Dynamic enhancement of blast-resistant ultra high performance fibre-reinforced concrete under flexural and shear loading

Abstract

Two independent projects are described in which drophammer techniques are used to investigate the dynamic increase factor (DIF) under both flexural and shear high-speed loading of a new ultra high performance fibre reinforced blast resistant concrete. The results from both studies correlate well. The results show that a DIF of the flexural tensile strength rising from 1.0 at 1 s -1 on a slope of 1/3 on a log (strain rate) versus log (DIF) plot can be used for design purposes. The results also show that no DIF should be used to increase the shear strength at high loading rates.

Development of an eco-friendly Ultra-High Performance Concrete (UHPC) with efficient cement and mineral admixtures uses

“…Due to the specific cementitious system of UHPC (very small water/binder ratio and relatively high SP amount), it is observed that the pozzolanic reaction of FA is significantly retarded, which causes that a very limited amount of FA can react with Ca(OH) 2 after curing for 91 days. Makita T. [76] Máca P. [77] Habel K. [78] Wang W. [79] Habel K. [80] Corinaldesi V. [81] Millard S.G. [82] S.L. Yang [14] Deeb R. [83] Yazici H. [84] Reference in this study y = 6.003x + 62.732 R 2 = 0.854 Fig.…”

“…11. Comparison of embedded CO 2 emission of the developed eco-friendly UHPC (EUHPC) and other UHPCs or UHPFRCs [14,[75][76][77][78][79][80][81][82][83][84].…”

The addition of synthetic fibres to concrete to improve impact/ballistic toughness

“…Impact by a high speed point load, such as a bullet, has similarities with a small standoff blast (Millard et al, 2009) and this has informed the test methodology. An explosion near a concrete wall causes a high speed compressive stress wave to load the front face of the wall (Millard et al, 2009), resulting in initial front face spalling Almansa and Canovas (1999).…”

Spalling of concrete subjected to blast loading

“…The sides of the specimen were damaged severely. The deflection was 295 mm on the left side and 310 mm on the 07005-p. 2 The area of the puncture is 0.26m 2 , volume 0.08m 3 , which represents 2.9% of the total volume of the specimen. Total volume of the damaged concrete (puncture + spalling) is 0.15m 3 , which represents 5.6% of the total volume of the specimen.…”

“…This rebound causes tensile stresses at the soffit of the material (as described in [2]). The concrete in the concrete cover is not able to cover these tensile stresses and spalls of the specimen (Fig.…”