Experimental Campaign to Verify the Suitability of Ultrasound Testing Method for Steel Fiber Reinforced Concrete Fortification Structures

Abstract

Fortification structures, both military and civilian, are designed to resist a blast explosion to some extent. Their technical condition after a blast load must be assessed in a fast and reliable way to enable the users’ decision about the future use of the structure. Preferably, for the assessment of the protective structure, the non-destructive testing method should be used. To assess the suitability of ultrasound testing method for fortification structures built from steel fiber reinforced concrete, an investigation in a laboratory and in situ was conducted, together with numerical simulation and statistical evaluation. The numerical simulation of the blast load of a steel fiber reinforced concrete slab was conducted using multiphysics simulation software with the aim to verify basic parameters of the field experiment. During the field tests, several slabs were loaded by plastic explosive and changes in the structure of the slabs, before and after the blast load, were examined using the ultrasound pass-through method. After the field tests, the slabs were subjected to a destructive laboratory test to determine their residual strength. Subsequently, the data sets obtained from the measurements were tested using functional data analysis. The results from the ultrasound pulse method show that specimens after a dynamic blast load can in some cases increase the strength of their cement matrix.

The Effect of Bottom Reinforcement Spacers on Reinforced Concrete Structures Loaded by Explosion

“…The reinforced concrete (RC) was produced as a reference material to the two sets of specimens made of steel fiber reinforced concrete (SFRC) and ultra-high-performance steel fiber reinforced concrete (UHPSFRC), used for the Experimental Campaign to Verify the Suitability of Ultrasound Testing Method for Steel Fiber Reinforced Concrete Fortification Structures, published in [13][14][15]. The recipe for 1 m 3 of mix is given in Table 1.…”

“…To simulate the blast loading of the structure, an improvised test structure was chosen to simulate the action of the test slab in a real structure by supporting the slab along the entire perimeter, and the explosive was suspended above the slab at a distance of 580 mm (Figure 2). The test structure was assembled from a precast reinforced concrete socket foundation [13]. This stand-off distance of the explosive from the slab was chosen in accordance with the assumption, based on experience with the blast loading of reinforced concrete structures, that the blast will cause ray-like crack development on the reverse side of the slab from the blast due to slab deflection without partitioning the slab into multiple fragments.…”

Study of the Healing Effect of Concrete with Supplementary Cementitious Materials after Early-Age Damage by Acoustic Emission Technique

“…The characteristic of real-time monitoring of acoustic emission technique can evaluate the material performance or structural integrity by analyzing the elastic wave signals. Thus, compared to other non-destructive testing (NDT) methods, such as digital imaging technology [7], ultrasound method [8], electrical resistivity [9][10][11], and computed tomography scanning method [12], the acoustic emission method is more convenient in data collection and analysis. In recent years, the acoustic emission method has developed considerably.…”

Post-impact flexural capacity of UHPFRC plates

“…This ensures the uniform resistance of the ballistic element in its entire volume, which is a clear advantage over conventional concrete bar reinforcement. Previous research on the dynamic testing of high-performance fibre-reinforced concrete and foam concrete is described in [6,7,8,9].…”