Laboratory mechanical properties and frost resistance of vibration-compacted cement–fly ash slurry and cement–fly ash-treated macadam mixtures

Abstract

The objectives of this study were to characterize the compaction and mechanical characteristics and frost resistance of vibration-compacted cement–fly ash slurry (CFAS) and cement–fly ash-treated macadam (CFATM) mixtures and recommend the optimal ratio and dosage of cement–fly ash (CFA) based on laboratory compaction experiments, unconfined compressive testing, indirect tensile testing, and frost resistance testing. The effects of the CFA ratio and dosage, curing age, and gradation type on the mechanical strength and frost resistance were analyzed, and strength prediction equations were presented. Then, the optimal CFA ratio and dosage are recommended. The results show that the mechanical strength of CFAS and CFATM mixtures increased nonlinearly with increasing curing age. Gradation type, CFA ratio, and CFA dosage affected the conventional, initial, and ultimate mechanical strengths of these mixtures. A CFATM mixture cured for a longer duration with self-developed skeleton-dense gradation and the addition of less fly ash exhibited better frost resistance. To maximize the mechanical strength of CFAS and CFATM mixtures, the CFA ratio should not exceed 1:1 and 1:1–1:1.5, respectively. In addition, 3.5%–4.0% cement and 4.0%–7.0% fly ash should be used in the CFATM base or subbase to obtain optimal results. This paper provides a new option for the design of CFAS and CFATM mixes.