CN108358564A - A kind of high ductility cement-base composite material and preparation method thereof - Google Patents

Abstract

The invention discloses a high-ductility cement-based composite material and a preparation method thereof, which comprises cement, fly ash, clean fine river sand, rubber powder, fiber, water reducing agent, latex powder, quick-setting agent and water composition. The high-ductility cement-based composite material of the present invention has high fracture energy and ultimate tensile strain, excellent crack resistance, adjustable four-point bending toughness index, and reasonable compressive strength, and can be used for coal mine deep shaft roadway support The shotcrete material in the structural system can be used for the shotcrete material for the initial support of railway engineering, highway engineering mountain tunnels, especially large deformation tunnels and severe bias tunnels.

Description

A kind of high ductility cement-based composite material and preparation method thereof

technical field

The invention relates to the technical field of civil engineering materials and their preparation, in particular to a high-ductility cement-based composite material and a preparation method thereof.

Background technique

Combined support methods such as anchor net spraying support, anchor net spraying + anchor cable support, anchor net spraying + beam + anchor cable support are generally used in deep coal mine roadways in my country. The shotcrete used in these support methods is composed of cement, coarse and fine aggregate, water, and quick-setting agent. The commonly used spraying methods include dry spraying, tidal spraying and wet spraying. The main disadvantages of this traditional shotcrete are low tensile strength, low ductility, and poor toughness. Uncoupling occurs in the deformation, and the pressure of the surrounding rock cannot be fully relieved, resulting in stress concentration in the local spray layer, which induces premature cracking and shedding of the spray layer, weakening or even losing the sealing and surface support of the surrounding rock. Cracking or falling off causes the integrity of the supporting structure to be lost, and the effect of joint supporting cannot be formed. Mountain tunnels such as railway engineering and highway engineering, especially tunnels with weak, broken, well-developed joints and severe bias tunnels, have nonlinear large deformation characteristics after excavation. Traditional shotcrete has serious deformation coordination with rock surfaces. Insufficient, often lead to cracking of the primary support layer, dislocation or even a whole fall off, so that the sealing and supporting functions of the primary support cannot be realized. Therefore, it is urgent to develop a material that meets the strength, high ductility and good toughness for deep shaft roadway support and large deformation tunnel instead of ordinary concrete shotcrete as support structure, so as to improve the reliability and safety of the support structure.

Contents of the invention

The object of the present invention is to aim at the defect of shotcrete material, to provide a kind of high fracture energy and ultimate tensile strain, strong crack resistance, four-point bending toughness index can be adjusted, compressive strength meets the requirements of initial support, and excellent coordination with rock surface deformation High ductility cement-based composite material and preparation method thereof.

In order to achieve the above object, the present invention adopts the following technical scheme: a high-ductility cement-based composite material, which is composed of cement, fly ash, clean fine river sand, rubber powder, fiber, water reducing agent, latex powder, quick-setting agent and Composition of water; the dosage per unit volume of the cement is 420~630Kg/m ³ , the dosage per unit volume of the fly ash is 420~630Kg/m ³ , the dosage per unit volume of the clean fine river sand is 517~700Kg/m ³ , The dosage per unit volume of the rubber powder is 34~66Kg/m ³ , the dosage per unit volume of the fiber is 31~44.2Kg/m ³ , the dosage per unit volume of the latex powder is 6.3~8.4Kg/m ³ , the water reducing The dosage per unit volume of the agent is 2.1~10.5Kg/m ³ , the dosage per unit volume of the accelerator is 63~84Kg/m ³ , the water-binder ratio is 0.36, when the fiber is PVA, the cement-sand ratio is 0.49, when the fiber is The cement-sand ratio of PP is 0.70; rubber powder is mixed into the cement-based composite material as a substitute for part of the clean river sand.

Further, the cement is ordinary Portland cement with a strength grade of 42.5MPa; the fly ash is Class I fly ash; the clean fine river sand has a maximum particle size of no more than 1.18mm, a fineness modulus of 1.0, and Ordinary river sand washed with water; rubber powder is 40 mesh to 80 mesh rubber powder without surface treatment; latex powder is dispersible ethylene-vinyl acetate copolymer (EVA); water reducing agent is polycarboxylate water reducing agent The solid content is 20%, and the water reduction rate is 20% to 30%; the accelerator is an alkali-free liquid accelerator; the water is clean drinking water or tap water.

