SU1206094A1 - Method of applying liquid concrete mixes - Google Patents

Description

The invention relates to the construction, can be used for the production of flat reinforced concrete elements in a horizontal position.

 This is an intensification of the compaction process and the increase in concrete strength.

The method is carried out as follows.

At the first stage of molding, after placing the concrete mix in the form, it is affected by a frequency ranging from 15 to 25 Hz, having vertical and horizontal components with such a ratio that the resulting vibration effect is directed under the ANGLE to the horizon from 10 to 45, and the horizontal component accelerations ranged from 1.5 to 2.5.,

These modes of vibroexposure well re-fix the concrete mix in the form, evenly fill it and tightly pack the components of the concrete mix. After the termination of the shaping, which ends in 0.5–1 min, the first vibration exciter switches off and turns on the second with a higher frequency, which exceeds the initial one 1.7–1.96 times in the range from 25 to 50 Hz with vertical oscillations and acceleration 3–7. This frequency is much more effective than the first one to dilute the cement dough, which is located in a tightly packed frame of concrete mixers. Therefore, there is an intensive consolidation of the concrete mix without significant movements in a short period of time from 0.5 to 1 minute.

Sample 1. Make samples of 10x10x30 cm in size FROM concrete mixtures with a stiffness index of 99 and 82 s. Portland cement mark 400, crushed stone fraction 10-20 mm. Different stiffness mixes get for. expense of change in water / cement ratio.

Samples are molded in the following order. The form is filled with a concrete mix at one time with some. excess. The vibration is switched on at a frequency of 15 Hz, acceleration 2 and direction of the resulting oscillation to the horizon of 10 °. The vibration compaction time in this mode is 30 seconds. When studying the behavior of concrete

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mixture under the action of her other modes of vibration noted the following. At frequencies below 15 Hz, the mixture is loosened and even ejected from the form, more than 25 Hz - there is no intensive repacking of a large filling machine. When the angle of inclination of the resulting oscillations outside the range of 10-45 ° is the loosening of the mixture.

ten . After turning off the vibration with oblique oscillations, the vertical oscillations with a frequency of 25.5 Hz and an acceleration of 4 for 40 s are reported with a mixture. For comparison

) 5 made samples according to the modes specified in the known method. All samples underwent heat and moisture treatment according to the modes 2 + 5 + 3.

Table 1 shows the technological parameters of sample molding and the results of their testing.

PRI mme R 2. Received delivery of a concrete mix, kg: Portland cement M500 330; crushed granite fraction

25 5 - 20 mm 1288; fine river sand 668; water 168 l. The stiffness of the concrete mix 40 C.

The necessary vibration modes for moldable samples are provided with two electrodynamic stands. All samples are molded, carried out at the first stage of compaction vibration with the direction resulting to the horizon at an angle of 45 °. After turning off the sloping

35 vibrations with a frequency of 25 Hz seal the seal with a vertically directed vibration with a frequency of 49 Hz. The total accumulation time is 60 seconds, the duration of each type of vib40

at 30 s. The test results for samples at 28 days old, given under normal standard conditions, are given in c. Table 2.

Thus, when compaction of samples according to the proposed mode with a ratio of the frequencies of the first and second stages within 1, 7 - 1.96, the highest values of the limit are obtained.

concrete strength. With a decrease in this ratio, it is likely that the intensity of the vibration at the second final stage of compaction is insufficient. With a higher frequency ratio of the first

and the second stage, partial decomposition of the concrete macrostructure formed at the first stage of compaction occurs.

1206094

Table 1

Method Stiffness Total Bulk Strength

molding mixture, with time mass, in compression

vibrop-kg / m MPa

lotneni, with

The proposed 9990239038.1

8270236036,5

Known for 99160231032.4

82120230029.2

 --.- - “. - ....-- - ". . - "" ". ,, "." ... "..

table 2

Frequency in stages Value Average limit

compaction frequencies of concrete strength

under compression, MPa

First Second

16301,8735,8

25491.9635.2

20341,7.36,1

15231,530.7

25602,430,4

15503,331,9

Compiler N.Ignatova Editor N.Tupitsa Tehred A. Boyko Proofreader-L.Patai

Order 8620/16 Circulation. Subscription

VNIIPI USSR State Committee for Inventions and Discoveries 113035, Moscow, Zh-35, 4/5 Raushsk nab.

Branch P1P Patent, Uzhgorod, st. Project, 4

Claims (1)

METHOD FOR SEALING RIGID CONCRETE MIXTURES by simultaneously vibrating them horizontally and vertically with vibrations with an inclination angle of the resulting component to the horizon of 10-45 ° and with a frequency of 15-25 Hz, which is convenient because intensification of the compaction process and increase the strength of concrete, after vibration exposure by horizontally and vertically directed vibrations, the concrete mix is affected by vertically directed vibrations with a frequency exceeding the original one by 1.7-1.96 times. ¹ 1206094 ²