Behaviour of fibre-reinforced cemented sand under flexural tensile stress

Abstract

In soil improvement, the insertion of cement to the soil matrix provides an increase in strength and rigidity of the material, whereas fibre addition provides an increase in ductility, reducing post-peak loss in strength. This research aims to experimentally analyse the mechanical behaviour of unreinforced and fibre-reinforced cemented sands under flexural tensile monotonic loading conditions. In order to do so, an experimental program was planned using silty sand (Arenito Botucatu), early strength Portland cement -CPIII, and polypropylene fibres 24 mm long and 0.023 mm thick. Three different dry unit weights (d) (18, 19 and 19.7 kN/m 3 ), three cement contents (3, 5 and 7%), and two fibre contents (0 and 0.5%) were chosen. Analysing the results, an increase in cement content generates an increase in flexural strength (qf) for all concentrations and the increase in d generated smaller qf gains, especially for lower cement contents. The addition of fibres generated a qf increase for lower d but at higher d there was a reduction in the influence of fibre addition on strength gain. The reduction can be attributed to an entanglement of the fibres in higher compaction strengths, disrupting the formation of cementitious bonds. However, based on a qualitative assessment, there was a noticeable reduction in post-peak strength loss due to fibre insertion. The parameter porosity/volumetric cement content (/Civ 0.28 ) was considered suitable to predict the qf mechanical behaviour of the studied composite.

Flexural Strength Characteristics of Fiber-Reinforced Cemented Soil

“…Including fibers in soil or soil-cement is a reinforcement method still incipient in the pavement area [7,19]. This technique is already used in cemented materials to control the cracks and prevent the material from a fragile and catastrophic failure [6,12,[20][21][22].…”

“…In terms of the mechanical performance of fibrous composites, most studies focus on unconfined compression [24,27,[29][30][31][32] and splitting tensile strength tests [3,8,[33][34][35] due to the availability and familiarity with the apparatus. However, these tests do not reflect the stresses on the pavement [7,12,19]. In fact, pavement structures are subject to flexural loads that cause tensile stress and crack at the bottom of the cemented base layer [35][36][37].…”