SE458755B - PROCEDURES FOR PREPARING EASY FLOWING CONCRETE MIXTURE - Google Patents

Description

458 755 2 the container and refill. This process only results in rapid preparation of mortar, but not of the activated suspension of the cement, since only intensive wetting, but not abrasion, heavy processes, g of cement crushing and others for gel formation can take place during the 30 second time period. . The process thus does not increase durability or hardening acceleration for concrete, which is produced from concrete mixtures with a light-flowing consistency. A method for intensifying both physical processes and chemical reactions between hard particles and a liquid stream is also known, which method comprises suspending the particles in the pulsating liquid stream, which in such addition, e.g. malt, äts-_ arnehâller a crush- which is used in the production of beer wort.

The resulting continuous suspension stream is subjected to a periodically delayed and accelerated movement inside special nozzles with a variable effective surface area (French Pat. No. 2,133,884). Depending on the effective surface area, the pressure speed of the liquid in the pulsating current also changes, respectively. When the liquid is heated to 70-75 ° C, the interaction between the substances is accelerated, which is atomized down to the molecular level. in nozzles from 1 to 30 m H 2 O; the reacting Due to the absence of cavitation, this process can not be used efficiently for processing cement particles and obtaining activated suspensions.

A process for preparing a preparation medium for concrete mixtures is also known, which process consists in mixing cement with preparation water in a ratio of 1: 0.001 - 1: 0.003. The resulting preparation medium is introduced into the concrete mixture, which is then subjected to vibration activation, which enables a reduction of the cement and water consumption in the concrete mixture by 10% (compared to the concrete composition obtained without activation) and the achievement of a concrete strength. for a sample (10x10x10) after permeation of 29.0 N / mmz (compare Soviet Inventor Certificate No. 681 012). However, this method is not applicable for the preparation of concrete mixtures with a light-flowing consistency, intended for high-strength concrete, as during the subsequent crushing of the cement by vibration activation it is necessary to introduce an additional amount of water into the concrete mixture due to higher water requirements for the mixture.

A process for obtaining an activated preparation medium for concrete mixtures is known, which process consists of a continuous mixing of water with 5-40% of the total volume consumption of cement mass in the concrete for 5-25 minutes. The highest strength for a sample of concrete 300 has been achieved during an activation time of 25 minutes. due to wear of part of the cement's grain surfaces (compare Soviet Inventor's Certificate No. 643,457). This method is not applicable to the production of concrete with higher strength from concrete mixtures with a light-flowing consistency, and can therefore not be used in the manufacture of densely reinforced reinforced concrete products and structures.

A process for preparing a preparation medium for concrete mixing is known, in which process cement is mixed with an excess amount of water heated to SOOC. In the obtained preparation medium, the ballast is introduced and then the concrete mixture is mixed for a longer period of time. The strength of the concrete sample increases by 20% and is achieved by increasing the hardness of the concrete mixture during wear of the grain surfaces of the cement and aggregate material and as a result of temperature rise, which accelerates the cement hydration process (compare Soviet Inventor Certificate No. 485,089). This method cannot be used for the production of high-strength concrete from concrete mixtures with a light-flowing consistency.

The process closest to that of the present invention is a process for preparing the preparation medium for concrete mixtures, which process consists of mixing the total amount of cement with water and subsequent vibrating activation of the resulting mixture by means of a two-powder vibrator. with the industrial tone frequency 50 Hz. The vibration activation of the preparation medium lasts from 5 to 10 minutes, after which the medium is used to prepare the concrete mixture (ie dry constituents are introduced for the finished concrete mixture).

The strength of concrete with activated preparation medium is doubled and reaches 80.0 N / mm 2 (compare Soviet Inventor Certificate No. 568 612).

The higher strength of the concrete is achieved through this process mainly due to an increase in the toughness of the concrete mixture when utilizing an opportunity for a low water-cement content. Such concrete mixtures can retain their easy-flowing consistency for up to 300 sec. and more, they can be manufactured by vibratory treatment and are subject to known technical and manufacturing difficulties in use; because they require a long-lasting vibrating gasket with loading. The introduction of an additional amount of water to preserve the desired easy-flowing consistency of the concrete mix has a negative effect on the increase in concrete strength until its complete loss. This method can not be used for the preparation of easily flowing concrete mixtures.

