CN1773280A - Method for determining hardened cement-base material shrinkaging and cracking - Google Patents
Method for determining hardened cement-base material shrinkaging and cracking Download PDFInfo
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- CN1773280A CN1773280A CN 200510110005 CN200510110005A CN1773280A CN 1773280 A CN1773280 A CN 1773280A CN 200510110005 CN200510110005 CN 200510110005 CN 200510110005 A CN200510110005 A CN 200510110005A CN 1773280 A CN1773280 A CN 1773280A
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Abstract
The present invention relates to a technological process for determining drying shrinkage cracking property of hardened cement base material. Said process includes the following steps: firstly, preparing hardened cement base material for test; pouring it into the between of internal mould and external mould of steel cylindrical test mould assembled by using external mould, internal mould and bottom plate: after it is formed, curing for 1-14 days, under the relative humidity with 5-20% heating in the speed of 2-10 deg.C/h to maximum temperature 40-80 deg.C, retaining constant temperature for 8-48h; finally adopting reading microscope to define crack width of external wall of test piece, and utilizing the crack width d to sectionally measure crack length Li, utilizing crack width weighted value Ai table and adopting W=sigma (Ai X Li) to calculate cracking weighted value W, and using it as characteristics of drying shrinkage cracking property of hardened cement base material. Said invention can obtain result within 3-20 days.
Description
Technical field
The present invention relates to the method for the dry dehydration shrinkage cracking performance of a kind of mensuration hardening cement base material (cement paste, mortar, concrete and compound substance thereof), belong to the Materials Science and Engineering science and technology field.
Background technology
Cement concrete material in the cement-based material is one of global consumption maximum, most popular manufactured construction materials.China's cement annual production has at present reached 8.6 hundred million tons, and a year cement concrete consumption has reached tens billion cubic meters.In the quite a long time from now on, cement concrete will be the main building materials that China's modern project is built.And, since its have applied widely, low price, easy moulding by casting, more durable, also can effectively utilize some using industrial solid wastes to make advantages such as energy saving and environment friendly building materials, and the irreplaceable effect of other material of performance in numerous building engineering fields.
It is low that but cement concrete also has tensile strength, ultimate tensile strength is little, impact strength is poor, be easy to shortcomings such as dehydration shrinkage cracking, especially because dry dehydration causes the concrete shrinkage cracking to make the engineering outward appearance, functions of use, be subjected to very big influence serviceable life etc., in case its dehydration shrinkage cracking, it is impervious greatly to influence it, freeze proof, anti-chemical mediator corrodes, performances such as anti-steel bar corrosion, cause shorten greatly serviceable life, maintenance cost rises in a large number, according to the interrelated data record, the U.S. is used for the concrete rehabilitation expense every year up to the more than one hundred billion dollar, and China also will be in hundreds billion of units.If the cracking problem can not get adequate solution, the expense that is used to keep in repair will further increase along with concrete being extensive use of.
Up to now, all do not measure cement concrete material dry shrinkage and cracking performance unified approach both at home and abroad.Present method is the cracking after engineering site is measured drying shrinkage, perhaps material is made into test block in addition, waits behind the drying shrinkage with apparatus measures and calculates the cracking performance of test block.But because the cement concrete material dry shrinkage and cracking need reach 3～6 months even the longer time, so measurement result is little to the directive significance of engineering construction, can only check and accept as construction quality at most.Can measure the long-term dry shrinkage cracking performance that produces of concrete within a short period of time, thereby levelling prescription, make the crack on concrete problem in time be resolved, overcome engineering circle and think the concrete prejudice of not splitting, solve the hang-up in this engineering of crack on concrete problem really, measure the dry shrinkage and cracking method by setting up, make the operating technique that prevents dry shrinkage and cracking obtain breaking through.
Summary of the invention
The objective of the invention is to disclose a kind of method of testing the dry shrinkage cracking performance of hardening cement base material dehydration, method with this drying dehydration shrinkage cracking performance can obtain the result in the short time in 3～20 days, thereby instruct the levelling of prescription, solve the cracking problem of cement concrete.
