CN105044314A - Rubber simulated concrete and plasticity adjustment simulation method thereof - Google Patents
Rubber simulated concrete and plasticity adjustment simulation method thereof Download PDFInfo
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- CN105044314A CN105044314A CN201510451587.2A CN201510451587A CN105044314A CN 105044314 A CN105044314 A CN 105044314A CN 201510451587 A CN201510451587 A CN 201510451587A CN 105044314 A CN105044314 A CN 105044314A
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Abstract
The invention discloses rubber simulated concrete and a plasticity adjustment simulation method thereof, and belongs to the technical field of building materials. According to the plasticity adjustment simulation method proposed based on the characteristic of the simulated concrete material being too high in brittleness and a series of experimental studies, the brittleness of the simulated concrete material can be improved by adding fine rubber particles into raw materials. Compared with the common simulated concrete, the rubber simulated concrete provided by the invention has the advantages that the compatibility of deformation during destruction is high, no brittle fracture is generated when the maximum load is borne, and a ductile failure phenomenon undergoing relatively large plastic deformation is emerged.
Description
Technical field
The present invention relates to material improvement technical field, particularly relate to and improve emulation concrete materials plasticity.
Background technology
Structural dynamic damage model test is not only the important means understanding large-sized concrete structural nonlinear dynamic response and eaerthquake damage form, also be the method for the testing numerical analysis correctness large reduced scale power destruction model test for large-sized concrete structure, require that realistic model material will have low-intensity or highdensity feature, and will ensure that its physico mechanical characteristic is similar to normal concrete.This makes to study the every mechanics parameter of concrete imitation vacuum material and performance becomes a new research field.Research for the key property such as bullet mould, compressive strength, tensile strength, constitutive relation of emulation concrete materials has document and elaborated.Emulation concrete materials adopts the formula approximate with common concrete material, and it is little more many than the coarse aggregate size of normal concrete to put concrete coarse aggregate size, causes the surface of contact of aggregate and sand-cement slurry much bigger compared with normal concrete; In addition, in emulation concrete materials, cement content is lower than normal concrete cement content, make the intensity of sand-cement slurry self and the cohesion of asking with aggregate lower.Based on these two aspects factor, the development that under External Force Acting, emulation concrete materials coheres crack comparatively normal concrete is fast, and mutually through with sand-cement slurry internal fissure, thus causes emulation concrete materials stress-strain curve descending branch comparatively steep, and fragility is larger than normal concrete.
Summary of the invention
In order to overcome above-mentioned the deficiencies in the prior art, the invention provides a kind of method improving emulation concrete materials plasticity.The technical solution adopted in the present invention is: adopt thin rubbery granule to replace the aggregate element of certain volume in emulation concrete materials to make rubber artificial concrete, by testing their physical and mechanical property, observe thin rubbery granule to the improvement situation of emulation concrete materials fragility.Emulation concrete materials match ratio is in table 1.
Table 1 benchmark emulation concrete materials (EC) and the concrete match ratio of rubber artificial:
％
| Code | Water | Cement | Breeze | Heavy crystalline flour | Barite | Silt |
| EC | 9.0 | 1.5 | 10.0 | 30.0 | 49.5 | |
| NC-20 | 9.0 | 1.5 | 8.4 | 23.2 | 37.9 | 20 |
| NC-25 | 9.0 | 1.5 | 8.3 | 21.9 | 34.3 | 25 |
| NC-30 | 9.0 | 1.5 | 8.2 | 19.6 | 31.7 | 30 |
| NC-35 | 9.0 | 1.5 | 8.1 | 17.3 | 29.1 | 35 |
Rubber artificial concrete, cement adopts 32.5MPa Portland cement; The particle diameter of mineral powder, heavy crystalline flour, barite sand for be converted into normal concrete aggregate size according to geometric similarity guide, 0.05 ~ 2.0mm, grain composition belongs to grating II district; Rubber grain particle diameter is the sports ground soft rubber particle of 1.45-1.55m; Replace the part coarse-fine aggregate in benchmark emulation concrete materials with rubber grain, its volume fraction replacing aggregate is 20%, 25%, 30% and 35%.
