CN1285508A - In-situ testing contrete compression strength by micro core sample method - Google Patents
In-situ testing contrete compression strength by micro core sample method Download PDFInfo
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- CN1285508A CN1285508A CN 99111665 CN99111665A CN1285508A CN 1285508 A CN1285508 A CN 1285508A CN 99111665 CN99111665 CN 99111665 CN 99111665 A CN99111665 A CN 99111665A CN 1285508 A CN1285508 A CN 1285508A
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Abstract
The method for site detecting compressive strength of concrete includes the following steps: at position to be detected setting 1-3 detection zones, at every detection zone using coring machine to drill out 10 microminiature concrete core samples with diameter of 15-30 mm, using planing machine to make core sample into cylindrical sample with height-diameter ratio of 1.0-2.0, according to mean-value of compressive strengths of test samples of every detection zone using the multiple relationships of Fcu.j=A+B(fcor.j).+C(fcor.j).2, etc. to obtain the reprosentive value fcu of standard compressive strength of concrete of measured position. Said invention uses microminiature core sample, does not affect structure strength of concrete, and is simple, easy to implement, and its data is reliable.
Description
The present invention relates to a kind of on-the-spot method that the direct compressive strength of the concrete of cast-in-place and prefabricated components is detected that is applicable to.Be specially adapted to the modern high-strength high-performance concrete of detected intensity scope at 30MPa-100MPa, this concrete is because water-cement ratio is lower, and structure is closely knit, and homogenieity is relatively good, and used maximum aggregate size generally is not more than 31.5mm.
Concrete is a kind of important building structural materials, at building operation and buildings between the operating period, the concrete actual strength is most important to the safety of fabric structure, thereby at the scene actual concrete structural strength is detected for the actual strength of understanding xoncrete structure very necessary, especially to concrete quality when with suspicion.At present, on-the-spot directly detection concrete crushing strength mainly contains and gets core method and pulling out method.The minimum core diameter of getting the core law regulation is 70mm, generally require more than the 100mm, this method is because the core size is very big, drill through difficulty, need in advance corning machine to be fixed on the xoncrete structure with expansion bolt, the core test specimen need cut and polish, the processing more complicated, and because bore diameter and the degree of depth are big, big to the structural strength infringement, thus priority project, thin-wall construction, reinforcing bar close packed structure etc. all inconvenience detect in this way; In addition, this method testing result is discrete big, and data are few, poor accuracy; And this detection method is directly to represent concrete structural strength with big core test specimen intensity level, can't be corresponding relatively with the general intensity index of The Concrete Structure Design and Construction control.And pulling out method is not because complicated operation and data accuracy are fine, thereby uses seldom yet.
The purpose of this invention is to provide a kind of in-situ testing contrete compression strength by micro core sample method, this method sampling is small, does not influence concrete structural strength substantially, and simple, data are reliable, and are easy to utilize.
For achieving the above object, the present invention takes following design proposal: this in-situ testing contrete compression strength by micro core sample method mainly comprises following step:
(1) delimit the survey district: delimit 1-3 at position that concrete is surveyed and survey the district;
(2) core boring sampling: diverse location drills through 10 of effective small cores with small-sized corning machine, core normal diameter (d) 15-30mm, 1-2 times of d of core height (h) in each surveys the district;
(3) processing test specimen: with small-sized Plane surface grinding machine the core section that drills through is processed, made section smooth, and make section and axis normal;
(4) compression test: will process qualified core test specimen and be placed on the usual pressure testing machine, and measure test specimen limit breaking pressure, the compressive strength of calculation testing piece by standard test method;
(5) calculate the concrete crushing strength typical value: obtain each earlier and survey district's core test specimen compressive strength mean value, with the small core mean compressive strength of small core compressive strength mean value substitution of trying to achieve and the relational expression of concrete standard pressure resistance virtue, calculate each and survey district's concrete standard compressive strength scaled value, the concrete standard compressive strength scaled value of difference being surveyed the district asks average again, obtain the position concrete standard compressive strength typical value of surveying, described relational expression can be parabolic relation f
Cu.j=A+B (f
Cor.j)
m+ C (f
Cor.j)
m 2
A=-3.0 in the formula ± 5.0; B=1.61 ± 5.00; C=-0.005 ± 0.01,
It also can be linear relation; f
Cu.j=A '+B ' (f
Cor.j)
m,
In the formula, A '=16.37 ± 5; B '=0.95 ± 0.2;
Or logarithmic relationship,
f
cu.j=A″+B″ln(f
cor.j)
m，
In the formula, A "=-153.82 ± 20; B "=56.49 ± 10;
Or power function relationship,
f
cu.j=A_，(f
cor.j)
m B_，
In the formula, A_=2.63 ± 0.5; B_=0.82 ± 0.2
Wherein: (f
Corj)
m: survey core mean compressive strength value in the district
f
Cuj: concrete standard compressive strength scaled value
A, A ', A ", A ", B, B ', B ", B " and C are regression coefficient.
