Abstract

The effect of waterproof membrane and steel reinforcement protection on the concrete bridge deck is modeled. The attention is paid to the durability prediction related to steel reinforcement corrosion initiation based on the chloride penetration. Thus 2-D finite element chloride ingress model is applied. The transient finite element model serves to solve Ficks second diffusion law using the computer tool compatible with the Matlab environment. The model focuses on the transport of chloride ions through a reinforced concrete bridge deck with and without the effect of waterproof membrane and on an estimate of the concentration of chlorides at the reinforcement level or in places with damage to the epoxide coating of the reinforcement. The model allows the incorporation of damage to the waterproof insulation under the asphalt coating. The time to chloride induced onset of corrosion is predicted and results are compared. The effect of water proof membrane reinforcement protection strategy typical for Central Europe and epoxy-coating protection widely used in North-Western United States is evaluated.

Abstract

L’objectiu és oferir una descripció dels ingressos actuals de la Generalitat de Catalunya i fer-ne una anàlisi crítica. També es dibuixaran les grans línies cap on hauria d’anar encaminada  la hisenda de la Generalitat en el futur més immediat.

Un primer punt serà descriure d’on provenen actualment els ingressos de la Generalitat. El bloc principal el proporciona el model de finançament autonòmic, mitjançant els tributs cedits (total i parcial) i les transferències de recursos. Un segon bloc el constitueix els ingressos propis de la Generalitat (tributs propis, ingressos patrimonials, etc.), que té un pes molt reduït. El tercer bloc el forma l’endeutament, fent especial referència al FLA. A més d’aquests tres blocs, es poden trobar altres transferències procedents bàsicament de l’Estat, però que no entren dins del model de finançament, essent baixa la seva importància relativa. Alhora de tots aquests ingressos es proporcionarà la seva quantia i pes relatiu.

El segon punt versarà sobre les mancances del model de finançament de la Generalitat. S’analitzaran les següents qüestions; la insuficiència de recursos que comporta el desequilibri vertical existent, quantificant-se; la manca de capacitat normativa i de gestió sobre els tributs cedits per part de l’Estat; l’absència d’un criteri d’equitat horitzontal i del principi d’ordinalitat que condueix a uns resultats totalment injustos i arbitraris.  En aquest apartat s’oferiran dades dels resultats actuals no només per a Catalunya sinó per a la resta d’autonomies, i es posarà en relleu la posició en recursos per habitant de la Generalitat respecte a la resta de comunitats autònomes.

El tercer punt farà referència al dèficit i a l’endeutament, i s’exposarà com aquest té relació amb el mal model de finançament a més de la greu crisi econòmica que hem passat.

El quart punt es dedicarà a descriure cap on hauria de derivar la hisenda de la Generalitat.

Abstract

Chloride ingress in the field structure is influenced by many factors. A non-destructive monitoring is a useful tool for assessing the health of reinforced structures. This study used array sensors to measure the temperature and electrical conductivity of concrete at depths from 10 mm to 140 mm. The electrical conductivity in concrete showed a continuous decrease during the exposure to 3% NaCl solution. A numerical modelling of multi-ion species migration in pore solution can explain the evolution of conductivity profile over exposing time. By comparing with several previous investigations, this study identified the pitfalls in using electrical conductivity or resistivity to monitor the chloride ingress in the exposed concrete. To obtain a correct information from the electrical monitoring system, the experimental and analysing process should consider the saturation degree of concrete, the hydration induced structure change, the leaching of ions, the ingress of chloride and composition of binders.

Abstract

Chloride ingress has been recognized as a main factor inducing the corrosion of offshore reinforced concrete structures. It is acknowledged that the chemical attack can lead to concrete property deterioration, which inevitably affects the reinforcement corrosion. Herein, the influence of the concrete aging on the chloride-induced corrosion initiation is systematically evaluated by a novel numerical framework. In this framework, the chemo-physical analysis is conducted based on coupled NernstPlanck model and Gibbs energy minimization model. The proposed method is first validated against reported experimental results. It is found that the chloride ingress is always accompanied by leaching of hydrates near the exposure surface, leading to the porosity enlargement. Moreover, due to chemical binding of chloride to monosulfoaluminate, ettringite continuously precipitates under the function of released sulfate ions. Through a series of numerical analyses, it is revealed that the newly formed hydrates impose competitive effects on chloride transportation due to the simultaneous pore-clogging and expansion-induced microcracks. Chloride-induced corrosion occurs earlier in the situation that the effect of microcracks overcomes that of pore clogging, otherwise, the corrosion is delayed.