Failure of Railway Embankment

This article deals with the failure of a railway embankment in North Peloponese. The geotechnical investigation that followed aimed to specify the causes of the failure. The results of the above investigation are presented, an evaluation of the causes of failure is discussed and the remedial measures which \u27have been taken are thoroughly described

Twenty Years After The Economic Restructuring Of Eastern Europe: An Economic Review

Twenty years ago, the world witnessed the beginning of one of the most dramatic changes in economic systems.  It was the 1989 revolutionary changes in Poland that initiated the collapse of the Soviet-style command economic system of Eastern Europe and the Soviet Union.  The economic system transformation that followed did not have any precedent or established theories to rely upon.  Thus, some countries opted for a “shock therapy” approach while most opted for the “gradual therapy” approach to economic restructuring.  This paper reviews the impact of such unprecedented economic transformation and attempts to shed some light on the relative success of such changes and policies -- twenty years after the collapse of the communist regime in Poland that initiated the ‘domino effect’ of the Eastern European command economies collapse

The effect of varying volume fraction of microcapsules on fresh, mechanical and self-healing properties of mortars

Spherical polymeric microcapsules, carrying liquid sodium silicate, were used for autonomic self-healing of mortars. Microcapsules were added at varying volume fractions (V$_f$), with respect to the cement volume, from as low as 4% up to 32% and their effect on fresh, mechanical and self-healing properties was investigated. For this purpose a series of techniques were used ranging from static mechanical testing, ultrasonic measurements, capillary sorption tests and optical microscopy. A detailed investigation was also carried out at the microstructural level utilising scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Results showed that although increasing V$_f$ resulted in a ~27% reduction in the mechanical properties, the corresponding improvement in the self-healing potential was significantly higher. Areal crack mouth healing reached almost 100%. Also, the measured crack depth and sorptivity coefficient reduced to a maximum of 70% and 54% respectively in microcapsule-containing specimens. SEM/EDX observations showed that the regions in the periphery of fractured microcapsules are very dense. In this region, high healing product formation is also observed. Elemental analysis revealed that these products are mainly ettringite and calcium-silicate-hydrate (C-S-H).Engineering and Physical Sciences Research Council (Project Ref. EP/K026631/1 – ‘‘Materials for Life”)This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.conbuildmat.2016.06.11

First UK field application and performance of microcapsule-based self-healing concrete

Maintaining the health and reliability of our infrastructure is of strategic importance. The current state of the UK infrastructure, and the associated huge costs of inspection, maintenance, repair and eventual replacement, is not sustainable and is no longer environmentally viable. The design of infrastructure, mainly concrete, remains traditional and poor material performance continues to be the main cause of deterioration and failure in our infrastructure systems. Biomimetic materials, that emulate natural biological systems in their ability to self-healing, provide an exciting and plausible solution. Embedding cementitious materials with in-built capabilities to sense and respond to their environmental triggers could potentially eliminate all external interventions and deliver a resilience infrastructure. The work presented in this paper forms part of a national initiative that has been developing biomimetic cementitious infrastructure materials which culminated in the first large-scale field trials of self-healing concrete in the UK testing four different but complementary technologies that were developed. This paper focuses on one self-healing technology, namely microcapsules, which contain a healing agent that is released on their rupture as a result of crack propagation. The paper will present details of the microcapsules used, their implementation in concrete and in the field trials and time-related, field and laboratory, assessment of the self-healing process. It also highlights challenges faced and improvements that are now on-going to produce the next generation of the microcapsule self-healing cementitious system

Polymeric microcapsules with switchable mechanical properties for self-healing concrete: synthesis, characterisation and proof of concept