Nor is the task of accelerating the hardening of the concrete during processing with heat and moisture under normal conditions for hardening solved.

The main object of the present invention is to provide a process for the preparation of a preparation medium for concrete mixtures with a light-flowing consistency, which medium can accelerate the hardening of concrete during processing with heat and moisture and under normal conditions for hardening.

This object is achieved by preparing a preparation medium for concrete mixtures with a light-liquid consistency by a process consisting of mixing cement and water, introducing yeast sulphite effluent into the resulting mixture and subsequently vibrating activating the prepared preparation mixture. diet, according to the invention, mixes cement and water in a weight ratio from 1: 1 to 1: 1.5, whereupon vibrating activation of the prepared preparation medium is effected to a pulsation frequency for the preparation medium of 600-950 Hz.

Thanks to the process proposed according to the invention, § 5 458 755 constitutes the time for hardening of concrete, which is produced using the prepared preparation medium, in isothermal regimes with heat and moisture processing at 70 ° C to obtain the desired strength, which is equal to 40 N / mmz, 10 hours. The nominal strength of steam-hardened concrete is in samples with a size of 10x10x10 cm after 28 days of hardening under normal conditions at a level of 65.5-67.5 N / mmz, while the cement consumption decreases by 20% compared to the for concrete, the preparation medium of which is produced without any vibration activation.

In order to maintain the effect of improving the flexibility of the concrete mixture by absorption and to preserve the increase in the strength of the concrete, it is according to the invention expedient to introduce the yeast sulphite liquor into the cement-water mixture in an amount of 0.03-0.1%, calculated on the concrete weight of the concrete mixture. .

Further objects and advantages of the present invention are explained in more detail below by a detailed description of the process according to the invention for the preparation of a preparation medium for concrete mixtures with a light-liquid consistency and by concrete examples of the preparation of these mixtures.

The present process for the preparation of a preparation medium for concrete mixtures consists of the following: Preparation medium, which is intended for the preparation of concrete mixtures, is prepared by mixing cement with water in a weight ratio of from 1: 1 to 1: 1, S in the presence of yeast sulphite liquor in an amount of 0.03-0.1% in relation to the cement weight in the concrete mixture. The resulting mixture in the form of an aqueous suspension of the cement is pumped by means of a pump through a pulse device, in which the preparation medium is subjected for a short time to multiple impulse effects to a pulsation frequency for the medium of 600-950 Hz. The obtained activated medium with yeast sulphite sludge is used for preparing the concrete mixture.

Outside the limits of the cement-water weight ratio (1: 1 - 1: 1.5), by reducing the relative amount of the processed cement, the activating effect of the preparation medium on the concrete mixture is reduced, while increasing the cement concentration in the preparation medium, its usefulness decreases in high frequency processing, such as a consequence of an increase in toughness above permitted values, which also leads to a reduction in the activation effect of the medium on the concrete mixture.

When the yeast sulphite liquor content decreases below 0.03%, the effect on the absorption plasticization of the concrete mixture decreases, which leads to the necessity to increase the amount of preparation water, while an increase in the yeast sulphite liquor content above 0.1% does not lead to any further increase in plasticization to reduce the strength of the concrete.

The high frequency vibration pulse processing of the preparation medium, which consists of cement-water suspension, at a pulsation frequency of 600-950 Hz, leads, as mentioned, to changes in the quality of the medium as dispersion system, namely: in addition to increasing the hard phase degree of dispersion, due to the additional crushing and wear of the cement granules, the hydrogen level in the preparation medium is raised by cleavage of some of the water molecules.

The instantaneous hydration of the cement particles at a grain size of less than 5 .mu.m by means of high-frequency machining leads to an increase in the volume of highly dispersed new hydrates in the form of a gel and to the intensive release of calcium hydroxide. contains hydrocarbon radicals with different degrees of polarity, leads to the development of absorption plasticization at the molecular level. As a result of the influence of the above factors, not only the moisture absorption capacity of the cement grains but also of the fine and coarse ballast increases when mixing the concrete mixture with the preparation medium, with the participation of intensive interaction between dipole water molecules and the aluminosilicate particles in their surface layers.