Invalid core is meant among the present invention: the big stone that runs through whole core section is arranged in the core that 1. drills through, and 2. there are open defects such as obvious crack or hole nest on the core surface, and 3. the core size is undesirable.
Each small core test specimen compressive strength is calculated as follows:
f
cor.i=4F
i/πd
i 2
Wherein: F
i: the failing load of surveying i small core compression test in the district
f
Cor.i: the compression strength value of surveying i small core in the district
d
i: the mean diameter of surveying i small core in the district
Surveying the small core test specimen mean compressive strength computing method in district is:
Remove maximal value and minimum value, get the arithmetic mean value of 8 test specimen compressive strength of residue:
(f
cor.j)
m=(∑f
cor.i-f
cor.max-f
cor.min)/8
A, B, definite method of coefficient values such as C is the bit size of earlier selected corning machine: get representative concrete proportioning some (quantity is determined to satisfy regional used concrete representativeness and regretional analysis requirement), to each proportioning, at indoor 6 of cube specimens mixing system 150mm * 150mm * 150mm, mark was supported to 28 days respectively, with three test specimen testing standard compressive strength wherein, three are used to drill through 10 effective small cores in addition, test the compressive strength of small core test specimen, then the standard compression strength value and the core mean compressive strength value of different proportioning concrete test blocks are carried out regretional analysis, obtain A, B, coefficient values such as C require the related coefficient should be more than 95%.
The position of surveying can only be delimited one and survey when distinguishing, and then get and survey district's concrete standard compressive strength scaled value by being surveyed position concrete standard compressive strength typical value; If the position of surveying can only be delimited two and survey the district, distinguish the mean values of concrete standard compressive strength scaled values by being surveyed position concrete standard compressive strength typical value with two surveys, ask mean time at the standard compressive strength scaled value of surveying the district to three, at first relatively survey the differences of distinguishing strength values for three, the rate that requires maximal value wherein or minimum value and intermediate value is less than 15%, otherwise gets three intermediate values in the numerical value by being surveyed part standard compressive strength typical value.
Among the present invention, the survey district arranges and bore core point position should avoid reinforcing bar as far as possible, can determine reinforcement location in the concrete by the reinforcement location detection instrument in case of necessity.The present invention should be used for the above concrete of C30, and less than C30, relatively large to the degree of injury of small core sample test specimen because of getting in core and the core process, the concrete standard compressive strength discreteness that converses thus is big, poor accuracy as if strength grade of concrete; In addition, detect the concrete of coarse aggregate size greater than 31.5mm with small core method, it is low that effective core is prepared into power, and compressive strength result is discrete big, thereby inapplicable.
During core boring sampling, certain angle tilts corning machine earlier, be drilled to a crescent at concrete surface, recover vertical pressurization more gradually, after waiting to get into predetermined depth, keeping rig to be rotated further under the situation, carefully drill bit is risen to concrete surface, cut off the water then, have a power failure, gently knock core with thin ironware, it is fractureed from the bottom, take out small core then.
Test specimen adds man-hour, with Plane surface grinding machine the core two ends are polished, polishing the qualified core test specimen that obtains should reach: the deviation of core test specimen mean diameter and nominal diameter is not more than 0.4mm, the maximum control deviation of the height of core test specimen is 0.05d, the irregularity degree of section is no more than 0.02mm, the non-perpendicularity of test specimen section and axis is no more than 2 °, and the surface exposed aggregate area of test specimen maximum ratio is not more than 20%.
