Comparative analysis of the effects of fibres, cement and biopolymer on soil improvement

Abstract

This study systematically examines the effects of these fibres at varying contents (0% to 0.5%), their combinations, cement content (0% to 12%), partial cement replacement with biopolymer (0% to 55%) and curing conditions (moisture-preserved and air-cured) on the UCS of soil. The optimal fibre content, which varied between 0.25% and 0.5% depending on the fibre type, corresponded to the highest UCS values achieved for each case. Additionally, the results demonstrated a consistent and significant increase in UCS with increasing cement content, reaching a maximum at 12% cement. The UCS of untreated soil was 447 kPa. The maximum increase in UCS for fibre-reinforced specimens was observed with 0.5% virgin polypropylene fibres, resulting in a 100% improvement. Among the stabilisers tested, cement demonstrated the most significant improvement in UCS, with a maximum increase of 414%. The optimal biopolymer content of 2.75% improved UCS by approximately 71%, showing a substantial gain over untreated soil. Although replacing cement with biopolymer resulted in a slight reduction in UCS compared to cement-only specimens, this substitution offers environmental advantages by reducing cement consumption. To correlate strength gains with internal structure, Scanning Electron Microscopy (SEM) analysis was conducted to observe microstructural changes in the treated specimens. © 2025 Informa UK Limited, trading as Taylor & Francis Group.