Miguel Vicente

Universidad de Burgos | UBU · Civil Engineering

This paper shows a new low-cost technology for the measurement of crack propagation in quasi-fragile materials based on a stereo pair of cameras and LED light spots. The two cameras record the displacement experienced by a series of LED white lights. For each frame, the X , Y and Z 3D coordinates of all the centroids of the LED points are obtained....

This study deals with the influence of the fiber concrete mesostructure on the size effect under compressive fatigue loading. For this purpose, three series of cylindrical specimens of steel fiber–reinforced concrete were fabricated. Before fatigue testing, all the cylinders were scanned and the main morphological, orientation, and distribution par...

Service-learning methodology is designed to combine student learning with service to society, promoting project-based learning and establishing a fruitful interrelationship between both academic and social spheres. This teaching method is neither frequently employed on technical degrees nor particularly on civil engineering degrees, even though the...

The size effect on the compressive fatigue behaviour of fibre-reinforced concrete is herein studied by testing cubes of 40 mm, 80 mm and 150 mm in edge length. Even though the compressive strength resulted the same in the three cases due to the ductility of the material in this range of sizes, the size effect was evident on the fatigue response of...

Long-term monitoring of horizontal movement of the top of vertical elements, such as towers of historical monuments or chimneys, remains a challenge with current solutions. In such structures, which are usually of high historical and cultural value, ageing and structural degradation directly impact their horizontal movement. This study presents a n...

This paper shows a teaching experience related to the use of computed tomography in the teaching of concrete for undergraduate students of the civil engineering degree. This experience reveals that computed tomography is a powerful tool to facilitate the understanding of all those aspects related to the microstructure of concrete, thus facilitating...

This paper shows the scientific possibilities of computed tomography for the study of concrete porosity. The enormous technological advances in computed tomography equipment used in materials research, with increasingly higher energy, better resolution and smaller pixel size will allow, in the near future, viewing pore sizes that are currently unth...

In this work, the effects caused by both the amount of air-entraining agent (AEA) and freeze-thaw cycles on microstructure of high-strength concrete have been analyzed. For this purpose, five series of concrete specimens have been manufactured, each of them containing a different amount of AEA. Then, all series have been subjected to up to 300 free...

Deflection measurements on structures continue to be a challenge with current sensor technologies. Material degradation and changes in the mechanical properties over time (e.g. creep and shrinkage in concrete bridges) directly impact the deflections exhibited by a structure. In this article, we introduce and discuss the evaluation of a novel laser-...

Bridge designers tend to extend the deck slab width beyond the exterior girders, over a distance called the overhang, to increase the width of the bridge without adding extra girders. Moreover, the screed machine used in finishing the surface of the deck slab usually rests on the edges of the overhang. The machine weight combined with the weight of...

Traditional bridge monitoring systems often require wired connections between sensors, a data acquisition system, and data center. The use of extension wires, conduits, and other costly accessories can dramatically increase the total cost of bridge monitoring. With the development of wireless technologies and the notable cost benefits, many researc...

La tomografía computerizada (TC) es una tecnología muy potente para el estudio de la microestructura de los materiales, lo que se refleja en la gran cantidad de trabajos publicados durante los últimos años. Más allá de su conocido uso en medicina, la TC se ha extendido a otros muchos campos científicos. En este trabajo se recogen algunos de ellos,...

This paper analyses the influence of the presence of polypropylene fibres in the microstructure of a high-strength self-compacting concrete by X-ray computed tomography and its consequences on the mechanical and fracture properties. The addition of PP fibres alters the pore structure of the concrete matrix, and this affects the macroscopic response...

La tomografía computerizada (TC) es una tecnología muy potente para el estudio de la microestructura de los materiales, lo que se refleja en la gran cantidad de trabajos publicados durante los últimos años. Más allá de su conocido uso en medicina, la TC se ha extendido a otros muchos campos científicos. En este trabajo se recogen algunos de ellos,...

Computed tomography (CT) scanning is a very powerful technology for microstructural study of materials, as can be checked in the huge amount of papers published in recent years. Beyond its well-known use in medicine, CT scanning has spread to many other scientific fields. Some of them are revised in this work, with particular interest in concrete t...

This paper analyzes the pore morphology of two different concrete mixtures (plain and fiber-reinforced) under two different curing conditions, through the use of a CT scanner and post-processing software. Twelve cylinders of 45.2 mm in diameter and 50 mm in height were cast. Half of the specimens were kept in a humidity-controlled room, at 20 °C an...