Development of the said processes leads to the preservation of the flexibility of the concrete mixture (without increasing hardness) and the effect of cement activation when excluding excess amount of surfactant leads to the strength of the concrete increasing and its hardening being accelerated. ; 7 458 755 If the pulsation frequency is lowered below 600 Hz, the activating effect of the preparation medium is reduced, which leads to a reduction in the strength of the concrete and an increase in its hardening time during heat and moisture processing. If you increase the pulsation frequency above 950 Hz, too much crushing of the cement occurs and this leads to the heat and moisture processing deteriorating the strength properties of the concrete and b reducing the increase of these properties.

Example 1 A preparation medium for concrete mixtures with a light-flowing consistency is prepared by mixing 176 kg of cement, 176 l of water and 132 g of yeast sulphite liquor in an ordinary mixer to a cement paste or suspension. This suspension is pumped through a pulse apparatus, where it is subjected to multiple vibrational pulse impulses for 1.5 - 2 minutes at a pulse frequency for the medium of 600 Hz.

The preparation medium thus activated is introduced into a rotatable concrete mixer with pre-dosed dry constituents of the concrete mixture in sufficient quantity to obtain 1 m3 of concrete: 264 kg of cement, 1130 kg of granite crushed stone with a grain fraction of 5-20 mm and 685 kg. quartz sand. As a result, you get a concrete mix with a light-flowing consistency with good workability of 5 sec. in vibrating packing. The curing time of the obtained concrete under isothermal regime during heat and moisture processing at 70 ° C, up to the desired final nånfastnet 40 N / mmz, is 10 hours. The strength of the permeated concrete (a sample 10x10x10 cm) after 28 days during the subsequent hardening under normal conditions is 66.0 N / mmz.

Example 2 Preparation medium for concrete mixtures with a light-flowing consistency is prepared according to Example 1, using 117 kg of cement, 176 l of water and 323 g of yeast sulphite liquor. Processing of the I 1 preparation medium with vibration-pulse effect takes place at a pulsation frequency of 950 Hz. 458 755 Ü 8 The preparation medium thus activated is introduced into a rotatable concrete mixer containing the pre-dosed dry components of the concrete mix to obtain 1 m3 of concrete: zoe kg of cement, 1130 kg of granite feces with a core frequency of 5-20 mm and 685 kg of quartz sand . The curing time of the obtained concrete under isothermal regime is 10 hours, the strength of the permeated concrete after 28 days of storage is 65.5 N / mmz.

Example gel 3 A preparation medium for concrete mixtures with a light-liquid consistency is prepared in the same way as in Example 1, turning 140 kg of cement, 176 l of water and 195 kg of yeast sulphite liquor.

Processing of the preparation medium with vibration-pulse effect takes place at a pulsation frequency of 775 Hz.

The preparation medium activated in this way is introduced into a rotatable concrete mixer with pre-dosed dry components for the concrete mixture to obtain 1 m3 of concrete: 160 kg cement, 1130 kg granite crushed stone with grain fraction S-20 mm and 685 kg quartz sand. The curing time of the obtained concrete under isothermal conditions to obtain a desired final strength is 9.5 hours and the strength of the soaked concrete after 28 days of storage is 67.5 N / mm 2. Example gel A concrete mixture is prepared for the production of seals lined articles and constructions with a light-flowing consistency equal to 5 sec. (for vibrating gaskets) and a final strength of 40 N / mmz during heat and moisture treatment at 70 ° C.

For 1 m3 of concrete, S50 kg of cement, 1075 kg of granite crushed stone with a grain fraction of 5-20 mm, 610 kg of quartz sand, 200 l of water and 0.7 kg (0.15%) of yeast sulphite liquor are consumed.

