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Arganda Del Rey, Spain

Segura I.,Cartif Technology Center | Sanchez E.,Technical University of Madrid | Moragues A.,Polytechnic University of Mozambique | Hernandez M.G.,CAEND CSIC UPM
Construction and Building Materials | Year: 2010

This work presents the results obtained in a long-term experiment focused on the study of the evolution of cementitious materials immersed in pig slurry at real conditions. Cement mortars were made with four different cement types and immersed in pig slurry for 48 months. Furthermore, to separate pure hydration process from pig slurry effect, mortar samples were immersed in water for 12 months at laboratory conditions. Compressive strength, X-ray diffraction and ultrasonic measurements were made in all samples. Ultrasonic measurements were made from ultrasonic images obtained from automatic ultrasonic inspections. Use of ultrasonic images has allowed the extraction of information about the state of the studied materials. An empirical relationship between ultrasonic velocity and compressive strength has been obtained and the long-term effect of pig slurry on cementitious materials has been determined. © 2010 Elsevier Ltd. All rights reserved. Source

Segura I.,Cartif Technology Center | Molero M.,CAEND CSIC UPM | Aparicio S.,CAEND CSIC UPM | Moragues A.,Polytechnic University of Mozambique
Measurement Science and Technology | Year: 2010

The combination of a staining method and an automatic digital image-processing algorithm is presented here, to measure degradation depths in cementitious materials. The measurement of those degraded depths is usually made by direct visual measurements, resulting in many errors and low reproducibility. The automatic digital image analysis (ADIA) method proposed here is mainly based on the differentiation of the degraded zone and the sound zone on the basis of the image histogram. The method comprises several steps, such as sample alignment, image calibration, background subtraction, image filtering, automatic segmentation and final measurement of the degraded depth. The algorithm developed has been used to measure the degraded depths of a set of decalcified cement mortars, made from different cement types and with varying w/b ratios. Relative to previous methods, this automatic procedure improves the precision (about 0.03 mm) and the statistical representation of the measurements. The results obtained by ADIA were compared with direct visual measurements with a very good correlation (R2 = 0.96) and a mean error of 6%. © 2010 IOP Publishing Ltd. Source

Molero M.,CAEND CSIC UPM | Segura I.,Cartif Technology Center | Aparicio S.,CAEND CSIC UPM | Hernandez M.G.,CAEND CSIC UPM | Izquierdo M.A.G.,Polytechnic University of Mozambique
Ultrasonics | Year: 2010

This paper deals with the measurement of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials, such as cementitious materials. To improve the measurement of this parameter on this kind of materials, a linear swept-frequency signal is used to drive an emitter transducer to conduct a through-transmission inspection in immersion. To filter out undesirable frequency content, time-frequency filtering and detection process are performed. The use of this method has been compared with two excitation techniques, the broadband and the narrowband pulses. The results obtained using the swept-frequency excitation together with the time-frequency filtering, allows the determination of the attenuation curves with high accuracy over a wide frequency range without the need for complicated equipment, and improves the effective bandwidth by using a unique pair of transducers. © 2010 Elsevier B.V. All rights reserved. Source

Molero M.,CAEND CSIC UPM | Segura I.,Cartif Technology Center | Hernandez M.G.,CAEND CSIC UPM | Izquierdo M.A.G.,Polytechnic University of Mozambique | Anaya J.J.,CAEND CSIC UPM
Ultrasonics | Year: 2011

This paper examines ultrasonic wave propagation through strongly heterogeneous materials such as cementitious materials, and deals meanly with the formulation of a multiphase approach of a self-consistent multiple scattering model, the so-called dynamic generalized self-consistent model (DGSCM) proposed by Yang [J. Appl. Mech. 70(2003) 575-582]. This extended model can describe the influence of the size and volume fraction of aggregates on cementitious materials, as well as the interaction, contribution, and influence of entrapped air voids together with the aggregates on frequency-dependent parameters such as the phase velocity and the attenuation coefficient. To show the performance of this approach, theoretical predictions were compared with experimental ultrasonic measurements over a wide frequency range from several mortar specimens with different features in their microstructure properties and concentrations of aggregates up to 60%. The multiphase approaches of both the DGSCM and the Waterman-Truell model (WT) were also compared. The obtained results of the multiphase DGSCM were found to be significantly better than those obtained from the N-phase WT model for ultrasonic measurements from cementitious materials at high aggregate concentrations. The feasibility of material characterization using the multiphase approach of DGSCM was also discussed. © 2010 Elsevier Ltd. All rights reserved. Source

Aparicio S.,CAEND CSIC UPM | Fuente J.V.,Spain Technological Institute for Construction | Ranz J.,CAEND CSIC UPM | Aliques J.,Spain Technological Institute for Construction | And 2 more authors.
RILEM Bookseries | Year: 2012

Traditionally, the study of cementitious materials has been performed using wired sensor technologies. Because these technologies are expensive and difficult to install, the use of wireless sensor networks has gained increasing importance. In this paper, the study of setting and hardening processes for two different types of self-compacting concrete (SCC) using a wireless monitoring system is reported. The monitoring system used to perform such study consists of a wireless sensor network using Cricket motes. These motes were purchased from Crossbow Technologies. For our research, the most important capability of Cricket motes is that they host a transmitter/receiver in the ultrasonic wavelength region. For monitoring the setting and hardening processes, the velocity of the ultrasonic pulse traveling across the material was measured, along with the humidity and temperature values both inside and outside the concrete sample. Multi-hop data transmission techniques were considered to monitor the velocity data. Several experiments were performed at the laboratory. A set of samples were manufactured with two types of SCC, in one type some portland cement was replaced by limestone filler. These specimens were exposed to different curing conditions. Although it was found that the ultrasonic acquisition was not very robust, the wireless sensor networks are an efficient technology for monitoring the early stages of self-compacting concrete. © RILEM 2013. Source

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