CN105300801A - Evaluation method of self-repairing effect of self-repairing cement-based material - Google Patents

Abstract

The invention relates to the field of methods for testing or analyzing concrete by virtue of the chemical or physical properties of a measuring material, particular to an evaluation method of the self-repairing effect of a self-repairing cement-based material. The evaluation method of the self-repairing effect of the self-repairing cement-based material is characterized in that the evaluation indexes comprise relative dynamic elasticity modulus, fracture behaviors (stress intensity factor recover rate and fracture toughness recover rate), constitutive behavior comparison, flexural rigidity recover rate and strength recover rate. The evaluation method comprises the following steps: step 1, preparing a test piece; step 2, prefabricating local cracks and dispersed cracks; step 3, testing all the parameters; step 4, completing self repairing; step 5, testing all the parameters; step 6, calculating, processing, and evaluating the repairing effect. The method is comprehensive in evaluation.

Description

The selfreparing effect evaluation method of self-repairing cement-base material

Technical field

Concrete method field is tested or analyzed to the chemistry or physical property that the present invention relates to by means of measuring material, is specially one.

Background technology

Use the widest as current building field, the material that consumption is maximum, the serviceable life of concrete material depends on its destructiveness to a great extent.In recent years, along with the research and apply of intellectual material, have and obtain extensive concern and research from the intelligent concrete of the functions such as perception, self diagnosis, selfreparing.Self-repair concrete has become the important component part of Fiber in Smart Structure, can solve and can not solve or insoluble technical matters with conventional fracture method for repairing and mending, to permanance and the security important in inhibiting of guaranteeing the great civil engineering work facilities such as body of groundwater architecture, skyscraper, dam, in addition, the weather impact failures such as earthquake, typhoon, tsunami are being alleviated and other destructive factors also have very large application prospect.Therefore, self-repair concrete is studied, automatically can detect in fracture district, automatically repair, recover or improve the usability of concrete material, become the development trend of concrete technology.

Present stage, domestic and international distress in concrete self-repair technology can be divided into crystallization patching, built-in support methods, marmem selfreparing and the selfreparing of compound substance sensor etc.Wherein, crystallization patching is in distress in concrete, form various water-fast crystalline solid, the gathering growth in interface, crack, thus it is closed that crack is progressively filled.According to the material and the mode that generate crystalline solid, crystalline deposit, penetrant crystalline selfreparing and microorganism self-healing etc. can be divided into.Built-in support methods has another name called bionical self-repair technology, in xoncrete structure, arrange various carrier, the chemical substance with cohesive action is included in carrier, when concrete substrate produces microfracture, carrier breaks, the chemical substance generation physical-chemical reaction discharged, forms self-healing network, realizes the repairing in crack.Compound substance sensor self-repairing system is primarily of self diagnosis compound substance and low viscosity epoxy resin thermoplastic tube composition.Self diagnosis compound substance itself can by selecting to heat specific position.Once produce crack in concrete, because overtension, by self diagnosis compound substance detectable signal, and then selectivity heating is carried out in increase resistance fracture position.Afterwards, the thermoplastic tube at crack place is fused into epoxy resin to crack of healing at crack place.

At present, Chinese scholars has done very many-sided research for self-repair material, and achieves certain achievement.But, in the evaluation of selfreparing effect, still there is many problems to be solved.Secondary loading that remediation efficiency evaluation method for cement-based material selfreparing is comparatively single, and evaluation means is only confined to the mechanical property aspects such as the compressive strength response rate of material mostly both at home and abroad, and embodiment is loading---unloading is repaired---.Direct effectively evaluating method is lacked in the relevant permanance improvement such as evaluating material rigidity, toughness, fracture behaviour, constitutive behavior, degree of impairment and impermeability, resistance to fouling, carbonization.

Summary of the invention

In order to overcome the defect of prior art, improve the unicity of existing self-repairing cement-base material repairing effect evaluation method, the one more comprehensive evaluation method of system is provided, the invention discloses a kind of selfreparing effect evaluation method of self-repairing cement-base material, its evaluation index comprises relative dynamic elastic modulus, fracture behaviour (comprising stress intensity factor response rate and fracture toughness response rate), constitutive behavior contrasts, bendind rigidity response rate and intensity response rate.

The present invention reaches goal of the invention by following technical solution:

A selfreparing effect evaluation method for self-repairing cement-base material, is characterized in that: implement successively as follows:

Step 1: according to different environment for use, according to the preparation of different Principles, there is the test specimen of the cement-based material of repair, the multiple repair modes such as crystallization patching, built-in support methods, marmem selfreparing can be selected without the buildings of particular/special requirement and groundwater regime; Concrete material for buildingss such as highway, ground and bridge piers can select liquid core fibre method; For petroleum engineering, the concrete material of Geological Engineering and part civil engineering work can select microorganism selfreparing method, described test specimen is long × wide × high prism for 40mm × 40mm × 160mm, described test specimen is divided into A, B two test group, A group is used for the fracture behaviour of exosyndrome material, constitutive behavior and mechanical behavior, and B group is for the change of exosyndrome material internal injury situation; Each test group needs 9 test specimens, and 3 test specimens in each test group are used for test benchmark intensity, and all the other 6 test specimens are used for the pre-destruction arranged in various degree, and the base material of described test specimen comprises cement paste, sand-cement slurry and concrete material;

