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How to deal with the damaged concrete specimen
Concrete Quality Control Problems: How to Address Before,
During the concrete placement the QC technician needs to communicate test results to the contractors (concrete foreman, ready-mix producer or RMP QC personnel and the site superintendent, and the QA person or owner’s representative). And all parties need to
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ASTM C31 - ACI Making and Curing Concrete Test Specimens
CylindersBeamsStandard CuringField CuringTransportingReporting When rodding cylinders, fill in: 2 layers (25 rods) for 4" dia cylinders; 3 layers (25 rods) for 6" dia cylinders; 4 layers (50 rods) for 9" dia cylinders.Tap outside of molds 10 - 15 times with a mallet or an open hand for each lift.When vibrating cylinders, fill in: 2 layers for all cylinder diameter sizes, but insert vibrator once for 4" dia cylinders, twice for 6" dia cylinders, and four times for 9" dia cylinders for both... When rodding cylinders, fill in: 2 layers (25 rods) for 4" dia cylinders; 3 layers (25 rods) for 6" dia cylinders; 4 layers (50 rods) for 9" dia cylinders.Tap outside of molds 10 - 15 times with a mallet or an open hand for each lift.When vibrating cylinders, fill in: 2 layers for all cylinder diameter sizes, but insert vibrator once for 4" dia cylinders, twice for 6" dia cylinders, and four times for 9" dia cylinders for both...Insert rod or vibrator 1 inch into the underlying lift.展开选择时，新内容将添加到焦点当区域上方在sicerts上
Numerical Simulation of Dynamic Mechanical Properties of Concrete
2019/2/20 The stress–strain curves of concrete specimens are shown in Figure 9. The peak values of strain and stress are shown in Figure 10 at the different strain-rates. The damage process of concrete specimens under different strain-rate compression levels is shown in Figure 11. The failure patterns at different rates are illustrated in Figure 12.
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Global assessment of concrete specimens subjected to freeze-thaw damage
2022/10/1 Freeze-thaw damage is one of the main deleterious processes of concrete in cold climates. This study intends to detect the ongoing freeze-thaw (FT) deterioration in concrete specimens through the use of the global assessment combining the results of the mechanical and microscopic evaluation, pressure tension (PT) and compressive strength test as well as the
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Fire-damaged concrete structures: how do we know
Setting up a specimen, conducting a fire test for damaging the specimen and sampling from the fire-damaged concrete specimen are simply described in this video file. Korea Institute of Civil Engineering and Building Technology (KICT)
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Procedure for Concrete Sample Preparation
2017/4/26 Curing is done just after finishing the concrete surface, as soon as it will not be damaged. The longer concrete is cured, the closer it will be to its best possible strength and durability. Concrete that is cured sufficiently is less likely to crack. The specimens are removed from the molds 24 hours after casting.
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Preparation, care and art of herbarium specimens - Royal
• Look through specimens by stacking and unstacking each specimen individually with the plant facing up. Do not page through specimens like pages in a book, or stack specimens with the plant facing downwards. • Never rest an object on a specimen. • Specimens can be damaged by sunlight, dust, wind, and moisture,
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Chapter 41 Tex-447-A, Making and Curing Concrete Test
Concrete Test Specimens Section 2 — Part I, Compressive Strength Specimens (Cylinders) 400-A, Concrete Test Procedures 41-5 06/00 – 11/04 ♦ The specimens are subject to the same tolerances as the molds. Sample The sample of concrete from which test specimens are made must be representative of the
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Assessing concrete strength in fire-damaged structures
2020/9/10 Values of coefficients modifying core strength due to specimen diameter, l/d ratio, concrete moisture content and damage caused by drilling are given in the American Standard [37]. For example, for specimens with a diameter of 50 mm, the recommended coefficient is 1.06, and for specimens with a diameter of 150 mm − 0.98.
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Meso-structure numerical simulation of concrete specimens
The comparison of gradations of three commonly used concretes with the Fuller gradation reveals that they accord very well. It infers that the Walraven function can be used to generate the random aggregate model (RAM) by means of Monte-Carlo method. On this basis, concrete is taken as a type of three-phase composite material composed of mortar matrix, aggregates and bonds
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Studies on repair and strengthening methods of damaged
2000/2/1 Specimens C2 and C3 represent the restored columns which were assumed to be heavily damaged by the Hyogoken-Nanbu earthquake. Specimen C2 is a RC column jacketed with welded wire fabric, in which the crushed concrete remained within the reinforcing cage, and the cross-section was enlarged by the placement of high-fluidity concrete.
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The Influence of a Damaged Concrete Cover on the
the place where the concrete cover is removed, as in specimen CSSBLUR, which is like specimen CSSBLU. In the specimen CSSBAL, all concrete cover is removed at midspan, at a distance of 600mm.
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(PDF) Numerical simulations of concrete specimens with the
2023/6/12 Local Continuum Damage Mechanics models cannot represent the entire degradation process in materials exhibiting strain-softening behaviors. It is well known that the rate equilibrium problem ...
