work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The first author wishes to express gratitude to the Thailand Research Fund (TRF) scheme ‘TRF Research Career Development Grant (2016-2018)’ for the financial support of this project (RSA5980070). The last author would like to acknowledge the financial support of the Thailand Research Fund (TRF) under the TRF Distinguished Research Professor grant number DPG6180002. The research team of the Civil Engineering Department in Chiang Mai University, Khon Kaen University, and Burapha University, Thailand, are also gratefully acknowledged for providing overview guidance and valuable input to this work.