Injection solution for brickwork restoration

Abstract

FIELD: construction materials.SUBSTANCE: invention relates in particular to compositions of injection solutions for the restoration and strengthening of stone and brick structures, and can be used to restore historical buildings and architectural monuments. The technical result of the invention is to ensure high penetrating ability, compressive strength of 73-75 MPa, adhesion to brick of 2.0-2.2 MPa, as well as physical and chemical compatibility with historical masonry materials while maintaining vapour permeability and the absence of efflorescence. The developed injection solution is recommended for the restoration of cracks, voids and delaminations in brickwork of architectural monuments and historical buildings.EFFECT: high penetrating ability, physical and chemical compatibility with historical masonry materials while maintaining vapour permeability and the absence of efflorescence.1 cl

Description

[0001] The invention relates to building materials, in particular to compositions of injection solutions for the restoration and strengthening of stone and brick structures, and can be used to restore historical buildings and architectural monuments.

[0002] Injection mortars based on cement, lime, polymer resins, and silicates are known. Disadvantages of cement mortars include a tendency to shrinkage, sedimentation, and poor penetration. Polymer mortars (epoxy, acrylate) have low vapor permeability and are incompatible with historical materials. Nanolime-based mortars are expensive and develop strength slowly.

[0003] The closest analogue is the injection mortar for strengthening stone structures according to patent RU 2511198 C1 "Waterproofing composition for protecting concrete and stone structures "MINSLASH-12"" (published: 10.04.2014). Solution composition: Portland cement 63%, quartz sand 0.16-0.63 mm 25.1%, microsilica 6.8%, sodium silicate 4.7%, polycarboxylate 0.23%, cellulose ether 0.17%.

[0004] The disadvantages of the known composition are insufficient penetration into fine cracks (less than 0.5 mm), suboptimal adhesion to historical brick (less than 1.8 MPa) and a high content of sodium silicate, which reduces long-term compatibility with masonry materials.

[0005] The technical result of the invention is to ensure high penetrating ability, compressive strength of 73-75 MPa, adhesion to brick of 2.0-2.2 MPa, as well as physical and chemical compatibility with historical masonry materials while maintaining vapor permeability and the absence of efflorescence.

[0006] The essence of the invention.

[0007] Injection mortar for brickwork restoration, containing Portland cement, quartz sand, superplasticizer and water, additionally contains ultra-dispersed microsilica with a specific surface area of ​​15,000-20,000 m 2 / kg with the following ratio of components, wt. %: Portland cement - 48.5-53.5; ultrafine microsilica - 5.0-9.2; quartz sand with a fineness modulus of 1.5-2.25 - 23.0-28.0; superplasticizer based on naphthalene sulfonate - 0.6-0.9; water - 13.5-17.8.

[0008] Implementation of the invention

[0009] Preparing the solution

[0010] 1. Dry mixing: Portland cement (CEM I 42.5N), ultrafine microsilica (7.5-8.0% of the solution weight) and quartz sand (binder:sand ratio = 1:3) are mixed in a mixer for 2-3 minutes.

[0011] 2. Preparation of the liquid phase: a superplasticizer based on naphthalene sulfonate (for example, "Polyplast SP-1") in an amount of 0.6-0.9% of the solution weight is dissolved in water (13.5-17.8% of the solution weight) with a water-cement ratio of 0.24-0.26.

[0012] 3. Mixing: add the liquid phase to the dry mixture while the mixer is running and mix for 5-7 minutes until a homogeneous plastic mass is formed.

[0013] 4. Control: mobility of the finished solution is 16-18 cm along the cone, pot life is 45-50 min (at +20°C).

[0014] Components:

[0015] Portland cement CEM I 42.5N (specific surface area 600 m 2 / kg, setting time 30-45 min) is the main binder. At a content below 48.5%, strength (<60 MPa) and adhesion (<1.5 MPa) decrease; above 53.5%, shrinkage increases (>1.2 mm / m) and vapor permeability decreases.

[0016] Ultrafine microsilica (SiO2≥92%, specific surface area 18000 m2m 2(BET particle size 0.15 µm) provides pozzolanic activity. At a content of less than 5%, the structure compaction effect is insufficient; at a content of more than 9.2%, water demand increases sharply and penetration capacity into cracks <0.3 mm decreases.

[0017] Quartz sand (fineness modulus 1.5-2.25, SiO292-96%) reduces shrinkage. Contents below 23% increase the risk of cracking, while contents above 28% reduce mobility (<15 cm) and flexural strength (<7.5 MPa).

[0018] Naphthalene sulfonate-based superplasticizer ("Polyplast SP-1") ensures workability at low water-cement ratios. At dosages below 0.6%, workability does not exceed 14-15 cm; at dosages above 0.9%, setting is delayed (>60 min) and mixture segregation is possible.

[0019] Example of specific implementation

[0020] Prepare the solution using the following ratio of components, wt. %: Portland cement CEM I 42.5H - 51.0; ultrafine microsilica - 7.5; quartz sand (Mkr = 1.8) - 25.0; superplasticizer "Polyplast SP-1" - 0.7; water - 15.8.

[0021] Water-cement ratio = 0.25. Mixing is carried out in a forced-action mixer.

[0022] The resulting solution has: cone spread - 17 cm; pot life - 48 min; compressive strength after 28 days - 74 MPa; adhesion to brick - 2.1 MPa; capillary porosity - 8.5%; vapor permeability - 0.025 mg / (m⋅h⋅Pa).

[0023] No efflorescence, mortar compatible with historic brickwork.

[0024] The developed injection mortar is recommended for the restoration of cracks, voids and delaminations in brickwork of architectural monuments and historical buildings.

Claims

An injection mortar for the restoration of brickwork, containing Portland cement, quartz sand, superplasticizer and water, characterized in that Portland cement of class CEM I 42.5 H is used and additionally contains ultra-dispersed microsilica with a specific surface area of ​​15,000-20,000 m 2 / kg with the following ratio of components, wt. %: Portland cement class CEM I 42.5 N - 48.5-53.5; ultrafine microsilica - 5.0-9.2; quartz sand with a fineness modulus of 1.5-2.25 - 23.0-28.0; superplasticizer based on naphthalene sulfonate - 0.6-0.9; water - 13.5-17.8.