Microcapsules, with sodium silicate solution as core, were produced using complex coacervation in a double, oil-in-water-in oil, emulsion system. The shell material was a gelatin–acacia gum crosslinked coacervate and the produced microcapsules had diameters ranging from 300 to 700 μm. The shell material designed with switchable mechanical properties. When it is hydrated exhibits soft and ‘rubbery’ behaviour and, when dried, transitions to a stiff and ‘glassy’ material. The microcapsules survived drying and rehydrating cycles and preserved their structural integrity when exposed to highly alkaline solutions that mimic the pH environment of concrete. Microscopy revealed that the shell thickness of the microcapsules varies across their perimeter from 5 to 20 μm. Thermal analysis showed that the produced microcapsules were very stable up to 190 °C. Proof of concept investigation has demonstrated that the microcapsules successfully survive and function when exposed to a cement-based matrix. Observations showed that the microcapsules survive mixing with cement and rupture successfully upon crack formation releasing the encapsulated sodium silicate solution.Financial support from the Engineering and Physical Sciences Research Council (EPSRC—United Kingdom) for this study (Project Ref. EP/K026631/1—‘Materials for Life’) is gratefully acknowledged

ΥΔΡΟΛΟΓΙΚΗ ΑΠΟΚΡΙΣΗ ΤΗΣ ΛΕΚΑΝΗΣ ΑΠΟΡΡΟΗΣ ΤΟΥ ΧΕΙΜΑΡΡΟΥ «ΜΠΑΣΔΕΚΗ» ΟΛΥΜΠΙΑΔΑΣ ΣΤΗΝ ΚΑΤΑΙΓΙΔΑ ΤΗΣ 25ης ΝΟΕΜΒΡΙΟΥ 2019

Στις 25 Νοεμβρίου του 2019, ισχυρή βροχόπτωση με υψηλή ραγδαιότητα έπληξε την Ανατολική Χαλκιδική που είχε ως αποτέλεσμα καταστροφικά πλημμυρικά φαινόμενα. Στην παρούσα εργασία αναλύεται η απόκριση της λεκάνης απορροής του χειμάρρου «Μπασδέκη», κοντά στον οικισμό της Ολυμπιάδας, κατά την διάρκεια του φαινομένου.  Για τον σκοπό αυτό εκτιμήθηκε η απορροϊκή βροχόπτωση με την μέθοδο του απορροϊκού συντελεστή Curve Number (CN) και το υδρογράφημα της πλημμύρας με τη χρήση του συνθετικού μοναδιαίου υδρογραφήματος της Soil Conservation Service (SCS). Επίσης, εφαρμόστηκε η μέθοδος των Stiny - Herheulidze για τον υπολογισμό της στερεοπαροχής. H μέγιστη πλημμυρική αιχμή εκτιμήθηκε ίση με 140,7 m3/sec και η στερεοπαροχή ίση με 44,8 m3/sec. Οι παραπάνω τιμές δεν μπόρεσαν να διοχετευτούν και το νερό υπερχείλισε από την κοίτη του χειμάρρου. Από την ανάλυση των παραγόντων πλημμυρογένεσης προέκυψε ότι η ραγδαιότητα της βροχόπτωσης και ο διαποτισμός του εδάφους, από τις βροχοπτώσεις προηγούμενων ημερών, συνέβαλαν στην δημιουργία του έντονου πλημμυρικού φαινομένου στην Ολυμπιάδα. Τα αποτελέσματα της παρούσας εργασίας συμβάλουν στην  κατανόηση των αιτιών και του μηχανισμού λειτουργίας των πλημμυρικών φαινομένων στα χειμαρρικά ρεύματα

Deficit and External Debt Effects on Money and Inflation in Brazil and Mexico: Some Evidence

The purpose of this study is to examine the monetarist propositions regarding the effects of budget deficits, external debt, and money growth on inflation in the cases of Brazil and Mexico. To this end, a money growth equation and a price equation have been specified and estimated for empirical analysis. In general, it is concluded that the government budget deficit is not a determinant of money supply growth or of inflation. External debt is found to be a significant factor of money growth. Also, the results suggest a significant effect of money supply growth on inflation.