During the test specimen compression test, the humidity of test specimen and the actual humidity of detected concrete are wanted basically identical, test specimen is accurately placed bearing plate center under the pressing machine, load equably continuously, loading speed is 160-250N/S, and concrete test method is undertaken by regulation in the national standard (normal concrete mechanical test method).
The device therefor of mentioning among the present invention all can be bought small core corning machine from market can adopt rock drill, only needs to change bit size, and same Plane surface grinding machine also can use existing device.
Advantage of the present invention: 1., compare, be easy to especially structurally drill through with existing big core core drilling method because small core diameter is very little, and very little to the infringement of structural strength; The core processing of 2. small core method also is easy to, and without sawing, can directly polish with Plane surface grinding machine, and easy being easy to of whole process operation grasped.3. small core method directly drills through test specimen and carries out the resistance to compression detection from xoncrete structure, can directly reflect concrete actual strength situation, has kept the advantage that big core is got the direct detected intensity of core method.4. small core method detects concrete strength because sampling amount is more relatively, and is representative strong, and the compressive strength discreteness of small core test specimen is also less than big core test specimen, thereby the accuracy of testing result is good, puts letter fiduciary level height.5. small core method is utilized pre-determined relational expression conversion concrete standard compression strength value, unite with concrete works design strength and delivery receiving acceptance intensity, promptly all be corresponding 150 * 150 * 150mm cube standard compressive strength, thereby have good comparability, be convenient to quality inspection and use.
The invention will be further described below in conjunction with embodiment:
Embodiment:
Selecting corning machine physical dimension for use is 350mm * 150mm * 90mm, drill bit internal diameter 19mm, external diameter 24mm, length 150mm, rotating speed 2010r/min.Control core test specimen diameter 19.0+0.04mm, core test specimen height 28.5 ± 1.0mm.
In the Beijing area, it is some to get representational different cement, sand, stone, admixture, additive, by 75 of different starting material, different mixture ratio design different intensity grades concrete proportionings, keep somewhere at least six of 150 * 150 * 150mm cube specimens respectively, mark is supported to 28d, by wherein three record the concrete standard compressive strength of this proportioning f
Cu, on other three groups of test specimens, drill through 10 effective small cores at random, measure core compressive strength mean value (f
Cor.j)
m, with the concrete f of different proportionings
CuWith (f
Cor.j)
mRelational expression returns parabolically, calculates A, B, the C coefficient value is respectively-3.07,1.61 and-0.005, and regression correlation coefficient r is 98.8%, greater than 95%, thus f
Cu, jWith (f
Cor, j)
mReduction formula be defined as:
f
cu，j=-3.07+1.61×(f
cor，j)
m-0.005(f
cor，j)
m 2????(1)
For easy to use, also formula 1 can be made corresponding chart (see figure 1), promptly according to (f
Cor.j)
mValue can directly be found f from chart
Cu.jValue.
