CN1987458B - Method for detecting anti-cracking performance of airport cement concrete road surface - Google Patents

Abstract

The testing method first prepares test piece: paving test piece of concrete inside die; using flat-plate vibrator to vibrate admixed materials of concrete; using bar beater to vibrate it to and back; then, leveling slurry on surface of test piece, and using steel spatula to finish operation. Test piece is placed to test box. Crack number, width, and length on concrete plate are observed, and crack reduction coefficient (CRC) is calculated. Finally, crack resistance grades in early stage of fiber mortar and fiber concrete are evaluated according to mean value of CRC in two stages of test. The invention can simulate states of cement concrete road surface under each condition such as different temperatures, different wind speeds and directions etc. In orthogonal test of crack resistance for two fibers in multiple levels and multiple factors, effect of crack test is obvious. Conclusion is identical between this method and standard test of cement mortar crack resistance.

Description

Method for detecting anti-cracking performance of airport cement concrete road surface

Technical field

The present invention relates to a kind of cement concrete performance method of inspection, particularly a kind of method for detecting anti-cracking performance of airport cement concrete road surface that is applicable to the anti-early-age shrinkage of cement concrete road surface crack shop experiment.

Background technology

Various countries are incomplete same to the test method in concrete early-age shrinkage crack at present, the test method of also not seeking unity of standard.Each class methods all is qualitative tests, promptly concrete is being retrained, testing under the situation in simulated environment, most probable amplification is carried out in concrete crack, relatively mix and do not mix the influence of fiber by such test to concrete, the early stage cracking resistance of mortar, effect is split in the resistance of analyzing variety classes, different geometric properties fibers, determines the reasonable volume of fiber.China in " the fiber concrete structure technology rules " of promulgation in 2004 (CECS38:2004) in the steel planar sheet of regulation employing 600mm * 600mm * 63mm.On each limit of mould two rows of welding (or fix with double nut) simultaneously totally 14 φ 10 * 100mm bolts (screw thread is elongated) to stretch to ground tackle inboard as constraint.After 2 hours, directly blow test specimen surface with variable speed fan in the concrete formation health, wind direction is parallel to the test specimen surface, wind speed 0.5m/s, and test ambient temperature should be 20 ℃ ± 2 ℃, and relative humidity is not more than 60%.Began to observe crack quantity, width and length after the moulding in 24 hours.Reduce coefficient as evaluation criteria with the crack.

Also the concrete cracking resistance method of inspection is not made stipulations in a series of designs of my Jun Chang road engineering, the job specifications.The designer generally with the cracking property test and testing method among " fiber concrete structure technology rules " (CECS 38:2004) appendix D as the design, test basis.But in the concrete practice process of my army's airport engineering, find that there is certain limitation in this kind method.Be embodied in:

1, " fiber concrete structure technology rules " (CECS38:2004) emphasis difference.This standard has mainly been considered the project quality inspection of upper flow regime, big cement consumption, and water cement ratio is low in the road surface concrete engineering, cement consumption is little, belongs to dry concrete.

2, " fiber concrete structure technology rules " test mould in (CECS38:2004) is not suitable for face engineering concrete.The particle diameter of aggregate mainly is based on 20mm～30mm specification in general covil construction, and that the maximum particle diameter in the road face engineering has reached 40mm is big.So the road surface concrete is difficult to build in this kind mould the inside, vibrates, health and observation.

3, " fiber concrete structure technology rules " (CECS38:2004) test in wind speed, environment temperature and engineering practice can not well coincide.Be subjected to effect of natural conditions less when house, high-building construction.And the airport concrete works belongs to large-area construction, and the actual state of road surface concrete is subjected to effect of natural conditions big.And the wind speed of " fiber concrete structure technology rules ", temperature regulation is lower, therefore can not finely reflect cracking resistance.

Owing to there is above-mentioned defective, if road face coagulating cement cracking resistance soil is tested according to the method that " fiber concrete structure technology rules " (CECS 38:2004) provides, vibrate difficulty, face is not easy to do, the surface slurry is less, the crack can not occur, and also just can't carry out the early stage cracking resistance test of face.

Summary of the invention

The objective of the invention is deficiency at the prior art existence, provide a kind of can be comprehensively, accurate simulated field natural conditions, can the fine method for detecting anti-cracking performance of airport cement concrete road surface that reflects the fiber concrete cracking resistance, thus experiment work quality and result's reliability guaranteed.