The adjustment analogy method of rubber artificial concrete plasticity, comprises the steps:
Step one, prepares the rubber artificial concrete of five kinds of different ratio: cement adopts 32.5MPa Portland cement according to the formula of table; The particle diameter of mineral powder, heavy crystalline flour, barite sand for be converted into normal concrete aggregate size according to geometric similarity guide, 0.05 ~ 2.0mm, grain composition belongs to grating II district; Rubber grain: particle diameter is the sports ground soft rubber particle of 1.45-1.55m; Rubber artificial concrete makes with the aggregates that rubber grain replaces in benchmark emulation concrete materials, and its volume fraction replacing aggregate is 20%, 25%, 30% and 35%, is designated as XC-20 respectively, XC-25, XC-30 and XC-35 tetra-kinds of rubber artificial concrete;
Step 2, test material preparation: each rubber artificial concrete preparation size is the cube uniaxial compression standard specimen 30 of 100mm × 100mm × 100mm, for uniaxial compression test; In the middle of the preparation of each rubber artificial concrete, the length of side is 70mm, and two ends are transitioned into the standard dog bone uniaxial tension test specimen 30 that the length of side is 100mm gradually, and this test specimen semipilot Partial Height 100mm, overall height 200mm are used for uniaxial tensile test; Each rubber artificial concrete preparation size is that the rectangular parallelepiped standard specimen 30 of 100mm × 100mm × 515mm is for four-point bending test;
Step 3, test piece maintenance: the average curing temperature of various test specimen 20 DEG C, relative humidity about 60%, curing age 24h;
The adjustment simulation of step 4 rubber artificial concrete plasticity:
Respective test is carried out to all test specimens of each rubber artificial concrete, compares the elastic modulus of four kinds of different rubber artificial concrete samples, compressive strength, resistance to compression peak strain, tensile strength, tension peak strain, bending and tensile strength, 4 maximum defluxions; Again compared with benchmark emulation concrete materials, between the optimal zone finding out rubber grain content.
Show that the concrete elastic modulus of rubber artificial, compressive strength reduce in various degree along with the increase of rubber grain volume fraction has, resistance to compression peak strain increases to some extent, and tensile strength, tension peak strain and four-point bending maximum defluxion then increase all to some extent; It should be noted that, the concrete deformability of rubber artificial and tensile strength always do not increase along with the increase of rubber grain content, but there is an optimum value.Rubber grain content exceedes the reduction of not only elastic modulus, compressive strength after this value can be more obvious, and tension peak strain also can reduce.The research of other scholars to normality rubber concrete also draws same conclusions.This research finds that optimum value should be within the scope of 25%-30%.
Beneficial effect of the present invention is, (1) compared with benchmark emulation concrete materials, the concrete bullet mould of rubber artificial, compressive strength decrease, resistance to compression and tension peak strain, four-point bending maximum defluxion all obviously increase, but the concrete tensile strength of rubber artificial increases than benchmark emulation concrete materials.(2) show obvious ductile characteristic during rubber artificial concrete destruction, in loading procedure, produce significant plastic yield, illustrate that it is most compared with the compatibility of deformation ability of benchmark emulation concrete materials.The concrete plasticity of rubber artificial does not always increase along with the increase of rubber grain content, but exist an optimum value, exceed or lower than this value not only elasticity modulus of materials can reduce more, tension, resistance to compression peak strain also can reduce.(3) this method in this paper can make the fragility of emulation concrete materials obtain good improvement, makes the constitutive relation of emulation concrete materials, damage-form and physical characteristics can more similar in appearance to normal concrete.When this kind of method being applied to the test of realistic model power destruction, truth during concrete prototype structure power destruction can be reflected better, and the method for producing this realistic model material is simple, convenient operation, safety non-pollution.
The present invention is widely used in model test to later emulation concrete materials material and engineering is actual has important practical significance.Benchmark emulation concrete materials stress-strain curve descending branch is comparatively steep, and fragility is larger than normal concrete.By adding rubber, the fragility of emulation concrete materials is improved.
Embodiment
1. experimental study
1.1 material and mixing ratio
Cement: 32.5MPa (compressive strength) Portland cement; The particle diameter of mineral powder, heavy crystalline flour, barite sand for be converted into normal concrete aggregate size according to geometric similarity guide, 0.05 ~ 2.0mm, grain composition belongs to grating II district; Rubber grain: particle diameter is the sports ground soft rubber particle of 1.45-1.55m.Rubber artificial concrete makes with the aggregates that rubber grain replaces in benchmark emulation concrete materials, and its volume fraction replacing aggregate is 20%, 25%, 30% and 35%, is designated as XC-20 respectively, XC-25, XC-30 and XC-35 (see table 1).
