CN109796167A - A kind of high tenacity concrete material selection method - Google Patents
A kind of high tenacity concrete material selection method Download PDFInfo
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Abstract
The invention discloses a kind of high tenacity concrete material selection method, include the steps that cementitious material selects；The step of fine aggregate selects；The step of coarse aggregate selects；The step of polymeric oxidizer；The step of fiber selects；The step of water-reducing agent selects.High tenacity concrete material selection method of the present invention measures the bent toughness of concrete using the size surrounded under load-displacement, after concrete is added according to certain polymer cement ratio in polymer emulsion, bent toughness promotes 6.5 times or more, wherein copolymer in cinnamic acrylic ester is added in concrete, and bent toughness promotes 17.6 times；After concrete is added according to certain volume volume in fiber, bent toughness promotes 8 times or more, and after wherein concrete is added in end hook type steel fibers 0.8%, bent toughness promotes 24.1 times；After polymer and fiber are added in concrete jointly according to a certain percentage, bent toughness is relatively individually added into polymer and fibrous material is enhanced again.
Description
Technical field
The present invention relates to materialogy technical field, in particular to a kind of selection method of concrete toughening raw material.
Background technique
High intensity, high rigidity, high tenacity are development trend of the civil construction field to concrete material performance requirement,
It is the requirement for meeting large-scale construction engineering to material cracking resistance and endurance quality.Compared with normal concrete, fiber concrete
It is more superior in terms of mechanical property, performances such as tension, bending resistance, the fracture of concrete etc. can be improved significantly, but fiber and water
There are boundary layers between mud matrix, and boundary layer is the weak area in composite material, and how to strengthen boundary layer then is steel fibre to mixed
Solidifying soil enhancing, toughening and prevent-crevice theory play a key effect.The general method using addition polymer and mineral admixture, has
Above-mentioned boundary layer may be made by strengthening, or even disappeared, to further increase the toughness of concrete.
Micro-mechanics studies of concrete result of study shows concrete material either in static load still in fatigue load
Under effect, destructive process is all the process that crack generates in interface and matrix, extends.Concrete is by hydrated cement paste
A kind of nonuniformity heterogeneous material of interfacial transition zone composition between body, aggregate and Behavior of Hardened Cement Paste and aggregate, gas existing for inside
The initial imperfections such as hole and microcrack, these genetic defects affect the generation of macrocrack, expansion process.
Extension of the crack in concrete is inevitable to be carried out towards the smallest path direction of required dissipation energy, extensions path
The property of material on the distribution of initial imperfection in concrete and extensions path is depended primarily on, extensions path is general
There are three types of situations: one is the interface extensions between aggregate and cement matrix；One is directly run through aggregate to extend；It is a kind of
It is to be extended in cement matrix.Mode of extension of the crack in concrete affects the intensity of concrete, deformation and failure
Energy.
In recent years, the CT research of X-ray concrete has become the hot subject of concrete material microfracturing process.
According to CT basic principle, concrete each component phsyical density is different, and the CT number for being reflected in each position on CT image is different, thus
Form the different striographs of gray scales such as aggregate, mortar, hole.After concrete sample stress generates micro-mechanical model, corresponding CT figure
As the reduction of position gray scale, linear or ring image, referred to as CT scale crackle are formed, is belonged to based on X ray CT resolution condition
Under micro-mechanical model, be the main study subject of concrete CT.
The Railway Tunnel liner structure more early built in the world generallys use plain concrete construction, when with operation
Between elapse, tunnel-liner non-structural crack continuously emerges and develops, maintenance work continue to increase, liner structure is durable
Property problem gradually protrudes, or even jeopardizes the operational safety of bullet train, and countries in the world are all in the corresponding measure of positive development test
With method, such as Germany is using to lining concrete is using single layer steel mesh pavement structure but steel mesh pavement structure cost is high, applies
Work is difficult, process time-consuming
Summary of the invention
Technical problem to be solved by the present invention lies in provide a kind of high tenacity concrete material selection method, be used in combination
This method is prepared for high intensity, high rigidity, high tenacity concrete material suitable for Railway Tunnel liner structure, and full
The concrete of sufficient structure design, construction requirement, the present invention is by three kinds of flyash, polymer emulsion, fiber materials in concrete
It singly mixes or mixes again, by the analysis to concrete flowability energy, intensity, bent toughness, fracture property, determine to mention with toughness
The optimum mix for being upgraded to the concrete on basis establishes concrete under micro-scale by the analysis to concrete fracture path
The evaluation method of toughness, and be applied in Railway Tunnel liner structure.
The technical solution of the present invention is as follows: providing a kind of 1, high tenacity concrete material selection method, which is characterized in that
The high tenacity concrete material selection method is for making toughening cement-based materials comprising following steps: cementitious material choosing
It selects, fine aggregate selection, coarse aggregate selection, polymeric oxidizer, fiber selects and water-reducing agent selection；
The cementitious material selection is specially using 52.5 portland cements of Wuhan Huaxin Cement Factory production, flyash
The I grade of flyash produced using Nanjing Cogeneration Power Plant；
The step of fine aggregate selection is specially fine aggregate selection are as follows: selecting maximum particle diameter is the river of 2.2~3.8mm
Sand, fineness modulus 2.2~2.4, continuous grading, 1.2~1.4g/cm3 of bulk density, 2.3~2.7g/cm3 of apparent density；
The coarse aggregate selects to be specially the basaltic broken stone for selecting maximum particle diameter as 14.5~15.5mm, apparent density
2.6~2.8g/cm3,1.4~1.7g/cm3 of bulk density, crush values 4.5~5.5%, clay content 0.6~0.8%, water absorption rate
0.18~0.23%；
The polymeric oxidizer is specially to select one of following five kinds of polymer or a variety of: ethene-vinyl acetate is total
Polymers, ethyl acrylate, copolymer in cinnamic acrylic ester, vinyl acetate-acrylate polymer, acid-organosilicon crylic acid
Ester；
The fiber selection is specially to select one of following fibers or a variety of: steel fibre, basalt fibre, poly- second
Enol fiber, cellulose fibre, modified polyester fiber；
Water-reducing agent selection is specially to select water-reducing rate 21%~24%, mobility require volume be 0.7%~
0.9% water-reducing agent.
