RU2385303C2 - Sealing mixture for waterproofing and concreting tunnel linings - Google Patents

Abstract

FIELD: construction. ^ SUBSTANCE: invention can be used namely for ensuring tightness of joints in reinforced concrete tunnel blocks routed in conditions of non-aggressive ground water, as well as for performing waterproofing. Mixture for waterproofing and concreting tunnel linings includes portland cement without any additions with activity of not less than 25.0 MPa in 1 day, expanding sulfoaluminate component- mixture CaO:Al2O3:SO3 at molar ratio (3.1-3.5):(0.9-1.2):(2.2-2.6), fine cellulose fibre with fibres 0.03-1.0 mm long, copolymer of vinyl acetate and vinyl versatate, tartaric acid or its soluble salts and quartz sand with particle size of 0.1-2.5 mm, at the following component ratio, wt %: the above portland cement 45-50, mixture CaO:Al2O3:SO3 2.5-3.5, tartaric acid or its soluble salts 0.010-0.025, copolymer 0.2-0.5, cellulose fibre 0.1-0.2, quartz sand - the rest. ^ EFFECT: simplifying and reducing the process durability, increasing initial strength of concreting material obtained from mixture, increasing thixotropy of mixture and preventing it from being slipped from ceiling and vertical surfaces, improving its sanitary characteristics. ^ 7 ex, 1 tbl

Description

The invention relates to injectable dry mixtures and can be used, in particular, to ensure the tightness of joints in reinforced concrete blocks of tunnels laid in non-aggressive groundwater, as well as for waterproofing.

Known dry sealing material, used, in particular, for waterproofing and monopolizing tunnel lining, which is a gypsum-alumina cement expanding in accordance with GOST 11052-74.

This material contains blast furnace slag, which is a waste of metallurgical production with uncertain properties, and therefore the physicochemical properties of cement according to GOST 11052-74 are not constant; cement strength is insufficient; due to the high content of SO ₃ (up to 17 wt.%), the durability of the material is insufficient; in addition, cement according to GOST 11052-74 emits hydrogen sulfide during mixing, which is unacceptable when working in a confined space of a tunnel.

Known sealing mixture, which can be used for monolithic and waterproofing of oil and gas wells, as well as tunnel lining. The mixture contains Portland cement clinker, slag, sulfate and alumina components; as an alumina-containing component, the mixture contains white sludge formed at the stage of deep desilination of aluminate solutions in the production of alumina by sintering from high-silicon alumina-containing ores, in the following ratio, wt.%:

White sludge from alumina production 4.0-8.0 Sulfate-containing component (% SO ₃ ) 2.0-5.0 Slag component 10.0-15.0 Portland cement clinker Rest

SU1435764.

The disadvantage of this mixture is the low mechanical strength of the material obtained from it, as well as the long hardening time.

Known sealing mixture for waterproofing tunnel lining, which can also be used to monopolize them; the mixture contains Portland cement, expanding sulfoaluminate component in the form of gypsum-alumina cement in combination with alumina cement and finely dispersed fiber in the form of asbestos in the ratio of components, wt.%:

Gypsum-alumina cement 27-30 Portland cement 27-30 Asbestos 9.5-10 Alumina cement 30-36

SU 300436.

This mixture is the closest technical solution in relation to the claimed invention by the totality of the common essential features and adopted as a prototype.

The disadvantages of the prototype are as follows:

- too short setting time (start of setting 4-10 minutes), which necessitates mixing small portions of the mixture, which should be used in a very short period of time. Due to the quick setting, the material is placed in the filled space in several stages using additional equipment - a coining hammer; the above complicates and increases the duration of the process;

- alumina and gypsum-alumina cement, which are part of the mixture, are characterized by instability of the chemical composition and properties, since they are a product of grinding alumina slag formed as waste from metallurgical production, which results in a low level of strength both in compression and in adhesion to the base;

- the mortar mixture does not have sufficient thixotropy, which causes it to slip from the ceiling and vertical surfaces;

- the presence of asbestos dramatically affects the sanitary and hygienic characteristics of the mixture.