Step 2: after test specimen arrives the length of time of 28day, to the specimen prefabricated localized cracks of A group, to the specimen prefabricated dispersion crackle of B group, described localized cracks is realized by the approach of cutting or preset thin slice, the length of described localized cracks, width and the degree of depth adjust according to actual needs, general, crack length scope is 10mm ~ 40mm; Crack width scope is 0.2mm ~ 2mm; Crack depth scope is 5mm ~ 15mm; Described dispersion crackle is realized by prestrain, the mode of prestrain comprises and pre-folding and precompressed, pre-fold and realized by omnipotent servo hydraulic machine, precompressed is realized by mortar pressing machine, the regional extent of described dispersion crackle adjusts according to actual needs, general, prefabricated dispersion crackle degree is 10% ~ 80% of peak load;

Step 3: test the fragmentation parameters of A group test specimen, constitutive behavior, bendind rigidity, rupture strength and these 5 performance index of compressive strength, test b group test specimen ultrasound wave is at the initial transmission velocity of wave of material surface;

Step 4: under A, B group test specimen being all placed in the environment of concrete standard curing condition and temperature 20 ± 2 DEG C, relative humidity 95%, maintenance 1day or 3day completes selfreparing;

Step 5: to the performance index in A, B group test specimen repeated test step 3 after reparation;

Step 6: computing is carried out to test data in step 3 and step 5, technical scheme flow process as shown in Figure 1, in Fig. 1, the process of test-reparation-second test as shown in Figure 2, show that evaluation index is to evaluate repairing effect, described evaluation index comprises relative dynamic elastic modulus, fracture behaviour, and constitutive behavior contrasts, bendind rigidity response rate and intensity response rate, wherein fracture behaviour comprises stress intensity factor response rate and fracture toughness response rate.

1. relative dynamic elastic modulus P:

What the dynamic modulus of elasticity characterized is the ratio of object stress and strain under dynamic load effect, and for the cement-based material before and after selfreparing, relative dynamic elastic modulus can reflect the packing change of test specimen before and after repairing from the side, and then characterizes repairing effect.

Dynamic elastic modulus E _dcomputing method as follows:

The initial surface velocity of wave V of its ultrasound wave at test specimen is tested before precompressed _r0, precompressed also, after reparation, measures the velocity of wave V of ultrasound wave in surface of test piece _r1, the situation of change of the front and back dynamic modulus of elasticity is repaired in contrast.

The dynamic elastic modulus E of solid material _dwith its surface wave speed V _rbetween relation by (1) formula calculate:

$E_d=\frac{{2(1+\mathrm{\μ})}^3}{0.87+1.12\mathrm{\μ}}\mathrm{\ρ}{V}_r^2--\left(1\right),$

(1) in formula: ρ---density of solid, μ---solid Poisson ratio, to maturing, μ is generally between 0.2 ~ 0.3, and for concrete material, μ gets 0.2 substitution (1) formula, then:

$E_d\frac{2{(1+\mathrm{\μ})}^2}{0.87+1.12\mathrm{\μ}}\mathrm{\ρ}{V}_r^2=3.159\mathrm{\ρ}{V}_r^2--\left(2\right),$

In (1) or (2) formula, get V _r=V _r0, obtain the initial dynamic elastic modulus E of B group test specimen _d0; Get V _r=V _r1, obtain the dynamic elastic modulus E after the selfreparing of B group test specimen _d1, then relative dynamic elastic modulus P calculates by (3) formula:

$P=\frac{V_r^2}{V_{r0}^2}\×100\%--\left(3\right);$

2. fracture behaviour K _iand K _iC:

By the stress of elastic plastic theory research component inside crack tip, strain and strain energy distribution, by the propagation behavior of breaking mechanics parameter research crackle, fracture behaviour comprises the analysis of the fragmentation parameters such as stress intensity factor response rate and fracture toughness response rate:

2.1 stress intensity factor response rate η (K _i):

Stress intensity factor exosyndrome material crack tip elastic stress field under stressed effect is strong and weak, and it is relevant with crackle size, component physical dimension and external carbuncle, can be used for the propagation law of evaluation hard brittle material crackle.