Preferably, the points for attention of the polymeric oxidizer are as follows:
A. selection has good preprocessing performance and mechanical stability, polymer easy to use；And
B. it selects to have no adverse effect hydrated cementitious, to Ca2+ the and Al3+ ion generated in cement hydration process
There is the polymer of higher stability；And
C. it selects to have after cement matrix hardens with hydrated product and between gathering materials and preferably coheres ability, and film-forming temperature
Low polymer；And
D. the polymer in hardened cement matrix with preferable water resistance and alkali resistance is selected；And
E. selection glass transition temperature is low, has the polymer of certain viscosity.
Preferably, the points for attention of the fiber selection are as follows:
A. selection intensity and elasticity modulus are above the fiber of cement matrix；And
B. there is good adhesion strength between selection and cement matrix, guarantee that the stress that cement matrix is born is passed by interface
Pass the fiber of its own；And
C. the thermal expansion coefficient between selection and cement matrix is close, guarantees that bond strength will not expand with heat and contract with cold between the two
The fiber being weakened in the process；And
D. the fiber of harmful chemical reaction cannot occur between selection and cement matrix；And
E. select volume fraction, size and distribution suitable, and the fiber of good dispersion property.
It preferably, further include fibers content selection, specifically includes the following steps:
Step 1, fibers content selection: using disorderly to the fiber critical size rate formula of discontinuous fiber composite material
(formula 2-1) is determined fibers content:
In formula: fmu- fiber concrete matrix ultimate tensile strength (MPa)；ffuThe ultimate tensile strength of-fiber
(MPa)；εmuThe strain of-fiber concrete matrix Ultimate Tensile；EfThe elasticity modulus of-fiber；
Step 2, water-cement ratio selection: calculating the water-cement ratio of concrete using formula (2-2),
In formula: fce- actual cement strength；A, B-empirical coefficient；fcu- Concrete Design compression strength；
The selection of polymer volume: step 3 calculates polymer theoretical dosage using formula (2-3):
In formula: Pm0- polymer theoretical dosage；- design of material water-cement ratio；- cement is in complete aquation
Cement ratio；D-polymer three-dimensional ulking thickness；S-hydrated product per surface area；ρ-density polymer；M0- polymer
Theoretical volume in cementitious material system；
Sand coarse aggregate ratio selection: step 4 is tested by mix workability and determines sand coarse aggregate ratio；
Step 5, Water Usage Per Unit Volume and binder total amount selection: by the slump of lining cutting position concrete,
And the time requirement of no slump-loss, determine Water Usage Per Unit Volume；
Conservation system selection: step 6 according to composite material strength rule (formula 2-4), determines conservation system:
σ=σmVm+σPVP (2—4)
In formula: σ-polyalcohol cement basis composite material strength；σm、VmIntensity, the volume of-cement mortar；σP、VP- poly-
Close intensity, the volume of object.
It preferably, further include bent toughness test, comprising: 100 × 100 × 400mm prism test specimen is used, using four
Point loading method, span 300mm, testing equipment are the electro-hydraulic servo universal electrical testing machine that company's production is newly thought carefully in Shenzhen,
It being loaded using displacement, loading speed 0.05mm/s, test data sheet bending load acts on lower concrete load-displacement,
Stop test when load reaches capacity the 10% of load.
It preferably, further include fracture property test, using plane strain fracture toughness KIC, energy to failure GF, critical crack point
Hold opening displacement δ0To characterize；Fracture toughness KIC, energy to failure GFCalculated respectively according to shown in formula (2- 5) and (2-6),
In formula: the geometric dimension of t, h, l, a0- concrete sample；W0Area under load versus deflection；M=m1+
2m2, wherein the beam weight between m1- fulcrum, the m2- loading weight of attachment；δ0The maximum immunity value that beam measures when being broken；When P- is loaded
The peak load (KN) that concrete sample is born.
Preferably, further include the microcosmic evaluation of concrete fracture path and toughness: using crack Critical growth stress, breaking
Broken face roughness is characterized；
The crack Critical growth stress is expressed as:
Gcrit=2 γsε2-D(2-8)
In formula: ε-scale factor；D-section fractal dimension；γsThe surface energy of-unit macroeconomic measure；
The fracture surface roughness R is indicated are as follows:
The present invention is beneficial to be had the technical effect that
(1) industrial residue, fiber, polymer and clinker complex technique, the different each component of chemical component are used
Performance is superimposed in structure-forming process, the effect for playing a role and having complementary advantages step by step on corresponding performance level, substantially
Degree improves the ability of cement matrix enhancing, toughening.The high performance cement-based composites that strength grade is 60MPa are prepared,
Resource and the energy can not only be largely saved, ecological environment is protected, and optimizes the microcosmic and microscopical structure of material, by force
Polymer is changed to the enhancing of cement matrix, toughening and prevent-crevice theory, crack can be effectively inhibited after they and fiber composite
Cause and extension, the stress for being passivated crack tip are concentrated, played the ability of very strong resistance to deformation and cracking, improved material
The bent toughness and fracture property of material.
(2) bent toughness of concrete, polymer cream are measured using the size surrounded under load-displacement
After concrete is added according to certain polymer cement ratio in liquid, bent toughness promotes 6.5 times or more, and wherein cinnamic acrylic ester is total
Polymers is added in concrete, and bent toughness promotes 17.6 times；After concrete is added according to certain volume volume in fiber, bending
Toughness promotes 8 times or more, and after wherein concrete is added in end hook type steel fibers 0.8%, bent toughness promotes 24.1 times；It will polymerization
After object and fiber add in concrete jointly according to a certain percentage, bent toughness is relatively individually added into polymer and fibrous material
It is enhanced again, after wherein copolymer in cinnamic acrylic ester and ultra-fine steel fibre are added in concrete, bending
Toughness improves 35.7 times.
(3) using the fracture toughness of fracture toughness and energy to failure evaluation concrete, polymer concrete fracture toughness is improved
15% or more, energy to failure promotes 1.6 times or more, and wherein the fracture toughness of copolymer in cinnamic acrylic ester improves 24.2%,
Energy to failure promotes 2.6 times；After fiber concrete, in addition to cellulose fibre, remaining each group Size Effects on Fracture Toughness of Concrete improve 25% with
On, energy to failure promotes 5 times or more, wherein fracture toughness improves 46.7% after concrete is added in ultra-fine steel fibre 0.8%, breaks
Can be promoted by splitting by 5.3 times；After polymer and fiber are added in concrete jointly according to a certain percentage, energy to failure more individually adds
Enter polymer and fibrous material is enhanced again, wherein copolymer in cinnamic acrylic ester and ultra-fine steel fibre add
After entering in concrete, fracture toughness improves 42.1%, and energy to failure improves 6.9 times.