Detect and use I. the concrete mix of design concrete C80 strength grade, get with the mark that coils the system of mixing and support six of 28d cube compressed concrete test blocks, test block size 200mm * 200mm * 200mm, three survey districts are done in choosing wherein three identical casting areas of three, after each survey district drills through 10 effective small cores respectively with above-mentioned small hand-held corning machine, is processed into qualified test specimen, measure small core compression strength value on 10 tonnage universal testing machines respectively, test result sees Table 1: table 1
| The sample numbering | ????1 | ????2 | ????3 | ????4 | ????5 | ????6 | ????7 | ????8 | ????9 | ????10 | Mean value (MPa) |
| District 1 | ??82.4 | ??70.1 | ??99.0 | ??126.2 | ??73.8 | ??117.9 | ??114.6 | ??83.6 | ??95.3 | ??89.7 | ??94.5 |
| District 2 | ??129.8 | ??85.6 | ??88.4 | ??60.8 | ??110.0 | ??78.3 | ??98.2 | ??68.9 | ??96.6 | ??120.5 | ??93.3 |
| District 3 | ??66.7 | ??86.8 | ??71.1 | ??92.3 | ??112.1 | ??112.9 | ??120.6 | ??98.4 | ??85.8 | ??75.9 | ??91.9 |
Calculating the concrete standard compressive strength scaled value of surveying district 1, survey district 2, survey district 3 by (1) formula is respectively:
f
cu1=-3.07+1.61×94.5-0.005×94.5
2=104.4
f
cu2=-3.07+1.61×93.3-0.005×93.3
2=103.6
f
cu3=-3.07+1.61×91.9-0.005×91．9
2=102.7
Because maximal value f
Cu1With minimum value f
Cu3With intermediate value f
Cu2The ratio that differs all surpass 15%, so, this tray concrete standard compressive strength typical value f
Cu0For:
f
cu0=(f
cu1+f
cu2+f
cu3)/3=(104.4+103.6+102.7)/3=103.6(MPa)
Other three test cubes are directly made compression test on 300 tons of pressing machinees, record the actual standard compressive strength f of this tray concrete
CuBe 99.8MPa, relative error is 3.8%, meets requirement of engineering precision.
Detect and use II. get the concrete square column of constructing 2 years, the former design strength grade of concrete is C40, square column length of side 1000mm, height 2000mm.Along the square column short transverse, three of equidistant placement are surveyed district's (as far as possible avoiding reinforcing bar) near center line; Each is surveyed the district and is of a size of 200mm * 200mm; Survey the district with above-mentioned small hand-held corning machine at each and drill through 10 effective small cores respectively, and be processed into qualified small core resistance to compression test specimen.Measure the compressive strength of each test specimen, the results are shown in Table 2: table 2
| The core numbering | ????1 | ????2 | ????3 | ????4 | ????5 | ????6 | ????7 | ????8 | ????9 | ????10 | Mean value (MPa) |
| Survey district's I | ??30.8 | ??34.3 | ??37.0 | ??38.1 | ??40.6 | ??32.9 | ??25.4 | ??35.6 | ??47.8 | ??44.9 | ????36.8 |
| Survey district's II | ??30.6 | ??43.6 | ??31.5 | ??29.8 | ??33.6 | ??37.0 | ??32.1 | ??35.7 | ??23.7 | ??54.1 | ????34.2 |
| Survey district's III | ??33.4 | ??32.8 | ??33.2 | ??36.6 | ??32.8 | ??34.7 | ??65.7 | ??36.9 | ??35.0 | ??21.9 | ????34.4 |
Calculating three concrete standard compressive strength scaled values of surveying the district by (1) formula is:
f
cu1=-3.07+1.61×36.8-0.005×36.8
2=49.4
f
cu2=-3.07+1.61×34.2-0.005×34.2
2=46.1
f
cu3=-3.07+1.61×34.4-0.005×34.4
2=46.4
Because maximal value f
Cu1With minimum value f
Cu2With intermediate value f
Cu3The ratio that differs all surpass 15%, so, this tray concrete standard compressive strength typical value f
Cu0For:
f
cu0=(f
cu1+f
cu2+f
cu3)/3=(49.4+46.1+46.4)/3=47.3(MPa)
Claims (6)
1, a kind of in-situ testing contrete compression strength by micro core sample method, it is characterized in that: it may further comprise the steps:
(1) delimit the survey district: delimit 1-3 at position that concrete is surveyed and survey the district:
(2) core boring sampling: diverse location drills through 10 of effective small cores with small-sized corning machine in each surveys the district, core normal diameter d 15-30mm, and 1-2 times of d of core height h:
(3) processing test specimen: with small-sized Plane surface grinding machine the core section that drills through is processed, made section smooth, and make section and axis normal:
