An Embedded Stress Sensor for Concrete SHM Based on Amorphous Ferromagnetic Microwires

A new smart concrete aggregate design as a candidate for applications in structural health monitoring (SHM) of critical elements in civil infrastructure is proposed. The cement-based stress/strain sensor was developed by utilizing the stress/strain sensing properties of a magnetic microwire embedded in cement-based composite (MMCC). This is a contact-less type sensor that measures variations of magnetic properties resulting from stress variations. Sensors made of these materials can be designed to satisfy the specific demand for an economic way to monitor concrete infrastructure health. For this purpose, we embedded a thin magnetic microwire in the core of a cement-based cylinder, which was inserted into the concrete specimen under study as an extra aggregate. The experimental results show that the embedded MMCC sensor is capable of measuring internal compressive stress around the range of 1-30 MPa. Two stress sensing properties of the embedded sensor under uniaxial compression were studied: the peak amplitude and peak position of magnetic switching field. The sensitivity values for the amplitude and position within the measured range were 5 mV/MPa and 2.5 mu s/MPa, respectively.

The patents in the introduction of reinforced concrete in Spain: "Alhondiga de Bilbao" case study

Reinforced concrete structures are introduced in Spain mainly by French influence. This happens in the late nineteenth century, following the scheme operating through proprietary systems prevailing in Europe. Systems initially have poor scientific support reaching, even early twentieth century, an impediment to the development of concrete structures, due to the lack of knowledge shown, as well as due to a series of accidents. Therefore, from the end of the first decade of the past century are enacted a series of regulations in many countries, that will change the design and calculation of reinforced concrete structure. The knowledge of the environment of the patent systems, its beginnings and the circumstances of their application allow us to understand the constraints of the early concrete structures, as presented in the Bilbao wine store (1906).

Optimization study of the structural HACFRA composition (Self Compacting Concrete Steel Fiber Reinforced)

The interest of HACFRA (self compacting concrete reinforced with steel fibers), is the combination of the residual strength increase and cracking decrease compared to plain concrete by the introduction of steel fibers in the mass with the advantages of the self-compacting. The paper presents an analysis of the influence of different components of the HACRFA and provides their selection, refered to the granular skeleton and to different steel fiber types and amount, in order to obtain an optimization of its features and structural behavior.