The present invention is directed to the dry dehydration shrinkage cracking of hardening cement base material problem present situation, at first, the dry dehydration shrinkage cracking Analysis on Mechanism of hardening cement base material starts with from being inquired into, get clear in analysis on the basis of its mechanism, designed the experimental provision of measuring cement concrete material sclerosis back dry shrinkage and cracking performance voluntarily, and explore a cover and quicken the technology of dry shrinkage and cracking, reach and to obtain its dry shrinkage and cracking key property data in the short period, solve the dry shrinkage and cracking problem for adopting an effective measure assay method is provided, for the cracking problem that solves in the engineering has been created advantage.Concrete method of testing is as follows:
At first test the hardening cement base material of usefulness: after cement-based material is pressed the proportioning metering of engine request by engineering request for utilization preparation, add stirring machine and stir (then adding other material simultaneously) for other cement-based material, the cement-based material that mixing prepares is poured between the interior external mold of die trial, and die trial is the steel garden tubular die trial that is assembled by external mold, internal mold (restriction liquid shrinkable) and chassis.Take out after 1～14 day through standard curing at the test specimen after the moulding between the inside and outside mould, put into the temperature adjustable scope between 20-100 ℃, the climatic chamber of the adjustable scope of humidity between 5-90%, under 5%-20% relative humidity condition, programming rate with 2 ℃/h-10 ℃/h is warming up to maximum temperature (40 ℃-80 ℃), carry out 6h-48h constant temperature then, quicken the quality of the forward and backward test specimen of drying shrinkage by weighing, reduce to the roughly stable experiment that finishes with dehydrating speed.Adopt reading microscope (reading accuracy is 0.01mm) to determine garden tubular hardening cement base material test specimen outer wall fracture width at last, and press fracture width d areal survey fracture length Li, the fracture width weights Ai that lists with table 1, employing formula W=∑ (Ai * Li) calculate cracking weighted value W, with this sign as the hardened cement-base material shrinkaging and cracking performance.Whole test obtained the result in 3～20 days.
Table 1 fracture width weights Ai table
| Fracture width d (mm) | 0＜d＜0.05 | 0.05＜d＜0.1 | 0.1＜d＜0.2 | 0.2＜d＜0.3 | 0.3＜d＜0.4 | 0.4＜d |
| Fracture width weights Ai | 0.025 | 0.05 | 0.1 | 0.2 | 0.3 | 0.4 |
The present invention has following advantage:
1. because exploring a cover, the present invention quickens the technology of dry shrinkage and cracking: in climatic chamber, 5～20% relative humidity, the programming rate of 2～10 ℃/h is warming up to 40～80 ℃ of maximum temperatures, 6～48h constant temperature, therefore can in the short time in 3～20 days, obtain test result, shorten 8～60 times of times than existing method.
2. because preparing the die trial of hardening cement base material, the present invention divide two kinds of different requirements of mortar die trial and concrete die trial to carry out, therefore, the present invention can be widely used in the dry dehydration shrinkage cracking performance of test cement paste, mortar, concrete and compound substance thereof.
3. technology of the present invention is simple, easy to operate, provides strong evidence for solving the crack on concrete problem, has very big actual application value and social value.
Embodiment
Embodiment 1
External diameter be 150mm, high for 150mm, thickness be that the steel cylinder of 30mm is as internal mold and as sand-cement slurry drying shrinkage obligatory point, with internal diameter 190mm, height is that 150mm, thickness are that the half rounds cylindrical shell of 10mm is to piecing together as external mold, the bottom with the diameter be 250mm, height be the 20mm steel disk as base plate, be assembled into the garden tubular hardening cement base material mortar die trial of cast mortar material between inside and outside mould.
The mortar die trial is in 32.5 Portland cements: sand: the ratio (mass ratio) of water=1: 1: 0.5 stirs 3min in mortar mixer, be cast between the inside and outside mould of mortar die trial, specimen molding after standard curing take out after 1 day, in being 5% casing, humidity quickens dry dehydration shrinkage cracking experiment, with the 2 ℃/h that heats up, constant temperature 0.5h, heat up again until 40 ℃, carry out 6h constant temperature then.Adopt reading microscope to determine fracture width, press fracture width d areal survey fracture length Li, with the fracture width weights Ai that table 1 is listed, (Ai * Li) calculating cracking weighted value W is 0.436cm to adopt the W=∑.
Embodiment 2
Adopt mortar die trial as embodiment 1, in 42.5 Portland cements: sand: the ratio (mass ratio) of water=1: 1: 0.5 stirs 3min in mortar mixer, be cast between the inside and outside mould of mortar die trial, specimen molding after standard curing take out after 3 days, in being 10% casing, humidity quickens dry dehydration shrinkage cracking experiment, heat up until 50 ℃ with the 5 ℃/h that heats up, constant temperature 1h temperature increasing schedule, carry out 12h constant temperature then.Adopt reading microscope to determine fracture width, press fracture width d areal survey fracture length Li, with the fracture width weights Ai that table 1 is listed, (Ai * Li) calculating cracking weighted value W is 0.713cm to adopt the W=∑.
Embodiment 3
Adopt mortar die trial as embodiment 1, in 32.5 Portland cements: sand: water: MH-1 fiber=1: 1: 0.5: 0.0017 ratio (mass ratio) stirs 3min in mortar mixer, be cast in the die trial of mortar dry shrinkage and cracking, specimen molding after standard curing take out after 7 days, in being 20% casing, humidity quickens dry dehydration shrinkage cracking experiment, heat up until 70 ℃ with the 10 ℃/h that heats up, constant temperature 2h temperature increasing schedule, carry out 24h constant temperature then.Adopt reading microscope to determine fracture width, press fracture width d areal survey fracture length Li, with the fracture width weights Ai that table 1 is listed, (Ai * Li) calculating cracking weighted value W is 0.092cm to adopt the W=∑.