The objective of the present invention is to simplify and reduce the duration of the process during the waterproofing and monolithic tunnel lining, increasing the initial strength obtained from the mixture of monolithic material, increasing the thixotropy of the mortar mixture and thereby preventing its creep from the ceiling and vertical surfaces, as well as improving sanitary and hygienic characteristics .

According to the invention, a mixture for waterproofing and monolithic tunnel lining, including Portland cement, an expanding sulfoaluminate component and a finely dispersed fiber, further comprises a copolymer of vinyl acetate and vinyl versatate, tartaric acid or its soluble salts and silica sand with a particle size of 0.1-2.5 mm, as an expanding sulfoaluminate component, a mixture of CaO: Al ₂ O ₃ : SO _{3 is used} with a molar ratio of (3.1-3.5) :( 0.9-1.2) :( 2.2-2.6), in as Portland cement used Portland cement without additives with ktivnostyu not less than 25.0 MPa after 1 day as a finely divided cellulosic fibers using a fiber with a size of 0.03-1.0 mm fibers, with the following component ratio, wt.%:

Portland cement without additives 45-50 mixture of CaO: Al ₂ O ₃ : SO ₃ at molar ratio (3.1-3.5) :( 0.9-1.2) :( 2.2-2.6) 2.5-3.5 tartaric acid or its soluble salts 0.010-0.025 copolymer of vinyl acetate and vinyl versatate 0.2-0.5 cellulose fiber 0.1-0.2 quartz sand rest

The applicant has not identified sources containing information about technical solutions identical to the present invention, which allows us to conclude that it meets the criterion of "novelty."

Portland cement is the basis of the mixture; Portland cement (in a specific example, PC 500-DO according to GOST 10178-85) provides a quick set of hardening strength, which Portland cement with additives (mineral) does not provide, since the content of active clinker in them is significantly lower. In addition, the activity of non-additive Portland cement should be at least 25.0 MPa after 1 day, since otherwise the strength of the hardened material in the early stages is insufficient to carry out such critical tasks as waterproofing and monolithic tunnel lining; material may fall out of the sealed joint, which is unacceptable. When the content of non-additive Portland cement is less than 45 wt.%, The strength decreases in the initial period, and when the content of this component is more than 50 wt.%, The setting time of the mixture increases and the strength of the solution also decreases.

A mixture of CaO: A1 ₂ O ₃ : SO ₃ is an expanding component, which ensures reliable retention of the solution in the sealed slots, and increases crack resistance. The molar ratio of CaO: Al ₂ O ₃ SO ₃ within the indicated limits (3.1-3.5) :( 0.9-1.2) :( 2.2-2.6) provides the formation of the ettringite phase according to the reaction: CaO Al ₂ O ₃ + 3CaO · SO ₂ · 0.5H ₂ O + 2CaO · H ₂ O + 28.5H ₂ O → 3CaO · Al ₂ O ₃ · 3CaO · 3SO ₃ · 32H ₂ O.

The formation of the ettringite phase in the initial period of hydration of the mixture provides a reduction in the setting time, high compressive strength, and the necessary expansion value. These properties are not sufficiently expressed when the content of CaO: Al ₂ O ₃ : SO ₃ in the mixture is less than 2.5 wt.%, And when the content of this component is more than 3.5 wt.%, The solution expands too much, which can lead to deformation and even destruction of the sealed structure.

The presence in the composition of the claimed mixture of tartaric acid or its soluble salts (tartrates) in an amount of 0.010-0.025 wt.% Allows you to provide the required setting time - 10-30 minutes When the content of this component is less than 0.010 wt.%, The setting time is less than 10 minutes, which is too short for the process of working with the mixture, and if it contains more than 0.025 wt.%, The setting time is more than 30 minutes, which can lead to the sliding of the mortar mixture from the compacted seam.

The use of a copolymer of vinyl acetate with vinyl versatate in an amount of 0.2-0.5 wt.% Provides giving the injection mortar mixture the plasticity necessary for free filling of the joints without additional mechanical compaction, increasing the adhesion strength of the mortar mixture to the base; prevention of sliding of mortar mix from vertical and ceiling surfaces is provided; when the content of this component in an amount of less than 0.2 wt.% does not provide the necessary mobility of the injection mortar and a sufficient amount of adhesion to the base; an increase in the content of vinyl acetate copolymer with vinyl versatate> 0.5 wt.% lengthens the setting time of the mortar mixture, slows down the kinetics of hardening of the solution.

