Flexural Behaviour of Cementitious Mortars with the Addition of Basalt Fibres.

Małgorzata Wydra,Piotr Dolny,Grzegorz Sadowski,Jadwiga Fangrat

doi:10.3390/ma14061334

Małgorzata Wydra, Piotr Dolny + Show 2 more

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https://doi.org/10.3390/ma14061334

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Abstract

The results of flexural tests of basalt fibre-reinforced cementitious mortars in terms of flexural strength and the occurrence of the bridging effect are summarised. Mixture proportions and curing conditions were altered for various series. The main parameters concerning mixture proportions were water to cement ratio (w/c), micro-silica and plasticiser addition and fibre dosage (1%, 3% and 6.2% by binder’s mass). Various curing conditions were defined by different temperatures, humidity and time. The influence of the amount of water inside the pores of the hardened cementitious matrix on the flexural strength values, as far as the impact of the alkaline environment on basalt fibres’ performance is concerned, was underlined. The designation of flexural strength and the analysis of post-critical deformations were also performed on the reference series without fibres and with the addition of more common polypropylene fibres. The bridging effect was observed only for the basalt fibre-reinforced mortar specimens with a relatively low amount of cement and high w/c ratio, especially after a short time of hardening. For the lowest value of w/c ratio (equalling 0.5), the bridging effect did not occur, but flexural strength was higher than in the case of non-reinforced specimens. Comparing mortars with the addition of basalt and polypropylene fibres, the former demonstrated higher values of flexural strength (assuming the same percentage dosage by the mass of the binder). Nevertheless, the bridging effect in that case was obtained only for polypropylene fibres.

Highlights

IntroductionThe performance properties of traditional construction mortars (including cementitious mortars) are based primarily on the specific proportions among the binder, the fine aggregate and water
The addition of basalt fibres was efficient in terms of the flexural strengthening of cementitious mortar only in the case of the lowest water to cement ratio, i.e., equal to 0.5 (Figure 4), even though the amount of added fibres was lowest in that case (5.0 kg/m3 )
It is worth mentioning that micro-silica and plasticiser were used in this mixture proportion (BCF3_28D)

Summary

Introduction

The performance properties of traditional construction mortars (including cementitious mortars) are based primarily on the specific proportions among the binder, the fine aggregate and water. Their high compressive strength makes them suitable as binding material in connections of two structural elements, such as brick to brick or any end connection of beam and column. Their limitations in such applications, result mostly from their brittle behaviour and the ease of cracking because of shrinkage, concentration of stresses, low tensile strength and weakness in impact resistance [1]. User demand is growing, which enforces the continuous development of mortar technology and production [2]

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