Described test specimen when 3 anti-foldings load, its crack tip stress intensity factor response rate η (K _i) calculate by (4) formula:

$\mathrm{\η}\left(K_I\right)=\frac{K_I\left(1\right)}{K_I\left(0\right)}\×100\%--\left(4\right);$

(4) in formula: stress strength factor K _icalculate by (5) formula:

$K_I=\frac{P_{\mathrm{MAX}}S}{{\mathrm{BW}}^{\frac{3}{2}}}f\left(\frac{a}{W}\right)--\left(5\right);$

(5) in formula, for geometrical form factors, calculate by (6) formula:

$f\left(\frac{a}{W}\right)=\frac{3{\left(\frac{a}{W}\right)}^{\frac{1}{2}}\{1.99-\frac{a}{W}(1-\frac{a}{W})[2.15-3.93\frac{a}{W}+2.7{\left(\frac{a}{W}\right)}^2\left]\right\}}{2(1+2\frac{a}{W}){(1-\frac{a}{W})}^{\frac{3}{2}}}--\left(6\right);$

(5) and in (6) formula: P _mAX---maximum load (N), S---nominal span (mm), B---specimen thickness (mm), W---specimen width (mm), a---crack length (mm) is unit used in bracket,

2.2 fracture toughness response rate η (K _iC)

In fracture is learned, usually carrying out exosyndrome material Anticrack by fracture toughness and cause the ability of construction instability, also known as fracture toughness, is the index weighing toughness of material quality.For the material of specifying, when keeping temperature consistent with rate of loading, its fracture toughness is a constant.The fracture toughness of material is larger, and expression impels the stress needed for instable growth of crack larger, i.e. more difficult fracture of component.

Described test specimen when 3 anti-foldings load, fracture toughness response rate η (K _iC) calculate by (7) formula:

$\mathrm{\η}\left(K_{\mathrm{IC}}\right)=\frac{K_{\mathrm{IC}}\left(1\right)}{K_{\mathrm{IC}}\left(0\right)}\×100\%--\left(7\right);$

(7) in formula: K _iC(0)---test specimen virgin fracture toughness; K _iC(1)---the fracture toughness after test specimen reparation;

(7) in formula, fracture toughness K _iCcalculate by (8) formula:

$K_{\mathrm{IC}}=\frac{M_{\mathrm{MAX}}}{{\mathrm{BH}}^{\frac{3}{2}}}f\left(\frac{a}{H}\right)--\left(8\right),$

(8) in formula: M _mAXcalculate by (9) formula:

$M_{\mathrm{MAX}}=\frac{(P_{\mathrm{MAX}}+G)S}{4}--\left(9\right),$

(8) in formula, for geometrical form factors, computing formula is:

$f\left(\frac{a}{H}\right)=2.9{\left(\frac{a}{H}\right)}^{\frac{1}{2}}-4.6{\left(\frac{a}{H}\right)}^{\frac{3}{2}}+2.18{\left(\frac{a}{H}\right)}^{\frac{5}{2}}-37.6{\left(\frac{a}{H}\right)}^{\frac{7}{2}}+38.7{\left(\frac{a}{H}\right)}^{\frac{9}{2}}--\left(10\right),$

(8) ~ (10) in formula: P _mAX---maximum load (N), M _mAX---maximum mid span moment (Nmm), G---loading test specimen weight, B---specimen thickness (mm), H---height of specimen (mm), a---crack length (mm) is unit used in bracket.

3. constitutive behavior:

Constitutive behavior comprises the force-displacement curve of material and the analysis of stress-strain curve.

3.1 force-displacement curves:

Force-displacement curve is realized by omnipotent servo hydraulic machine, contrast specimen repairs the force-displacement curve of front and back, the peak load before and after repairing with analysis of material, maximum displacement, destructive process and destructive characteristics etc., and then the fracture behaviour changing features evaluating that it repairs front and back.

3.2 stress-strain curves:

Stress-strain curve is realized by omnipotent servo hydraulic machine and foil gauge, and contrast specimen repairs the stress-strain curve of front and back, the compressive deformation process before and after repairing with analysis of material, the i.e. generation of cement-based material internal fissure and the change of evolution.

Before and after the reparation of 3.1 and 3.2 in test curve comparative analysis,

1) phase slope within 30% of peak value is larger, and the ability of the resistance to deformation of this test material is larger, if this phase slope of testing of materials curve after repairing obviously increases, illustrates that the ability of its resistance to deformation is improved preferably;

2) because cement-based material is hard brittle material, be difficult to the extension of test to curve descending branch, after repairing, if curve descending branch is obvious with the growth extension trend of displacement or strain, illustrate that the toughness of this material improves, fragility declines;

3) area that force-displacement curve or stress-strain curve and horizontal ordinate surround can represent the energy that material needs in destructive process to a great extent, the area surrounded is larger, the energy that material damage needs is larger, if the area that the curve after repairing and horizontal ordinate surround obviously increases, then illustrative material obtains good reparation, its usability be improved significantly.

4. bendind rigidity response rate η _p:

Rigidity be material or component in elastic range, cause the power required for unit displacement, i.e. the scale-up factor that is directly proportional of load and displacement, in order to the ability of exosyndrome material resistance to deformation.The complete damage curve of test specimen is analyzed, because concrete material in destructive process, can think elastic deformation stage in the starting stage stressed, scope is stressed within 30% of peak load, within this stage, the slope of force-displacement curve is the rigidity P of material.

The bendind rigidity response rate of cement-based material calculates by (11) formula:

${\mathrm{\η}}_P=\frac{P}{P_0}\×100\%--\left(11\right),$ Be accurate to 0.01,

(11) in formula: P---prestrain also with the bendind rigidity calculated value (MPa) of group cement slurry test specimen after repairing, is accurate to 0.1MPa,

P ₀---with the bendind rigidity calculated value (MPa) of group cement slurry test specimen when destroying completely, being accurate to 0.1MPa, is unit used in bracket.