Further, the fibers are polyvinyl alcohol (PVA) fibers or polypropylene (PP) fibers, the tensile strength of the polyvinyl alcohol (PVA) fibers is 1200-1500 MPa, the equivalent diameter is 39 μm, and the density is 1.3 g/cm ³ , The dosage per unit volume is 18.3~26.0Kg/m ³ ; the tensile strength of the polypropylene (PP) fiber is 400~650MPa, the equivalent diameter is 48μm, the density is 0.91g/cm ³ , and the dosage per unit volume is 12.7~18.2Kg/m ³ .

A method for preparing a high-ductility cement-based composite material, comprising the following steps: pour the weighed cement, fly ash, rubber powder, latex powder, and clean fine river sand into a mixer, and dry mix for 2 to 3 minutes Mix the various materials evenly; then mix the weighed water and polycarboxylate superplasticizer evenly, pour the mixed solution into the mixer, and stir at a low speed for 3~4 minutes until the slurry can flow evenly; At the same time, slowly add fiber, and stir quickly after adding fiber for 5-6 minutes to obtain fresh slurry; when in use, mix the weighed quick-setting agent at the rear end of the nozzle of the injection device through vacuum negative pressure suction and mix with the fresh slurry to obtain this High ductility cementitious composites invented and sprayed.

Compared with the prior art, the present invention has the following beneficial effects: the high ductility cement-based composite material of the present invention has high fracture energy and ultimate tensile strain, excellent crack resistance, and adjustable four-point bending toughness Index, reasonable compressive strength, can be used as shotcrete material in coal mine deep shaft roadway support structure system, can be used as shotcrete material for initial support of railway engineering, highway engineering mountain tunnels, especially large deformation tunnels and severe bias tunnels.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Embodiment 1: A kind of high ductility cement-based composite material, it is made up of cement, fly ash, clean fine river sand, rubber powder, fiber, water reducer, latex powder, quick-setting agent and water; Described cement unit volume The dosage is 520Kg/m ³ , the dosage per unit volume of the fly ash is 520Kg/m ³ , the dosage per unit volume of the clean fine river sand is 610Kg/m ³ , and the dosage per unit volume of the rubber powder is 50Kg/m ³ . The fiber is polyvinyl alcohol (PVA) fiber, the dosage per unit volume is 38Kg/m ³ , the dosage per unit volume of the latex powder is 7.4Kg/m ³ , the dosage per unit volume of the water reducer is 6Kg/m ³ , the The amount of accelerator per unit volume is 74Kg/m ³ , the water-binder ratio is 0.36, and the cement-sand ratio is 0.49.

Embodiment 2: A kind of high ductility cement-based composite material, it is made up of cement, fly ash, clean fine river sand, rubber powder, fiber, water reducer, latex powder, quick-setting agent and water; Described cement unit volume The dosage is 420Kg/m ³ , the dosage per unit volume of the fly ash is 420Kg/m ³ , the dosage per unit volume of the clean fine river sand is 517Kg/m ³ , and the dosage per unit volume of the rubber powder is 34Kg/m ³ . The fiber is polypropylene (PP) fiber, the dosage per unit volume is 31Kg/m ³ , the dosage per unit volume of the latex powder is 6.3Kg/m ³ , the dosage per unit volume of the water reducer is 2.1Kg/m ³ , the The dosage of accelerator per unit volume is 63Kg/m ³ , the ratio of water to cement is 0.36, and the ratio of cement to sand is 0.70.