(4) compression test: will process qualified core test specimen and be placed on the usual pressure testing machine, and measure test specimen limit breaking pressure by standard test method, the compressive strength of calculation testing piece:
(5) calculate the concrete crushing strength typical value: obtain each earlier and survey district's core test specimen compressive strength mean value, with the small core mean compressive strength of small core compressive strength mean value substitution of trying to achieve and the relational expression of concrete standard compressive strength, calculate each and survey district's concrete standard compressive strength scaled value, the concrete standard compressive strength scaled value of difference being surveyed the district asks average again, obtain the position concrete standard compressive strength typical value of surveying, described relational expression can be parabolic relation f
Cu.j=A+B (
Fcor.j)
m+ C (f
Cor.j)
m 2
A=-3.0 in the formula ± 5.0; B=1.61 ± 5.00:C=-0.005 ± 0.01,
It also can be linear relation; f
Cu.j=A '+B ' (f
Cor.j)
m,
In the formula, A '=16.37 ± 5:B '=0.95 ± 0.2;
Or logarithmic relationship,
f
cu.j=A″+B″ln(f
cor.j)
m，
In the formula, A "=-153.82 ± 20; B "=56.49 ± 10:
Or power function relationship,
f
cu.j=A_(f
cor.j)
m B_，
In the formula, A_=2.63 ± 0.5:B_=0.82 ± 0.2
Wherein: (f
Corj)
m: survey core mean compressive strength value in the district
f
Cuj: concrete standard compressive strength scaled value
A, A ', A ", A _, B, B ', B ", B_ and C are regression coefficient.
2. in-situ testing contrete compression strength by micro core sample method according to claim 1 is characterized in that: the diameter d of small core is 19mm, and the core ratio of height to diameter is 1.5, relational expression f
Cu.j=A+B (f
Cor.j)
m+ C (f
Cor.j)
m 2In A be-3.07, B is 1.61, C is-0.005.
3. in-situ testing contrete compression strength by micro core sample method according to claim 1 and 2, it is characterized in that: the qualified test specimen in processing back should satisfy diameter deviation less than 0.4mm, height tolerance is less than 0.05d, test specimen end face irregularity degree is no more than 0.02mm, the non-perpendicularity of end face and axis is no more than 2 °, the maximum ratio of the surface exposed aggregate of test specimen is not more than 20%, the mean compressive strength of described test specimen is the maximal value with 10 core compression strength values, minimum value is removed, and calculates the arithmetic mean of 8 core test specimen compression strength values of residue and surveys the small core test specimen mean compressive strength in district as this.
4. in-situ testing contrete compression strength by micro core sample method according to claim 1 and 2, it is characterized in that: the position of surveying can only be delimited one and survey when distinguishing, and then get this survey district concrete standard compressive strength scaled value by being surveyed position concrete standard compressive strength typical value;
5. be characterised in that according to claim 1 or 2 described in-situ testing contrete compression strength by micro core sample method: the position of surveying can only be delimited two and survey the district, then get two survey district's concrete standard compressive strength scaled values by the typical value of the concrete standard compressive strength in survey position.
6. in-situ testing contrete compression strength by micro core sample method according to claim 1 and 2, it is characterized in that: ask mean time at the standard compressive strength scaled value of surveying the district to three, at first relatively survey the differences of distinguishing strength values for three, the rate that requires maximal value wherein or minimum value and intermediate value is less than 15%, otherwise gets three intermediate values in the numerical value by being surveyed part standard compressive strength typical value.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101551380A (en) * | 2009-05-01 | 2009-10-07 | 徐州建筑职业技术学院 | Method for estimating concrete strength of thin-walled structure by using small core sample strength |