5. mechanical property and intensity response rate η _fand η _f:

Intensity is one of most important index in concrete material application, and at cement-based material after self-repair function, the leading indicator evaluating its repairing effect is exactly whether intensity replys or increase.Working strength response rate of the present invention analyzes the Strength Changes situation that front and back repaired by test specimen, comprises 3 rupture strength response rates and compressive strength response rate.

5.1 rupture strength response rate η _fcalculate by (12) formula:

${\mathrm{\η}}_f=\frac{R_f}{R_{f0}}\×100\%--\left(12\right),$ Be accurate to 0.01,

(12) in formula: R _f---prestrain also with the rupture strength measured value (MPa) of group cement slurry test specimen after repairing, is accurate to 0.1MPa,

R _f0---with the rupture strength measured value (MPa) of group cement slurry test specimen when destroying completely, being accurate to 0.1MPa, is unit used in bracket.

R _fand R _f0the arithmetic mean of Ying Yisan test specimen rupture strength test findings is as measured value, when the difference of three test specimen rupture strength maximal values or minimum value and intermediate value exceedes 15% of intermediate value, should reject this value, then the arithmetic mean getting all the other two values is as measured value; When maximal value and minimum value all exceed 15% of intermediate value, intermediate value should be got as measured value.

5.2 compressive strength response rate η _ccalculate by (13) formula:

${\mathrm{\η}}_c=\frac{R_c}{R_{c0}}\×100\%--\left(13\right),$ Be accurate to 0.01,

(13) in formula: R _c---precompressed also with the compressive strength determination value (MPa) of group cement slurry test specimen after repairing, is accurate to 0.1MPa,

R _c0---with the compressive strength determination value (MPa) of group cement slurry test specimen when destroying completely, being accurate to 0.1MPa, is unit used in bracket.

R _cand R _c0the arithmetic mean of Ying Yisan test specimen compressive strength test result is as measured value.When the difference of three test specimen compressive strength maximal values or minimum value and intermediate value exceedes 15% of intermediate value, this value should be rejected, then the arithmetic mean getting all the other two values is as measured value; When maximal value and minimum value all exceed 15% of intermediate value, intermediate value should be got as measured value.

The selfreparing effect evaluation method of described self-repairing cement-base material, is characterized in that:

C part in step 6 c.1 with reparation c.2 before and after in test curve comparative analysis:

1) if this phase slope of testing of materials curve after repairing increase to former slope 120% and above time, then think that this phase slope obviously increases;

2) if curve descending branch with the growth of displacement or strain extend trend extend to original 120% and above time, then think that to increase extension trend obvious;

3) if the area that curve and horizontal ordinate after repairing surround obviously increase to original area 130% and above time, then think that area obviously increases.

Beneficial effect of the present invention is as follows:

(1) when characterizing for cement-based material selfreparing effect, compared with existing research, the control diversification more of test condition of the present invention, to self-healing element proportioning, curing condition, curing age, crackle form, different explanation has all been done in the aspects such as precrack region and test mode;

(2) method of the evaluation repairing effect proposed is widely used in the various self-healing evaluations based on different principle, compared with existing evaluation method, method of the present invention is replied the performance of repairing front and back cement-based material and is evaluated more comprehensively, comprise mechanical property, fracture property, degree of impairment and permeance property etc.;

(3) method evaluating selfreparing effect is systematically proposed:

A) for self-repair material, when being in after material internal cracked zone completes self-healing process, the stress distribution in crack district can being changed, show as the change of broken curve and fragmentation parameters.So, use fracturing mechanics knowledge to carry out evaluation to cement-based material self-healing properties and to can yet be regarded as a kind of method reliably;

B) ability of rigidity exosyndrome material resistance to deformation.By to the computational analysis of repairing front and back specimen stiffness, the change of its non-deformability can be obtained, also indirectly reflect micro-crack and the micropore number of test specimen inside, embody the change of the packing of test specimen to a certain extent;

What c) dynamic modulus of elasticity characterized is the ratio of object stress and strain under dynamic load effect.In concrete works uses, the conventional dynamic modulus of elasticity measures the degree of impairment of concrete material inside, and then the relevant durability index such as frost resistance, corrosion resistivity of evaluation material.For the cement-based material before and after selfreparing, the dynamic modulus of elasticity can reflect the packing change of test specimen before and after repairing from the side, and then characterizes repairing effect.

Accompanying drawing explanation

Fig. 1 is the technical scheme process flow diagram in the present invention;

Fig. 2 is the process flow diagram of test-reparation-second test in Fig. 1;

Test unit schematic diagram when Fig. 3 is embodiment 1 and 2 enforcement;

Fig. 4 is the functional image of different microcapsules volume prestrain 30% and the rigidity value after repairing and rigidity rate of growth in embodiment 2;

The functional image of the situation of change of stress intensity factor after different prestrain reparation when Fig. 5 is different microcapsules volume in embodiment 1;

Fig. 6 be embodiment 1 with in 2 during prestrain 30% under different microcapsules volume test specimen repair before and after the functional image of rupture strength response rate;

Fig. 7 is the functional image that in embodiment 4, the relative dynamic elastic modulus contrast of front and back is repaired in precompressed 30% and 60%.

