RU2267466C1 - Dry building mixture - Google Patents

Abstract

FIELD: building industry, in particular building materials based on mixed lime/cement binders useful in preparation of building mortars.

SUBSTANCE: claimed mixture contains cement binder (Portland cement); mineral plasticizer (hydrated lime); filler; organic additive; antifreeze additive; wherein as filler limestone sand containing 90-95 mass % of CaCO₃ and having particle size of 0.001-4.0 mm is used. Said limestone sand represents waste from calcium oxide production and according to grade size is taken in the next ratio (mass %): grade of 0.001-0.09 mm 1.4-9.9; grade of 0.09-0.80 mm 47.1-59.9; grade of 0.8-1.2 mm 11.3-21.4; grade of 1.2-2.00 mm 0.1-15.7; grade of 2.00-4.00 mm 0.1-20.8. As organic additive alkoxysilane, which represents redispersible hydrophobic agent. Additionally claimed mixture contains solid waste from soda ash production and active mineral filler. More particularly dry mixture contains (mass %): Portland cement 18.0-26.5; hydrated lime 0.001-8.000; limestone sand 68.300-73.797; active mineral filler 0.001-2.000; antifreeze additive 1.0-2.7; redispersible hydrophobic agent 0.05-0.50; waste from soda ash production 0.01-0.50. Alkoxysilane is a polymerization product of silane and polyvinyl alcohol and has bulk weight of 220-320 g/dm³. As active mineral filler active silica named as "carbon white" may be used, and as antifreeze additive sodium nitrite, or potash, or sodium formate, or mixture of calcium nitrate with urea in mass ratio of 2:1. Abovementioned solid waste from soda ash production has the next essentially constant composition (mass %): CaCO₃ 51-69; CaSO₄ 2-8; CaCl₂+NaCl 2-7; Ca(OH)₂ 7-16; SiCO₂ 10-18. Dry mixture of present invention may be used at law temperature, namely from +3 to -25°C.

EFFECT: dry building mixture of increased frost resistance, high adhesiveness to substrate and high water-retaining ability.

5 cl, 1 tbl

Description

The invention relates to the field of construction, namely, building materials based on mixed lime-cement binders, and can be used for the preparation of mortars for the production of masonry and plastering at low positive and negative temperatures, with high frost resistance.

In recent decades, dry mixes for the preparation of mortar have become widespread, allowing to bring construction technologies to a qualitatively high level - this is a higher quality of work performed, reduction of production losses, reduction of losses due to the small packing of dry mixes, reduction of transportation costs due to reduction in transportation . When working with dry mixes, downtime situations are excluded due to the lack of fresh mortar at the facility (there is no dependence on the operation of the mortar-concrete unit and transport), since dry mixes can be stored on site for a long time without loss of quality.

Dry building mixes containing lime-cement binder, sand as aggregate and organic additives (water-retaining, surface-active, adhesive, etc.) are widely known [Building materials. Ed. G.I. Gorchakova - M., "Higher School", 1982]. Before use, such a packaged mixture is shut with water.

In accordance with the standard (GOST 28013-98), mortars must comply with the main quality indicators: mobility, water retention capacity, delamination, average density.

Known dry building mixture, including cement, sand, lime binder, optionally containing a polymer binder, mica, titanium dioxide [A.SSSR No. 391097, IPC C 04 B 28/02, 1973].

Also known is a dry building mixture, including cement, sand, lime binder, polymer binder, mineral filler. At the same time, chalk with a mass fraction of sodium chloride of not more than 1.5% and a waste of the production of caustic soda and brine purification of not more than 4.0% are used as a mineral filler. As a lime binder, lime fluff is a waste product for the production of calcium carbide, calcined lime is a waste product for the production of calcium carbide and calcium hypochloride, as a polymer binder, polyvinyl chloride is a waste product for the production of polyvinyl chloride and, in addition, thermal power plant ash and methyl cellulose [Pat. RU No. 2162827, IPC С 04 В 28/02, 1999].

Also known is a dry building mixture containing, wt.%:

cement - 40-55, quartz sand - 45-55, lime mixture for rocks - 0.5-2.0, plasticizer based on methyl cellulose and methoxypropyl cellulose - 0.4-0.5. [Pat. RU No. 21119467, IPC С 04 В 28/02, 1996].