Embodiment 4
The making of concrete die trial: external diameter be 150mm, high for 150mm, thickness be that the steel cylinder of 30mm is as internal mold and as cement concrete drying shrinkage obligatory point, with internal diameter 350mm, height is that 150mm, thickness are that the half rounds cylindrical shell of 10mm is to piecing together as external mold, the bottom with the diameter be 450mm, height be the 20mm steel disk as base plate, be assembled into the concrete die trial of deposit concrete material between inside and outside mould.
Cement concrete is in 42.5 Portland cements: sand: stone: water: MPH-1 fiber=1: 1.85: 2.98: 0.46: 0.002 ratio (mass ratio) stirs 3min in concrete mixer, be cast between the inside and outside mould of concrete die trial, specimen molding after standard curing take out after 14 days, in being 5% casing, humidity quickens dry dehydration shrinkage cracking experiment, heat up until 80 ℃ with the 2 ℃/h that heats up, constant temperature 0.5h temperature increasing schedule, carry out 48h constant temperature then.Adopt reading microscope to determine fracture width, press fracture width d areal survey fracture length Li, with the fracture width weights Ai that table 1 is listed, (Ai * Li) calculating cracking weighted value W is 0.037cm to adopt the W=∑.
Claims (1)
1, a kind of method for determining hardened cement-base material shrinkaging and cracking, it is characterized in that: at first test the hardening cement base material of usefulness by engineering request for utilization preparation, after cement-based material is pressed the proportioning metering of engine request, behind the adding stirring machine stirring and evenly mixing cement-based material for preparing is poured between the interior external mold of die trial; Die trial is the steel garden tubular die trial that is assembled by external mold, internal mold and chassis; Take out after 1～14 day through standard curing at the test specimen after the moulding between the inside and outside mould, put into the temperature adjustable scope between 20-100 ℃; In the climatic chamber of the adjustable scope of humidity between 5-90%, under 5～20% relative humidity conditions, programming rate with 2～10 ℃/h is warming up to 40～80 ℃ of maximum temperatures, carry out 6～48h constant temperature then, adopt reading microscope to determine test specimen outer wall fracture width at last, and press fracture width d areal survey fracture length Li, the fracture width weights Ai that goes out with fracture width weights Ai tabular, employing formula W=∑ (Ai * Li) calculate cracking weighted value W, with this sign as the hardened cement-base material shrinkaging and cracking performance; Whole test obtained the result in 3～20 days.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200510110005 CN1773280B (en) | 2005-11-03 | 2005-11-03 | Method for determining hardened cement-base material shrinking and cracking |
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| CN 200510110005 CN1773280B (en) | 2005-11-03 | 2005-11-03 | Method for determining hardened cement-base material shrinking and cracking |
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| CN1773280A true CN1773280A (en) | 2006-05-17 |
| CN1773280B CN1773280B (en) | 2010-12-01 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1866004B (en) * | 2006-06-09 | 2010-05-12 | 宁波工程学院 | Test method for crack-resistant performance of concrete and outside-square inside-round test apparatus therefor |
| CN104501757A (en) * | 2014-12-15 | 2015-04-08 | 中国南方航空工业(集团)有限公司 | Measuring method for thickness of cavity |
| CN105445419A (en) * | 2015-01-21 | 2016-03-30 | 长沙理工大学 | Accelerated drying shrinkage testing method of semi-rigid base material of inorganic binding material |
| CN107561251A (en) * | 2017-09-22 | 2018-01-09 | 北京建筑大学 | A kind of cement-based material cracking sensitivity test device and method of testing |
| CN109738618A (en) * | 2018-12-06 | 2019-05-10 | 同济大学 | A kind of preliminary method for early warning of cement-based material plastic shrinkage cracking |
-
2005
- 2005-11-03 CN CN 200510110005 patent/CN1773280B/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1866004B (en) * | 2006-06-09 | 2010-05-12 | 宁波工程学院 | Test method for crack-resistant performance of concrete and outside-square inside-round test apparatus therefor |
| CN104501757A (en) * | 2014-12-15 | 2015-04-08 | 中国南方航空工业(集团)有限公司 | Measuring method for thickness of cavity |
| CN105445419A (en) * | 2015-01-21 | 2016-03-30 | 长沙理工大学 | Accelerated drying shrinkage testing method of semi-rigid base material of inorganic binding material |
| CN107561251A (en) * | 2017-09-22 | 2018-01-09 | 北京建筑大学 | A kind of cement-based material cracking sensitivity test device and method of testing |
| CN109738618A (en) * | 2018-12-06 | 2019-05-10 | 同济大学 | A kind of preliminary method for early warning of cement-based material plastic shrinkage cracking |
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| Publication number | Publication date |
|---|---|
| CN1773280B (en) | 2010-12-01 |
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