Embodiment

The present invention is further illustrated below by way of specific embodiment.

Embodiment 1 and 2

Embodiment 1 and 2 all adopts microcapsules self-repairing cement-base material.

First preparation has the microcapsules of self-healing properties.The ratio of microcapsule granule quality and microcapsules finished product (i.e. microcapsule emulsion system) gross mass is the solid content of microcapsules.In embodiment 1 and 2, the solid content of microcapsules is all 40%.Raw material ratio is as shown in table 1:

Table 1:

Starting material	Mass fraction
		Epoxy resin	14
Styrene	1.5
		Phenmethylol	2
Sodium dodecylbenzenesulfonate	1.25
		Octyl phenyl polyoxyethylene	1.25
Benzoyl peroxide	0.3
		Divinyl is stupid	0.08

Potassium persulfate	0.3
		Deionized water	22

Preparation process is as follows:

(1) each component materials is taken by proportioning;

(2) will be that after thinning agent dilution, epoxy resin joins in bottle bucket class container with phenmethylol, agitation and dilution;

(3) sodium dodecylbenzenesulfonate is as emulsifying agent, and octyl phenyl polyoxyethylene is as surfactant, and both mixed with deionized water, dispersed with stirring, after 8 minutes, joins in reaction unit, mixes with epoxy resin, stirring and emulsifying 10 minutes;

(4) using as the benzoyl peroxide of catalyzer and the stupid mixed liquor of divinyl and styrene mix and blend, be added drop-wise in reaction unit.Capping device, pumps the air in device, passes into argon gas.Under keeping argon gas atmosphere, be warming up to 70 DEG C, stirring rate 400rmp, successive reaction 5hour;

(5) in reaction unit, drip the potassium persulfate solution that mass concentration is 1%, continue reaction 3hour.

Subsequently, in embodiment 1 and 2, all adopt 40mm × 40mm × 160mm cement paste test block, test the mechanical property of cement based test specimen after the selfreparing of microcapsules, fracture property, the recovery situation of the aspects such as constitutive behavior.

The water-cement ratio of the present embodiment sample used is fixed as 0.3, and microcapsules volume is 0%, 1% and 2%.

In the starting material that embodiment 1 and 2 is used, microcapsules are the microcapsule emulsion prepared in the present embodiment, and solid content is 40%; Cement adopts PO42.5 level Portland cement; Hardening agent adopts aqueous epoxy curing agent, and volume is 1.3 times of microcapsules solid content.Test material mixture ratio is as shown in table 2:

Table 2:

Microcapsules volume (%)	Cement (g)	Water (g)	Microcapsules (g)	Hardening agent (g)
					0	600	180	0	0
1	600	171	15	7.8
					2	600	162	30	15.6

The raw material ratio that embodiment 1 and 2 adopts is consistent, and after shaping, embodiment 1 puts into concrete standard fog room maintenance 28day, and embodiment 2 puts into calcium hydroxide aqueous solution maintenance 28day.

Embodiment 1 is consistent with the test method of 2, and concrete steps are as follows:

(1) prepare sample according to Sample Prep Protocol of the present invention, each test group prepares 9 test specimens, and wherein 3 test specimens are used for test benchmark intensity, and other 6 test specimens are used for the pre-destruction arranged in various degree;

(2), after test specimen arrives the length of time, at side Cutting Length 40mm, width is 0.5mm, and the degree of depth is the crack of 10mm;

(3) carry out 3 bending tests to 3 test specimens of each test group, the rupture strength of sample under the different curing condition of measurement different addition quantity, final data gets the mean value of three test datas;

(4) another 6 test specimens of method to each test group provided according to technical scheme and foregoing summary part carry out pre-destruction in various degree, and wherein 3 precompressed degree are 30%, and other 3 precompressed degree are 60%.After indoor leave standstill 1day, be again loaded on test specimen destroy completely, measure the test figure of its each side.

(5) test specimen fractureed is carried out compression test, the compressive strength of sample under test different condition, final data gets the mean value of three test datas;

(6) 6 test specimens fractureed separately getting each test group carry out precompressed in various degree, wherein 3 precompressed degree are 30%, other 3 precompressed degree are 60%, be again loaded on test specimen and destroy completely after indoor leave standstill 1day, measure the compressive strength after its reparation;

(7) method provided according to technical scheme is carried out process to test data and is calculated, and evaluates its remediation efficiency.

Fig. 3 is shown in by 3 bending test device schematic diagram.

