Abstract
This paper presents an experimental study on the dynamic compressive behaviour of polypropylene (PP) fibre reinforced concrete under various strain rates using split Hopkinson pressure bar (SHPB) equipment. The effects of PP fibre content and strain rate on the dynamic compressive stress-strain relationship and failure patterns were estimated. The results indicated that the addition of PP fibre enhanced the dynamic compressive properties of concrete mixtures although it resulted in a significant reduction in workability and a slight decrease in static compressive strength. Considering the workability, static compressive strength and dynamic compressive behaviour, the optimal PP fibre content was found to be 0.9 kg/m3 as the mixture exhibited the highest increase in dynamic compressive strength of 5.6%, 40.3% in fracture energy absorption and 11.1% in total energy absorption; further, it showed the least reduction (only 5.8%) in static compressive strength among all mixtures compared to the reference mixture without fibre. For all mixtures, the dynamic compressive properties, energy absorption capacity, strain at peak stress, ultimate strain and dynamic increase factor (DIF) were significantly influenced by strain rate, i.e., strain rate effect. When the strain rate was relatively low, PP fibres were effective in controlling the cracking, and the dynamic compressive properties of PP fibre reinforced mixtures were improved accordingly.
Highlights
Concrete is the most widely used construction material in the world [1]
The slump test was conducted in accordance with ASTM C143-15a [32] to determine the workability of all fresh concrete mixture, where the test involved in measuring the vertical displacement difference
The workability, static compressive strength and dynamic compressive properties of concrete reinforced with PP fibres with various fibre content (i.e., 0.9, 1.8, 2.7 and 3.6 kg/m3 ) were investigated and compared with those of the reference mixture without fibre (PP00)
Summary
Normal concrete is inherently brittle when subjected to static (including tensile and flexural) and high-velocity dynamic loadings, and is susceptible to cracking induced by unsuitable curing conditions, freeze-thawing and shrinkage [2,3,4,5]. High-strength concrete is usually supplied by the protective structures under dynamic impact loading. In order to overcome the aforementioned shortcomings, many researchers have attempted to incorporate randomly distributed short fibres (i.e., steel, polypropylene and basalt fibres) into the concrete matrix. The inclusion of these short fibres into the concrete results in a significant increase of Materials 2019, 12, 1797; doi:10.3390/ma12111797 www.mdpi.com/journal/materials
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