Mixing and compaction of fibre- and lime-modified cohesive soil

Abstract

Citation: GELDER, C. and FOWMES, G.J., 2015. Mixing and compaction of fibre-and lime-modified cohesive soil.Proceedings of the ICE -Ground Improvement, 169 (2), pp. 98-108.Additional Information:• Fibre reinforcement is a versatile method of increasing the shear strength of soils for earthwork applications. However, research to date has encountered a number of problems when utilising cohesive host soils. The aim of this study was to develop a suitable site-applicable method of mixing fibre into cohesive host soils. Intermediate plasticity clay reinforced with monofilament polypropylene fibres was used in the laboratory investigations. In order to mix the fibres successfully, the initial moisture content of the host soil was increased prior to the introduction of fibres. By introducing quicklime, excess moisture was removed through the hydration process, and a portion of free water was effectively held within aggregations of flocculated clay particles, thereby having little influence on the dynamic boundaries. Fibrous inclusions within the clay clods resisted compactive effort, forming an interlocked structure. As a result, the optimum moisture content increased and the maximum dry density decreased. This trend was heavily dependent on the interfacial shear resistance along the fibre boundary, which consequently decreased as the water content increased or the compactive effort was increased. Results from strength tests confirmed that both peak and post-peak shear strength increased, creating a more ductile material capable of maintaining shear strength at high levels of strain.

Effect of Polypropylene Fibers on the Shear Strength–Dilation Behavior of Compacted Lateritic Soils

“…The behavior of the maximum dry unit weight did slightly reduce with the inclusion of fibers in the sandy soil, while the optimum gravimetric water content did not change. The results of other studies show similar compaction curves for soils with and without fiber reinforcement [54][55][56], where no significant alterations were evidenced.…”

Reinforcing effect of recycled polypropylene fibers on a clayey lateritic soil in different compaction degrees

“…Maximum dry unit weight values did not change with fiber inclusion in the clayey soil, while the optimum water content values slightly increased. Results of no significate alterations in the compaction curves of soilfiber mixtures were evidenced by others studies (Gelder & Fowmes, 2016;Kumar & Singh, 2008;Marçal et al, 2020;Mirzababaei et al, 2013).…”

Editorial

“…The third paper by Gelder and Fowmes (2016) describes a study to develop a suitable site (field) scale applicable method of mixing polypropylene fibres into cohesive host soils, employing elevation of moisture content to facilitate mixing of the fibres and subsequent use of lime to then reduce the moisture content of the fibre-reinforced clay to workable levels. Addition(s) of fibres has been shown to increase both peak and post peak shear strength, and to improve the characteristics of the soils, increasing their ductility.…”