Title: Comparative Performance Assessment of Rice Husk Ash-Lime-Cement Blends for Pavement Subgrade Improvement: A Mechanistic-Empirical Approach
Authors: Eng. Catherine Mugai , Prof. (Eng). Bernadette Sabuni, Prof. Edward Neyole, Dr. Faith Mugai
Volume: 9
Issue: 12
Pages: 39-43
Publication Date: 2025/12/28
Abstract:
Expansive soils require stabilization to achieve adequate performance in pavement structures. This study presents a comparative assessment of rice husk ash (RHA), lime, and cement blends applied to expansive clays from Kirinyaga County, Kenya. Laboratory tests included Atterberg limits, Proctor compaction, unconfined compressive strength (UCS), and soaked California Bearing Ratio (CBR). Mix designs evaluated 0-20% RHA with 2-6% lime or 2-6% cement, allowing a mechanistic-empirical comparison. Findings show that RHA-lime blends significantly reduce plasticity and enhance workability, whereas RHA-cement blends yield higher early strength and CBR values due to rapid hydration reactions. While cement achieves the highest mechanical performance, RHA-lime provides superior cost efficiency and environmental compatibility. The results provide quantitative decision-support for selecting stabilizer blends in low-volume road construction under Kenyan conditions. This study extends beyond Mugai et al. (2020) by including multi-stabilizer comparison, strength-plasticity interaction analysis, and mechanistic-empirical pavement implications.