| CN102426143A (en) * | 2011-09-22 | 2012-04-25 | 中国建筑科学研究院 | Method and device for detecting compressive strength of concrete by shearing resistance method |
| CN102721617A (en) * | 2012-07-11 | 2012-10-10 | 深圳中建院建筑科技有限公司 | Method for detecting concrete compression strength by using single shear method |
| CN104132842A (en) * | 2014-06-30 | 2014-11-05 | 安徽省建筑科学研究设计院 | Square pile body concrete total cross section intensity examination method |
| CN104515704A (en) * | 2014-12-26 | 2015-04-15 | 北京市道路工程质量监督站 | Test method for semi-rigid base core sample compressive strength |
| CN104964874A (en) * | 2015-05-26 | 2015-10-07 | 宿州学院 | Pit sand concrete compressive strength detection method and apparatus thereof |
| CN105699116A (en) * | 2016-01-22 | 2016-06-22 | 中国长江三峡集团公司 | Concrete dam coring method |
| CN110726585A (en) * | 2019-11-26 | 2020-01-24 | 上海市建筑科学研究院有限公司 | On-site micro-loss sampling detection method for block strength of masonry structure |
| CN110823704A (en) * | 2019-10-15 | 2020-02-21 | 山东大学 | TBM-carried rock slag online compressive strength testing system and method |
| CN111077065A (en) * | 2019-12-30 | 2020-04-28 | 广东交科检测有限公司 | Method for measuring damaged depth of concrete after high temperature through grouped compression resistance of core samples |
| CN111157343A (en) * | 2020-03-02 | 2020-05-15 | 河北省建筑科学研究院有限公司 | Method for measuring compressive strength of grouting material core sample |
| CN111896546A (en) * | 2020-07-02 | 2020-11-06 | 上海市建筑科学研究院有限公司 | New and old concrete joint surface quality detection method based on drilling and core drilling sampling |
| CN112033810A (en) * | 2020-01-20 | 2020-12-04 | 廊坊市阳光建设工程质量检测有限公司 | Device and method for detecting compressive strength of concrete by cambered surface opposite compression method |
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1999
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| CN101551380A (en) * | 2009-05-01 | 2009-10-07 | 徐州建筑职业技术学院 | Method for estimating concrete strength of thin-walled structure by using small core sample strength |
| CN102426143A (en) * | 2011-09-22 | 2012-04-25 | 中国建筑科学研究院 | Method and device for detecting compressive strength of concrete by shearing resistance method |
| CN102721617A (en) * | 2012-07-11 | 2012-10-10 | 深圳中建院建筑科技有限公司 | Method for detecting concrete compression strength by using single shear method |
| CN104132842B (en) * | 2014-06-30 | 2016-03-30 | 安徽省建筑科学研究设计院 | A kind of square pile pile concrete total cross-section ruggedness test method |
| CN104132842A (en) * | 2014-06-30 | 2014-11-05 | 安徽省建筑科学研究设计院 | Square pile body concrete total cross section intensity examination method |
| CN104515704B (en) * | 2014-12-26 | 2017-09-19 | 北京市道路工程质量监督站 | A kind of test method of semi-rigid type base core sample compression strength |
| CN104515704A (en) * | 2014-12-26 | 2015-04-15 | 北京市道路工程质量监督站 | Test method for semi-rigid base core sample compressive strength |
| CN104964874A (en) * | 2015-05-26 | 2015-10-07 | 宿州学院 | Pit sand concrete compressive strength detection method and apparatus thereof |
| CN105699116A (en) * | 2016-01-22 | 2016-06-22 | 中国长江三峡集团公司 | Concrete dam coring method |
| CN105699116B (en) * | 2016-01-22 | 2018-03-27 | 中国长江三峡集团公司 | A kind of concrete dam coring method |
| CN110823704A (en) * | 2019-10-15 | 2020-02-21 | 山东大学 | TBM-carried rock slag online compressive strength testing system and method |
| CN110726585A (en) * | 2019-11-26 | 2020-01-24 | 上海市建筑科学研究院有限公司 | On-site micro-loss sampling detection method for block strength of masonry structure |
| CN111077065A (en) * | 2019-12-30 | 2020-04-28 | 广东交科检测有限公司 | Method for measuring damaged depth of concrete after high temperature through grouped compression resistance of core samples |
| CN112033810A (en) * | 2020-01-20 | 2020-12-04 | 廊坊市阳光建设工程质量检测有限公司 | Device and method for detecting compressive strength of concrete by cambered surface opposite compression method |
| CN111157343A (en) * | 2020-03-02 | 2020-05-15 | 河北省建筑科学研究院有限公司 | Method for measuring compressive strength of grouting material core sample |
| CN111896546A (en) * | 2020-07-02 | 2020-11-06 | 上海市建筑科学研究院有限公司 | New and old concrete joint surface quality detection method based on drilling and core drilling sampling |
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