HU199089B - Method for producing premixtures for concrete - Google Patents

Abstract

Cement, water and yeast-sulphite waste liquor are mixed to form make-up medium for high slump concrete mix. Medium is pref. activated by pulsed vibrations at 600-950 Hz. Cement to water mass ratio is pref. 1:1-1.5 and yeast-sulphite waste addn is pref. 0.03-0.1% of cement mass in concrete.

Description

FIELD OF THE INVENTION This invention relates to a process for the preparation of a pre-mix for Cementable Concrete. Bulk concrete can be made into large steel reinforced concrete elements and structures.

The concrete premix prepared according to the invention is primarily used for concrete structures but has other uses: in certain processing operations, it is necessary to classify the particles of bulk powder or slurry mixtures by specific gravity, which is usually carried out in liquids of different specific gravities. For example, the concrete premix produced according to the invention is suitable for the classification of slag fly ash slurry from power plants.

A suspension suitable for the preparation of construction mortar is disclosed in U.S. Patent No. 1,145,481. According to British Patent Specification, they are prepared by slurrying cement with water and then mixing the slurry with vane mixer so vigorously that cavitation effects occur.

During the process, 25% of the cement particles will gel, their wettability will increase, and accordingly the adsorption activity of the slurry will increase, while the remaining particles will remain unchanged.

For intensive contact between cement and water, see No. 487,779. British Patent Specification proposes vortex flow. The method involves dispensing water through the entire system of dispensers, adding small amounts of dry material such as cement, clay or other sprayable material, and circulating the resulting aqueous suspension with a pump for 30 seconds, swirling and emptying and refilling the vessel. . The process is suitable for the rapid preparation of mortar, but activated slurries cannot be prepared because 30 seconds allowed for contact is sufficient to moisten the cement particle, but the surface is not rubbed, milled, activated, so the treatment does not increase the strength of the concrete. accelerates.

It is also known to intensify the physical and chemical processes between solids and liquids. The process involves suspending the solid particles (malt in the brewing process) in a pulsed fluid stream. The continuous fluid flow of the slurry, flowing through special nozzles, periodically slows down and accelerates (French Patent No. 2,133,884), depending on the actual cross-section of the variable free nozzle. Depending on the free cross-section, the nozzle pressure also varies between 1 and 30 water columns and the fluid velocity changes accordingly. Heating the liquid to 70-75 ° C accelerates the reaction of the reacting components; pulsed motion disperses the substances at the molecular level. However, due to the lack of cavitation, the process is not suitable for the treatment of cement particles and for the preparation of activated cement slurries.

The preparation of a premix for use in the preparation of Rnton is described in U.S. Patent No. 881,012. Soviet Patent Specification No. According to the process, cement and water are mixed in a ratio of 1: 0.0001: 0.003, the premix thus obtained is added to the concrete and the concrete mixture is activated by vibration. As a result of the treatment, to achieve the same strength (29.0 MPa on a 10x10x10 specimen, after steam treatment), 10% less paint and water is required compared to unactivated concrete. However, the above process is not suitable for the preparation of a bulk concrete mix for the production of high strength heton because:. the. activated week more urine, requires.

It is further known to provide a process for the preparation of an activated pre-concrete mixture in which 5-40% by weight of the total cement requirement of the concrete. It is mixed with water for 25 minutes (US Patent No. 643,457). With 300 grade cement, the highest strength was achieved when the surface of some of the cement was demolished after 25 minutes of treatment. However, the process is not suitable for the production of high-strength concrete and steel-reinforced, hexagonal structures.

Concrete mix. for preparing a suitable premix, see U.S. Patent No. 485,089. U.S. Patent No. 4,198,125, which discloses that cement is mixed with excess water heated to about 50 ° C. The resulting premix is added to some additive and then the concrete mix. stir for a long time. 20% strength increase on cubic specimens. measured, in part, cement and. surface degradation of additive particles, in part. is the result of hydration at elevated temperatures.

Finally, there is a known method by which. all the cement in the concrete is mixed with water and the resulting slurry is activated by vibration on a dipole shaker at 40 Hz for 5 to 10 minutes. The pre-mix thus prepared contains the other dry constituents of the concrete.

