Method to prepare concrete mix

FIELD: construction.

SUBSTANCE: method to prepare concrete mix consists in the fact that previously 50% of the rated amount of cement is mixed with tempering water, containing superplasticiser of the condensation product on the basis of sodium salt of naphthalenesulphonic acid and formaldehyde - RELAMIX T2 and hardening accelerator - sodium sulphate, exposed to mechanical and chemical activation in a rotor-pulsation device for 2 minutes with subsequent mixing of the remaining part of cement and fillers.

EFFECT: increased strength, mobility of concrete mix, frost resistance and water impermeability.

2 cl, 1 tbl

 

The invention relates to the field of construction, in particular to the technology of preparation of concrete mixtures used for the manufacture of concrete and reinforced concrete products and structures in monolithic and precast construction.

Known method of preparing a concrete mixture, comprising mixing part of the calculation of the dose of fluid mixing with cement in the mixer-activator introduction the remaining part of the calculation of the dose of fluid mixing in the mixer with filler, the subsequent introduction obtained in the mixer-activator slurry in the mixer and the final stirring of the resulting mixture, characterized in that the liquid, the mixing water is used, which pre-pour into the mixer-activator in the amount of 40÷70% of theoretical (prescription) dose of fluid mixing, which is in the process of filling in the mixer-activator activate (EN 2496748 AND, pub. 27.10.2013).

The disadvantage of this invention is the low strength of the resulting concrete, as well as the technical complexity of the process of preparation of the concrete mix.

Known method of preparing a concrete mixture, comprising mixing a binder, aggregates, mixing water, in which dissolved glycerol in an amount of 0.05-0.3% by weight of cement, manufacture mechanical activation at the end of stage 1 of the process structureo�education. A mixture of sand and cement shut part of the calculation for the mixing amount of water with the calculated amount of glycerol and the remainder water, which contains a hardening accelerator, together with the coarse aggregate is introduced into the concrete mixture after preliminary stirring for 1.5 to 2.5 min (EN 2097364 AND, pub. 27.11.1997).

The disadvantage of this invention is a long process of preparation of concrete mixtures and the low strength of the resulting concrete.

The prototype of this invention is a method of producing a concrete mixture that includes pre-activation of parts of cement from its estimated quantity, the superplasticizer and the subsequent mixing with the rest of the cement, aggregate and water. The activation is carried out by stirring in water at W/C=0.5 to 1.0 for 40-45 min, and the portion of cement is 10% of the calculated quantity (RU 2371412 C1, pub. 27.10.2009).

The disadvantage of this invention is the high energy intensity and the duration of the process of preparation of concrete mixtures and low strength of the resulting concrete.

The object of the present invention - increase the growth rate of the concrete strength in the early stages of hardening, especially on the first day, while maintaining their high grade strength, high frost resistance and water resistance.

Results� is achieved by a method for the preparation of the concrete mix, including a preliminary activation part from the calculated amount of cement with mixing water containing superplasticizers and subsequent mixing with the rest of the cement and the aggregates according to the invention mechanochemical activation is carried out by stirring in an aqueous medium in a rotary pulsation apparatus with a rotational speed of the working body 5000 rpm for 2 min, a part of cement is 50% of the estimated quantity, as a superplasticizer additive used is a condensation product based on sodium salt of naphthalene sulfonic acid and formaldehyde - RELAIX T2 and the hardening accelerator is sodium sulfate.

The result is also achieved by the fact that the consumption of additives is 1% by weight of cement.

As a superplasticizer additive used "REEMIX T2 - condensation product based on sodium salt of naphthalene sulfonic acid and formaldehyde (hereinafter additive "REEMIX T2") TU 5870-002-14153664-04 with amendment No. 1.

As the hardening accelerator used additive sodium sulphate on THE 38-10742.

Method of preparation of concrete mix is as follows.

For the preparation of concrete mixture production of the composition of the used cement M400 D20 PC Ulyanovsk plant that meets the requirements of GOST 31108-2003, ne�OK Kamsko-Ustinsky field meets the requirements of GOST 8736-93 and GOST 8735-88 and gravel Kamsko-Ustinsky deposits that meet the requirements of state standards for concrete, with the following ratio (wt.h.):

Cement: sand: gravel=1:1,13:2,68.

The consumption of cement per 1 m3concrete amounted to 490 kg.

Mechanochemical activation was performed in a rotary pulsation apparatus RPA Pp. 8-55A-2.2 UZ TU 5132-001-70447062.

Previously 50% of the estimated amount of cement mixed with the mixing water, which is pre-dissolved these supplements, and was subjected to mechanochemical activation (MCA) in a rotary pulsation apparatus with a rotational speed of the working body 5000 rpm for 2 min, followed by stirring the remaining part of cement, coarse and fine aggregate in the mixer for at least 5 minutes.

The dosage of the supplements Reemix T2 was 1% by weight of cement, the dosage of the hardening accelerator is sodium sulfate was 1% by weight of cement.

Of concrete mixes produced samples - cubes with dimensions of 10×10×10. After 1, 3 and 28 days normal curing, the samples were subjected to mechanical tests. The strength of the samples was determined in accordance with GOST 18105-86. Frost resistance of samples was determined in accordance with GOST 10060.3-95, water-resistance in accordance with GOST 12730.5-84, the mobility of the concrete was determined in accordance with GB�against GOST 10181.1-81.

The results of physico-mechanical tests of the samples are given in table 1.

Table 1
№ p/pName additivesThe MOSS, minThe dosage of the additive in % by weight cementW/COK, cmThe average density of concrete, kg/m3The compressive strength, MPaMorosettiThe water resistance
1 day3 days28 days
2T2+SN11+10,3111247028,8*271%a46,4159%a 64,5127%aF500W14
4T2+SN21+10,3114249035,2332%a56,4193%a76,2150%aF600W16
5 (prior art)C-3400,70,359255010,6100%a 100%a50,8100%aF150W6
Note*: above the line shows the average value of the indicator; below the line is a relative value in % from the prototype.
**: SN - sodium sulfate.

Based on the data obtained show that the concrete is obtained from mechanically activated cement slurry with additives of superplasticizer has a compressive strength at day old in to 3.32 times more than concrete, obtained by analog. In a three-day and 28-day old concrete, obtained by this method has a compressive strength respectively of 1.93 and 1.5 times higher than the strength of concrete obtained according to the prior art. Frost resistance of concrete F600 and water resistant W16. Slump in determining the mobility of a concrete mix was 14 cm

1. Method of preparation of concrete mix, including a preliminary activation part from the calculated amount of cement with mixing water containing superplasticizer and accelerator of hardening, the subsequent mixing with the rest of the cement and for�animelee, characterized in that the mechanochemical activation is carried out by stirring in an aqueous medium in a rotary pulsation apparatus for 2 min, a part of cement is 50% of the estimated quantity, as a superplasticizer additive used is a condensation product based on sodium salt of naphthalene sulfonic acid and formaldehyde - RELAIX T2 and the hardening accelerator is sodium sulfate.

2. A method according to claim 1, characterized in that the consumption of additives, taken in specified ratio is 1% by weight of cement.



 

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2 tbl

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