(4) concrete fracture path is tracked using CT measuring technology, and the size of Fracture Surfaces of Concrete is carried out
It calculates, normal concrete crack extension interfacial transition zone between cement matrix and aggregate, the extension of polymer concrete crack can be with
Through large-sized aggregate, spike protein gene or rupture failure is presented in fiber concrete and fiber-reinforced polymer concrete, is adopted
Show that fiber-reinforced polymer Fracture Surfaces of Concrete area is the 3.5 of normal concrete with toughness microstructures evaluation index R
Times, i.e., fracture path is tortuous, and the plane of disruption is coarse, and dissipate more energy in fracture propagation process.
(5) by fiber-reinforced polymer concrete be applied to Railway Tunnel liner structure in, not only working performance,
Intensity, endurance quality meet design and construction requirement, and intensity still meets design requirement after 720d, and concrete surface is bright and clean,
It is visible by naked eyes crack.
Detailed description of the invention
Fig. 1 is in the embodiment of the present invention, when 56d age, the compression strength and tensile splitting strength of each series concrete
Figure；
Fig. 2 is the flexural toughness figure of concrete in the embodiment of the present invention；
Fig. 3 is typical duty load-displacement curve figure of the polymer concrete (a) of 56d age in the embodiment of the present invention；
Fig. 4 is typical duty load-displacement curve figure of fiber concrete (b) in the embodiment of the present invention；
Fig. 5 is typical duty load-displacement curve figure of fiber-reinforced polymer concrete (c) in the embodiment of the present invention；
Fig. 6 is the geometric dimension schematic diagram of concrete sample in the embodiment of the present invention；
Fig. 7 is (a) polymer concrete Series P-CMOD curve graph in the embodiment of the present invention；
Fig. 8 is (b) fiber concrete Series P-CMOD curve graph in the embodiment of the present invention；
Fig. 9 is (c) fiber-reinforced polymer concrete P-CMOD curve graph in the embodiment of the present invention.
Specific embodiment
One, raw material selects
(1) cementitious material
Cement is using the production of Wuhan Huaxin Cement FactoryPortland cement, flyash use Nanjing Cogeneration Power Plant
I grade of flyash of production.Cement, the mineral composition of flyash, chemical component and physical property are shown in Table shown in 1~5.
The mineral composition of 1 clinker of table
The chemical composition of 2 clinker of table
The Physical and mechanical properties of 3 cement of table
The chemical composition of 4 flyash of table
The physical property of 5 flyash of table
(2) fine aggregate
Selecting maximum particle diameter is the common river sand of 2.36mm, fineness modulus 2.3, continuous grading, bulk density 1.3g/
Cm3, apparent density 2.5g/cm3。
(3) coarse aggregate
Maximum particle diameter is the basaltic broken stone of 15mm, apparent density 2.7g/cm3, 1.5 g/cm of bulk density3, crush values
5%, clay content 0.7%, water absorption rate 0.2%.
(4) polymer
For the polymeric oxidizer in cement-based material, should fully consider its with cement, gather materials it is whether compatible, again
Consider the stability and working performance of polymer itself, therefore includes: a. with good preprocessing performance to its basic demand
And mechanical stability, it is easy to use；B. hydrated cementitious is had no adverse effect, to the Ca generated in cement hydration process2+With
Al3+Ion has higher stability；C. have after cement matrix hardening with hydrated product and between gathering materials and preferably cohere ability,
And film-forming temperature wants low；D. there is preferable water resistance and alkali resistance in hardened cement matrix；E. glass transition temperature wants low,
With certain viscosity.
Currently used polymer material type includes water-soluble polymer, polymer emulsion, redispersible polymer
Powder and liquid polymers, the present invention select ethylene-vinyl acetate copolymer (DB), ethyl acrylate (A700), styrene-
Acrylate copolymer (AD66), vinyl acetate-acrylate polymer (GD56) and organic silicon acrylic ester (2900T) five
Kind polymer emulsion, physicochemical properties are as shown in table 6.
The various polymer physical chemistry properties of table 6
(5) fiber
According to composite material principle, the fibrous material as activeness and quietness will meet following condition: a. fiber it is strong
Degree and elasticity modulus will be higher than cement matrix；B. there is good adhesion strength between fiber and cement matrix, guarantee cement matrix
The stress of receiving passes to fiber by interface；C. the thermal expansion coefficient between fiber and cement matrix is close, and guarantee sticks between the two
Knotting strength will not be weakened in process of expansion and contraction；D. harmful chemical reaction cannot occur between fiber and cement matrix；e.
Volume fraction, size and the distribution of fiber must be suitable for, and fiber dispersion can be good.
The present embodiment chooses steel fibre (2 kinds), basalt fibre (BF), vinal (PVAF), cellulose fibre
(CF), six kinds of fibers of modified polyester fiber (PETF), the physical and mechanical parameter of fiber are shown in Table 7.
The various fibrous physics mechanical properties of table 7
(6) water-reducing agent
The PCM high-efficiency water-reducing agent of poly-carboxylic acid that Jiangsu Botexin Materials Co., Ltd provides, water-reducing rate 20%~25%, root
Requiring volume according to mobility is 0.6%~1%.
Two, mix-design
The present invention uses flyash, polymer emulsion, fiber MULTIPLE COMPOSITE toughening technology, is ensuring working performance, intensity
On the basis of, prepare three serial high-performance concrete materials: polymer concrete, fiber concrete and fiber reinforcement are poly-
Object concrete is closed, and the bent toughness and fracture property of three serial concrete are tested and optimized, determines concrete
The best-of-breed technology route of toughening, the test variety and volume of fiber and polymer material are shown in Table 11.
(1) fibers content
The definition of the critical fiber volume rate of Fiber-reinforced Quasi-brittle matrix composite is: after MATRIX CRACKING, fiber energy
When undertaking composite material cracking after minimum fiber volume rate or MATRIX CRACKING needed for load composite material bearing capacity will not under
The minimum fiber volume rate that must be mixed drops.Fiber critical size rate is the turning point of two kinds of failure modes of concrete, works as fibre
When tieing up volume less than fiber critical size rate, after MATRIX CRACKING, the load shifted because fiber cannot undertake MATRIX CRACKING, this
Shi Jiti causes to destroy immediately once cracking, and is in brittle break state；When fibers content is greater than fiber critical size rate, base
After body cracking, fiber can undertake the load of matrix transfer, or even bearing capacity is made to continue to improve.