As a preparation medium, water was used. The process for producing the concrete mixture with a light-flowing consistency consists of mixing the mixing components in a concrete mixer. This final process achieves the final strength of the concrete as above only after 18 hours of isothermal treatment, which increases the energy consumption for the permeation of the concrete by 30-35% compared to that required in the process described in Example 1. , wherein in addition the strength of the permeated concrete after 28 days of subsequent hardening is only 52.5 N / mm. Example 5 The preparation medium for a concrete mixture with a light-flowing consistency is prepared in a similar manner as in Example 1, the processing medium being processed by vibration-pulse action at a pulsation frequency of 50 Hz. The preparation medium activated in this way is mixed with the dry components of the concrete mixture as in Example 1.

When preserving the good workability of the concrete mixture, the durability of the concrete obtained is only 45.1 N / mmz and the vapor hardening period of the concrete is 18 hours.

This is because in order to preserve the desired easy-flowing consistency of the concrete mixture during the further crushing of the cement, as a result of its dispersion increase, more water must be introduced, which is caused by greater water demand. This has a negative effect on the strength properties of the concrete due to the higher water cement number.

Example 6 (Carried out according to the procedure described in Soviet Inventor Certificate No. 568 612, which relates to concrete mixtures with a light-liquid consistency.) The preparation medium of the concrete mixture is prepared by mixing 550 kg of cement and 220 l of water. The resulting mixture is vibration activated by means of a two-pole vibrator with a frequency of 50 Hz. The activated preparation medium was used for the production of a concrete mixture with a light-flowing consistency with a material consumption of 1 m3: 1075 kg of crushed stone with a grain fraction of 5-20 mm, 590 kg of quartz sand. Thereby a concrete with a strength 458 755 10 2 was obtained. . ... _ _ heat of 57.8 N / mm after soaking with subsequent storage for 28 days. The concrete hardening time for heat and moisture treatment under isothermal conditions at 7000 up to the desired 80% hardness was 18 hours.

Example gel 7 A concrete mixture with a light-liquid consistency of 5 sec is produced for the production of densely reinforced articles and structures. (for vibrating gaskets) and a final strength of 40 N / mmz during heat and moisture treatment at 70 ° C.

For 1 m3 of concrete, 440 kg of cement, 1130 kg of crushed stone with a grain fraction of 5-20 mm, 705 kg of kmnissï fi, 150 l of water and 3.52 kg (0.8%) of superplasticizing additives are consumed.

Water was used as the preparation medium. The concrete mixture is prepared by mixing the components in a concrete mixer.

This process results in the above-mentioned final strength only after 18 hours of isothermal treatment, which increases the energy consumption of the concrete permeation by 30-35% compared with that of the process described in Example 1; in this case, the strength of the hardened concrete after 28 days of subsequent curing is only 54.0 N / mm 2.

The comparison table of physico-mechanical properties of concrete obtained from concrete mixtures according to the above example: 11 458 755 1. Consistency of the concrete mixture, sec 5 S 5 5 2. Material consumption for 1 m3 concrete 2.1 cement, kg S50 440 440 550 2.2 crushed stone, kg 1075 1130 1130 1075 2.3 sand. kg 610 705 685 590 2.4 water. 1 200 158 176 220 Addition in 2 from cement paste: 2.5 superplasticising additives _ 0.8 - - 2.6 yeast sulphite effluent 0.15 - 0.03 0.15 3. Curing time for heat and moisture treatment under isothermal conditions at 70 ° C front to the desired 80% - strength, i-hours 18 18 10 18 4. The strength of the steam-hardened concrete after storage under normal conditions 1 28 days.

N / mm? 52.5 s4.o ss, o 57.8

Claims (2)

A process for the preparation of a preparation medium for concrete mixtures with a light-liquid consistency, which consists in mixing cement with water, introducing yeast sulphite effluent into the resulting mixture and then vibrating activating the prepared preparation medium characterized in that a mixture of cement and water 1 is first carried out in a weight ratio of 1 to 1: 1, 5, after which vibration activation of the prepared preparation medium is carried out to a pulsation frequency of the preparation of 600-950 Hz. Process according to Claim 1, characterized in that a yeast-sulphite liquor 1 is added to the cement-water mixture 1 in a proportion of 0.03-0.1%, calculated on the cement mass in the concrete mixture.