RU2423331C1 - Fibre-concrete mixture - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to compositions of concrete mixtures for making monolithic and precast concrete structures used in construction. The fibre-concrete mixture, which contains portland cement, basalt fibre, plasticiser, sand and water, contains plasticiser in form of S-3 superplasticiser or Melflux 265 IF hyperplasticiser, sand in form of fractionated quartz sand with the following distribution of fractions, %: Fr. 1.25-0.63 60, Fr. 0.63-0.315 20, Fr. 0.315-0.14 20, and also microsilica, with the following ratio of components in wt %: portland cement 25-30, microsilica 3-4, said plasticiser 0.3-0.9, basalt fibre 1.5-2.0, fractionated quartz sand 55-60, water - the rest. ^ EFFECT: high flexural, tensile, tensile splitting and compression strength, as well as high frost resistance. ^ 2 tbl

Description

The invention relates to compositions of concrete mixtures for the manufacture of both monolithic and precast concrete structures used in construction.

The known composition of the fiber-reinforced concrete mixture according to the patent of the Russian Federation No. 2288198 "Concrete mixture", IPC C04B 28/02 // C04B 14/38 // C04B 111/27, publ. 11.27.2006., According to which the concrete mixture includes Portland cement, quartz sand, mineral fiber and water, and waste minerals of basalt fiber production are used as mineral fiber in the following ratio of components, wt.%: Portland cement 20-22, quartz sand 43-44, waste products of basalt fiber 3,5-5, the rest is water.

The disadvantages of the mixture are insufficient bending strength, compression, splitting, frost resistance.

The closest is the composition of the fiber-reinforced concrete mixture, including cement, quartz sand and mineral fiber (see the description of the patent of the Russian Federation RU No. 2114081, IPC C04B 28/02 // C04B 111/20 from 09/19/95).

Products of known composition have insufficient bending, compression, tensile strength during cracking and frost resistance.

The objective of the invention is to obtain a composition of fiber-reinforced concrete with high bending strength, tensile strength during cracking and compression, as well as high frost resistance.

The result is achieved in that in the fiber-reinforced concrete mixture containing Portland cement, basalt fiber, plasticizer, sand and water, according to the invention, C-3 superplasticizer or Melflux 265 IF hyperplasticizer is contained as plasticizer, fractionated quartz sand with fractional distribution,%: Fr. 1.25-0.63 60, Fr. 0.63-0.315 20, Fr. 0.315-0.14 20, and additionally silica fume in the following ratio of components, wt.%:

Portland cement 25-30 Silica fume 3-4 The specified plasticizer 0.3-0.9 Basalt fiber 1.5-2.0 Fractionated quartz sand 55-60 Water rest

In the proposed composition of the concrete mixture used:

- Portland cement M500D0 GOST 10178-85;

- silica fume MK-85 of the Chelyabinsk Metallurgical Plant with the following chemical composition, wt.%: SiO ₂ 85-90, CaO 0,3-0,68, K ₂ O + Na ₂ O 0,91-1,85, Al ₂ O ₃ 0.68-0.79, MgO 0.78-1.01, Fe ₂ O ₃ 0.44-0.69, C 0.6-0.9, S 0.2-0.3, losses after calcination 2 7-4.2. The content of amorphous SiO ₂ is at least 70%;

- as a plasticizer, the superplasticizer C-3 TU 6-36-0204229-625 based on the condensation products of naphthalene sulfonic acid with formaldehyde or the polycondensation product based on modified polycarboxylate - Melflux 265 IF hyperplasticizer manufactured by Degussa Constraction Polymers (SKW Trostberg, Germany));

- basalt fiber with a length of 9 mm and a diameter of 10 μm (chopped from a multifilament yarn of parallel basalt fibers), TU 64-16625423-01;

- fractionated quartz sand GOST 8736-93 with the following distribution by fractions, wt.%: Fr. 1.25-0.63 60, Fr. 0.63-0.315 20, Fr. 0.315-0.14 20.

The use of ordinary Portland cement, a plasticizer in the concrete, reducing the water demand of the concrete mixture without losing its mobility, silica fume, increasing the strength of concrete, basalt fiber, evenly distributed over the volume of concrete and significantly increasing its flexural and tensile strength when cracked, optimally selected fractional composition of quartz sand, allowing to obtain the highest density of concrete, provide high physical and mechanical characteristics of the mater Ala.

Concrete mixture was prepared as follows. Portland cement was pre-mixed with basalt fiber, silica fume and fractionated quartz sand in a paddle concrete mixer for 30 s until a homogeneous dry mixture was obtained. Then, the amount of water with the plasticizer previously dissolved in it was added to the dry mixture to ensure the required mobility and mixed for 90 s. Compaction of the mixture was carried out on a laboratory vibratory platform. Concrete hardening took place at a humidity of 95-100% and an ambient temperature of + 18 ... 22 ° C. Concrete was tested for strength at the age of 28 days, frost resistance was determined at the age of 28 days.

The compositions of concrete for comparison are given in table 1. Compounds 1, 2 are optimal. Compositions 5 and 6 - beyond - are given to justify the choice of the amount of basalt fiber in the optimal composition. Composition 7 is a prototype. Physico-mechanical characteristics of the proposed material are shown in table.2.

Based on the analysis of the data in Table 1 and Table 2, it can be seen that with a basalt fiber content of 1.5% and an optimal dosage of plasticizer (0.3% Melflux 2651F or 0.6% C-3), the compressive strength of the reinforced concrete increases when bending and tensile when cracked in equally moving mixtures (OK = 15-17 cm).

Testing of concrete was carried out in laboratory conditions according to the methods described in GOST 10180-90, GOST 10181-2000, GOST 10060.1-95.

table 2 Concrete composition Cone draft, cm Strength at the age of 28 days, MPa Frost resistance cycles on compression when bending cracking tensile one 17 110 19 13 380 2 ^fifteen 95 16 12 360 3 16 93 17.5 11.5 340 four fifteen 86 15.4 9.9 320 5 7 75 12 8 300 6 5 60 7 5 270 7 (prototype) - 36.9-46.5 9.1-15.2 6.2-9.6 160

A comparison of the test results of the prototype and the proposed solution (optimal composition 1) shows that the strength increased: compression by 137 ... 198%, bending by 25 ... 109%, tensile strength when cracked by 35 ... 110%, frost resistance increased by 138% .

Claims (1)

Fiber-concrete mixture containing Portland cement, basalt fiber, plasticizer, sand and water, characterized in that it contains C-3 superplasticizer or Melflux 2651F hyperplasticizer, fractionated quartz sand with fractional distribution,%: Fr. 1.25-0.63 60, Fr. 0.63-0.315 20, Fr. 0.315-0.14 20, and additionally silica fume in the following ratio of components, wt.%:
Portland cement 25-30 Silica fume 3-4 The specified plasticizer 0.3-0.9 Basalt fiber 1.5-2.0 Fractionated quartz sand 55-60 Water rest