Technical scheme of the present invention is: a kind of method for detecting anti-cracking performance of airport cement concrete road surface is characterized in that this method may further comprise the steps;

(1) concrete sample is paved in mould, undertaken by the order in edges of boards, Ban Jiao and the plate of mould when paving;

(2) with flat-plate vibrator concrete mix is vibrated after concrete sample is built, answer pointwise to vibrate when vibrating, Da Shi sinks in the concrete mix, carries out in proper order line by line after the surperficial bleeding again, each displacement should be overlapping in length and breadth, and roughly levelling is carried out on the test specimen surface;

(3) ram round vibration 2 times with bar, should ram by slowly even mobile bar, drive concrete slab surface residual bubble out of, make the further bleeding in concrete slab surface, as concavo-convex phenomenon occurs, levelling in time; When filling up, select the more concrete mixture of gravelstone for use, forbid to use full mortar;

(4) the vibrate back that finishes is carried out levelling with scraping steel to the surperficial slurry of concrete sample;

(5) smear with plastics after the levelling or wood is smeared further to carry slurry and press down gravelstone and made face, be advisable with 1～2 time;

(6) smear the receipts face with steel;

(7) wipe one's face after operation finishes, should in time clear up the mucilage of template end face, and be put on the indentation that template edge marks together dark about 5mm with steel;

(8) test specimen cast, jolt ramming and floating after immediately test specimen is placed chamber, under the effect of heat lamp, surface temperature of concrete is controlled at 45 ℃ ± 3 ℃, and directly blow the test specimen surface with variable speed fan, wind direction is parallel to the test specimen surface, wind speed 5m/s, shine and close heat lamp after 4 hours, continuation is directly blown the test specimen surface with variable speed fan, test ambient temperature should be 25 ℃ ± 2 ℃ this moment, relative humidity is not more than 60%, begins to observe crack quantity, width and the length of concrete slab after the moulding in 16 hours;

(9) fracture length is as the criterion with the naked eyes visible crack, measures its length with steel ruler, and being similar to and getting two ends, crack air line distance is fracture length, when obviously bending appears in the crack, represents fracture length with broken line length sum; Measure fracture width with reading microscope, get near the fracture width of crack mid point and represent this fracture width;

(10) calculate the crack total area by following formula:

$A_{\mathrm{cr}}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ω}}_{i,\max }{l}_i$

In the formula, A _Cr-test specimen crack name the total area, mm ²Be designated as A for the fiber concrete test specimen _Fcr, contrast is designated as A with the benchmark test specimen _Mcr

ω _{I, max}-Di i bar crack name fracture width is got near the fracture width of this crack mid point, mm;

l _i-Di i bar crack length, mm;

Calculate the crack by following regulation and reduce coefficient η:

$\mathrm{\η}=\frac{A_{\mathrm{mcr}}-A_{\mathrm{fcr}}}{A_{\mathrm{mcr}}}$

Evaluate fibre mortar and fiber concrete cracking resistance grade in length of time morning by the mean value of two-stage test η at last.

The present invention compared with prior art has the following advantages: the present invention is owing to increased irradiation in chamber, devices such as variable speed fan, new mould has strengthened concrete restraint device, therefore can simulate cement concrete road surface different temperatures under solar radiation, different wind speed, state during wind direction, in to two kinds of multilevel multifactorial cracking resistance orthogonal tests of fiber, test cracking effect is obvious, in analysis to two kinds of fibre crack-resistance performances, the best fiber species that draws, length, the every index of volume and sand-cement slurry cracking resistance test (" fiber concrete structure technology rules " (CECS38:2004)) gained conclusion is identical.

Description of drawings

Fig. 1 is the structural representation of chamber 2 among the present invention.

Fig. 2 is the vertical view of mould 1 among the present invention.

Fig. 3 is the A-A cutaway view Amplified image of Fig. 2.

Embodiment

The invention will be further described below in conjunction with accompanying drawing.

