Abstract

In this paper, two aerogel-based renders are characterized based on in-situ testing of walls prototypes. The in-situ tests to assess the mechanical performance are: pull-off, surface impact tests and compressive strength on collected samples. The physical performance includes the water resistance and thermal conductivity coefficient. The tests carried out to assess water-resistance are: Karsten tube, moisture meter and capillary water absorption of collected samples. The thermal performance was tested based on infrared thermography and thermal conductivity transient method. The combination of these in-situ tests allowed a better performance characterization of the aerogelbased renders and characterized the applied renders. These results were carried out under two national research projects (Nanorender and P2020 PEP).

Abstract

Earthfills are anthropogenic soil massifs that were originated by different processes than those observed in traditional soil mechanics, thus revealing some deviations to the behaviour of common natural soils. The common characterization of earthfills is based in discontinuous testing such as nuclear densimeter gauge used together with laboratory compaction tests and the stiffness evaluation obtained from plate load tests, which does not give answers in the context of strength evaluation (Cruz et al. 2008; Cruz et al. 2006). The case study presented herein refers to the geotechnical characterization of an earth fill composed by evolutive materials obtained from the de-structuration of schists, which has developed excessive settlements. The performed geotechnical characterization consisted in boreholes and regular SPT tests, Dynamic Probing (DPSH), Piezocone (CPTu) and Marchetti Dilatometer (DMT) tests, as well as triaxial, shear box, consolidation and identification tests. DMT and CPTu tests were selected not only to obtain strength and stiffness parameters, but also because of its ability to access stratigraphy and unit weights. The whole set of obtained results are presented, compared and discussed, revealing a clear convergence between results as well as some interesting particularities that may be useful in fill characterization.

Abstract

This study focuses on evaluating in-situ permanent deformation in fine-grained soils through the application of a specially designed Repeated Light Weight Deflectometer (LWD) test. The primary objective is to investigate how water content and applied stress levels influence permanent deformations in the field. Additionally, the study aims to assess the utility of LWD-derived data in predicting permanent strains. Results indicate a significant correlation between permanent deformations and key parameters, such as the number of load cycles, applied stress levels, and water content. It is observed that permanent deformations increase proportionally with these variables, particularly in cases of elevated water content and higher stress levels. The soil demonstrates an increased susceptibility to accumulating permanent deformations, persisting even after numerous LWD load applications. In response to these findings, a predictive model is presented to estimate accumulated permanent strain, exhibiting a commendable fit to data for moisture contents up to 22%, corresponding to an average water content of 19%. Ultimately, this research underscores the pivotal role of water content and applied stress levels in determining permanent deformation characteristics in fine-grained subgrade soils. The study also provides a valuable predictive model derived from repeated in-situ LWD measurements, offering critical insights into the field permanent deformation behaviour of subgrade soil. This simple and time-saving test enhances engineering practices for pavement design and construction.