Test result is as shown in Table 3 and Table 4:

Table 3: embodiment 1 and 2 three anti-folding test results:

Table 4: embodiment 1 and 2 compression test results:

By the test of embodiment 1 and 2, test findings is analyzed, can following preliminary concluding remarks be obtained:

(1) in the test of prefabricated localized cracks, to destroy in advance and after repairing, test specimen usability has improvement in various degree, illustrate to cement-based material, to there is good repairing effect at microcapsules;

(2) in intensity reply, in the result of prefabricated localized cracks and dispersion crackle, rupture strength and the compressive strength response rate of test specimen all improve along with the raising of precompressed degree.When microcapsules volume is 1%, the compressive strength of test specimen and the response rate of rupture strength are all greater than test specimen when volume is 2%, and in addition, the microcapsules remediation efficiency in embodiment 1 is greater than the remediation efficiency of test specimen in embodiment 2.

Part test the results are shown in Figure 4.

Special instruction: when what Fig. 6 represented is prestrain 30%, under different microcapsules volume, the situation of front and back rupture strength response rate repaired by test specimen, show the rupture strength response rate of material when microcapsules volume is 1% in figure and be better than rupture strength response rate when volume is 2%, possible reason is: the microcapsules mixed are emulsion system, containing a large amount of emulsifying agents, its surface active composition can cause hardened cement paste porosity greatly to increase, test specimen packing is poor, and the repair of microcapsules is difficult to embody in second-rate system.

Embodiment 3 and 4

Embodiment 3 and 4 all adopts mineral self-repairing cement-base material.

Embodiment 3 and 4 all adopts 40mm × 40mm × 160mm concrete test block, characterizes the situation of change of material internal degree of injury after mineral selfreparing.

First preparation has the concrete material of mineral self-healing properties.In embodiment 3 and 4, Binder Materials adopts PO42.5 level Portland cement; Fine aggregate is river sand, and modulus of fineness is 2.2; Coarse aggregate 5mm ~ 25mm continuous grading; Swelling agent adopts UEA swelling agent; Water reducer adopts polycarboxylate water-reducer.Raw material ratio is as shown in table 5:

Table 5:

After specimen molding, embodiment 3 puts into concrete standard fog room maintenance 28day, and embodiment 4 puts into calcium hydroxide aqueous solution maintenance 28day.

Embodiment 3 is consistent with the test method of 4, and concrete steps are as follows:

(1) sample is prepared according to Sample Prep Protocol of the present invention;

(2) after test specimen arrives the length of time, the initial dynamic modulus of elasticity of sample under the different curing condition of measuring and calculation different materials proportioning;

(3) to the crackle of embodiment 3 and embodiment 4 specimen prefabricated 30% and 60%, its dynamic modulus of elasticity of measuring and calculation again after indoor leave standstill 1day.

Part test the results are shown in Figure 7.

Compared with the 1st, 2,3 group of test specimen, the 4th group of test specimen adds the combination of swelling agent, sulphate aluminium cement and chemical agent in match ratio, makes it possess the prerequisite of ore deposit selfreparing.Have the test specimen of mineral self-repair function after pre-destruction also self-healing, its relative dynamic elastic modulus has to be increased significantly, and in addition, the test specimen repairing effect of standard curing is better than the foster test specimen of water.Illustrate that, under mineral self-repair function, the packing of test specimen inner structure increases greatly, inherent vice reduces.

The change of relative dynamic elastic modulus reflects the change of test specimen internal injury situation.After the prepressing, there is crackle in test specimen inside, and the crystalline deposit effect of mineral carries out reparation to it makes it healing, and crack number and area reduce, and inner structure packing increases, so relative dynamic elastic modulus rises.

Claims (3)

1. a selfreparing effect evaluation method for self-repairing cement-base material, is characterized in that:

In described selfreparing effect evaluation method, evaluation index used comprises relative dynamic elastic modulus, fracture behaviour, constitutive behavior contrast and bendind rigidity response rate and intensity response rate,

Implement successively as follows:

Step 1: preparation has the test specimen of the cement-based material of repair, described test specimen is divided into A, B two test group, A group test specimen is used for the fracture behaviour of exosyndrome material, constitutive behavior and mechanical behavior, B group test specimen is used for the change of exosyndrome material internal injury situation, and the base material of described test specimen comprises cement paste, sand-cement slurry and concrete material;

Step 2: after described test specimen arrives the length of time of 28day, to the specimen prefabricated localized cracks of A group, described localized cracks is realized by the approach of cutting or preset thin slice; To the specimen prefabricated dispersion crackle of B group, described dispersion crackle is realized by prestrain, and the mode of prestrain comprises and pre-folding and precompressed, and pre-fold and realized by omnipotent servo hydraulic machine, precompressed is realized by mortar pressing machine;

Step 3: test the fragmentation parameters of A group test specimen, constitutive behavior, bendind rigidity, rupture strength and these 5 performance index of compressive strength, test b group test specimen ultrasound wave is at the initial transmission velocity of wave V of material surface _r0;

Step 4: under A, B group test specimen being all placed in the environment of concrete standard curing condition and temperature 20 ± 2 DEG C, relative humidity 95%, maintenance 1day or 3day completes selfreparing;

Step 5: to the performance index in A, B group test specimen repeated test step 3 after reparation; Namely test the fragmentation parameters of A group test specimen after selfreparing, constitutive behavior, bendind rigidity, rupture strength and these 5 performance index of compressive strength, the ultrasound wave of test b group test specimen after selfreparing is at the transmission velocity of wave V of material surface _r1;