The random fiber critical size rate formula (formula 2-1) to discontinuous fiber composite material of present invention use, and according to
Existing experience is determined fibers content:
In formula: fmu- fiber concrete matrix ultimate tensile strength (MPa)；
ffuThe ultimate tensile strength (MPa) of-fiber；
εmuThe strain of-fiber concrete matrix Ultimate Tensile；
EfThe elasticity modulus of-fiber.
For general C60 concrete, the ultimate tensile strength f of concrete substratemu=4.11MPa, coagulation soil matrix
The Ultimate Tensile strain stress of bodymu=100 × 10- 6, the ultimate tensile strength and elasticity modulus of fiber used be shown in Table 6.Number
According to substitute into formula (2-1) calculate various fibers critical size rate it is as shown in table 9.
The present invention considers the shadow of construction cost, Concrete Design requirement etc. on the basis of refering to great number tested data
It rings, finally determines that the volume volume of various fibers is 0.1%~2%, preferably 0.8%.
9 fiber critical size rate of table
(2) water-cement ratio
It is C60 that the present invention, which selectes concrete design strength grade, and wherein the quality such as flyash replace 30% cement, is used
The water-cement ratio of formula (2-2) calculating concrete.
In formula: fce- actual cement strength, f in the present embodimentce=1.13 × 52.5=59.325MPa；
A, B-empirical coefficient, the present embodiment use rubble, take 0.46,0.07 respectively；
fcu- Concrete Design compression strength, f in the present embodimentcu=60+1.645 × 6=69.87MPa.
Each coefficient value is substituted into the water-cement ratio of formula (2-2) concrete are as follows:
In view of the restriction of the factors such as execution conditions, material context, it is 0.1-0.9 that the present invention, which selectes water-cement ratio, preferably
0.35。
(3) polymer volume
According to the inierpeneirating network structure of polymer and cement matrix water ratio limit model and polymer and cement matrix, push away
Polymer theoretical dosage is exported, as shown in formula (2-3):
In formula: Pm0- polymer theoretical dosage (kg)；
- design of material water-cement ratio, the present embodiment take 0.35；
Cement ratio of-the cement in complete aquation, the present embodiment take 2.63；
D-polymer three-dimensional ulking thickness is calculated by each polymer molecular structure and is determined；
S-hydrated product per surface area, the present embodiment take 200m2/g；
ρ-density polymer (g/cm3)；
M0Theoretical volume (%) of-polymer in cementitious material system.
Each parameter value is substituted into formula (2-3), the theoretical volume that various polymer are calculated is shown in Table shown in 10.
10 polymer theoretical volume of table
The resulting theoretical volume for polymer is calculated in table 10, assumes that polymer can be complete in cement matrix
Expansion.Actually polymer is it is not possible that mix is uniform, it is difficult to be fully deployed, can there is some reunion shapes.Furthermore polymer can also
It is filled in the holes of some structures, in gap, therefore the actual amount of polymer material is higher than calculated value, but considers
Polymer material price costly, therefore the present embodiment choose various polymer volumes be gel material content 8~
11%, preferably 10%.
(4) sand coarse aggregate ratio
The variation of sand coarse aggregate ratio can be such that the total surface area gathered materials has a greater change, to the workability and quality of mixing and stirring material have compared with
It is big to influence.Since the factor for influencing sand coarse aggregate ratio is more, sand coarse aggregate ratio can be by test or according to existing empirically determined, then again
It is tested and is determined by mix workability.
Include two kinds of steel fibres in fiber selected by the present embodiment, concrete can be made when steel fibre mixes in concrete
Mobility decline, it is necessary to increase sand coarse aggregate ratio, but the too high intensity that can make concrete of sand coarse aggregate ratio declines, and comprehensively considers these two aspects
It influences, sand coarse aggregate ratio is chosen to be 0.42 by the present embodiment.
(5) Water Usage Per Unit Volume and binder total amount
Under water-cement ratio certain condition, Water Usage Per Unit Volume should make mixture reach the workability of requirement, convenient for applying
Work.The slump for the lining cutting position concrete that Tunnel Design requires is 160mm~200mm, and without the slump within 30min
Loss, according to regulation in " design of common concrete proportioning regulation " (JGJ55-2000), the present embodiment is chosen unit volume and is used
Water is 160kg.
(6) conservation system
The factor of polymer concrete performance is influenced other than the type of cement and performance, the type of polymer and volume,
Conservation system is very important a ring.There are many type of polymer, have certain effect to the modification of concrete, still
Variety classes, its effect of the polymer of different manufacturers production are different, and required maintenance method is also different.
Optimal conservation system, i.e., under the conservation system, each component material sufficiently goes out positive efficiency, macroscopically shows
For the raising of comprehensive performance.In polyalcohol cement basis composite system, according to composite material strength rule (formula 2-4):
σ=σmVm+σPVP (2—4)
In formula: σ-polyalcohol cement basis composite material strength；
σm、VmIntensity, the volume of-cement mortar；
σP、VPIntensity, the volume of-polymer.
σ is set to reach maximum, then σmWith σPWhen respectively reaching maximum value, it is suitable to be only, i.e., cement must abundant aquation,
Polymer must sufficiently form a film simultaneously.But the two be it is contradictory, hydrated cementitious is that the more water the easier, therefore general maintenance is leaching
In water or in steam so as to hydrated cementitious it is abundant with it is complete；And form a film that be that the fewer water the easier make latex more preferably form a film, because
This, which only looks for one in centre, can both be optimal approach, so that σ is reached maximum, i.e., optimal curing condition.This hair
The factors such as bright consideration type of polymer, volume, determine conservation system be concrete demoulding after first in standard curing room (temperature 20
± 2 DEG C, humidity > 90%), then move to maintenance (temperature > 10 DEG C, relative humidity 65%) in air.
In conclusion it is 0.35 that the present embodiment concrete, which selectes water-cement ratio, and sand coarse aggregate ratio 40%, the dosage of each component material:
Cement 315Kg/m3, flyash 135Kg/m3, fine aggregate 690Kg/m3, coarse aggregate 1035Kg/m3, water 160Kg/m3, polymer
22.5Kg/m3, fiber volume volume 0.8%, 2.7~4.5Kg/m of water-reducing agent3, table 10 is each series concrete number.
Each series concrete of table 10 number
Note: (1) C0 is normal concrete；
(2) fiber-reinforced polymer coagulation soil series is preferably to be obtained based on series of polymers and fiber campaign result
Out.
