Materials Literature
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The introduction of a fifth group of amphiboles, the Na–Ca–Mg–Fe–Mn–Li group, defined by 0.50 < B(Mg,Fe2+,Mn2+,Li) < 1.50 and 0.50 ≤ B(Ca,Na) ≤ 1.50 atoms per formula unit, with members whittakerite and ottoliniite, has been required by recent discoveries of B(Li,Na) amphiboles. These, and other new discoveries,…
We present results of a joint computational and experimental study for a series of annulated metalloporphyrins in order to establish structure−property relationships. Specifically, we have examined the effects of substitution by meso -tetraphenylation, tetrabenzo and tetranaphtho annulation, and effects of changing th…
The objective of this paper is to study the evolution of the failure probability of the concrete beams to estimate the service life of a sea bridge in the southeast region of Brazil. The mechanism of deterioration analyzed in the study was the corrosion of the reinforcing bars. The models utilized for that are related…
Flexible, free-standing piezo and pyroelectric composite with 0 to 3 connectivity was made up from Lead Zirconate Titanate (PZT) powder and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) copolymer. The pyroelectric and the piezoelectric longitudinal (d33) coefficients were measured. A 50/50 vol.% PZT/PVDF-HF…
High performance concrete (HPC) is an interesting material that has been long attracting the interest from the scientific and technical community, due to the clear advantages obtained in terms of mechanical strength and durability. Given these better characteristics, HFC, in its various forms, has been gradually repla…
Shrinkage reducing admixtures (SRAs) are viable alternatives for reducing plastic shrinkage cracking in concrete. The objective of the present paper is to study early age plastic shrinkage in restrained concrete elements, where three different SRAs have been used. The influence of the admixture is analyzed through the…
Properties of fresh concrete play a relevant role on placing and consolidation; and its design strength and durability depends on them. It is well known too that the concrete temperature during placing affects all its properties in different ways and extent. This paper presents the influence of placing temperature of…
A bibliographical revision of the existent literature allows showing symptoms of alkali-silica reaction (ASR) in highways, and the practical and economic method uranyl acetate to confirm the presence of ASR. The existence of reaction in concrete pavements of Chihuahua City was verified by a visual observation of patte…
In the production of portland cement, grinding aids are used to improve the grinding stage and reduce the energy required to achieve the required fineness. These additives remain in the final product and they might influence the characteristics and properties of the cement, and thus, mortar and concrete. This paper pr…
The construction pathology of housing built on expansible clays is one of the most requested topics to be investigated in order to obtain solutions mainly in housing of social interest. A vision of the solution alternatives is presented that are being applying in Venezuela and specifically in the cities of Barquisimet…
The present work discusses some principles of materials selection and examines a few selection criteria and contexts in which this technical activity takes place. Emphasis is given to the concept of Merit Indices, and to the methodology employed for its deduction. The Materials Properties Charts and their integration…
The phenomenological analysis of recrystallization data is described. The concept of microstructural path is briefly introduced as well as some of its relevant equations. The correct equation for the impingement compensated chord length is introduced and used here for the first time. The theory is then applied to data…
The effect of silver addition as a promoter in alumina supported cobalt oxide catalysts is investigated in this study. The Co/Al2O3 and Ag/Co/Al2O3 catalysts were prepared by incipient wetness impregnation. The catalysts were characterized by inductively-coupled plasma spectrometry, X-ray diffraction (XRD), temperatur…
The use of recycled concrete as aggregate for the production of new concretes is a consequence of the shortage of natural resources and the environmental problems due to the storage of residual building materials. In this paper the following results are given: compressive strength, rebound numbers, ultrasonic pulse ve…
The purpose of this investigation was to evaluate the microhardness of two laboratory-processed composites (Artglass; belleGlass) and two direct placement composites (Filtek Z250; Alert), after aging in distilled water. Twenty cylinders (8 mm diameter; 2 mm height) per tested material were prepared and stored in 10 ml…
The effects of composition and resulting morphology on the rheology of thermoplastics filled with different talc platelets were studied in the 0-22% range of volume fraction, Φ. The sufficiently filled polymer composites exhibit a rheological behavior which significantly differs from the pure polymers used in this wor…
From the RCPT publication, this test has been frequently used in the concrete structures durability assessment. This test it could be determined in a relatively short time the material permeability, within a rank or quality level that allows comparing concretes as far as their characteristics. In this document, is pre…
Electrochemical repair methods are based on the application of an impressed direct current between the reinforcement and an auxiliary electrode placed at the concrete surface. In the case of realkalisation, the aim of the treatment consists in restoring the alkalinity of the concrete around the rebar to repassivate it…