Step 6: computing is carried out to the test data that step 3 and step 5 obtain, show that evaluation index is to evaluate repairing effect, described evaluation index comprises relative dynamic elastic modulus, fracture behaviour, constitutive behavior contrasts, bendind rigidity response rate and intensity response rate, wherein fracture behaviour comprises stress intensity factor response rate and fracture toughness response rate;

A. dynamic elastic modulus E _dcalculate by (1) formula:

$E_d=\frac{{2(1+\mathrm{\μ})}^3}{0.87+1.12\mathrm{\μ}}\mathrm{\ρ}{V}_r^2--\left(1\right),$

(1) in formula: ρ---density of solid, μ---solid Poisson ratio;

In (1) formula, get V _r=V _r0, obtain the initial dynamic elastic modulus E of B group test specimen _d0; Get V _r=V _r1, obtain the dynamic elastic modulus E after the selfreparing of B group test specimen _d1, then relative dynamic elastic modulus P calculates by (2) formula:

$P=\frac{V_{r1}^2}{V_{r0}^2}\×100\%--\left(2\right);$

B. fracture behaviour comprises stress intensity factor response rate and fracture toughness response rate:

B.1 stress intensity factor response rate η (K _i) calculate by (3) formula:

$\mathrm{\η}\left(K_I\right)=\frac{K_I\left(1\right)}{K_I\left(0\right)}\×100\%--\left(3\right);$

(3) in formula: K _i(0)---test specimen primary stress intensity factor; K _i(1)---the stress intensity factor after test specimen reparation;

(3) in formula, stress strength factor K _icalculate by (4) formula:

$K_I=\frac{P_{\mathrm{MAX}}S}{{\mathrm{BW}}^{\frac{3}{2}}}f\left(\frac{a}{W}\right)--\left(4\right);$

(4) in formula, for geometrical form factors, calculate by (5) formula:

$f\left(\frac{a}{W}\right)=\frac{3{\left(\frac{a}{W}\right)}^{\frac{1}{2}}\{1.99-\frac{a}{W}(1-\frac{a}{W})[2.15-3.93\frac{a}{W}+2.7{\left(\frac{a}{W}\right)}^2\left]\right\}}{2(1+2\frac{a}{W}){(1-\frac{a}{W})}^{\frac{3}{2}}}--\left(5\right);$

(4) and in (5) formula: P _mAX---maximum load (N), S---nominal span (mm), B---specimen thickness (mm), W---specimen width (mm), a---crack length (mm) is unit used in bracket;

B.2 fracture toughness response rate η (K _iC) calculate by (6) formula:

$\mathrm{\η}\left(K_{\mathrm{IC}}\right)=\frac{K_{\mathrm{IC}}\left(1\right)}{K_{\mathrm{IC}}\left(0\right)}\×100\%--\left(6\right);$

(6) in formula: K _iC(0)---test specimen virgin fracture toughness; K _iC(1)---the fracture toughness after test specimen reparation;

(6) in formula, fracture toughness K _iCcalculate by (7) formula:

$K_{\mathrm{IC}}=\frac{M_{\mathrm{MAX}}}{{\mathrm{BH}}^{\frac{3}{2}}}f\left(\frac{a}{H}\right)--\left(7\right);$

(7) in formula: M _mAXcalculate by (8) formula:

$M_{\mathrm{MAX}}=\frac{(P_{\mathrm{MAX}}+G)S}{4}--\left(8\right);$

(7) in formula, for geometrical form factors, calculate by (9) formula:

$f\left(\frac{a}{H}\right)=2.9{\left(\frac{a}{H}\right)}^{\frac{1}{2}}-4.6{\left(\frac{a}{H}\right)}^{\frac{3}{2}}+2.18{\left(\frac{a}{H}\right)}^{\frac{5}{2}}-37.6{\left(\frac{a}{H}\right)}^{\frac{7}{2}}+38.7{\left(\frac{a}{H}\right)}^{\frac{9}{2}}--\left(9\right);$

(7) ~ (9) in formula: P _mAX---maximum load (N), M _mAX---maximum mid span moment (Nmm), G---loading test specimen weight, B---specimen thickness (mm), H---height of specimen (mm), a---crack length (mm) is unit used in bracket;

C. constitutive behavior comprises force-displacement curve and the stress-strain curve of material:

C.1 force-displacement curve is realized by omnipotent servo hydraulic machine, and the force-displacement curve of contrast A group test specimen before and after selfreparing, to analyze the peak load rate of growth η (P of A group test specimen before and after selfreparing _mAX), maximum displacement rate of growth η (D _mAX), destructive process and destructive characteristics;

Peak load rate of growth η (P _mAX) calculate by (10) formula:

$\mathrm{\η}\left(P_{\mathrm{MAX}}\right)=\frac{P_{\mathrm{MAX}}\left(1\right)}{P_{\mathrm{MAX}}\left(0\right)}\×100\%--\left(10\right);$