Embodiment 3: A kind of high ductility cement-based composite material, it is made up of cement, fly ash, clean fine river sand, rubber powder, fiber, water reducer, latex powder, quick-setting agent and water; Described cement unit volume The dosage is 630Kg/m ³ , the dosage per unit volume of the fly ash is 630Kg/m ³ , the dosage per unit volume of the clean fine river sand is 700Kg/m ³ , and the dosage per unit volume of the rubber powder is 66Kg/m ³ . The fiber is polyvinyl alcohol (PVA) fiber, the dosage per unit volume is 44.2Kg/m ³ , the dosage per unit volume of the latex powder is 8.4Kg/m ³ , and the dosage per unit volume of the water reducer is 10.5Kg/m ³ , The amount of the quick-setting agent per unit volume is 84Kg/m ³ , the water-binder ratio is 0.36, and the cement-sand ratio is 0.49.

Embodiment 4: A kind of high ductility cement-based composite material, it is made up of cement, fly ash, clean fine river sand, rubber powder, fiber, water reducer, latex powder, quick-setting agent and water; Described cement unit volume The dosage is 630Kg/m ³ , the dosage per unit volume of the fly ash is 420Kg/m ³ , the dosage per unit volume of the clean fine river sand is 700Kg/m ³ , and the dosage per unit volume of the rubber powder is 34Kg/m ³ . The fiber is polyvinyl alcohol (PVA) fiber, the dosage per unit volume is 44.2Kg/m ³ , the dosage per unit volume of the latex powder is 6.3Kg/m ³ , and the dosage per unit volume of the water reducer is 10.5Kg/m ³ , The amount of the quick-setting agent per unit volume is 63Kg/m ³ , the water-binder ratio is 0.36, and the mortar-sand ratio is 0.49.

Embodiment 5: A kind of high ductility cement-based composite material, it is made up of cement, fly ash, clean fine river sand, rubber powder, fiber, water reducer, latex powder, quick-setting agent and water; Described cement unit volume The dosage is 600Kg/m ³ , the dosage per unit volume of the fly ash is 500Kg/m ³ , the dosage per unit volume of the clean fine river sand is 550Kg/m ³ , and the dosage per unit volume of the rubber powder is 60Kg/m ³ . The fiber is polypropylene (PP) fiber, the dosage per unit volume is 40Kg/m ³ , the dosage per unit volume of the latex powder is 7Kg/m ³ , the dosage per unit volume of the water reducer is 8Kg/m ³ , and the quick-setting The dosage per unit volume is 70Kg/m ³ , the water-binder ratio is 0.36, and the mortar-sand ratio is 0.70.

In the above examples 1-5, the cement is ordinary Portland cement with a strength grade of 42.5MPa; the fly ash is Class I fly ash, and its main chemical components are SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CaO , MgO, SO ₃ , Na ₂ O, K ₂ O; clean fine river sand is ordinary river sand with a maximum particle size of no more than 1.18mm, a fineness modulus of 1.0, and washed with water; rubber powder is 40 mesh to 80 mesh Rubber powder without surface treatment; the fiber is polyvinyl alcohol (PVA) fiber or polypropylene (PP) fiber, the tensile strength of polyvinyl alcohol (PVA) fiber is 1200~1500MPa, the equivalent diameter is 39μm, and the density is 1.3g/cm ³ ; The tensile strength of polypropylene (PP) fibers is 400~650MPa, the equivalent diameter is 48μm, and the density is 0.91g/cm ³ ; the latex powder is dispersible ethylene-vinyl acetate copolymer (EVA); the water reducer is polycarboxylate water reducing agent The solid content is 20%, and the water reduction rate is 20% to 30%; the accelerator is an alkali-free liquid accelerator; the water is clean drinking water or tap water.

When the high-ductility cement-based composite material described in Examples 1-5 is prepared and used, the cement, fly ash, rubber powder, latex powder, clean fine river sand and other materials with a set quality are weighed and poured into the mixer together. In the process, dry mix for 2~3 minutes until all materials are mixed evenly; mix the water of the set quality and high-performance water reducer evenly, then pour the mixed solution into the mixer, and stir at a low speed for 3~4 minutes until the slurry can Flow evenly; slowly add fiber while stirring at a low speed, and stir rapidly for 5-6 minutes after adding fiber; put the freshly mixed slurry into the test mold, vibrate and compact it, smooth the surface, and remove the mold after 24 hours of indoor curing; It is made by curing for 28 days under standard curing conditions (20±2°C, RH>95%). When it is used for spraying concrete materials in deep well roadways or large deformation tunnels, the quick-setting agent is sucked in by vacuum at the rear end of the nozzle and mixed with the freshly mixed slurry, and sprayed onto the rock surface to become the primary support material.

