This investigation presents the procedure within the National Plan of Bridge Corrosion Evaluation from the Mexican Ministry of Transport and Communications(SCT in Spanish), and the Mexican Transport Institute (IMT in Spanish). The first part of this Plan includes the evaluation from the corrosion point of viewof about 6,500 federal government bridges within Mexico, and correlates the effect of the environment on bridge durability. This work also includes theinventory used and the process of discrimination to obtain the number of bridges that show corrosion degradation as a function of their geographical position.The discrimination analysis was performed with a Global Positioning System (GPS), which was used to locate using geographic coordinates each bridgeof the inventory and correlate the environment in which the bridge is exposed, and the corrosion degradation. At the moment only 7% of the total 6,500bridges of the inventory used showed some type of corrosion degradation. The bridges in this inventory with some corrosion damage are being inspectedto obtain the pathology and determine the best way to repair them.
Skid resistance is a measurement of the friction offered by a pavement. There exist many types of equipment (tribometers) to measure skid resistance, butthe measures obtained with two different equipment can not be directly compared. To solve that, two method to harmonize measures are commonly used.One method uses correlation equations between tribometers, and the other method permits to obtain a friction index (IFI, International Friction Index) thatis independent of the equipment used. This last method was defined in the widely known experiment developed by the World Road Association (PIARC).In Chile, both methods was used. In this paper a third method has been derived from the IFI relationships. It developed correlation equations between skidresistance registered with different equipment. Using such equations, equivalent skid resistance values that correspond to one type of tribometer can beobtained from skid resistance measures performed with another tribometer to different texture values. This method was applied to obtain harmonizationequations between GripTester and British Pendulum. The results show a good correlation between both equipments, and a statistically significant incidenceof the texture in the predicted equivalent skid resistance value.
This research intends to identify both inexpensive and durable construction materials. Steel, glass and polymer fibers are feasible, expensive alternatives.Natural fibers can be a real possibility for developing countries, due to the fact that these kinds of fibers are available in great quantities, while they arealso renewable. Natural fiber affected mainly by the alkalinity of the cementitiuos matrix in the concrete. The durability of the composite will depend onthe protection which the fiber has, and on the impermeability features of the cementitiuos matrix.
Is work deals with the physic seismic vulnerability of the B module of the San Ignacio medical facility using the structural reliability technique. This studywas based on a dynamic spectral model of the building, by varying actions (moment, shear and axial force) generated in the model and resorting to thirty(30) response spectra with different return period. It also resorted to the study of the pathology of materials, in which destructive and non-destructive assayswere conducted to study the resistance variation of the main structural elements that are part of the structure (columns, beams, capitols). By comparing theactions and resistance curves, probable failure indexes where evaluated and different local and global failures where evaluated in the face of a seismicevent. These results are similar to those obtained in a study (Amezquita, et al 2002) developed by the Civil Engineering Department of the PontificiaUniversidad Javeriana, indicating a problematic situation in the structure.
This paper aims at determining the influence of additives in the corrosion of reinforced concrete structures by using electrochemical techniques. Theirinfluence on the mechanical properties is determined . The authors perfomed chemical analyses of the additives, characterizing the steel measure the pH,and evaluat the compressive and flexural strength of the concrete, the porosity and water absorption. The methodology was carried out according to ASTMand ACI standards. The action of the admixtures was evaluated and their effects on the corrosion of reinforced concrete were measured using corrosionpotentials and corrosion rates. The carbonatation and penetration of chlorides was also determined. The study was suplemented by a morphologiccharacterization using a scanning electron microscope. Specimens with and without reinforcement were elaborated, three of each were tested for obtainingan average. Prismatic specimens without reinforcement were also cast with the following chemical additives: Air-entraining, plasticizers, retardants,accelerating, coloring and fly ash. After curing, they were exposed to an aggressive atmosphere with sodium chloride. The corrosion potential in accordanceto ASTM C876 standard, revealed that cylinders had corrosion, and the rate corrosion of the cylinders exposed in sodium chloride corresponds a of moderatecorrosion degree.
The only viable means of countering the spread of new HIV infections is sexual behavior change. It has been argued that the content of behavior preventionprograms should include basic, accurate information on risk that is communicated repetitively and intensively in forums that promote open discussion andparticipant involvement. Therefore, effective HIV(The Human Immunodeficiency Virus) and AIDS communication involves providing relevant and meaningfulinformation accurately, consistently, reiteratively, and repetitively using multiple methods, mediaums, and languages, including vernacular, that build onprevious HIV and AIDS (Acquired Immunodeficiency Syndrome) knowledge while at the same time recognizing the differing personal backgrounds ofworkers in an environment conducive to open an uninhibited interaction. Drawing from anecdotal evidence gathered during a series of national multistakeholderworkshops as well as the findings of knowledge, attitude and behavior (KAB) surveys of two samples, namely a sample of 300 constructionworkers in South Africa and another of 400 workers in Namibia, the authors argue for greater involvement of construction employers in structured managementled and targeted HIV and AIDS communication programs designed to influence sexual behavior. Considering that television and radio were the most popularand influential mass mediaums of communication, employers are encouraged to support, reinforce and complement HIV and AIDS campaigns and messagesvia these mediaums as part of primary health promotion programs. The authors recommend that employers create opportunities for HIV and AIDS educationof workers by their peers.
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