Influence of fibre reinforcement on the post-cracking behaviour of a cement-stabilised sandy-clay subjected to indirect tensile stress

Abstract

Cristelo N et al., Influence of fibre reinforcement on the post-cracking behaviour of a cement-stabilised sandy-clay subjected to indirect tensile stress, Construction and Building Materials, Elsevier, 138: 163-173, 2017. 2 3 Influence of fibre reinforcement on the post-cracking 4 behaviour of a cement-stabilised Sandy-Clay subjected to 5 indirect tensile stress 6 7 8 a,22 23 24 25Cristelo N et al., Influence of fibre reinforcement on the post-cracking behaviour of a cement-stabilised sandy-clay subjected to indirect tensile stress, Construction and Building Materials, Elsevier, 138: 163-173, 2017. Abstract 26 27 An experimental campaign was carried out to determine the influence of polypropylene fibre 28 content and length on the post-cracking response of a Sandy-Clay stabilised with different 29 cement contents. Three main sets of specimens were prepared: cement-stabilised specimens 30 with two cement contents (5% and 10%); fibre-reinforced specimens with three fibre contents 31 (0.1%, 0.2% and 0.3%) and cement-fibre-reinforced specimens combining the mentioned fibre 32 and cement contents. Tensile tests on the fibres and indirect tensile tests and triaxial 33 compression tests on the prepared specimens were conducted. Results show that the post-34 cracking behaviour is strongly affected by the combination of fibre and cement content as well 35 as fibre length. Pull-out was the governing failure mode. Post-peak tension loss rate increased 36 with fibre content, as a result of the loss of influence of the fibres on the post-peak behaviour. 37On the contrary, an increase in fibre content resulted in higher pre-peak strength gain rates and 38 higher peak stresses. 39 40 41 Cement stabilisationCristelo N et al., Influence of fibre reinforcement on the post-cracking behaviour of a cement-stabilised sandy-clay subjected to indirect tensile stress, Construction and Building Materials, Elsevier, 138: 163-173, 2017. 4 complex material in terms of tensile strength, especially on the post-peak stress segment of the 70 load-displacement curve. This structural response has not yet been fully characterised, and is 71 thus the main subject of the present paper. 72 73 In general, the fibres are responsible for an increase of the compressive and shear strength, 74 especially at the post-peak and residual (post-cracking) stages, and the extent of such 75 improvement is intrinsically dependent of several factors, such as: fibre properties, geometry 76 and content; fibre distribution and orientation within the matrix; existence and magnitude of 77 artificial cementation (using, for instance, Portland cement or lime); and fibre-soil bonding 78 (stress-slip behaviour).79 80 The present paper aims a thorough characterisation of the tensile stress post-peak response of a 81 polypropylene fibre reinforced sandy-clay. It is part of an extensive research programme 82 designed to understand the mechanical response of a very common Portuguese soil, when 83 reinforced with fibres, as well as the potential need for additional chem...

Soil reinforcement through addition and subsequent carbonation of wollasonite microfibres

“…Compared to the natural soil (S), the ITS of the W 15% S and W 20% S specimens increased by 400% and 638%, respectively. These results are consistent with those obtained by other researchers (Fatahi et al 2012;Correia et al 2015;Cristelo et al 2017) who assessed the indirect tensile response of artificially cemented soils reinforced with polypropylene fibres. They reported a sharp increase in the ITS peak value in addition to substantial modifications in the post-peak behaviour.…”

“…The indirect tensile test (ITS) was adopted in this study due to its simplicity and suitability. It was conducted based on ASTM D3379, as well as other relevant literature detailing this experimental procedure, either in soils (Dexter and Kroesbergen 1985;Cristelo et al 2017) or rock (Yu et al 2006) specimens. For this study, cylindrical specimens 100 mm in length and 50 mm in diameter were used, with similar curing conditions to those described for the UCS specimens.…”

“…Discrete fibre reinforcement is one of the physical methods of soil improvement, in which the strength of the original soil is enhanced by the addition of a reinforcing agent with high tensile strength (Tang et al 2007;Consoli et al 2012;Estabragh et al 2012;Fatahi et al 2012;Hejazi et al 2012;Correia et al 2015;Cristelo et al 2015Cristelo et al , 2017. Among different reinforcing possibilities, fibres represent a very interesting option for engineering applications, mainly due to their adaptability to conventional mixing techniques and low cost of fabrication (Lin et al 2010;Botero et al 2015;Huat 2016, 2017).…”

Splitting Tensile Strength of Cement Soil Reinforced with Basalt Fibers

“…The fiber has been used for improving the mechanical properties of the cement soil for many years. Previous studies had pointed out that whether increasing cement content or mixing basalt fiber will improve the splitting tensile strength of the cement soil [ 32 , 33 , 34 ]. The results of this study show that the splitting tensile strength of the cement soil reinforced with basalt fiber is indeed always greater than that of plain cement soil, and this difference will be enlarged with the development of curing time.…”

“…Several studies have proved that the fiber addition will help in achieving a great development in the strength of soils improved with lower cement content, and the impact of fiber length on the strength of the cement soils cannot be overlooked [ 5 , 34 , 38 ]. If longer basalt fiber is used, the mixing of the fiber and the cement soil would be very difficult and cause the distribution of the fiber in the cement soil to be extremely uneven.…”