As shown in Figure 1, the chamber of using among the present invention 2 comprises casing 2-1, the top that is positioned at casing 2-1 is provided with heating arrangement 2-2 and heat sink 2-3, a side side that is positioned at casing 2-1 is provided with variable speed fan 2-4, and the casing 2-1 of a relative side with variable speed fan 2-4 is provided with window shutter 2-5; Described heat sink 2-3 is connected with compressor 3, and described compressor 3, heating arrangement 2-2, heat sink 2-3 and variable speed fan 2-4 are electrically connected with control enclosure 2-7 by lead, and control enclosure 2-7 is arranged on the lateral wall of casing 2-1.The base plate that is positioned at casing 2-1 is provided with cushion block 2-6, and mould 1 is placed on the cushion block 2-6; Described heating arrangement 2-2 is a heat lamp, and heat sink 2-3 is a condenser pipe; Described base plate 1-1 is steel plate or composite plate, and side plate 1-2 is the section bar channel-section steel.

As shown in Figures 2 and 3, the mould 1 that uses among the present invention comprises base plate 1-1 and side plate 1-2, fixedly connected by bolt 1-6 between adjacent biside plate 1-2 and side plate 1-2 and the base plate 1-1, the inboard that is positioned at side plate 1-2 is provided with linear pull bar 1-4 perpendicular to side plate 1-2, and the inboard that is positioned at adjacent biside plate 1-2 junction is provided with Shape pull bar 1-3, The two ends of shape pull bar 1-3 are separately fixed on described two adjacent side plate 1-2, and base plate 1-1 adopts to be not less than the thick steel plate of 5mm or to be not less than the thick composite plate of 20mm and makes, and the upper surface of base plate 1-1 is equipped with polyethylene film separation layer 1-5.

The present invention includes following steps;

(1) concrete sample is paved in mould 1, undertaken by the order in edges of boards, Ban Jiao and the plate of mould 1 when paving;

(2) to build the back be that the flat-plate vibrator of 250W vibrates to concrete mix with power to concrete sample, answer pointwise to vibrate when vibrating, Da Shi sinks in the concrete mix, carries out in proper order line by line after the surperficial bleeding again, each displacement should be overlapping in length and breadth, and roughly levelling is carried out on the test specimen surface;

(3) ram round vibration 2 times with power 250W bar, should ram by slowly even mobile bar, drive concrete slab surface residual bubble out of, make the further bleeding in concrete slab surface, as concavo-convex phenomenon occurs, levelling in time; When filling up, select the more concrete mixture of gravelstone for use, forbid to use full mortar; Bar rams thick with 3～5cm, and the bottom surface is that the timber of 14cm * 80cm is made, and iron sheet should be wrapped up in its bottom surface;

(4) the vibrate back that finishes is carried out levelling with scraping steel to the surperficial slurry of concrete sample;

(5) smear with plastics after the levelling or wood is smeared further to carry slurry and press down gravelstone and made face, be advisable with 1～2 time;

(6) smear the receipts face with steel;

(7) wipe one's face after operation finishes, should in time clear up the mucilage of template end face, and be put on the indentation that template edge marks together dark about 5mm with steel;

(8) test specimen cast, jolt ramming and floating after immediately test specimen is placed chamber 2, under the effect of heat lamp 2-2, surface temperature of concrete is controlled at 45 ℃ ± 3 ℃, and directly blow the test specimen surface with variable speed fan 2-4, wind direction is parallel to the test specimen surface, wind speed 5m/s, shine and close heat lamp after 4 hours, continue directly to blow the test specimen surface with variable speed fan 2-4, test ambient temperature should be 25 ℃ ± 2 ℃ this moment, relative humidity is not more than 60%, begins to observe crack quantity, width and the length of concrete slab after the moulding in 16 hours;

(9) fracture length is as the criterion with the naked eyes visible crack, measures its length with steel ruler, and being similar to and getting two ends, crack air line distance is fracture length, when obviously bending appears in the crack, represents fracture length with broken line length sum; With scale division value is the reading microscope measurement fracture width of 0.01mm, gets near the fracture width of crack mid point and represents this fracture width;

(10) calculate the crack total area by following formula:

$A_{\mathrm{cr}}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ω}}_{i,\max }{l}_i$

In the formula, A _Cr-test specimen crack name the total area, mm ²Be designated as A for the fiber concrete test specimen _Fcr, contrast is designated as A with the benchmark test specimen _Mcr

ω _{I, max}-Di i bar crack name fracture width is got near the fracture width of this crack mid point, mm;

l _i-Di i bar crack length, mm;

Calculate the crack by following regulation and reduce coefficient η:

$\mathrm{\η}=\frac{A_{\mathrm{mcr}}-A_{\mathrm{fcr}}}{A_{\mathrm{mcr}}}.$

Early the length of time, the cracking resistance grade can be evaluated according to following table by the mean value that two-stage is tested η for fibre mortar, fiber concrete.