But the well-known building mixtures (masonry and plaster) have a common drawback - the inability to perform work at an ambient temperature below + 5 ° C. This circumstance is the main limiting factor for a vigorous increase in the consumption of dry mixes, since negative air temperatures prevail for a considerable part of Russia for 6 months or more. Carrying out construction work under these conditions requires either the use of various antifreeze additives, or one of the methods of winter concreting with heating or the use of special binders.

In connection with the foregoing, the relevance of the composition for work in winter conditions is undeniable.

Closest to the proposed invention - the prototype - is a building mixture of grade B 7.5, containing, wt.%:

Cementing agent (Portland cement) - 18

Aggregate (natural sand fraction <2.5 mm) - 82

Organic additive (S-3 superplasticizer - 2% by weight of cement)

Antifrosty additive - 1% by weight of cement,

moreover, the additives are introduced in excess of 100% and the mixture of cement, superplasticizer and additives is mechanically activated with an acceleration of 10-20 g. As an antifreeze additive, potash is used [Pat. RU No. 2182137, IPC С 04 В 28/02, 2000].

The disadvantages of this mixture are that when used as a masonry mortar, this composition is inconvenient in use, has low workability and low adhesion to the brick. The amount of adhesion to the base is not indicated in the description of the invention, however, based on the data of [F. M. Lea the chemistry of cement and concrete, London, 1956] it follows that in order to obtain a masonry mortar with high workability, which has good adhesion to the base, mineral plasticizers must be added to the composition: lime, clay or organic plasticizers, or mineral fillers. In addition, the introduction of from 1 to 5% antifreeze additives by weight of cement does not allow the mixture to be used at temperatures below minus 5 ° C [SNiP 82-101-98].

Based on the above data, this mixture has limitations on the type of work performed, in which it can be used because of its weak water-holding ability.

The objective of the invention is to develop a composition of a dry building mixture designed to work in conditions of temperatures from +3 to -25 ° C, which meets the requirements of builders for workability, having a high amount of adhesion to the base, having a high water retention capacity. Additionally, the invention provides a method for the disposal of waste from the production of soda ash as a component in a dry building mix. The problem is solved in that the mixture, including cement binder, mineral plasticizer, aggregate, organic additives, anti-frost additive, hydrated lime is used as mineral plasticizer, and limestone sand with CaCO ₃ content _of 90-95 wt.% And dimensions are used as aggregate particles from 0.001 to 4.0 mm - waste production of a fraction of limestone fed to the calcination in the production of calcium oxide, and limestone sand, depending on the size of the fraction taken in the following ratio, wt.%:

fraction 0.001-0.09 mm 1.4-9.9 0.09-0.80 mm 47.1-59.9 0.80-1.2 mm 11.3-21.4 1.20-2.00 mm 0.1-15.7 2.00-4.00 mm 0.1-20.8

as an organic additive, the product of the polymerization of silane and polyvinyl alcohol is used - as a redispersible water-repellent agent, it additionally contains solid waste from the production of soda ash (TOC) - an active mineral filler, and the dry mixture has the following composition, wt.%:

Portland cement 18.0-26.5 hydrated lime 0.001-8,000 limestone sand 68,300-73,797 active mineral filler 0.001-2,000 antifreeze supplement 1.0-2.7 redispersible water repellent agent - 0.05-0.50 Soda ash production waste (CBT) 0.01-0.50

It uses:

- as a binder - Portland cement without additives, GOST 10178-85;

- as a mineral plasticizer - hydrated lime;

- as a filler - limestone sand with a particle size of from 0.001 to 4.0 mm - the waste product of the fraction of limestone fed to the firing in the production of calcium oxide;

- as an active mineral filler - amorphous silica under the trademark "white soot".

The introduction of an active mineral filler pursues the goal of increasing workability, improving adhesion to the base (by increasing the contact area and the number of bonds formed by calcium hydrosilicates), reducing salt formation (due to pore colmatation by the products of the pozzolanic reaction) and increasing the strength of the structure.

Filler "White soot" is produced according to GOST 18307-78.