After testing, the compressive strength of the high ductility cement-based composite material prepared in the above examples 1-5 is 20.5~30.9MPa, the ultimate tensile strain is 0.32%~1.35%, the fracture energy is 1.08~4.93J, and the four-point bending toughness The index ranges from 30.0 to 108.0.

It should be noted that the above-mentioned embodiments are only several specific implementation modes of the present invention, but should not be construed as limiting the patent scope of the present invention. For those skilled in the art, several evolutions or improvements made without departing from the idea of the present invention all belong to the protection scope of the present invention.

Claims (4)

1. a kind of high ductility cement-base composite material, it is characterised in that：By cement, flyash, clean thin river sand, rubber powder, fibre Dimension, water-reducing agent, latex powder, accelerator and water composition；The cement Amount per unitvolume is 420 ~ 630Kg/m³, the flyash Amount per unitvolume is 420 ~ 630Kg/m³, the clean thin river sand Amount per unitvolume is 517 ~ 700Kg/m³, the rubber powder Amount per unitvolume is 34 ~ 66Kg/m³, the fiber Amount per unitvolume is 31 ~ 44.2Kg/m³, the latex powder unit volume Dosage is 6.3 ~ 8.4Kg/m³, the water-reducing agent Amount per unitvolume is 2.1 ~ 10.5Kg/m³, the accelerator is unit volume Dosage is 63 ~ 84Kg/m³；Water-cement ratio is 0.36, and cement mortar rate is 0.49 or 0.70；Glue in the water-cement ratio and cement mortar rate is The gelling agent being made of cement and flyash, sand are clean thin river sand.

2. a kind of high ductility cement-base composite material according to claim 1, it is characterised in that：The cement is common Portland cement, strength grade 42.5MPa；Flyash is I grades of flyash；Clean thin river sand is no more than for maximum particle diameter 1.18mm, fineness modulus 1.0, the common river sand washed with water；Rubber powder is the not surface treated rubber powder of mesh of 40 mesh ~ 80； Latex powder is dispersible ethylene-vinyl acetate copolymer (EVA)；Water-reducing agent is polycarboxylate dehydragent, solid content 20%, Water-reducing rate is 20%~30%；Accelerator is alkali-free liquid accelerator；Water is the drinking water or tap water of cleaning.

3. a kind of high ductility cement-base composite material according to claim 1, it is characterised in that：The fiber is poly- second Enol（PVA）FiberOrPolypropylene（PP）Fiber, the polyvinyl alcohol（PVA）1200 ~ 1500MPa of fibre tensile strength, equivalent 39 μm of diameter, density 1.3g/cm³, Amount per unitvolume is 18.3 ~ 26.0Kg/m³；The polypropylene（PP）Fiber, tensile strength 400 ~ 650MPa, 48 μm of equivalent diameter, density 0.91g/cm³, Amount per unitvolume is 12.7 ~ 18.2Kg/m³；When fiber is poly- Vinyl alcohol（PVA）Cement mortar rate is 0.49 when fiber, when fiber is polypropylene（PP）Cement mortar rate is 0.70 when fiber.

4. a kind of preparation method of high ductility cement-base composite material, which is characterized in that include the following steps：By that will weigh Good cement, flyash, rubber powder, latex powder, clean thin river sand are poured into together in blender, and mixing 2 ~ 3min of dry mixing is to various Material is uniformly mixed；Then load weighted water and polycarboxylate dehydragent are uniformly mixed, mixed solution are poured into blender, 3 ~ 4 min of stirring at low speed to slurry being capable of Uniform Flow；It is slowly added to fiber while stirring at low speed, is added after fiber quickly 5 ~ 6 min of stirring obtain fresh paste；Load weighted accelerator is passed through into negative pressure of vacuum in injection apparatus nozzle rear end when in use Sucking is mixed with fresh paste, is obtained the high ductility cement-base composite material of the present invention and is sprayed use.