Slump Test (Workability)

In order to determine the consistency of concrete, the most generally used method is the slump test method, which may be performed either in the laboratory or on the job site. It is not recommended for use with either wet or extremely dry concrete. This test was carried out in accordance with ISO 1191:1959. When conducting the slump test, a metallic mould in the shape of a cone with an interior size of is used.

Slump cone testing process

The interior surface of a mould should be dust-free and coated with lubricating oil to facilitate removal of the mould for measuring unit weight. This mould should be filled in four layers, with each layer being tamped 25 times using a tamping rod. Finally, the top surface must be smoothed with a trowel to complete. The plate of the slump equipment should be dust-free. After filling and finalising the specimen's top surface, the mould should be progressively raised by rotating slowly. After removing the mould, the height of the concrete should be measured immediately with a measuring tape, and the reduced amount of cement from the maximum height of the mould is

referred to as the slump value. This measurement should be obtained no later than two minutes after mould has been removed. Using hot water to speed up the curing process

Some few cubes also were tested within 28-29 hours, giving a strength of 28 days, and curing was done using the IS 9013-1978 rapid curing by boiling technique.

Boiling water method for cube

3.7.2 Compressive Strength

Compression testing is the most often performed test on hardened concrete, owing to its simplicity. And partially because the majority of concrete's desirable characteristics are qualitatively connected to its compressive.

The compressive strength of concrete was determined using 150 mm (long) x 150 mm (wide) x 150 mm specimens (depth).

The aggregate's nominal size does not exceed mm. The specimens were evaluated after 7 and 28 days totally invested in a water tank, in accordance with IS 516:1959 for concrete strength testing methods.

Compressive strength = P/A , Unit = N/mm2 Where, P = Load A = Area of Specimen

Flexural Strength



The strength of the concrete, as we all know, is relatively weak in compression and relatively strong in tension. However, in RC frames, little reliance is placed just on strength of concrete because reinforced steel bars are supplied in flexural members to resist all of the tensile forces.

Flexural of all mixtures was determined using a beam specimen with dimensions of 700 mm (length) × 150 mm (wide) x 150 mm (height) (depth).

Mechanical properties are evaluated on hardened concrete by preparing different samples like beams, cubes and cylinders. As far as tests are concerned, compression test, split tensile test, flexural test, water absorption test, rapid chloride permeability test. These all are performed on hardened samples to evaluate the mechanical properties at different curing days 7,14,21,28,56,90 days but 28 days strength is recommended for acceptance and durability is checked at a longer period of 56, 90 and 120 days.

Mainly compressive strength. it is measured by compression in a press on concrete cylinders 32 cm high and 16 cm in diameter and having hardened for 28 days.

You need atleast (1) Compressive strength (2) Tensile strength and (3) Stress strain curve. So do a cube test for (1), split tensile test for (2), and Cylinder test with extenso-meter for (3).

Other properties like (4) poisson, (5) shear transfer coefficients, are literature references or educated guesswork.

It all depends on what you are going to do with it. I've written the above with the idea that you are going to some sort of FE analysis with it.

Ntwari,

Concrete is one of the most commonly used construction materials due to its durability, affordability, and availability. Despite its widespread use and familiarity, understanding the mechanical properties of concrete is essential to ensuring its optimal performance. First, strength is the most important mechanical property of concrete. Compressive strength is the ability of concrete to resist compressive loads, such as those applied during construction. A compressive strength test is performed to determine the compressive strength of concrete. This test typically involves placing a concrete cylinder in a testing machine and applying a gradually increasing load to the cylinder until failure. The load at which the cylinder fails is then noted and used to determine the material’s compressive strength. The second mechanical property of concrete is toughness. Toughness is the ability of concrete to resist impact loads, such as those encountered during an earthquake. The most common test for determining the toughness of concrete is the Charpy impact test. In this test, a concrete sample is placed in the testing machine, and a swinging pendulum is released from a specific height. The energy absorbed by the model is then measured and used to determine the toughness of the concrete. The third mechanical property of concrete is elasticity. Elasticity is the ability of concrete to return to its original shape after being deformed. This property is an essential factor in the design of structures, as it determines how much the system can move before it is damaged. The most common test used to assess the elasticity of concrete is the elastic modulus test. This test involves applying a compressive load to a concrete specimen and measuring the strain in the sample. The strain is then used to calculate the elastic modulus of the concrete. Finally, tensile strength is the fourth mechanical property of concrete. Tensile strength is the ability of concrete to resist tensile loads, such as those applied during construction or an earthquake. The most common test for determining the tensile strength of concrete is the split tensile test. In this test, a concrete sample is placed in a testing machine, and a gradually increasing tensile load is applied to the model until it fails. The load at which the specimen fails is then noted and used to determine the tensile strength of the concrete.

Understanding the mechanical properties of concrete is essential to ensure its optimal performance. The four most important mechanical properties of concrete are strength, toughness, elasticity, and tensile strength. Tests are available to determine each of these properties, and they should be used to ensure that the concrete used in a particular project is suitable for its intended purpose.

References:

American Concrete Institute. (2020). Compressive Strength of Concrete | Cube Test, Procedure, Results. Retrieved from https://www.theconstructor.org/concrete/compressive-strength-of-concrete/27128/

Civil Engineering Academy. (2020). Charpy Test – Procedure, Uses, Results, and Calculation. Retrieved from https://www.thecivilengg.com/charpy-test/

Schweiger, D. (2020). Compressive Strength of Concrete - Cube Test, Procedure, Results. Retrieved from https://www.civilengineeringacademy.org/tensile-strength-of-concrete/

Tensile Strength: Tensile strength of concrete is measured by pulling a cylindrical or prismatic specimen in tension until it fails. The tensile strength is then calculated based on the cross-sectional area of the specimen and the load applied. Compressive Strength: Compressive strength of concrete is tested by loading a cylindrical or cubic specimen under a uniformly applied axial compressive load until it fails. The compressive strength is then calculated based on the cross-sectional area of the specimen and the load. Flexural Strength: Flexural strength of concrete is carried out by loading a beam made of concrete under a bending moment until it fails. The flexural strength is then calculated based on the beam's cross-sectional area and the load applied. Bulk Modulus: Bulk modulus of concrete is tested by measuring the volumetric strain of a sample when a certain force is applied to it. The bulk modulus is then calculated using the change in volume and the applied force. Durability: Durability of concrete is measured by measuring how well it resists damage from external elements such as weather, water, chemicals, etc. Specific tests are used to determine the durability of concrete such as freeze-thaw, water absorption, abrasion resistance, compressive strength, and chemical resistance.

The basic mechanical property of concrete is its compressive strength. Tensile strength (e.g. using flexural strength test, Brazilian method - splitting a cylinder along the diameter, pull-off, WST, etc.) or compressive modulus of elasticity are also tested, but not so often.