This research develops a new low-cost energy dissipation system, capable of being implemented in residential structures in developing countries with high seismic activity, in which the current solutions are not economically viable. These residential structures are entirely made of precast concrete elements (foundations, walls, and slabs). A solutio...

The response ranges of three principal mechanical parameters were measured following cyclic compressive loading of three types of concrete specimen to a pre-defined number of cycles. Thus, compressive strength, compressive modulus of elasticity, and maximum compressive strain were studied in (i) plain, (ii) steel-fiber-reinforced, and (iii) polypro...

The effects of the fiber orientation and content on the behavior of steel fiber-reinforced concrete (SFRC) under static and cyclic compressive loads are studied using the computed tomography (CT) technique, and the resistance mechanisms of the fibers are carefully observed. The results suggest that the intrinsic scatter in the fatigue life could be...

During bridge construction, many loads affect its behavior and can be critical to its future performance. The screed machine and the fresh concrete loads acting on the overhang portion of the deck slab are very significant since they cause unbalanced eccentric loads, resulting in deflection of the overhang and rotation of the exterior girders. More...

The unbalanced eccentric loads on the overhang portion of the deck slab during construction cause excessive rotation in the exterior girders and deflection of the overhang formwork. Hence, issues during the construction occur in addition to future deficiencies in the deck slab. This study investigates the effect of different lateral bracing system...

In this paper, two concrete mixtures of plain concrete (PC) and steel fiber-reinforced high-performance concrete (SFRC) have been scanned in order to analyze the variation of the pore morphology during the first curing week. Six cylinders of 45.2-mm diameter 50-mm height were performed. All of the specimens were kept in a curing room at 20 °C and 1...

Wide flange beams are widely used in the United States for bridge design and construction. During the overhang construction of the bridge, torsional loads are often induced due to the fresh concrete load and the use of a deck finishing machine located on the overhang formwork. These torsional moments sometimes cause excessive exterior girder rotati...

The monitoring of static vertical deflections on bridges is still a first-level technological challenge. These data are very useful to understand and to assess the behavior of structural elements in civil engineering, especially for the case of long-term monitoring. The reason is that the material degradation processes and the changes of the mechan...

Pore morphology and its changes at an early age in two different mortar mixtures are analyzed by means of a CT-Scan and DIP software. Both mixtures share the same cement paste composition. The only difference between them is the inclusion of 0.1% by volume of steel fibers in one paste and its omission from the other paste. A total of six specimen c...

Computed tomography (CT) technique is of increasing interest in research related to concrete technology. This technology provides the possibility of visualize the internal structure of concrete, including pores, cracks, aggregates and fibres. In this paper, the CT scan is used to determine the position and orientation of the fibres in case of steel...

This paper demonstrates the widely accepted hypothesis that the compressive testing is a particular case of a cyclic test where failure occurs during the first cycle. To perform this, a test on 32 fiber-reinforced high-performance concrete specimens have been carried out. Sixteen of them have been tested under low-cycle fatigue compressive loading...

The correlations between fiber orientation and residual tensile strength and fracture energy in steel-fiber-reinforced concrete are analyzed with Computed Tomography (CT) Scanning, Digital Image Processing (DIP) software, and the Wedge Splitting Test (WST). A mixture containing 2% by volume of steel fibers was performed to cast a total of six prism...

Over the past two decades, immense research efforts at a global level have extended CT-Scan technology across several engineering fields. The state-of-the-art of the most relevant research related to the use of CT-Scanning is presented in this paper, which explores microstructural studies of materials used in various fields of engineering, with esp...

Fiber-reinforced concrete (FRC), its behavior, and the effects of cyclic loading on its internal microstructure are studied in this paper. Particular attention is given to the evolution of the residual tensile strength of the fiber-reinforced concretes and damage following cyclic flexural loading. A numerical equation is also proposed to estimate t...

Most fatigue models for concrete under compression assume, as an axiom, that compressive tests are a limit case for a cyclic test where failure is achieved in the first cycle. This is supported by the fact that the crack patterns obtained in both cases are similar to the naked eye. This paper focuses on verifying whether this observation is correct...

The mechanical behavior under flexural tensile stress of fiber-reinforced concretes is strongly conditioned by fiber density and orientation; in particular, the residual strength values under tensile stress forces. However, although a lot of research has been conducted to understand how the casting and type of compaction affects the fiber distribut...