Three, raw material mix
The technology of preparing of concrete is in addition to optimization material composition, in order to enable each component is uniformly distributed in system, preparation
Method is to guarantee the importance of Bending Concrete toughness.Its key technology be flyash, cement, polymer emulsion it is equal
Being uniformly distributed in even mixing and fiber cement substrate.Fiber being uniformly distributed there are mainly two types of method in cement matrix,
First is that " wet after first doing " mixing method, the second is fiber is uniformly sprinkled into while cement matrix wet-mixing.Due to second
Method must have the equally distributed special equipment of fiber, otherwise do not only low efficiency but also dangerous by manpower work, therefore should not adopt
With the present embodiment is using blending method wet after first doing thus: fiber, coarse aggregate, fine aggregate, cement are first subjected to dry companion,
It evenly spreads to fiber in mixture, then adds water and stirs.
The present invention compared polymer emulsion series, fiber series and fiber-polymer series to cement matrix first
Reinforcing effect, match ratio is shown in Table 8.When concrete to 56d age, take out 100 × 100 × 100mm test cube into
Row compression strength and tensile splitting strength test, test method are shown in " standard for test methods of mechanical properties of ordinary concrete " (GB/T
50081-2002).When 56d age, the compression strength and tensile splitting strength of each series concrete are as shown in Figure 1.
From in Fig. 1 we it can be concluded that 1) polymer incorporation after, concrete 56d age compressive strength rate is general
Logical concrete decline 10%~15%, this is because elasticity modulus is remote after polymer emulsion polymerize in hydrolysis product of cement
Lower than Behavior of Hardened Cement Paste and the elasticity modulus of aggregate, therefore tensile stress can only be born and compression can hardly be born；In addition polymer
After cement mortar and the tensile strength of concrete improve, the form of Compressive failure is generally failure by shear.Polymer is strong because shearing
It spends low and becomes the weak intercalated layer on shear surface, shearing strength is reduced, so that compression strength be made to reduce；But Split-tension of Rolled is strong
Degree compares normal concrete and improves 50%~70%, this is because polymer, in concrete in tension, crack tip is moulded
Property area, absorb crack extension needed for energy, make crack be become stablizing extension from unstable propagation, improve the original of fracture strength
Cause.2) after fiber incorporation, the compressive strength rate normal concrete of steel fibre and vinal concrete 56d improve 30%,
Various other fiber concrete variations are unobvious；Tensile splitting strength improves 20% or more, and wherein steel fibre and polyvinyl alcohol are fine
It ties up concrete and improves 80%；3) after concrete is added in polymer and fiber, polymer on concrete compressive strength is overcome not
Benefit influences, and compression strength improves 10%~15% compared with normal concrete, slightly less than fiber concrete, but tensile splitting strength compared with
Normal concrete improves 2 times, wherein improves 2.3 times after steel fibre and copolymer in cinnamic acrylic ester mixing.
Four, bent toughness is tested
Bend test uses 100 × 100 × 400mm prism test specimen, using 4 loading methods, span 300mm,
Testing equipment is the electro-hydraulic servo universal electrical testing machine that company's production is newly thought carefully in Shenzhen, is loaded using displacement, and loading speed is
0.05mm/s, test data sheet bending load act on lower concrete load-displacement, when load reaches capacity the 10% of load
When stop test.
From macroscopic perspective, toughness absorbs the energy of energy until being defined as material or structure from load action to failure
Power, it can use energy method, characterize toughness with the area surrounded under load-deflection curves.Lotus is bent by calculation testing piece
The area carried under sag curve obtains the flexural toughness (Fig. 2) of concrete, the results are shown in Table 12.
Normal concrete, polymer concrete (a), fiber concrete (b), the fiber-reinforced polymer coagulation of 56d age
Soil, the typical duty load-displacement curve of (c) are as shown in Figure 3.
As can be seen that measuring concrete using the size surrounded under load-displacement from Fig. 3 and table 11
Bent toughness, after concrete is added in polymer emulsion, bent toughness promotes 6.5 times or more, wherein cinnamic acrylic ester
Copolymer is added in concrete, and bent toughness promotes 17.6 times；Fiber be added concrete after, bent toughness promoted 8 times with
On, after wherein concrete is added in end hook type steel fibers, bent toughness promotes 24.1 times；By polymer and fiber according to certain
After ratio adds in concrete jointly, bent toughness is relatively individually added into polymer and fibrous material is enhanced again,
After wherein styrene-acrylate copolymer and steel fibre are added in concrete, bent toughness improves 35.7 times.
The bent toughness of the various concrete of table 11
Five, fracture property is tested
In order to which the bend-carrying capacity to steel fiber reinforced concrete component after cracking is studied, the present invention uses three-point bending
The research of toughness properties after beam test cracks to steel fiber reinforced concrete.Test is adopted 100mm × 100mm × 515mm and is cut
Mouth beam test specimen, generating depth with saw cut is the prefabricated crack 20mm.Three are carried out using 810 hydraulic servo rigidity matching of MTS
Point load, span 400mm.The two support points and load(ing) point that testing machine is contacted with test specimen are made using the round steel of diameter 30mm
Fulcrum, and guarantee that load(ing) point and a support can roll, loading device signal is as shown in Figure 4.It is adopted automatically by computer
Collect the available fracture open displacement and load Value Data by camber beam of data, as shown in Figure 5.Added when test with Bit andits control
Speed is carried, is loaded using dullness, loading velocity 0.02mm/s.In loading procedure, pass through computer-automatic collection midspan load
It is displaced with crack tip.Stop load when fracture width reaches 5mm.
Fracture toughness is characterization material under quasi-static loads as the common mechanical parameter for measuring material cracking resistance
It prevents macroscopic cracking from extending the index for resisting fracture energy with component, commonly uses critical stress intensity factors, that is, plane strain fracture
Toughness KIC, energy to failure GFAnd critical crack tip opening displacement δ0Parameters are waited to characterize.Fracture toughness KIC, energy to failure GFRespectively
It is calculated according to shown in formula (2-5) and (2-6), calculated result is shown in Table 9.
In formula: t, h, l, a0 --- the geometric dimension of concrete sample, as shown in Figure 4；
W0--- the area under load versus deflection；
M=m1+2m2, wherein the beam weight between m1-fulcrum, the m2-loading weight of attachment；
δ0--- the maximum immunity value that beam measures when being broken；
The peak load (KN) that concrete sample is born when P- is loaded.