- as an antifrosty additive - sodium nitrite, the chemical formula NbB ₂ (TU-11303-3-14-89) or potash, the chemical formula K ₂ CO ₃ (GOST 106-90-73), or sodium formate (TU 2432-011 -00203803-98), or a mixture of calcium nitrate (GOST 4142) with urea (GOST 2081) in a mass ratio. 2: 1. The introduction of an antifreeze component, an electrolyte, allows to lower the temperature of water crystallization in the pores of the solution, helps to accelerate hydration processes and has a water-reducing effect due to the redistribution of the electron density of the starting minerals and hydration products.

- a highly reactive redispersible agent - alkyloxysilane - a product of the polymerization of silane and polyvinyl alcohol (for example, ELOTEX water repellent under the trademark "Seal 80" - bulk loose powder with a bulk density 220-320 g / dm ³ ) in an amount of 0.05-0.5 wt.%. Studies have shown that at negative air temperatures the evaporation of moisture from the solution is negligible, and the bulk of the liquid phase is given to the capillaries of the base (ceramic, silicate brick). The use of dispersible organosilicon compounds (alkyl-oxysilanes) makes it possible to quickly transfer the water repellent from a dry state to a fine dispersion during mixing of the mixture with water. When the first portions of the dispersion of water repellent get into the capillary of the base (brick), due to the action of the additive, the wettability of the walls of the capillary decreases, as a result of which the loss of water from the solution slows down.

It should be noted that the use of a water repellent agent prevents the occurrence of efflorescence by reducing moisture migration in the capillaries and increasing the frost resistance of the solution.

- as an additional mineral filler - solid waste from the production of soda ash (TOC), which are formed at the stage of ammonia regeneration, are not used and are dumped into the sludge collector.

The proposed dry construction mixture uses dried TOC waste with a moisture content of not more than 0.1%, TU 6-18-21-06-85 "Powder from soda production waste".

The TOC waste has the following, almost constant, composition, wt.%:

CaCO ₃ 51-69 CaSO ₄ 2-8 CaCl ₂ + NaCl 2-7 Ca (OH) ₂ 7-16 SiO ₂ 10-18

The novelty of the invention is:

- as an organic additive - a component that prevents the rapid migration of water from a solution into a substrate, and a blocker of salt formation, at a negative air temperature, a dispersible organosilicon hydrophobizing agent (alkyloxysilane) is used;

- as an active mineral additive use "white soot";

- instead of natural sand, limestone sand of certain fractions is used;

- In addition, solid waste from the production of soda ash is used.

The presence of all these listed significant differences indicates the novelty and inventive step of the invention.

As a result of the proposed technical solution, a dry masonry mixture was obtained, the use of which under conditions of temperatures of +3 ...- 25 ° C allows us to obtain a grade of mortar for compression M75-M100.

Preparation of the dry mixture is as follows.

First, fractionated sand is prepared, the fractions of which are indicated above. For this, the waste limestone fraction, less than 30 mm, is dried, crushed and dispersed into the claimed fractions. Further, all components after weight dosing in the required ratio are fed to the mixer, in which the mixture is obtained ready dry mixture. Then the mixture is packaged in bags or in mobile silos.

The tests are carried out according to the methods of GOST 5802-86.

Examples of the preparation of the inventive mixture and its tests are presented in the table.

Based on the data presented, it can be concluded that the inventive dry mortar can be prepared and used in many areas where it is often minus temperatures, has high water-holding ability, strength characteristics, is workable, can reduce salinization (due to pore clogging by the products of the pozzolanic reaction )

In addition, this invention also solves the environmental problem - solid waste from the production of soda ash that is currently not fully utilized is disposed of, but discharged into the so-called “White Seas”.

