Summary of Pruebas de concreto con base en normas NMX y ASTM

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This video discusses the tests that can be used to determine the quality of concrete, based on standards NMX and ASTM. The presenter, Fermin Rivera, goes over how to test concrete in both fresh and hydrated states, and outlines the standards that are applicable in each case. He also demonstrates how to properly calibrate testing equipment.

• 00:00:00 This video discusses the tests that can be used to determine the quality of concrete, based on standards NMX and ASTM. The presenter, Fermin Rivera, a technical advisor for Jónsi México, explains that, in theory, you can determine the quality of concrete by testing it fresh and after it has been in contact with water. He also discusses the standards that are applicable to concrete in both a fresh and an aged state. After this brief introduction, the presenter goes on to discuss concrete in a hydrated state, and how to determine the quality of that concrete based on the applicable standards.
• 00:05:00 The video demonstrates how to perform concrete tests based on the NMX and ASTM standards. The concrete undergoes gradual hardnessening, and it is important to know the characteristics in fresh and hardened states. These characteristics are related to evaluation stages, which are divided into two stages: first, concrete tests in fresh state; and second, the determination of the acceptability or rejection of a concrete mixture in construction and in plant concrete production. The method is suitable for concrete mixtures with a performance rating of 5 cm to 23 cm. The tolerances for coating application are defined by the standard, with three ranges for ratings ranging from reven (less than 5 cm) to mientos (more than 5 cm). For mixtures with a performance rating of 5 cm to 10 cm, the tolerance is 2 cm to 2.5 cm; for mixtures with a performance rating of 10 cm or greater, the tolerance is 3 cm to 3.5 cm. For mixtures with performance ratings of 5 cm to 10 cm, the tolerance is 2 cm to 2.5 cm for mixtures with a performance rating of 10 cm or greater, the tolerance is 3 cm to 3.5 cm.
• 00:10:00 This test is used to measure the consistency and control the uniformity of concrete for making the settlement test. Metal or plastic instruments with a base of 8 inches in diameter, a height of 12 inches, and a top part of 4 inches are used. Flooring extensions in the cone of settlement will serve to hold the cone and prevent any movement while the concrete is being filled and ground. The hand tools will be used to lift the cone once it is filled. The finished concrete must be clean and free of cracks for the ASTM standard test to be conducted. A semiesquare-pointed steel rod is used to measure lengths marked in increments of one fourth of a inch or less. The instrument's length must be at least 12 inches. The cone is placed in a wetted surface near the sample composition obtained under the ASTM standard, and holds it in place with its feet. Then, he starts to fill the mold in three layers, each approximating one third of the mold's volume. He places the concrete in the mold using the spoon, moving it around the circumference of the opening to ensure a uniform distribution. The first layer should fill the cone to a depth of 70 millimeters or one third of the mold's total volume. The second layer
• 00:15:00 This video discusses various tests that can be used to determine the concrete's compressive strength, including the NMX and ASTM tests. The lowest part of the lever and the center of the original surface of the displaced concrete are measured, and an estimate of the settlement is provided in terms of inches or centimeters. If during the test a part of the mass slides or flows noticeably, the test is abandoned and a new one is performed on another portion of the same sample. Finally, a summary of the procedure is provided for ASTM C143.
• 00:20:00 This video explains how to test concrete using the NMX and ASTM standards. A thermometer is used to measure the temperature of the concrete and it is submerged into the concrete after being submerged in the concrete mass. After two minutes, the temperature is stabilized and then the temperature of the concrete is taken. If the temperature of the concrete is greater than the specified temperature, the vástago is not in complete contact with the concrete and the vástago is tapped around. If the temperature of the concrete is below the specified temperature, the vástago is in complete contact with the concrete. The vástago is then hit around the circumference of the concrete in the mass to ensure that the entire mover surrounds the vástago or the sensor of the temperature meter. Based on this, the temperature recorded by the thermometer is assumed to be representative of the concrete in the case of the NMX and ASTM standards. There are two other applicable tests: the air content of the concrete and the determination of the amount of trapped air in the concrete expressed as a percentage. The method of pressure is mentioned in the NMX and ASTM standards. The type A sensor is an instrument that has a column and measures the air trapped in the
• 00:25:00 This video demonstrates how to perform concrete tests based on the NMX and ASTM standards. The normativa is the one that should be used to measure the air pressure type B for lightweight porous materials or any other type of porous material. The 158 NMX and 173 ASTM standards apply here. It is very important to know what type of concreto we are using in order to be able to determine the method to be used for the determination of this characteristic. We will see another video. This test determines the content of air in concrete normal and heavy. To perform this test, you need to have calculated the correction factor. To do this test using the pressure method, you use the following equipment: a pressure air gauge type B a rubber or cloth head with a rectangular metal bar a flat packaged planar right-handed steel bar of at least 3 millimeters thickness and 20 millimeters width a compacting round, straight-edged flat metal plate a rectangular steel plate with 6 millimeters thickness a flat shovel to place the concrete inside the gauge an air flow tube and calibration cups Start the test by wetting the calibration cup. The compacting wheel and shovel place the calibration cup