The measurement of static vertical deflections on bridges continues to be a first-level technological challenge. These data are of great interest, especially for the case of long-term bridge monitoring; in fact, they are perhaps more valuable than any other measurable parameter. This is because material degradation processes and changes of the mech...

The use of porous concrete in structural elements subjected to compression cyclic loads is inevitable in those situations in which it is necessary to withstand, simultaneously, important amount of freeze-thaw cycles and cyclic loads. However, the presence of pores, which is essential to withstand freeze-thaw cycles, can drastically reduce the fatig...

The high scatter of the compressive fatigue life of concrete and fiber reinforced concrete, which may normally reach two orders of magnitude, is caused not only by material heterogeneity, but also by the random nature of the unwanted eccentricity during the tests. It mainly arises from misalignments due to manual specimen centering, although tolera...

Long-term monitoring of in-service bridges is useful for estimating the structural condition and [...]

p>During the last two decades, there has been a significant increase of the number of footbridges including elevators. This is a very interesting solution to reduce the space of the lateral accesses to the bridge and to increase the comfort of the users, especially in case of handicapped users. In addition, the progressive reduction of the costs of...

The effect of fatigue loads on one of the main mechanical properties of fiber-reinforced high strength concrete (FRHSC) is studied in this work. In particular, this paper analyzes the variations in the residual tensile strength of steel fiber-reinforced concretes following cyclic flexural loading, which causes a predefined level of damage. To do so...

Esta investigación se centra en analizar la relación que existe entre la orientación de las fibras y su densidad, por un lado, y la resistencia residual a tracción del hormigón reforzado, por otro. Para ello se fabricó una viga pared de hormigón reforzado con fibras metálicas, del que se extrajeron una serie de probetas prismáticas, de diferentes z...

Fatigue is the process of mechanical degradation of a material, which leads to its collapse. Repeated load applications with a maximum value lower than the one that provokes the static failure of the material, causes internal damage in the material that, progressively, reduces its mechanical capacity until it finally collapses. The increasingly wid...

El hormigón sumergido ha sido utilizado en la construcción desde la antigüedad, generalmente ante la imposibilidad, o inconveniencia, de conseguir un recinto seco para su puesta en obra. Sin embargo, esta utilización se ve perjudicada por el lavado de las partículas de cemento de la masa de hormigón, lo cual produce un deterioro de sus propiedades...

The variations of three residual mechanical parameters in a set of partially prestressed, precast concrete I-beams after being subjected to concentrated high-level cyclic loading are presented and discussed. These three mechanical parameters are flexural stiffness, natural frequency, and crack width. Two precast prestressed I-beams were tested unde...

This paper evaluates variations in the residual tensile strength of prismatic specimens made of steel fiber-reinforced high-strength concrete (SFRHSC) attributable to flexural cyclic loading. All specimens were previously subjected to a three-point static bending load test until the first flexural crack appeared. In these cases, no notched specimen...

There has been a rapid development of high-speed rail in Spain. Many bridges have been constructed to carry these lines. The relevant Spanish design codes require static and dynamic testing of these structures for acceptance of the design and construction before opening for service; such testing is considered too costly in some other countries. Thi...

This paper discusses the residual modulus of elasticity of and maximum compressive strain in high‐strength concrete (HSC) and fibre‐reinforced high‐strength concrete (FRHSC) after being subjected to axial high‐stress‐level cyclic loading. The paper presents a specific procedure for evaluating the residual values of these mechanical parameters of co...

Computed tomography (CT) is a nondestructive technique, based on absorbing X-rays, that permits the visualisation of the internal structure of materials in micron-range resolution. In this paper, the CT scan is used to determine the position and orientation of the fibres in steel fibre-reinforced high-strength concrete elements. The aim of this pap...

A limited number of investigations have been carried out to assess the cyclic bond behaviour of reinforcing steel bars in underwater concrete (UWC). An experimental campaign with 57 pull-out specimens was undertaken, testing one mixture previously developed and characterized to be used in a cable-stayed bridge project. Half of the specimens were ca...

This paper describes the development of a computerized closed-loop testing facility for experimentally obtaining the stress-strain behaviour of high strength concrete specimens under combined compression and bending. Using this closed-loop computerized testing facility, 240 test specimens were tested to failure. The test variables were geometry or...