Table 1
dry masonry mixes for work at a temperature of +3 ...- 25 ° C Components content, mass. share,% one 2 3 four 5 6 7 8 9 10 prototype Portland cement eighteen twenty twenty twenty twenty 21.6 21.6 21.6 21.6 26.5 eighteen limestone sand 70.5 70,749 69.7 69.1 68.3 67.1 68.1 67,199 73,797 60,2 including fractions: 0.0001-0.09 mm 5,4 1.4 1.4 1.4 1.4 9.9 9.9 9.9 9.9 18.5 - 0.09-0.8 mm 52,2 52,2 52,2 52,2 52,2 47.1 47.1 47.1 47.1 59.9 - 0.8-1.2 mm 12.8 12.8 12.8 12.8 12.8 11.3 11.3 11.3 11.3 21,4 - 1.2-2.0 mm 12.8 12.8 12.8 12.8 12.8 15.7 15.7 15.7 15.7 0.1 - 2.0-4.0 mm 16.8 20.8 20.8 20.8 20.8 16 16 16 16 0.1 - hydrated lime 7 7 7 7 7 7 7 7 0.001 8 - quartz sand - - - - - - - - - - 81.46 sodium nitrite 2 2 2 2 2 2 - - 0.5 2.6 - sodium formate - - - - - - one - - - - potash - - - - - - - - 2.1 - 0.18 urea calcium nitrate - - - - - - - 2.1 - - - white soot 2 0.001 one 1,5 2 2 2 2 2 one - water repellent 0 0.05 0.1 0.2 0.5 0.1 0.1 0.1 0.001 0.5 - TOC waste 0.5 0.2 0.2 0.2 0.2 0.2 0.2 0.001 0.001 0.2 - C-3 - - - - - - - - - - 0.36

Continuation of table 1 Mixture parameter value one 2 3 four 5 6 7 8 9 10 prototype w / t ratio 0.145 0.113 0.125 0.135 0.143 0.145 0.147 0.151 0.15 0.165 0,101 Mobility by immersion cone, cm 6-7 6-7 6-7 6-7 6-7 6-7 6-7 6-7 6-7 6-7 7-9 Water retention capacity,% According to GOST 5802 98.8 98.7 98.8 98.9 99.8 98.8 98.7 99.1 99.0 99,2 98.1 on ceramic brick 88.3 90.1 95.7 96.4 97.1 95.6 95.3 95.8 92.1 98.3 93.2 on silicate brick 90,4 90.7 96.7 97.1 98.3 96.8 96.5 96.9 94.5 98.8 - Application Temperature ° C -fifteen -twenty -fifteen -fifteen -fifteen -fifteen -fifteen -fifteen -25 -fifteen -fifteen Hardening strength 28 days, kg / cm ² : when bending - 25 27 29th 28 33 38 29th 31 24 - on compression 55 105 one hundred 98 95 119 126 107 115 77 one hundred Adhesion Strength, MPa 0.55 0.15 0.25 0.37 0.73 0.77 - 0.55 0.35 0.3 0.15 Brand for frost resistance fifteen thirty - thirty 25 - - > 50 > 50 thirty 25

Claims (5)

1. Dry mortar, including cement binder - Portland cement, mineral plasticizer, aggregate, organic additive, antifrosty additive, characterized in that hydrated lime is used as mineral plasticizer, and limestone sand with CaCO ₃ content _of 90-95 wt. % and particle sizes from 0.001 to 4.0 mm - the waste product of the fraction of limestone fed to the firing in the production of calcium oxide, and limestone sand, depending on the size of the fraction taken in the following ratio and, wt.%: Fraction 0.001-0.09 mm 1.4-9.9 0.09-0.80 mm 47.1-59.9 0.80-1.2 mm 11.3-21.4 1.20-2.00 mm 0.1-15.7 2.00-4.00 mm 0.1-20.8 as an organic additive, alkyloxysilane is used as a redispersible hydrophobizing agent, it additionally contains solid waste from the production of soda ash (TOC) and an active mineral filler, the dry mixture has the following composition, wt.%: Portland cement 18.0-26.5 Hydrated lime 0.001-8,000 Limestone sand 68,300-73,797 Active Mineral Filler 0.001-2,000 Antifrosty supplement 1.0-2.7 Redispersible water repellent agent - 0.05-0.50 CBT soda ash production waste 0.01-0.50 2. The dry building mixture according to claim 1, characterized in that alkyloxysilane is a polymerization product of silane and polyvinyl alcohol, having a bulk density of 220-320 g / DM ³ . 3. The dry building mixture according to claim 1, characterized in that active silica under the trademark "white carbon black" is used as an active mineral filler. 4. The dry building mix according to claim 1, characterized in that either sodium nitrite, or potash, or sodium formate, or a mixture of calcium nitrate with urea is used as an antifrosty additive in a ratio of 2: 1 wt. 5. The dry building mix according to claim 1, characterized in that the solid waste from the production of soda ash (TOC) has the following, almost constant composition, wt.%: CaCO ₃ 51-69 CaSO ₄ 2-8 CaCl ₂ + NaCl 2-7 Ca (OH) ₂ 7-16 SiO ₂ 10-18