It is shown in Fig. 5 and table 9, using the fracture toughness of fracture toughness and energy to failure evaluation concrete, polymer emulsion adds
After entering concrete, fracture toughness improves 15% or more, and energy to failure promotes 1.6 times or more, and wherein cinnamic acrylic ester is copolymerized
The fracture toughness of object improves 24.2%, and energy to failure promotes 2.6 times；Fiber concrete, in addition to cellulose fibre, remaining each group is mixed
Solidifying soil fracture toughness improves 25% or more, and energy to failure promotes 5 times or more, after wherein concrete is added in end hook type steel fibers, breaks
It splits toughness and improves 46.7%, energy to failure promotes 5.3 times；Polymer and fiber are added in concrete jointly according to a certain percentage
Afterwards, energy to failure is relatively individually added into polymer and fibrous material is enhanced again, wherein cinnamic acrylic ester
After copolymer and steel fibre are added in concrete, fracture toughness improves 42.1%, and energy to failure improves 6.9 times.
The fracture property of 12 concrete of table
In short, according to the test result of bent toughness, fracture toughness and energy to failure, copolymer in cinnamic acrylic ester
After concrete is added, toughness compares normal concrete, polymer concrete and fiber concrete and is greatly improved, and
Toughness is determined as selected best test match ratio due to selected other samples in test.
Six, the microcosmic evaluation in concrete fracture path and toughness
From the toughness index of toughness definition, i.e., toughness is defined as material or structure under load action and reached brokenly
The ability that energy is absorbed until bad or failure, can be summarized as four seed types:
(1) the big of energy directly energy method: is absorbed until destroying with load versus deflection institute envelope surface product representation material
It is small；
(2) intensity method: using concrete under the conditions of given deformation possessed bearing capacity as evaluation toughness finger
Mark；
(3) the ratio of energy: being radix by the toughness of a certain characteristic point of concrete, with the ratio of itself and set point toughness
As toughness index；
(4) method of characteristic point: according to the index body for more set points that the characteristic point on concrete load versus deflection proposes
System.
1, the proposition of concrete microstructure toughness index
The present invention proposes crack Critical growth criterion, the definition of crack Critical growth stress for the ductile rupture of material
Are as follows:
In formula: γs--- it the surface of unit macroeconomic measure can, it is assumed that crack is extended along rectified path.
But the not straight extension in actually any crack, bending extension, break surface is coarse, recessed
Convex injustice, it is contemplated that the fractal characteristic of concrete material break surface, the present invention correct formula (2-7) are as follows:
Gcrit=2 γsε2-D(2-8)
In formula: ε --- scale factor；The fractal dimension of D --- section
Above formula shows that real material is broken required ratio of energy dissipation formula (2-7) and greatly, therefore to be destroyed using real material
When the ratio between critical extension force and the critical extension force of ideal toughness material be used as toughness index, may be expressed as:
Toughness index R is actually the ratio between Fracture Surfaces of Concrete area and its projected area, and referred to as the plane of disruption is coarse
Degree.
2, the microscopic sdIBM-2+2q.p.approach of toughness of concrete
Plane of disruption pattern under the present invention acts on bending load by X-CT technology before and after concrete fracture compares
Compared with, and the dimensional parameters of the region of fracture are calculated.Test specimen uses the prism of 100 × 100 × 400mm, selects C0, PM-
3, FC-2, PFC-3 are as subjects, and each group CT images of concrete is as shown in Figure 6.
From the perspective of fracture theory analysis, the material with ductile deformation's ability is when crack extends, crack tip
Nearby since stress is concentrated, local stress is more than yield strength, and nearby local material generates plastic deformation to crack tip, then
Crackle extends forward.Fig. 6 (1) show crack in normal concrete and extends, it is seen that light-weight aggregate one is encountered on the extensions path of crack
As be along interfacial transition zone between cement matrix and aggregate.Fig. 6 (2), which is shown in normal concrete, adds polymer
Lotion reduces original interface when polymer emulsion and cement matrix are intertwined, and form continuous space reticular structure
Rigidity, can absorb more energy in destructive process, and the adhesion strength of cement matrix and aggregate is improved, it is suppressed that crack
Formation, network structure can continuous transmission force, stress concentration drops, even if polymer also can be across splitting when generating crack
Line simultaneously inhibits crack to extend, therefore will pass through the biggish aggregate of partial size when the extension of crack, can also be along small particle aggregate and cement
The interface of matrix extends, this will make the extensions path in crack become winding complex, extends the path of crack extension, and dissipation is split
Energy to failure in expansion process is stitched, and then substantially improves the toughness of concrete.Fig. 6 (3) show crack in steel fiber reinforced concrete and expands
Exhibition, when fiber is by curved and tension, after the MATRIX CRACKING of tensile region, fiber, which will play, to be undertaken pulling force and keeps matrix crack slow
The effect of extension also remains certain residual stress between matrix crack.Remnants with the extension in crack, between matrix crack
Stress gradually reduces, and there is fiber biggish deformability can continue to undertake the pulling force on section, until fiber is from matrix
It extracts, this process gradually occurs, and fiber just plays apparent toughening effect in the process, and really fiber adds
Enter so that fracture energy of concrete has measured release gradually, and improves the toughness of concrete.Fig. 6 (4) show steel fibre
Enhance crack extension in polymer concrete, since polymer and fiber are playing outside respective toughening advantage, polymer can be with
Improve the interfacial transition zone (test and Analysis on Mechanism are shown in chapter 5) between steel fibre-cement collective and cement collective-aggregate,
Therefore the path of crack extension, energy to failure in dissipation fracture propagation process are extended, and then greatly improves the tough of concrete
Property.The surface area and volume of Fracture Surfaces of Concrete are calculated, as a result as shown in table 13, and with concrete proposed above
Toughness evaluation index R carries out toughness assessment, it can be seen that compares normal concrete, polymer concrete, fiber concrete and fibre
The plane of disruption area and toughness index R of dimension enhancing polymer concrete are respectively increased 1.96 times, 2.49 times and 3.57 times, reflection
It is that the plane of disruption is more coarse in concrete, fracture path is more tortuous in fracture process, and need to dissipate more energy, from
And achieve the effect that toughening, it matches with test result.
The various Fracture Surfaces of Concrete sizes of table 13
Specific embodiment 1: application of the fiber-reinforced polymer concrete in tunnel-liner engineering
According to the principle of New Austrian Tunneling Method, Tunnel Engineering can be considered two stages construct, the first stage construct underground engineering it is main
Supporting, including anchor pole, steel mesh, steel arch-shelf and gunite concrete etc.；Second stage cast-in-place concrete construction inner lining,
Including bottom plate or inverted arch.
