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Abstract: This paper intends to express the physical model ClinConc in a more engineer-friendly way. Through the numerical evaluation it has been found that there exist good correlations between the time-dependent factors for chloride binding and for diffusion coefficient, and between the laboratory measured diffusion coefficient and the apparent one, the latter is a result of the combined effects of material properties and environmental actions. Therefore, the ClinConc model can be expressed by the similar error function as used in many empiric models, but with the proper physical procedures, that is, modeling free chloride transport taking free chloride as diffusion potential and then calculating the total chloride content taking into account the non-linear chloride binding. The modeled chloride profiles are in good agreement with the measured ones, even though further study is needed to clarify the expansion coefficient for the concrete containing silica fume and other pozzolanic additions. [Copyright &y& Elsevier]

Abstract: This paper provides an improved mathematical analysis of chloride penetration into concrete employing a time-dependent diffusion coefficient for the solution of Fick''s second law of diffusion. In the paper the possible errors caused by the application of oversimplified mathematical expressions used in some models for the evaluation of service life of reinforced concrete structures are discussed. The results from this mathematical analysis demonstrate that some models based on the oversimplified error function complement (ERFC) solutions may easily overestimate the service life by orders of magnitude, especially when the age factor is high. Some chloride profiles after up to 10 years'' field exposure were used to compare the oversimplified with the improved models. The results show that both the oversimplified and the improved models fairly well predict the 10 years'' chloride ingress in Portland cement concrete, but the oversimplified ERFC model significantly underestimates the chloride ingress in concrete with fly ash. [Copyright &y& Elsevier]

Colloidal CdSe/ZnS core/shell nanocrystals (NCs), which were dispersed in SiO2 sol, were utilized to fabricate a SiO2:NCs/TiO2 all-dielectric photonic band gap (PBG) structure. The third-order nonlinear refractive index (n2) of the PBG structure was nearly triple of that of the SiO2:NCs film due to the local field enhancement in the PBG structure. The photoinduced change in refractive index (Dn) could shift the PBG band edge, so the PBG structure would show significant transmission modification, whose transmission change was ~17 folds of that of the SiO2:NCs film. Under excitation of a 30GW/cm² femtosecond laser beam, a transmission decrease of 80% was realized. [ABSTRACT FROM AUTHOR]

This paper investigates the deterioration of reinforced concrete with carbon fiber reinforced polymer (CFRP) anode after polarization. The steel in the concrete was first subjected to accelerated corrosion to various extents. Then, a polarization test was performed with the external attached CFRP as the anode and the steel reinforcement as the cathode. Carbon fiber reinforced mortar and conductive carbon paste as contact materials were used to adhere the CFRP anode to the concrete. Two current densities of 1244 and 2488 mA/m², corresponding to the steel reinforcements were applied for 25 days. Electrochemical parameters were monitored during the test period. The deterioration mechanism that occurred at the CFRP/contact material interface was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The increase of feeding voltage and the failure of bonding was observed during polarization process, which might have resulted from the deterioration of the interface between the contact material and CFRP. The formation and accumulation of NaCl crystals at the contact material/CFRP interface were inferred to be the main causes of the failure at the interface. [ABSTRACT FROM AUTHOR]