• 00:30:00 The video discusses testing for concrete using the NMX and ASTM standards. The stabilizing closure of both valves placed on the cover is opened and the main air valve is opened between the air chamber and the sampling container with the main air valve open for small, rapid strikes with the hammer for a few seconds to release any trapped air bubbles. The pressure indicator is gently tapped with the hand to help stabilize the sample. The reading is recorded on the pressure indicator's label. The percentage of air present is then deducted from the calculated factor of correction to determine the concrete's air content. After the air is released from the chamber, the cover is opened and the valves are freed. The cover is then cleaned and completely replaced. Next, we present a summary of the procedure for ASTM231. [Música] [Música] [Música] Okay, continuing with the next slides, we'll see the tests applicable to hardened concrete. I mean the most common test and the one requested the most when it comes to hardened concrete is the determination of resistance. It can be defined as the maximum resistance measured in a specimen of concrete under axial loading. Usually it is expressed in kilograms per
• 00:35:00 The video discusses various tests used to determine the concrete's strength, including the Mortero test, which uses a mixture of Portland cement and sand. The video also covers the Módulo Elástico test, which measures the elasticity of a concrete sample in order to determine its breaking point.
• 00:40:00 This video demonstrates how to perform concrete tests based on the NMX and ASTM standards. One test used is the referen- ced 7 m 78 beam. This method involves creating a concrete beam with defin- ed dimensions, including a height that is equal to the separation between the load support points. The machine is used to measure flexi- on, and the load supports must have a separation of 15 cm from each other. The beam must be at least 50 cm high and 15 cm wide. The second test used is the determination of the real flexural strength of a pre-stretched concrete beam. This test is performed by testing a sample of three concrete beams without removing any material from the area of doubt. The limita- tion is that the beams must not have any foreign material. The third test used is the determination of the deformation of a test specimen. This test is performed by applying a load to a test specimen and measuring the deformation. The relation- ship between the test specimen and the load must be 2 to 1. The limita- tion is that the test specimens must be of the same size as the actual beams. All of these tests must be performed in accordance with the NMX or ASTM standards. If the actual beam size
• 00:45:00 This video discusses the tests used to determine the concrete's compliance with NMX and ASTM standards. The video first explains that the average resistance of all the concrete core samples must be greater or equal to the design resistance, and that no individual core sample must be below the 75% design resistance. The video then goes on to explain the three-point testing method, and how it corresponds to the core samples produced in the mold. The final point of the video is that, in fresh condition, concrete can be difficult to work with due to its rapid fragility and tendency to form rafts.
• 00:50:00 This video discusses the testing of concrete using two standard measures, the National Minimum Ergonomic Standards (NMX) and the American Society for Testing and Materials (ASTM). The video explains that if our concrete has a minimum stiffness, then beams where we show concrete support beams are for flat surfaces where there is vehicle movement. Thank you, Danielle, for your question. The correct way to take the reading of the strength of concrete is to measure from the bottom of the beam to the middle of the beam, not from the top down. It is also important that the reading be taken in the center of the beam displaced from the main mass of concrete. Doing it incorrectly can result in the average reading being three readings incorrect. Concrete with cold additives is defined in the standard as having a minimum of 18,000 square root of factor ( Ra ) of modulus of rupture. Concrete with a basaltic additive has a minimum of 14,000 square root of factor ( Ra ) of modulus of rupture and then there is no modulus elastique specified, but it should be the one determined by the structural engineer in their analysis of possible lateral deformations the building may experience. For determining the amount of elasticity
• 00:55:00 The presenter discusses the use of concrete testing procedures based on the NMX and ASTM standards. Tests are conducted at a distance of 2 hours, with 30 minutes delay before arriving at the work site. The temperature is optimal for fast progress, and time is allowed for placement. The proper adhesives are used for long distances, and it is recommended to use temperature control along with a retardant compound. When cement is used for long distances, an additional stabilizer is necessary to prevent water absorption prematurely. Calibration of the testing equipment is recommended at least once a year, and should be done intermittently, as needed. Operational tests of cement and additives are best done annually. Thank you to the audience for their questions. Today, we will answer more questions. First, we will talk about calibrating testing equipment. For operational use, it is recommended to calibrate once a year. Next, we will discuss the importance of calibration for cement and additive meters. Finally, we will talk about some of our upcoming programs. Thank you, everyone, for listening. Have a good day.