Concrete made with activated premixture can double the strength of conventionally produced concrete, up to 80.0 MPa (Soviet Patent No. 568612). The higher strength is primarily due to the reduced water to cement ratio. Such a concrete mix can be vibrated, but often it is. it must be added to the concrete in order to preserve its bulk, which will adversely affect the final strength.

SUMMARY OF THE INVENTION It is an object of the present invention to provide, by varying process parameters, a premix that accelerates the hardening of concrete under the conditions of wet-wet curing.

SUMMARY OF THE INVENTION The present invention relates to a process for the production of a pre-blend melt 23

HU 199089 Β ton, during which cement water and sulphite slurry are mixed by vibration. The process is characterized by mixing 1 part by weight of cement with 1 to 1.5 parts by weight of water and activating the mixture by vibrating at 600-950 Hz.

During the wet-wet concrete maturation, the concrete prepared with the premix prepared according to the invention hardens at 70 ° C for 10 hours, during which time it reaches a transport strength (40 MPa). The 10x10x10 cm concrete specimen has a hardness of 65.5-67.5 MPa after 28 days of curing. Compared to concrete made with non-activated premix, the amount of cement required during the application of the premix according to the invention was reduced by 20%.

In order to maintain the flowability of the mixture, it is desirable to add from 0.03 to 0.1% by weight of sulfite impurity slurry based on the total amount of cement in the cement-water mixture.

The process according to the invention will now be described in more detail.

At a cement-to-water ratio of 1: 1 to 1: 1.5, the cement is mixed with water in the presence of 0.03 to 0.1% by weight of sulfite slurry. The amount of sulfite slurry is based on the total weight of the cement. The resulting aqueous cement slurry is pumped to a vibration device, where it is subjected to a pulsating vibration at a frequency between 600 and 950 Hz for a short period of time.

The parameters of the process according to the invention will be explained below. The use of less than 1: 1.5 cement reduces the activating effect; with more than 1: 1 cement, the premix will be dense enough to reduce or eliminate vibration, reducing the activating effect.

Sulphite waste liquor, when added in amounts of less than 0.03%, is not sufficient to preserve the pourability of the concrete. Greater than 0.1% no longer exerts a higher leveling effect, only reducing the concrete strength.

Vibration at frequencies between 600 and 950 Hz changes the quality of the dispersion system by increasing the dispersion degree of the solid phase during the subsequent grinding and rubbing of the surface of the cement particles, and increasing the pH of the liquid as the water molecules dissociate. Instant hydration of cement particles with a particle size of less than 5 µm under conditions of high-frequency treatment causes an increase in the volume of the newly formed highly dispersed hydrate, gel formation and calcium hydroxide precipitation. Under these conditions, the incorporation of the surfactant enhances the effect of adsorption plasticization.

The processes listed above ensure that the concrete mix remains workable without increasing its viscosity. Due to the absence of excess surfactant, the concrete becomes harder and hardens faster.

If the vibration frequency is less than 6 Hz, the activating effect of the premix is reduced, which adversely affects the strength of the concrete, while at the same time the water vapor aftertreatment strength is already greatly increased.

Example 1

By mixing 176 kg of cement, 176 liters of water and 132 sulphite slurries in a conventional mixer, a premix is prepared for high-melt concrete. The slurry is pumped through a pulsator · with a 6 Hz vibration multiplied by 1.5 to 2 minutes of stubble time.

264 kg of cement, 1130 kg of 5-20 n granite debris and 685 l of quartz honts, ie 1 m ^{3 of} concrete, are dry-mixed in a rotating concrete mixer and the premix is added. We get very good melt concrete, which has a workability of 5 seconds with vibration compaction. ΪΟ ^ Ό-οη, in isothermal water-warmed-wet post-treatment, the bet hardens to the required delivery strength in <10 hours. Steam treated concrete is stored under normal conditions for 28 days; 10x10x10 cnt specimen solid. 66.0 MPa.

Example 2

Example 1 was carried out with 117 liters of cement, 176 liters of water and 323 g of sulphite. using a lye, the vibration handles are performed at a frequency of 950 Hz.

Concrete is fed to the activated premix · rotary type mixer, which has been in the 1 m ³ b <tonhoz materials, viz. 206 kg cement, 1130 1 A mixture of granules of 5-20 mm grain size »685 kg of quartz sand. / under isothermal conditions, the vapor hardens during vaporization over a period of 10 hours, and after one day of storage has a strength of 65.5 MPa.

