RU1822402C - Process for preparation concrete mix - Google Patents

Abstract

The claimed method for preparing a concrete mixture relates to building materials. A stranded invention is the intensification of the set and the increase in concrete strength due to the activation of a part of the mortar component of the concrete mixture during preliminary preparation in a turbulent mixer-activator. The essence of the invention: the activation of part of the mortar component is carried out at a water-cement ratio (B / 11) P, ... 5.0 and a fine aggregate content of 5 ".". 1003 of its total amount over 0.8 ... 1.2 period of the final preparation of concrete mix „3 tab. Ј

Description

The alleged invention relates to the field of building materials, in particular, to methods for preparing concrete mix for the manufacture of precast and monolithic reinforced concrete structures.

The closest in technical essence and the achieved effect to the claimed method is the method of preliminary wave of activation of cement dough in the preparation of concrete mix 0 The method involves the preliminary preparation of a cement-water suspension in H / C 0.9 ... 1.0 at a cement content in an amount of 40 or more of its total consumption in concrete. Suspension is prepared with simultaneous activation

cement in a separate mixer of intensive mixing for 5 ... 10 min, at a frequency of rotation of the mixer 1500 .. „. 900 min. The activated slurry is then fed to another mixer, where it is mixed with the remaining cement and aggregates.

Activation by this method provides an increase in the degree of hydration of the cement, a higher uniformity of the cement stone and, consequently, an increase in the compressive strength of concrete after heat treatment by 312; after 28 days by 33 ... 43%. The cement savings from the sale of the obtained effect are 13.3 ... 17.6%,

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The disadvantages of this method include the activation of only water-cement slurry, which leads to the underutilization of the potential strength of concrete. In addition, a significant duration of high-intensity mixing (5 ... 10 min) dramatically reduces the productivity of concrete-mixing plants. Therefore, an increase in the strength of the prototype cannot be achieved in real production conditions, and we can talk about saving cement only theoretically, which is the main disadvantage of the prototype,

The aim of the invention is to enhance the kit and increase the strength of concrete.

Distinguishing it from the prototype, activation during preliminary preparation of a part of the mortar component containing a part of cement and water at 0, Si В / Ц Ј5.0, as well as fine aggregate in the range of 5.0 .. "100.02; from its amount in the concrete mixture, during 0.8 ... 1.2 period of the final preparation of the concrete mixture.

The essence of the proposed invention is that the activation of a part of the mortar component with preliminary mixing of a part of cement with water at 0.5 V / Ts Ј 5.0 and fine aggregate in an amount of 5 ... 10% provides intensification and an additional increase in strength and reduced cooking time.

P. p and m. The influence of the features of the proposed method, prototype on the intensification of the set and increase the strength of concrete was tested on six compositions of concrete mix with PC 2 ... 3 cm in a wide range of consumption of component components (table.

Preliminary preparation and activation of cementitious (cement paste) or mortar component was carried out by mixing in a turbulent mixer-activator CA-AO. The final preparation of the concrete mixture was carried out in concrete mixer C.

With a closed shutter and a running electric motor, a turbulent mixer-activator is loaded with a floor per dose of mash water. After 7 .. „10 s (after the entire dose of water has left the receiving hopper of the dispenser)

part of the cement dose is loaded and mixing is carried out for 10 .. „15 s, then a fine aggregate (5 g.“ 100%) is loaded over a period of at least 10 s and final mixing takes place over 2P ... 3O s, after which the component is unloaded with the shutter open in the concrete mixer within .5 ... 7 s. The remaining cement, fine aggregate (in case of partial dosing into the activator) and coarse aggregate are loaded into a working concrete mixer for S.0015 s before the shutter of the mixer-activator opens. After the activated mortar component is discharged, the concrete mixture is mixed for 3–5 seconds and then the ready concrete mixture is unloaded.

The following materials were used to prepare the concrete mixture. Portland cement of the Akhangaran plant, NGCT 26.5, setting time - 2 hours 10 minutes, end - b hours 5 minutes, cement activity -I, 5 MPa density - 3.1 $ g / cm3. Fine aggregate was sand with a true density of 2.67 g / cm3, bulk density of V Й 80 kg / m3, particle size modulus, M kp 2.65, and clay and dust particles, 0.85. Crushed stone of the 5 ... 20 mA fraction was used as a coarse filling of 7 bodies. The density of grains of crushed stone is 2.68 g / cm3, bulk density is 13NW kg / m3, crushability is LR8, voidness is 8.23; the content of clay and dust particles is $ 0.9.

Sampling of the concrete mixture, determination of its workability, molding and testing of the samples was carried out according to the unified methodology in accordance with the current GOST “Samples - cubes of 15 15 x 15 cm in size were tested after 1 and 28 days of hardening under normal conditions.

As a result of the tests, it was found that the proposed method for the preparation of concrete mixture has a significant advantage over the analogue and prototype (tables. 2 and 3

Data analysis table. 2 shows that for concrete prepared by the proposed method, the compressive strength after 1 day of hardening exceeds the base case by ().,. 90S ;,

analogue to 1b „, 30, prototype to 7 ... 0%.

The advantage of the proposed method is noted (Table 3), and after 28 days of hardening, the excess of permeability compared to the base case is 17..27%, with the analogue U ..., with the prototype - $ 7 ... 11.

Thus, the proposed method due to the distinguishing features: preliminary activation of a part of the mortar component of the concrete mixture at 0.5 I / C 5.0 and a fine aggregate content of 5 .. about 1003; of its total amount, it allows to intensify the set of strength at an early age and increase the strength of concrete in comparison with a solution that is close in technical essence and the methods for preparing concrete mix used in production. The implementation of the proposed method in a production environment provides savings of 12 ...

182: cement upon reaching design targets for concrete strength.

Claims (1)

The claims A method of preparing a concrete mixture, including the activation of part of the cement by mixing it with water in a mixture activator pre with subsequent final mixing of the activated mixture with the other components of the concrete mixture in the concrete mixer, which are both clean and effective, in order to intensify the set and increase the strength of concrete, to efficiently use the technological equipment, part of cement with a water-cement ratio of 0.5ЈV / C; 5.0 together with fine aggregate in an amount of 5-100% of the total amount for 0.8-1.2 period of the final mixing of the components Concrete mixes table 2 Comparative indicators of concrete strength (MPa) under compression at the age of 1 day Table 1 8 Continuation of the table. 2