In formula (10): P _mAX(0)---the peak load of test specimen original upload; P _mAX(1)---the peak load that test specimen reparation loads afterwards for the second time;

Maximum displacement rate of growth η (D _mAX) calculate by (11) formula:

$\mathrm{\η}\left(D_{\mathrm{MAX}}\right)=\frac{D_{\mathrm{MAX}}\left(1\right)}{D_{\mathrm{MAX}}\left(0\right)}\×100\%--\left(11\right);$

In formula (11): D _mAX(0)---the maximum displacement of test specimen original upload; D _mAX(1)---the maximum displacement that test specimen reparation loads afterwards for the second time;

C.2 stress-strain curve is realized by omnipotent servo hydraulic machine and foil gauge, the stress-strain curve of contrast A group test specimen before and after selfreparing, compressive deformation process before and after repairing with analysis of material, i.e. the generation of cement-based material internal fissure and the change of evolution;

C.1 with reparation c.2 before and after in test curve comparative analysis,

1) phase slope within 30% of peak value is larger, and the ability of the resistance to deformation of this test material is larger, if this phase slope of testing of materials curve after repairing obviously increases, illustrates that the ability of its resistance to deformation is improved preferably;

2) because cement-based material is hard brittle material, be difficult to the extension of test to curve descending branch, after repairing, if curve descending branch is obvious with the growth extension trend of displacement or strain, illustrate that the toughness of this material improves, fragility declines;

3) area that force-displacement curve or stress-strain curve and horizontal ordinate surround can represent the energy that material needs in destructive process to a great extent, the area surrounded is larger, the energy that material damage needs is larger, if the area that the curve after repairing and horizontal ordinate surround obviously increases, then illustrative material obtains good reparation, its usability be improved significantly.

D. bendind rigidity response rate η _pcalculate by (9) formula:

${\mathrm{\η}}_P=\frac{P}{P_0}\×100\%--\left(12\right),$

(12) in formula: P---prestrain also repairs the rear bendind rigidity calculated value with group cement slurry test specimen,

P ₀---with the bendind rigidity calculated value of group cement slurry test specimen when destroying completely;

E. intensity response rate comprises rupture strength response rate and compressive strength response rate:

E.1 rupture strength response rate η _fcalculate by (13) formula:

${\mathrm{\η}}_f=\frac{R_f}{R_{f0}}\×100\%--\left(13\right),$

(13) in formula: R _f---prestrain also repairs the rear rupture strength measured value with group cement slurry test specimen,

R _f0---with the rupture strength measured value of group cement slurry test specimen when destroying completely;

E.2 compressive strength response rate η _ccalculate by (14) formula:

${\mathrm{\η}}_c=\frac{R_c}{R_{c0}}\×100\%--\left(14\right),$

(14) in formula: R _c---precompressed also repairs the rear compressive strength determination value with group cement slurry test specimen,

R _c0---with the compressive strength determination value (MPa) of group cement slurry test specimen when destroying completely.

2. the selfreparing effect evaluation method of self-repairing cement-base material as claimed in claim 1, is characterized in that:

During step 1, the prism of the test specimen of preparation to be length × wide × height be 40mm × 40mm × 160mm, in each test group, the quantity of test specimen is no less than 9, and the test specimen quantity of the test benchmark intensity in each test group is no less than 3, and all the other test specimens are used for the pre-destruction arranged in various degree;

During step 6,

A step calculates dynamic elastic modulus E by (1) formula _dtime, μ gets 0.2, then:

$E_d=\frac{2{(1+\mathrm{\μ})}^3}{0.87+1.12\mathrm{\μ}}{\mathrm{\ρV}}_r^2=3.159\mathrm{\ρ}{V}_r^2--\left(15\right);$

Step e calculates rupture strength response rate η by (13) formula _ftime, R _fand R _f0using the arithmetic mean of three test specimen rupture strength test findings as measured value, when the difference of three test specimen rupture strength maximal values or minimum value and intermediate value exceedes 15% of intermediate value, reject this value, then the arithmetic mean getting all the other two values is as measured value; When maximal value and minimum value all exceed 15% of intermediate value, get intermediate value as measured value;

Step e calculates compressive strength response rate η by (14) formula _ctime, R _cand R _c0using the arithmetic mean of three test specimen compressive strength test results as measured value, when the difference of three test specimen compressive strength maximal values or minimum value and intermediate value exceedes 15% of intermediate value, reject this value, then the arithmetic mean getting all the other two values is as measured value; When maximal value and minimum value all exceed 15% of intermediate value, get intermediate value as measured value.

3. the selfreparing effect evaluation method of self-repairing cement-base material as claimed in claim 1 or 2, is characterized in that:

C part in step 6 c.1 with reparation c.2 before and after in test curve comparative analysis:

1) if this phase slope of testing of materials curve after repairing increase to former slope 120% and above time, then think that this phase slope obviously increases;

2) if curve descending branch with the growth of displacement or strain extend trend extend to original 120% and above time, then think that to increase extension trend obvious;

3) if the area that curve and horizontal ordinate after repairing surround obviously increase to original area 130% and above time, then think that area obviously increases.