Volume 10Enero - Diciembre 2020

The following study evaluated the viability of a modification in the procedure established in ASTM C1609 in order to lay evidence of the usefulness, or not, of the aforementioned standard in the testing of synthetic fiber reinforced concrete (SNFRC). Likewise, a comparison between the results obtained in flexural tests developed in accordance with EN14651 and those provided by the American statute was realized. A pseudoductil performance was found for SNFRC in which the addition of fibers allowed the concrete to resist loads even after its modulus of rupture was reached. Also, it was determined that a reduction in the loading rate established in ASTM C1609 allows for a higher probability of success for the test, especially when low fiber content is used. Furthermore, the speed reduction did not affect the results provided by the test. The European standard did not cause any inconvenience in the test execution, nevertheless, its results were not completely comparable to those obtained via de American normative.

The modulus of elasticity is a property of great importance in the structural calculation, which allows understanding the relationship between the stress and the deformation of an evaluated material, in this matter, a correct prediction of the modulus of elasticity of concrete allows the Structural Engineer design elements or structures that perform as it were conceived.

In this investigation an equation to calculate the modulus of elasticity determine were determined for two mixtures of self-compacting concrete (SCC) with nominal strength of 70 MPa at the age of twenty-eight days.
The only variable analyzed in this study was the type of hydraulic cement: cement modified with initial high strength limestone and modified cement with pozzolana. For fresh concrete the following testwere analyzed
comparatively: temperature (ASTM C1064), unit weight (ASTM C138), air content (ASTM C231) and unrestricted flow (ASTM C1611). For hardened concrete, the compressive strength (ASTM C39), elastic modulus, Poisson ratio and shear modulus (ASTM C469) were studied.

Infiltration in buildings is one of the most frequent problems and, in most cases, is the product of pipe leaks, construction defects, among others. Their detection is difficult, since they do not present external manifestations in the first phases. Infrared thermography may be a potential technique for detecting these defects, since it does not need direct contact with the inspected structure and has real-time results. Thus, this article aims to evaluate infrared thermography to detect infiltrations due to accidental causes. The methodology of the work consisted in the inspection of the common areas of a multifamily condominium with a thermographic camera and the use of a humidity detector, in a complementary way. The results allowed to prove that the detection was possible with small thermal gradients, around 0.4 °C to 1.5 °C, where the affected areas were visualized with lower temperature due to the thermal inertia of the water. In the inspection for infiltration verification, the technique showed a rapid detection of this pathological manifestation and can be used as an auxiliary tool

Building Information Modeling (BIM) is a new methodology that has been growing in recent years within Costa Rica. However, this diffusion has generated isolated attempts, mainly from the private sector. In order to the current capability of the country in the use of the BIM, some interviews were distributed among the public, private and academic sectors; which were used in conjunction with the “Adoption Point” and “Macro-Maturity Components” models developed by Billial Succar and Mohamad Kassen. This permitted to understand the starting point of a potential implementation of the BIM methodology at the national level and develop a series of tasks to implement the BIM methodology in the country. That roadmap was validated by a committee of experts who have extensive knowledge about the current situation at the national level. The product of this work is an adoption process or roadmap for the incorporation of the BIM methodology during the planning, design, construction and operation phases of public works in Costa Rica as a tool to improve the management of construction projects.

This article presents the development curves of compressive strength through curing time for concrete mixtures made with three types of modified cements marketed in Costa Rica, and their combination with national aggregate from sources of pit and river. The cements used for the investigation were MM/A (E-C) – 28, MM/B (P-C) – 28 and MP A – AR, defined according to regulation RTCR 479:2015 Materiales de Construcción. Cementos Hidráulicos. Especificaciones. Due to the lack of resistance development curves for concrete made with different types of modified cements and aggregates commercialized in the country, the objective of this investigation was focused on obtaining such curves and the resistance development percentage. All the material used, was characterized according to the ASTM o INTECO standards procedures; it was also verified that the aggregates and cement to be used were adequate by the parameters established in ASTM C33/C33M-18 and INTE C147:2018, respectively. Cylindrical specimens of 150 mm x 300 mm were used to determinate the compressive resistance, being failed at 3, 7, 28 and 56 days; following a mix design determined from the ACI 211-91. A statistical analysis was performed to the generated data to establish relationships and support the results obtained. With this investigation it was possible to demonstrate that the cements commercialized in Costa Rica with a degree of blast furnace slag are able to present a significant resistance gain in the concrete after the 28 days of curing, the greater compressive resistance of the concrete is generated when using river aggregate, and generally the strength of the concrete does not vary significantly when using the same type of cement for different aggregates.