Jose A. Ortiz-Lozano

Application of InSAR and Gravimetry for Land Subsidence Hazard Zoning in Aguascalientes, Mexico

In this work we present an application of InSAR and gravimetric surveys for risk management related to land subsidence and surface ground faulting generation. A subsidence velocity map derived from the 2007–2011 ALOS SAR imagery and a sediment thicknesses map obtained from the inversion of gravimetric data were integrated with a surface fault map to produce a subsidence hazard zoning in the city of Aguascalientes, Mexico. The resulting zoning is presented together with specific recommendations about geotechnical studies needed for further evaluation of surface faulting in these hazard zones. The derived zoning map consists in four zones including null hazard (stable terrain without subsidence), low hazard (areas prone to subsidence), medium hazard (zones with subsidence) and high hazard (zones with surface faulting). InSAR results displayed subsidence LOS velocities up to 10 cm/year and two subsidence areas unknown before this study. Gravimetric results revealed that the thicker sediment sequence is located toward north of Aguascalientes City reaching up to 600 m in thickness, which correspond to a high subsidence LOS velocity zone (up to 6 cm/year).

Effects of Static Magnetic Fields on the Physical, Mechanical, and Microstructural Properties of Cement Pastes

This paper presents the results of an experimental study carried out to comprehend the physical, mechanical, and microstructural behavior of cement pastes subjected to static magnetic fields while hydrating and setting. The experimental methodology consisted in exposing fresh cement pastes to static magnetic fields at three different magnetic induction strengths: 19.07, 22.22, and 25.37 Gauss. The microstructural characterization makes evident that there are differences in relation to amount and morphology of CSH gel; the amount of CSH is larger and its morphology becomes denser and less porous with higher magnetostatic induction strengths; it also shows the evidence of changes in the mineralogical composition of the hydrated cement pastes. The temperature increasing has no negative effects over the cement paste compressive strength since the magnetostatic field affects the process of hydration through a molecular restructuring process, which makes cement pastes improve microstructurally, with a reduced porosity and a higher mechanical strength.

Characterization of the Mechanical Properties of Ancient Masonry from a Non-destructive Method In Situ

This paper presents a methodology for determining the mechanical properties of the masonry elements by mean of seismic techniques and how these are included in a numerical model of a case study of a building. This work presents partial results of a research in process of doctoral thesis. It is part of the line of Non-Destructive Test (NDT) in situ that uses the measuring of seismic waves travel time to obtain shear and compressional waves; with these parameters it is possible to obtain the mechanical properties of the masonry of ancient buildings as Young’s Module, Poisson Ratio and density. The obtained data comes from a case study, the Temple of San Antonio de Padua, located in Aguascalientes, Mexico. In addition, a numerical model developed in SAP2000 is presented with the characterized properties obtained from the analysis. Results of this research will contribute future numerical analysis because it will be possible to obtain the values of each part of the building, and in this way, offer more reliable information about the behavior of the building.

Surface structure changes in cement paste exposed to 10.6μm laser radiation

We report the changes occurring in cement pastes irradiated by 10.6μm CO2 laser at different stages of hydration. Raman spectroscopy, X-rays and Scanning Electronic Microscopy (SEM) techniques had been used to observe molecular structural changes. Intensity of cement paste Raman peaks after laser irradiation was monitored in samples irradiated 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 days after their preparation. Applied laser power changed Raman peaks intensity at 187.5cm-1, 563cm-1, 695cm-1, 750cm-1, 897cm-1, 1042cm-1 and 1159cm-1 that corresponds to compounds already presents in cement pastes. X ray diffraction and SEM images confirm the recrystalization of cement paste compounds into new phases (alite and belite) after irradiation. The produced changes show a clear dependence on the applied laser power density and age of samples.