(1) lining cutting is not an independent structure, and the performance of load and own that it is born is by surrounding formation characteristic
Control builds the problem of lining cutting is country rock and structure collective effect in underground structure, and emphasis is the stabilization of country rock itself
Property condition
(2) lining cutting as shell by load redistribution to country rock.Since country rock and gunite concrete deform together,
So the flexibility that lining cutting should be increased make its in conjunction with country rock more preferably, preferably by load redistribution to country rock.Country rock becomes
The secondary lining that shape applies after stablizing is only used for additional load caused by undertaking country rock water pressure, long-term creep, and opens later
Digging influences caused by the construction of Parallel Tunnel branch hole.
Therefore key is to guarantee that lining cutting and country rock are fully integrated together in lining construction, gives full play to country rock carrying energy
Power makes it control country rock and harmful deformation does not occur.
China for liner structure processing according to the difference of country rock grade, plain concrete is used for II, III grade of country rock
Structure, and reinforced concrete structure is used for IV grade or more country rock, recently as the development of high speed railway construction, in force
Extensively, fibre has also tentatively been used in II, III grade of country rock in the railway construction of the high speed such as Zheng Xi, expensive wide, wide Shenzhen and Hong Kong and Line for Passenger Transportation
Dimension concrete structure splits the Plastic settlement cracks and plastic shrinkage of concrete using random distribution of the fiber in concrete
Effective inhibiting effect of seam, not only reduces project cost, and tentatively solves the problems, such as puzzlement lining cutting non-structure fissure.
The tunnel A is located at Guangxi Zhuang Autonomous Region city B, and overall length 8531m is that longer, construction hardly possible is excavated in expensive wide Line for Passenger Transportation
Spend a tunnel of larger (there are the unfavorable geologies such as high temperature, rock burst, radioactivity, the developments of part position of fault underground water), design
It is required that service life is 100 years.Strength grade of concrete is C30, and the slump requires 160~200mm, concrete local environment
Grade is T2 (carbonization grade), H1 (chemical erosion grade), according to " railway concrete durability design of structure temporary provisions "
The regulation of (iron builds [2005] No. 157), electric flux are less than 1200C.Lining cutting (is used for using fiber-reinforced polymer concrete
III, under IV grade of wall rock condition) and normal concrete (under II grade of wall rock condition), lining cutting layer is with a thickness of 45cm.
Lining concrete structure raw materials are as follows: cement is conch board PO42.5；Sand is the korneforos Huang Dong coarse sand, carefully
Spend modulus 2.6；Stone is rubble, 5~16mm of particle size range, 16~31.5mm；Additive is high-efficiency water-reducing agent of poly-carboxylic acid NOF-
AS；Flyash is II grade, fineness 19.8%；Water is tap water；Steel fibre is what Bekaert company provided
RN80/50BN, polymer emulsion are the AD66 that Tong Yang Chemical Co., Ltd. in Shanghai provides, steel fibre and polymer emulsion parameter
Explanation is seen above, the match ratio for testing section concrete uses shown in table 14, " wet after first doing " of construction method as described above
Method carries out.
14 test section concrete mix unit of table: kg/m3
Two section concrete working performance test result of tunnel-liner, is shown in Table 15.Two sections of secondary lining test section coagulations
Native research conditions show: fiber-reinforced polymer concrete is easy to use in the actual construction process, and workability and mobility are good
It is good, do not occur phenomena such as isolation, bleeding；The working performances such as concrete stirring, pumping, perfusion are good.
When pouring two secondary lining test section concretes, concrete sample has been reserved respectively, with tunnel lining structure
Concrete cured under same condition (in tunnel temperature (16 ± 5) DEG C, humidity (50 ± 10) %), to the intensity and durability of concrete
Index is tested, and is shown in Table 15.Fiber-reinforced polymer concrete crushing strength meets the design requirement of C30, impervious etc.
Grade and chloride permeability coefficient reach design requirement, and every intensity and endurance quality index are superior to normal concrete.
15 concreter's performance of table, intensity and durability index
After secondary lining pouring molding, periodic monitoring is carried out to its surface appearance and intensity index, to determine its work shape
Whether state still can be used normally.Fig. 7 indicates 60d, 180d, 360d and 720d lining concrete surface state after molding, can
To see that fiber-reinforced polymer concrete surface is bright and clean, appearance is good, does not find microcrack, also without fibrous caking, appear
Phenomenon is tested the intensity of above-mentioned each age concrete with reisilometer, is shown in Table 16, meets the requirement of strength design of C30.
16 different larval instar value of concrete strength (rebound method) of table
All above-mentioned primary implementation methods for this intellectual property, there is no setting limitations to implement this otherwise
Kind new method and/or new product.Those skilled in the art will utilize this important information, modify above content, to realize class
As executive condition.But it is all based on modification of the invention or transformation new method, belong to the right of reservation.
The above described is only a preferred embodiment of the present invention, be not that the invention has other forms of limitations,
Any person skilled in the art is changed or is modified as equivalent variations possibly also with the technology contents of the disclosure above
Equivalent embodiment.But without departing from the technical solutions of the present invention, according to the technical essence of the invention to above example institute
Any simple modification, equivalent variations and the remodeling made, still fall within the protection scope of technical solution of the present invention.
Claims (7)
1. a kind of high tenacity concrete material selection method, which is characterized in that the high tenacity concrete material selection method is used
In making toughening cement-based materials comprising following steps: cementitious material selection, fine aggregate selection, coarse aggregate selection, polymer choosing
It selects, fiber selection and water-reducing agent select；
The cementitious material selection is specially using 52.5 portland cements of Wuhan Huaxin Cement Factory production, and flyash is using south
I grade of flyash of capital steam power plant production；
The step of fine aggregate selection is specially fine aggregate selection are as follows: selecting maximum particle diameter is the river sand of 2.2~3.8mm, carefully
Spend modulus 2.2~2.4, continuous grading, 1.2~1.4g/cm3 of bulk density, 2.3~2.7g/cm3 of apparent density；
The coarse aggregate selects to be specially to select maximum particle diameter for the basaltic broken stone of 14.5~15.5mm, and apparent density 2.6~
2.8g/cm3,1.4~1.7g/cm3 of bulk density, crush values 4.5~5.5%, clay content 0.6~0.8%, water absorption rate 0.18~
0.23%；
The polymeric oxidizer is specially to select one of following five kinds of polymer or a variety of: ethylene-vinyl acetate copolymer,
Ethyl acrylate, copolymer in cinnamic acrylic ester, vinyl acetate-acrylate polymer, organic silicon acrylic ester；
The fiber selection is specially to select one of following fibers or a variety of: steel fibre, basalt fibre, polyvinyl alcohol are fine
Dimension, cellulose fibre, modified polyester fiber；
Water-reducing agent selection is specially to select water-reducing rate 21%~24%, and it is 0.7%~0.9% to subtract that mobility, which requires volume,
Aqua.