The use of cellulose fiber as the fibrous component ensures the ecological purity of the mixture. The structural feature of the cellulose fiber, which is a tube hollow inside, additionally provides a high thixotropy of the mortar mixture - increased mobility at the time of application of the load due to the release of free water from the fiber and a subsequent reduction in mobility after unloading, which prevents the mortar from sliding off the vertical and ceiling surfaces . When the content of cellulose fiber is less than 0.1 wt.%, These properties are little manifested, and when its content is above 0.2 wt.%, The water demand of the mixture increases significantly, which leads to a deterioration in its basic characteristics. Quartz sand is a filler, increases crack resistance, is involved in the regulation of the kinetics of phase formation.

Thus, the implementation of the distinguishing features of the claimed invention provides the above important new properties of the object.

The applicant has not found any sources of information containing information about the impact of the claimed distinctive features on the technical result achieved as a result of their implementation. This, according to the applicant, indicates that this technical solution meets the criterion of "inventive step".

The table shows the properties of solutions prepared from the claimed mixture with different ratios of the starting components.

The following describes an example of obtaining a solution from a mixture having the highest properties (example 3 in the table).

475 kg of Portland cement without additive PC-500-DO with an activity of more than 25.0 MPa, 28 kg of a mixture of CaO: Al ₂ O ₃ : SO ₃ with a molar ratio of 3.36: 1.02: 2.40, 0.2 were introduced into the mixer kg of tartaric acid, 3 kg of a copolymer of vinyl acetate and vinyl versatate, 1 kg of cellulose fiber; the components were mixed for 3 minutes. Then, aggregate - quartz sand (0.1-2.5 mm) was introduced into the mixer, the mixture was additionally mixed for 3 minutes. Mixing of the dry injection mixture with water was carried out at the place of use. The required amount of water was poured into the mixer - (W / T = 0.15) 150 L per 1 ton of the mixture, then the dry mixture was poured, the mortar mixture was mixed for 2 minutes, after which it was ready for use.

The solution according to examples 1, 2, 4, 5, 6, 7 and according to the prototype was prepared similarly.

Due to the possibility of adjusting the setting time and increasing it to 10-30 minutes, it is possible to put the mortar into the seam being sealed in one step without the use of additional equipment - a coining hammer, which makes it possible to simplify and reduce the duration of the joint sealing process; increases the initial strength (in 1 day) obtained from a mixture of solid monolithic material; the thixotropy of the mortar mixture increases and its creep from the ceiling and vertical surfaces is thereby prevented.

The components of the dry injection mixture produced by the industry are widely available. The technology for the preparation and use of dry injection mixture is implemented using standard equipment. This determines the compliance of the claimed invention with the criterion of "industrial applicability".

Claims (1)

A mixture for waterproofing and monolithic tunnel lining, including Portland cement, an expanding sulfoaluminate component and a finely dispersed fiber, characterized in that it further comprises a copolymer of vinyl acetate and vinyl versatate, tartaric acid or its soluble salts and silica sand with a particle size of 0.1-2.5 mm, in this case, as a expanding sulfoaluminate component, a mixture of CaO: Al ₂ O ₃ : SO _{3 is used} with a molar ratio of (3.1-3.5) :( 0.9-1.2) :( 2.2-2.6) , as Portland cement used Portland cement without additives with ac ivnostyu not less than 25.0 MPa after 1 day as a finely divided cellulosic fibers using a fiber with a size of 0.03-1.0 mm fibers at the following component ratio, wt.%:
Portland cement without additives 45-50 mixture of CaO: Al ₂ O ₃ : SO ₃ at molar ratio (3.1-3.5) :( 0.9-1.2) :( 2.2-2.6) 2.5-3.5 tartaric acid or its soluble salts 0.010-0.025 copolymer of vinyl acetate and vinyl versatate 0.2-0.5 cellulose fiber 0.1-0.2 quartz sand rest