Fly ash-cement based concrete for road construction: engineering properties and pavement design

This research investigates various fly ash (FA) levels of 0%, 15%, 25%, and 35% for cement replacement in concrete, specifically for rural roads in southern Vietnam. The slump values of the fresh concrete mixture were kept under 40 mm to maintain workability based on the requirement of rigid pavement. Concrete's mechanical properties, including its elastic modulus, flexural strength, and compressive strength, and the abrasion resistance were examined at three different stages of curing of 7, 28, and 56 days. Results indicated FA may not contribute to strength development as effectively as cement at early stages. However, the strength of concrete achieved the highest value at a 15% FA replacement level at the long-term curing age. The findings indicated that FA could enhance the long-term strength of concrete regarding its flexural and compressive strengths. According to the results of the abrasion resistance test, abrasion loss rises between 3.2 kg/m2 and 4.21 kg/m2 as FA increases. Finally, the calculation results revealed that 15% and 25% of FA replacement for cement can be used in rigid pavement with good performance.