Concrete heavy v10 m150 technical characteristics. Concrete M150 class B12.5. Raw materials and their ratio

This article presents a mix development procedure for high performance concrete mixes. Since rheological parameters and compressive strength are fundamental properties of concrete at two different stages of production, instead of using the water-cement ratio and compressive strength, the correlation between rheological parameters and compressive strength was used. The water-cement ratio and volume-to-volume paste were also determined from the rheological behavior and used in the mix design.

In the proposed method, the designer can evaluate rheological parameters such as yield strength and plastic viscosity at the design stage for a given strength, in addition to concrete components. Key words: rheology, yield strength, plastic viscosity, mix design, high performance concrete.

The main purpose of the mix design method is to obtain the proportions of concrete ingredients that can be used for the first test batch to produce a specific concrete for a specific strength, durability and performance. The design of the mixture provides the proportions of the original mixtures, which must be more or less modified to meet the desired specific characteristics. High performance concrete does not necessarily require high strength, but the dosage of the mix should be such that the permeability is as low as possible for the specific use.

The mixing of high performance concrete is different from ordinary concrete because the water-binder ratio is very low, and it may contain mineral additives that change the properties of fresh and hardened concrete 1. In addition, the compaction or compaction coefficient can be adjusted using a large range of water, reducing impurities without changing the water content.

Workability must be compatible with these fundamental needs in order to achieve high concrete performance. To do this, the mixture must be such that it can be vibrated and it is permeable enough to pass through overfilled rebar. Therefore, a minimum draft of 100 mm is preferred. 3. Durability is associated with low permeability. High strength and low permeability are related because high strength requires low pore volume, although the two are not necessarily related.

Thus, the remaining two characteristics, which require careful control and monitoring at the production stage, are characterized by high strength and high machinability. At present, single-point workability tests are considered incapable of adequately characterizing the performance of today's much more advanced concrete mixes 4, 5. Researchers consider fresh concrete to be liquid and use liquid rheological methods to describe specific behavior 6-8.

Concrete as a fluid is most often considered to behave like a Bingham fluid with a good accuracy of 4.5. In the Bingham model, the flow is determined by two parameters: yield strength and plastic viscosity. Yield strength and plastic viscosity are considered fundamental parameters of fresh concrete rheology. There are no assumptions in existing mixture design methods to have an idea about the evaluation of rheological parameters such as yield strength and plastic viscosity.

The water-cement ratio is a weak predictor of compressive strength in high-strength concrete 9. Most often, purely empirical procedures based on test mixes are used. The method uses the relationship between design parameters and rheological properties. The designer can evaluate the new rheological properties of the concrete at the design stage in addition to the mixing ratios for the target force.

The cement used throughout the experiment was regular Portland cement. Locally available alluvial sand within the laboratory was used throughout the pilot study unless otherwise noted. As a coarse aggregate, crushed stone aggregates with a nominal maximum size of 16 mm were used. Normal tap water was used for all fresh concrete mixes.

A polycarboxylic polymer with an established retarding effect has been used as additives to reduce the amount of water. The concrete was mixed in an inclined mixer. The following mixing sequence was adopted. At present, a large number of highly effective concrete mixes have been prepared in the laboratory. Rheological tests were carried out to study the effect of percentage sand, sand zones such as coarse, medium and fine, coarse aggregate nominal size, and volumetric volumetric volume of the paste.

To determine the rheological parameters, the average value of three measurements was taken. It consists of a flat round paddle plate with a diameter of 150 mm, driven by a motor through a gearbox. The lamellar plate is mounted coaxially with a cylindrical container with a sleeve and bearing to ensure precise alignment. The cylindrical container is provided with vertical ribs of 20 mm with a pitch of 60 mm around the circumference. The ribs are also welded to the bottom of the cylinder. The effective gap between the bottom and the cutting surface is 75 mm.

Proportions of concrete M150

The effective concrete height above the paddle plate is also 75 mm. The non-slip condition at the top of the cylinder is achieved by creating a mesh with a high thickness of 20mm. The blade mill can be detached as needed. The number of revolutions of the blade plate is measured by a non-contact infrared digital tachometer by focusing on a reflective tape glued to the spindle. The spindle has a pulley welded to it, which is used for calibration purposes only. A spring balance is mounted on the spindle pulley, fixed on a stationary object.

Do-it-yourself concrete production

When the motor is on, the spring balance blocks its rotor and the spring balance reading is noted. This arrangement gives braking torques at different voltages. In the present study, the concrete was sheared at each step for 30 seconds. A stepwise increasing sequence of shear stresses followed by decreasing shear stress was used and a downward curve was drawn to draw a flow curve. Fluid can be used in shear mode. It responds to an applied magnetic field with a change in rheological behavior.

In many technical applications, the Bingham model can be effectively used to describe the properties of underlying fluids. It was noted that both readings agree quite well. A detail of the setup has been provided elsewhere 13. The expression for the total torque in a real rheometer is given by the formula.

Substituting them into equation 1, we have the following equation. Equation 2 above is in Bingham form. Comparing equation 2 with Bingham's equation, the total shear stress in terms of torque can be expressed as. The overall shear strain rate over rotation frequency can be written as.

According to the graph of values, there is a flow curve from which τ 0 and μ can be obtained. After completion of the rheological tests, the fresh concrete mixtures were again transferred to the concrete mixer. The balance of concrete and mortar remaining in the cylindrical container was cleaned by hand and transferred to the mixer. The concrete mixes were then mixed for two minutes and transferred to a bucket. The concrete was placed into a cubic shape in three layers; each layer is compacted by 16 mm rod 25 times. The final compaction was achieved using a vibration table in a standard way.

Between 1-2 hours of casting, when the surface of the concrete in the cube molds was dry, a curable wax-based compound was sprayed onto the surface of the concrete. After 24 hours of casting, the concrete cubes were cured in a curing tank for 28 days. The compressive strength was determined after 28 days and the average of the three readings was reported as the required force.

Proposed mixing procedure method. The proposed mixing method is a combination of empirical results and mathematical calculations based on the absolute volume method. The procedure is initiated by selecting different mixture characteristics or material proportions in the following sequence.

Evaluation of the yield strength and viscosity of plastic. In the mix design procedure, test batches are prepared in the laboratory and workability is measured after all concrete components have been reached. If the performance criterion is met, the cubes or cylinders are cast for a compressive strength test. If the desired level of workability is not achieved, adjustments to the concrete constituents are made again and a test batch is prepared. The fact that rheological parameters are fundamental properties of fresh concrete and compressive strength is the most important cured property of concrete, correlation curves between rheological properties and compressive strength of concrete have been used in the mix design.

Details of the correlation can be found elsewhere 14. It has been noted that the optimal dose of highly active water-thinning admixtures is about 5% by weight of cement, beyond which it does not significantly reduce the yield strength and plastic viscosity. The ratio of aqueous cement and the volumetric volume of the paste.

In fact, there may be various combinations of water-cement ratio and paste volume to sum up the volume ratio. The water-cement ratio can be obtained for a given target strength. Extrapolation can be performed to obtain values ​​not shown in the figure.

Composition and proportions

The content of coarse aggregate depends on the shape of the particles. The cement content can be simply calculated once the volume ratio of the bulk paste and the water-cement ratio are specified. Corrections must be made in the mix design for different sand zones and maximum coarse aggregate sizes.

Now, by comparing the yield strength and plastic viscosity values ​​of various other blends with the rheological parameters of the reference blend, correction factors have been calculated and presented. These correction factors were derived from the experimental results of changing the rheological parameters with sand gradation and the maximum size of coarse aggregates.