.?. example

By mixing 140 kg of cement, 176 liters of water and 195 sulphite slurries, a premix was prepared according to Example 1. The suspension is exposed to a vibration of 775 Hz.

The activated premix is fed into a rotating concrete beater, where already 160 kg of cements are 1130 kg of granules of 5-20 mm grain size

HU 199089 Β and 685 kg of quartz sand were dry mixed. The concrete hardens under isothermal conditions 9 to 5 hours to transport strength. After 28 days of storage, the strength of the steam-treated concrete is 67.5 MPa. 5

Example 4

For the production of heavily reinforced structures 10, a concrete mix having a workability of 5 seconds is obtained by vibratory compacting, which achieves a strength of 40 MPa during a 70 ° C steam treatment.

^m3 concrete 550 kg of cement, 1075 kg of 15 gránitzúzalékot 5-20 mesh size,

610 kg of quartz sand, 200 liters of water and 0.7 kg (0.15%) of sulfite impurities are used.

Instead of the premix, the dry ingredients are mixed with water. The technology for the production of bulk concrete consists of mixing raw materials in a concrete mixer.

During the steaming, this concrete only reaches the transport strength after 18 hours, which means that compared to Example 1, the energy required for steaming is 30-35% higher. The strength after 28 days of storage is only 52.5 MPa.

Example 5

In Example 1, the only difference is that the premix is activated by vibrating at 50 Hz. The live blends were mixed with the dry components as described in Example 1.

The workability of the concrete mixture is adjusted with water. The steaming takes 18 hours and the concrete strength is only 45.1 MPa. That's 40 because. additional water had to be added to maintain workability, and the increased water-cement ratio adversely affected the strength of the concrete.

Example 6 (According to the Soviet copyright certificate No. 568,612)

550 kg of cement and 200 liters of water premix are prepared and the resulting suspension is activated by shaking on a diphobic shaker at 50 Hz. Activated premix is used to make concrete using 1075 kg of 5-20 mm particles of 590 kg of quartz sand per cubic meter of the following material. The strength of the steam-treated 28 day-stored concrete is 57.8 MPa. During isothermal steam treatment at 70 ° C, the concrete reaches an 80% strength value in 18 hours.

Example 7

In the manufacture of heavily reinforced structures with vibration compacting, a 5-second workability ·) concrete mixture is obtained which, at 70 ° C steam treatment, achieves a strength of 40 MPa.

Using 440 kg of cement per m ^{3 of} concrete, 1130 kg of 5-20 mm granite chips, 705 kg of quartz sand, 150 liters of water and 3.52 kg (0.8%) of hetero-plasticizer are used.

Instead of premixing, the dry components are mixed with water using a concrete mixer.

The concrete has a required transport strength only after 18 hours of steaming, which means a 30-35% higher energy expenditure compared to Example 1. The strength of the steam-treated concrete stored for 28 days was 54.0 MPa.

The following table shows the characteristics of the concrete obtained by different technologies! summarize.

Parameter 4th Technology a 7.1. Example 6 workability, sec 5 5 δ 5 material requirement for 1 m ^{3 of} concrete cement, kg 550 440 440 550 rock chippings, kg 1075 1130 1130 1075 sand, kg 610 705 685 590 water, 1 200 158 176 220 betonplasztifikátor crowd% - 0.8 - - szulfitalkohol pomace 0:15 - 0:03 0:15 curing time at 70 ° C steam treatment is 80% up to strength 18 18 10 18 concrete stored for 28 days strength MPa 52.5 54.0 66.0 57.8

Claims (2)

PATENT CLAIMS CLAIMS 1. A process for the preparation of a bulk mix for concrete mixes comprising the step of cement, water and sulfur slurry. The mixture is stirred and activated by vibration, characterized in that 1 part by weight of cement is mixed with 1 to 1.5 parts by weight of water and the vibration activation of the suspension is effected by vibration at a frequency of 600-950 Hz. A process according to claim 1, characterized in that the cement-water slurry contains from 0.03 to 0.1% by weight of the sulfite slurry based on the aggregate content of the concrete mixture. We are added.