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Temperature response and moisture transport in damaged concrete
2016/10/1 Five concrete specimens, C-25–C-85, were compressed under uniaxial loads up to 25%, 40%, 55%, 70% or 85% of the cylindrical compressive strength with a sustained duration of 30 min, corresponding to different damage levels. One concrete specimen, C-0, was not subjected to any load; hence it was used as a control or measure to compare the ...
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A DIC-Based Study on Compressive Responses of Concrete after
2019/6/26 The concrete specimens were cured for 24 h in plastic molds, and then were de-molded and cured in water for 28 days. To ensure moisture content stability, the specimens were air-dried in a laboratory for about 60 days before heating. ... The assessment of fire damage concrete usually begins with visual observation of color changes, cracking and ...
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Comprehensive Testing of Sulfate Erosion Damage of Concrete
2022/10/20 The strength test of the concrete specimens was used as a reference and test [40,41], to compare the protected specimens with the unprotected specimens and analyze the protection effect of the silane coating, so as to establish a method to analyze and evaluate the protection effect under sulfate erosion and to judge the effectiveness and effect ...
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(PDF) Numerical simulations of concrete specimens
2023/6/12 Local Continuum Damage Mechanics models cannot represent the entire degradation process in materials exhibiting strain-softening behaviors. It is well known that the rate equilibrium problem ...
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Temperature response and moisture transport in damaged concrete
2016/10/1 Five concrete specimens, C-25–C-85, were compressed under uniaxial loads up to 25%, 40%, 55%, 70% or 85% of the cylindrical compressive strength with a sustained duration of 30 min, corresponding to different damage levels. One concrete specimen, C-0, was not subjected to any load; hence it was used as a control or measure to compare the ...
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A DIC-Based Study on Compressive Responses of Concrete after
2019/6/26 The concrete specimens were cured for 24 h in plastic molds, and then were de-molded and cured in water for 28 days. To ensure moisture content stability, the specimens were air-dried in a laboratory for about 60 days before heating. ... The assessment of fire damage concrete usually begins with visual observation of color changes, cracking and ...
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Comprehensive Testing of Sulfate Erosion Damage of Concrete
2022/10/20 The strength test of the concrete specimens was used as a reference and test [40,41], to compare the protected specimens with the unprotected specimens and analyze the protection effect of the silane coating, so as to establish a method to analyze and evaluate the protection effect under sulfate erosion and to judge the effectiveness and effect ...
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Lesson 5 Preparation and Curing of Concrete Test Specimens
Air-entrained concrete is typically specified in areas of the country where frost- related damage can occur (ConcreteNetwork, n.). ... Volumetric Method 3 Volumetric air content tests start with a concrete specimen of known volume consolidated into a container. The difference in fluid levels before and after agitation is recorded as the air ...
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Automated identification of compressive stress and damage in concrete
2022/5/15 To this end, many studies have been focused on damage assessment and localization in concrete structures, such as the proposed global static and dynamic response-based techniques using the static displacement or strain response of structures or relied upon the response of low-frequency vibrations of the structure [3], [4], [5], [6].Other local nondestructive
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Specimen Preparation Concrete Microscopy Library - University
The specimens are then cut or ground to expose a fresh surface, and that surface is then polished using a series of successively finer grades of diamond paste. This polishing stage is necessary to remove cutting and grinding damage, and to expose an unaltered cross section of
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Example of Satisfactory Failure of the Cube Specimen according
Peridynamics has been increasingly used for the study of damage and failure behaviors of reinforced concrete (RC) structures, e.g., cracking, fragmentation, and interface debonding due to its ...
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Degradation Mechanism of Concrete Subjected to External Sulfate
For precast concrete specimens, the strength showed a relatively stable increase tendency during the immersion, especially for concrete specimens immersed in 3% and 5% sulfate solutions. ... it takes less time for sulfates to penetrate internal concrete regions and brings a great deal of damage to concrete structures. Moreover, the tensile ...
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Analyzing cyclic loading behavior of concrete structures: A
2023/12/1 The limitations become particularly problematic when dealing with complex crack patterns [19] or the growth of cracks in ... To further investigate the accuracy of the proposed model in the prediction of damage growth in the concrete specimen, we plot the numerical compressive and tensile damage patterns in Fig. 24, along with the observed ...
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Application of petrographic examination techniques to the
2009/7/1 The information gained from microscopical examination of concrete samples is now regularly used to aid the decision of whether to repair, or demolish fire-damaged concrete structures. It is less well known that the same petrographic examination techniques can be successfully applied to other fire-damaged building materials such as natural stone ...
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Carbon Nanofiber Cement Sensors to Detect Strain and Damage of Concrete
Figure 9 shows the stress–strain curves for two different damage tests, where stress was applied to the concrete specimen in accordance to the setup detailed in the Material and Methods section above. Concrete specimen strain was registered every second during the tests by means of two strain gages adhered to the concrete surface.
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How to deal with rain damaged concrete - Allcon
Repairing rain damaged concrete. A concrete floor dusts under traffic because the wearing surface has been weakened, normally as a result of water damage whilst finishing. Depending on the severity of the damage, a surface densifier or concrete hardener can be used to harden or densify the surface.
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The thermal and mechanical properties of coarse aggregates, cement mortar, and cement concrete specimens of varying mix proportions were studied after exposure to a range of high temperatures.
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