Limit is split performance ratings	Evaluation criteria
		One-level	η≥70
Secondary	55≤η＜70
		Three grades	40≤η＜55

Claims (1)

1. a method for detecting anti-cracking performance of airport cement concrete road surface is characterized in that this method may further comprise the steps;

(1) concrete sample is paved in mould, undertaken by the order in edges of boards, Ban Jiao and the plate of mould when paving; Mould comprises base plate and side plate, is bolted to connection between adjacent biside plate and side plate and the base plate, and the inboard that is positioned at side plate is provided with the linear pull bar perpendicular to side plate, the inboard that is positioned at adjacent biside plate junction be provided with "

" the shape pull bar, " " two ends of shape pull bar are separately fixed on described two blocks of adjacent side plates, base plate adopts to be not less than the thick steel plate of 5mm or to be not less than the thick composite plate of 20mm and makes, and the upper surface of base plate is equipped with the polyethylene film separation layer;

(2) with flat-plate vibrator concrete mix is vibrated after concrete sample is built, answer pointwise to vibrate when vibrating, Da Shi sinks in the concrete mix, carries out in proper order line by line after the surperficial bleeding again, each displacement should be overlapping in length and breadth, and roughly levelling is carried out on the test specimen surface;

(3) ram round vibration 2 times with bar, should ram by slowly even mobile bar, drive concrete slab surface residual bubble out of, make the further bleeding in concrete slab surface, concavo-convex phenomenon occurs, levelling in time; When filling up, select the more concrete mixture of gravelstone for use, forbid to use full mortar;

(4) the vibrate back that finishes is carried out levelling with scraping steel to the surperficial slurry of concrete sample;

(5) smear with plastics after the levelling or wood is smeared further to carry slurry and press down gravelstone and made face, be advisable with 1～2 time;

(6) smear the receipts face with steel;

(7) wipe one's face after operation finishes, should in time clear up the mucilage of template end face, and be put on the indentation that template edge marks together dark 5mm with steel;

(8) test specimen cast, jolt ramming and floating after immediately test specimen is placed chamber, under the effect of heat lamp, surface temperature of concrete is controlled at 45 ℃ ± 3 ℃, and directly blow the test specimen surface with variable speed fan, wind direction is parallel to the test specimen surface, wind speed 5m/s, shine and close heat lamp after 4 hours, continuation is directly blown the test specimen surface with variable speed fan, test ambient temperature should be 25 ℃ ± 2 ℃ this moment, relative humidity is not more than 60%, begins to observe crack quantity, width and the length of concrete slab after the moulding in 16 hours; Described chamber comprises casing, the top that is positioned at casing is provided with heating arrangement and heat sink, a side side that is positioned at casing is provided with variable speed fan, the casing of a relative side with variable speed fan is provided with window shutter, described heat sink is connected with compressor, described compressor, heating arrangement, heat sink and variable speed fan are electrically connected with control enclosure by lead, control enclosure is arranged on the lateral wall of casing, the base plate that is positioned at casing is provided with cushion block, mould is placed on the cushion block, and described heating arrangement is a heat lamp, and heat sink is a condenser pipe, described base plate is steel plate or composite plate, and side plate is the section bar channel-section steel;

(9) fracture length is as the criterion with the naked eyes visible crack, measures its length with steel ruler, and being similar to and getting two ends, crack air line distance is fracture length, when obviously bending appears in the crack, represents fracture length with broken line length sum; Measure fracture width with reading microscope, get near the fracture width of crack mid point and represent this fracture width;

(10) calculate the crack total area by following formula:

$A_{\mathrm{cr}}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ω}}_{i,\max }{l}_i$

In the formula, A _Cr-test specimen crack name the total area, mm ²Be designated as A for the fiber concrete test specimen _Fcr, contrast is designated as A with the benchmark test specimen _Mcr

ω _{I, max}-Di i bar crack name fracture width is got near the fracture width of this crack mid point, mm; l _i-Di i bar crack length, mm;

Calculate the crack by following regulation and reduce coefficient η:

$\mathrm{\η}=\frac{A_{\mathrm{mcr}}-A_{\mathrm{fcr}}}{A_{\mathrm{mcr}}}$

Evaluate fibre mortar and fiber concrete cracking resistance grade in length of time morning by the mean value of two-stage test η at last.

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