1.2 test method
The cube standard specimen that employing is of a size of 100mm × 100mm × 100mm does uniaxial compression test; In the middle of adopting, the length of side is 70mm, and two ends are transitioned into the square (i.e. standard dog bone test specimen) that the length of side is 100mm gradually, and the standard dog bone test specimen of its middle test portion height 100mm, overall height 200mm does uniaxial tensile test; The rectangular parallelepiped standard specimen that employing is of a size of 100mm × 100mm × 515mm does four-point bending test.Average curing temperature 20 DEG C during test, relative humidity about 60%, curing age 24h.Uniaxial compressive, tensile test loading speed are respectively 0.6,0.06mm/min.Due to elastic modulus and all low than normal concrete 1 ~ 2 number level of intensity of emulation concrete materials material, therefore loading equipemtn adopts SANS board 1-10t type universal testing machine, and according to test needs, charger can self-changeable.Data acquisition system (DAS) adopts SANS testing machine to carry software, and picking rate can reach 104 times/s, ensure that in process of the test the accuracy recording data.
2 test result analysis
The concrete uniaxial compression of rubber artificial, uniaxial tension, four-point bending and tensile pressure ratio test findings are in table 2.Table 2 shows, the tensile strength that four-point bending test and uniaxial tensile test obtain is very close, and error is within 5%, and illustrate that it is all feasible for surveying concrete tensile strength in this way, precision also meets testing requirements.
Table 2 emulation concrete materials experimental data table
From table 2, compared with benchmark emulation concrete materials, the concrete elastic modulus of rubber artificial, compressive strength reduce in various degree along with the increase of rubber grain volume fraction has, resistance to compression peak strain increases to some extent, and tensile strength, tension peak strain and four-point bending maximum defluxion then increase all to some extent; The resistance to compression peak strain of XC-20, XC-25, XC-30 and XC-35 is respectively 1.12 of EC, 1.26,1.36 and 1.27 times, tension peak strain is increased to 1.42,1.81,2.29 and 1.92 times of EC, four-point bending maximum defluxion brings up to about 1.8,2.2,2.9 and 3.2 times of EC; XC-20, XC-25 and XC-30 improve about 4.1%, 13.9% and 25.6% compared with the tensile strength (axle draws the mean value with cripping test) of EC respectively.With other scholars to compared with the result of General Purpose Rubber concrete test, the concrete tensile strength of rubber artificial increases, and all the other mechanical characteristics are then basically identical.Compared with the General Purpose Rubber concrete that cement content is more, in rubber artificial concrete grout and the good performance of rubber grain cohesion more outstanding; Rubber grain add the grating further improving particles of aggregates in concrete, snap-in force when adding material tension between crack place aggregate (comprising rubber grain), rubber grain is distributed on rupture surface and bears pulling force as row's little spring, so this reason that to be also rubber artificial concrete tensile strength higher.
Benchmark emulation concrete materials and the concrete axial compression of rubber artificial, axle tension-strain full curve.Can find out from the descending branch of each trial curve, when external load exceedes peak load, EC destroys immediately, linear steeper; When the external load of XC reaches maximal value, crack not yet causes material to destroy completely, and test specimen still has certain adaptability to changes, and descending branch is subsequently milder.Visible, rubber grain mix the fragility improving emulation concrete materials largely, enhance its deformation performance.
Tensile pressure ratio (ratio of Tensile strength and compressive strength) is the important indicator weighing material plasticity, and tensile pressure ratio is larger, and the plasticity that material list reveals, toughness, deformation performance are stronger.From the comparison of tensile pressure ratio, XC-20, XC-25, XC-30 and XC-35, apparently higher than EC, are respectively about 1.18,1.37,1.85 and 1.90 times of EC; In addition, their four-point bending maximum defluxion reaches 1.13,1.48 respectively, 1.81 and 1.98mm, prove rubber can effectively absorbing material fracture time release energy, play and toughness reinforcingly subtract crisp effect.