2. a kind of high tenacity concrete material selection method as described in claim 1, it is characterised in that: the polymeric oxidizer
Points for attention are as follows:
A. selection has good preprocessing performance and mechanical stability, polymer easy to use；And
B. it selects to have no adverse effect hydrated cementitious, have to Ca2+ the and Al3+ ion generated in cement hydration process higher
Stability polymer；And
C. it selects to have after cement matrix hardens with hydrated product and between gathering materials and preferably coheres ability, and low poly- of film-forming temperature
Close object；And
D. the polymer in hardened cement matrix with preferable water resistance and alkali resistance is selected；And
E. selection glass transition temperature is low, has the polymer of certain viscosity.
3. a kind of high tenacity concrete material selection method as described in claim 1, it is characterised in that: the fiber selection
Points for attention are as follows:
A. selection intensity and elasticity modulus are above the fiber of cement matrix；And
B. there is good adhesion strength between selection and cement matrix, the stress for guaranteeing that cement matrix is born passes to it by interface
The fiber of itself；And
C. the thermal expansion coefficient between selection and cement matrix is close, guarantees that bond strength will not be in process of expansion and contraction between the two
The fiber being weakened；And
D. the fiber of harmful chemical reaction cannot occur between selection and cement matrix；And
E. select volume fraction, size and distribution suitable, and the fiber of good dispersion property.
4. a kind of high tenacity concrete material selection method as described in claim 1, it is characterised in that: further include fibers content
Selection, specifically includes the following steps:
Step 1, fibers content selection: using disorderly to fiber critical size rate formula (the formula 2- of discontinuous fiber composite material
1), fibers content is determined:
In formula: fmu- fiber concrete matrix ultimate tensile strength (MPa)；ffuThe ultimate tensile strength (MPa) of-fiber；
εmuThe strain of-fiber concrete matrix Ultimate Tensile；EfThe elasticity modulus of-fiber；
Step 2, water-cement ratio selection: calculating the water-cement ratio of concrete using formula (2-2),
In formula: fce- actual cement strength；A, B-empirical coefficient；fcu- Concrete Design compression strength；
The selection of polymer volume: step 3 calculates polymer theoretical dosage using formula (2-3):
In formula: Pm0- polymer theoretical dosage；- design of material water-cement ratio；Cement ratio of-the cement in complete aquation；
D-polymer three-dimensional ulking thickness；S-hydrated product per surface area；ρ-density polymer；M0- polymer is in gelling material
Theoretical volume in Material system；
Sand coarse aggregate ratio selection: step 4 is tested by mix workability and determines sand coarse aggregate ratio；
Step 5, Water Usage Per Unit Volume and binder total amount selection: by the slump of lining cutting position concrete, and,
Time requirement without slump-loss, determines Water Usage Per Unit Volume；
Conservation system selection: step 6 according to composite material strength rule (formula 2-4), determines conservation system:
σ=σmVm+σPVP (2—4)
In formula: σ-polyalcohol cement basis composite material strength；σm、VmIntensity, the volume of-cement mortar；σP、VP- polymer
Intensity, volume.
5. a kind of high tenacity concrete material selection method as described in claim 1, it is characterised in that: further include bent toughness
Test, comprising: 100 × 100 × 400mm prism test specimen is used, using 4 loading methods, span 300mm, testing equipment
The electro-hydraulic servo universal electrical testing machine that company's production is newly thought carefully for Shenzhen is loaded, loading speed 0.05mm/s using displacement,
Test data sheet bending load acts on lower concrete load-displacement, stops surveying when load reaches capacity the 10% of load
Examination.
6. a kind of high tenacity concrete material selection method as described in claim 1, it is characterised in that: further include fracture property
Test, using plane strain fracture toughness KIC, energy to failure GF, critical crack tip opening displacement δ0To characterize；Fracture toughness KIC、
Energy to failure GFCalculated respectively according to shown in formula (2-5) and (2-6),
In formula: the geometric dimension of t, h, l, a0- concrete sample；W0Area under load versus deflection；M=m1+2m2,
Beam weight between middle m1- fulcrum, the m2- loading weight of attachment；δ0The maximum immunity value that beam measures when being broken；Concrete when P- is loaded
The peak load (KN) that test specimen is born.
7. a kind of high tenacity concrete material selection method as described in claim 1, it is characterised in that: further include concrete broken
It splits the microcosmic evaluation of path and toughness: being characterized using crack Critical growth stress, fracture surface roughness；
The crack Critical growth stress is expressed as:
Gcrit=2 γsε2-D(2-8)
In formula: ε-scale factor；D-section fractal dimension；γsThe surface energy of-unit macroeconomic measure；
The fracture surface roughness R is indicated are as follows:
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| CN111724869A (en) * | 2020-06-17 | 2020-09-29 | 中国铁道科学研究院集团有限公司铁道建筑研究所 | Shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method |
| CN112530528A (en) * | 2020-11-27 | 2021-03-19 | 华能西藏雅鲁藏布江水电开发投资有限公司 | Concrete carbonization parameter prediction method, device and experimental system |
| CN112577811A (en) * | 2020-08-11 | 2021-03-30 | 长沙理工大学 | Experimental test method for shear strength of CA mortar and concrete bonding contact surface |
| CN116283145A (en) * | 2023-03-14 | 2023-06-23 | 西南交通大学 | High-strength and high-toughness heat-insulation functional sprayed concrete for high-temperature hot water tunnel |
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Cited By (4)
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| CN111724869A (en) * | 2020-06-17 | 2020-09-29 | 中国铁道科学研究院集团有限公司铁道建筑研究所 | Shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method |
| CN112577811A (en) * | 2020-08-11 | 2021-03-30 | 长沙理工大学 | Experimental test method for shear strength of CA mortar and concrete bonding contact surface |
| CN112530528A (en) * | 2020-11-27 | 2021-03-19 | 华能西藏雅鲁藏布江水电开发投资有限公司 | Concrete carbonization parameter prediction method, device and experimental system |
| CN116283145A (en) * | 2023-03-14 | 2023-06-23 | 西南交通大学 | High-strength and high-toughness heat-insulation functional sprayed concrete for high-temperature hot water tunnel |
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