By the damage-form analysis to EC and XC-30 test specimen, its load is at once to peaking after there is longitudinal crack can to find EC, and major fracture accelerates to extend expansion subsequently, and load declines very fast, substantially loses load-bearing capacity when test specimen surrounded surface material falls back; XC-30 is when pressurized, namely many cracks has been there is in load before not reaching peak value, now load rising tends towards stability, when many inclined crack run through at the bright wind of surface of test piece, load starts to decline, but comparatively slow, until surface of test piece material comes off one after another, when load drops to very low, the thorough unstable failure of test specimen.Can find EC tensile test specimen originally load rise rapidly, fall instantaneously when reaching peak value, test specimen does not have obvious sign before destroying, crack after occurring immediately extending transversely along test specimen, run through, test specimen brittle fracture is two sections; XC-30 start tension time phenomenon and EC similar, when load rises to about 70% of Tensile strength, curve slows down, and after there is bending micro-crack, load reaches peak value, but test specimen does not destroy completely, micro-crack is in the expansion of test specimen internal stability, and load declines very fast; After this there is visual crack, expand very fast and run through.Drawing crack is sewn in expansion process and is obstructed because running into rubber grain.And rubber grain Absorbable rod portion of energy, keep the integrality of test specimen.By experiment, known in rubber artificial concrete sample BENDING PROCESS, breaking part rubber grain not only bears part bending load as numerous little spring, also can stop the expansion of micro-crack, delay the appearance in new crack.In the developing stage of rubber artificial inside concrete micro-crack, time near micro-crack tip extension to rubber grain, rubber grain can produce distortion, crack tip stress is eased, thus inhibits the expansion in crack.Show the ductility of material.
It should be noted that, the concrete deformability of rubber artificial and tensile strength always do not increase along with the increase of rubber grain content, but there is an optimum value.Rubber grain content exceedes the reduction of not only elastic modulus, compressive strength after this value can be more obvious, and tension peak strain also can reduce.The research of other scholars to normality rubber concrete also draws same conclusions.This research finds that optimum value should be within the scope of 25%-30%.When rubber grain volume fraction in rubber artificial concrete lower than or when exceeding this value, the tensile strength of material and peak strain all can reduce.
Claims (2)
1. rubber artificial concrete, is characterized in that cement adopts 32.5MPa Portland cement; The particle diameter of mineral powder, heavy crystalline flour, barite sand for be converted into normal concrete aggregate size according to geometric similarity guide, 0.05 ~ 2.0mm, grain composition belongs to grating II district; Rubber grain particle diameter is the sports ground soft rubber particle of 1.45-1.55m; Replace the part coarse-fine aggregate in benchmark emulation concrete materials with rubber grain, its percent by volume span replacing aggregate is between 25%-30%.
2. the adjustment analogy method of rubber artificial concrete plasticity, is characterized in that comprising the steps:
Step one, prepares rubber grain and accounts for four kinds of rubber artificial concrete that aggregate volume number percent is respectively 20%, 25%, 30% and 35%: cement adopts 32.5MPa Portland cement; The particle diameter of mineral powder, heavy crystalline flour, barite sand for be converted into normal concrete aggregate size according to geometric similarity guide, 0.05 ~ 2.0mm, grain composition belongs to grating II district; Rubber grain: particle diameter is the sports ground soft rubber particle of 1.45-1.55m; Rubber artificial concrete makes with the aggregates that rubber grain replaces in benchmark emulation concrete materials, and its volume fraction replacing aggregate is 20%, 25%, 30% and 35%, is designated as XC-20 respectively, XC-25, XC-30 and XC-35 tetra-kinds of rubber artificial concrete;
Step 2, test material preparation: each rubber artificial concrete preparation size is the cube uniaxial compression standard specimen 30 of 100mm × 100mm × 100mm, for uniaxial compression test; In the middle of the preparation of each rubber artificial concrete, the length of side is 70mm, and two ends are transitioned into the standard dog bone uniaxial tension test specimen 30 that the length of side is 100mm gradually, and this test specimen semipilot Partial Height 100mm, overall height 200mm are used for uniaxial tensile test; Each rubber artificial concrete preparation size is that the rectangular parallelepiped standard specimen 30 of 100mm × 100mm × 515mm is for four-point bending test;
Step 3, test piece maintenance: the average curing temperature of various test specimen 20 DEG C, relative humidity about 60%, curing age 24h;
The adjustment simulation of step 4 rubber artificial concrete plasticity:
Respective test is carried out to all test specimens of each rubber artificial concrete, compares the elastic modulus of four kinds of different rubber artificial concrete samples, compressive strength, resistance to compression peak strain, tensile strength, tension peak strain, bending and tensile strength, 4 maximum defluxions; Again compared with benchmark emulation concrete materials, between the optimal zone finding out rubber grain content.
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| CN106365530A (en) * | 2016-08-26 | 2017-02-01 | 昆明理工大学 | Large-size concrete structure simulation model material and preparation method of same |
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| CN201386250Y (en) * | 2009-02-26 | 2010-01-20 | 南京工业大学 | Composite material lattice sandwich pipe confined concrete pier column with functions of cushioning and energy absorbing |
| CN201991100U (en) * | 2010-11-19 | 2011-09-28 | 青岛理工大学 | Rubber concrete energy-consuming and shock-absorbing device for ultrahigh steel structure |
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