CN106257267B - Method for determining optimum water content and maximum dry density by static pressure method - Google Patents
Method for determining optimum water content and maximum dry density by static pressure method Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 117
- 238000000034 method Methods 0.000 title claims abstract description 85
- 230000003068 static effect Effects 0.000 title claims abstract description 11
- 238000012360 testing method Methods 0.000 claims abstract description 123
- 238000003825 pressing Methods 0.000 claims abstract description 6
- 239000004568 cement Substances 0.000 claims description 26
- 239000000203 mixture Substances 0.000 claims description 25
- 239000000463 material Substances 0.000 claims description 19
- 238000002156 mixing Methods 0.000 claims description 14
- 238000007789 sealing Methods 0.000 claims description 12
- 238000011068 loading method Methods 0.000 claims description 5
- 238000013461 design Methods 0.000 claims description 4
- 239000010705 motor oil Substances 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 2
- 238000005303 weighing Methods 0.000 claims description 2
- 238000001035 drying Methods 0.000 abstract description 2
- 239000002689 soil Substances 0.000 description 21
- 238000005056 compaction Methods 0.000 description 19
- 230000002706 hydrostatic effect Effects 0.000 description 15
- 238000011049 filling Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 239000011398 Portland cement Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910001710 laterite Inorganic materials 0.000 description 1
- 239000011504 laterite Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
- G01N5/04—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by removing a component, e.g. by evaporation, and weighing the remainder
- G01N5/045—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by removing a component, e.g. by evaporation, and weighing the remainder for determining moisture content
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/02—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/02—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume
- G01N2009/022—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume of solids
- G01N2009/024—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume of solids the volume being determined directly, e.g. by size of container
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Abstract
The invention provides a method for determining the optimal water content and the maximum dry density by a static pressure method, which comprises the steps of applying pressure to a molded test piece; calculating the water content omega and the dry density rho; establishing a quadratic relation curve by taking the water content omega as a horizontal axis and the dry density rho as a vertical axis, taking an extreme value of the dry density as a maximum dry density, and taking the water content corresponding to the maximum dry density as an optimal water content, wherein the dry density and the water content are determined by a formula
And formula
Description
Technical Field
The invention belongs to the field of traffic civil engineering, and particularly relates to a method for determining the optimal water content and the maximum dry density by adopting a static pressure method.
Background
The common methods for determining the optimum water content and the maximum dry density are a compaction test method and a vibration compaction test method, the method for forming the cylindrical test piece and the beam test piece is a static pressure method, and the compaction method, the vibration compaction method and the static pressure method have different action principles.
The specification stipulates that the determination method of the optimal water content and the maximum dry density of the cement stabilized macadam is a compaction test method, the impact factors of the compaction test result are numerous, and the workload of the compaction test is large.
Disclosure of Invention
In order to overcome the above technical problems of the prior art, the present invention provides a method for determining an optimum moisture content and a maximum dry density using a static pressure method, which can greatly reduce the workload. The object of the invention is to determine the optimum water content and the maximum dry density of cement stabilized macadam by means of the hydrostatic method.
The purpose of the invention is realized by the following scheme:
a method for determining the optimum water content and maximum dry density by static pressure method includes applying pressure to a molded test piece; calculating the water content omega and the dry density rho; and establishing a quadratic relation curve by taking the water content omega as a horizontal axis and the dry density rho as a vertical axis, taking the extreme value of the dry density as the maximum dry density, and taking the water content corresponding to the maximum dry density as the optimal water content.
Preferably, the preparation of the shaped test piece comprises the following steps:
A. preparing samples with different preset water contents w; for a specimen of φ 50mm × 50 mm: one test piece needs 210g to 240g of dry soil; for a test piece of φ 100mm × 100 mm: one test piece needs about 2000g-2200g of dry soil; for a test piece of phi 150mm x 150 mm: one test piece needs about 6000g-6400g of dry soil;
B. stuffing a test material;
C. and after the material sealing is finished, adding cement with a preset quantity c, uniformly mixing, and forming a test piece within 1 hour after the mixing is finished. The cement stabilized macadam cement is generally used in an amount of 3% to 6% of the mixture, and therefore the predetermined amount c is 3% to 6%.
In any of the above embodiments, it is preferable that the step A is carried out by preparing 5 to 8 samples having different predetermined water contents w. The method for determining the optimal water content and the maximum dry density comprises the steps of forming a quadratic curve by the dry density and the water content, then obtaining an extreme value to obtain the optimal water content and the maximum dry density, and if the parts of a sample are too small, the extreme value cannot be obtained; however, if the number of samples is too large, the cycle length is increased and the workload is increased.
In any of the above embodiments, it is preferable that step A is carried out by preparing 6 to 7 samples having different predetermined water contents w. The number of samples from 6 to 7 can ensure the obtainment of extreme values without increasing the workload.
Preferably, in any scheme, in the step B, when the material is sealed, engine oil is coated on the inner wall of the test mold.
In any of the above schemes, preferably, in the step B, when the material is subjected to stuffy material, the water adding amount is 1-2% lower than the preset water content.
In any of the above embodiments, it is preferable that the step C is performed so that the size of the test mold used in molding the test piece is selected according to the maximum nominal particle size of the design gradation. Fine soil: the diameter of the test mould is multiplied by the height of the test mould is multiplied by 50mm phi and 50 mm; medium-particle soil: the diameter of the test mould is multiplied by the height of the test mould is multiplied by phi 100mm and multiplied by 100 mm; coarse-grained soil: the diameter of the test mould is multiplied by 150mm and 150 mm;
in any of the above embodiments, preferably, the step C is performed by adding the reserved water during the blending process.
Preferably, in any of the above embodiments, step C is performed, and when the test piece is formed, the lower cushion block matched with the test mold is usedPlacing the mixture into the lower part of a test mold, exposing for 2cm, pouring the mixture into the test mold for 2-3 times, slightly and uniformly inserting a tamper rod after each pouring, approximately filling the test mold with the mixture, enabling an upper cushion block matched with the test mold to be just placed into the test mold, and recording the mass m of the filled mixture1. A lower cushion block matched with the test mold is placed at the lower part of the test mold, the exposed size cannot be too small, otherwise, the test piece can be completely pressed into the test mold; the exposed dimension should not be too large, which would result in incomplete filling of the sample.
In any of the above embodiments, the pressure is preferably applied at a load rate of 1 mm/min. The loading rate of pressurization is not easy to be too large, otherwise, the sample can be broken; too small a loading rate of pressurization would result in a long determination cycle and time waste.
In any of the above embodiments, the pressure is preferably applied to 500KN and the unloading is maintained for 2min or more.
In any of the above embodiments, the pressure is preferably applied under 500KN and the pressure is maintained for 3min before unloading.
In any of the above embodiments, the pressure is preferably maintained at 500KN and then the pressure is unloaded after 5 min.
In any of the above embodiments, the pressure is preferably maintained at 500KN and then the pressure is unloaded after 7 min.
In any of the above embodiments, the pressure is preferably maintained at 500KN for 10min before unloading.
In any of the above embodiments, the pressure is preferably applied under 500KN and the pressure is maintained for 30min before unloading.
In any of the above embodiments, the pressure is preferably applied under 500KN and the pressure is maintained for 50min before unloading.
In any of the above embodiments, the unloading is preferably performed after maintaining the pressure for 120min under 500KN while applying the pressure.
Preferably, in any of the above schemes, after the pressure is unloaded, the test mold is removed, the height h of the test piece is measured, the volume V of the test piece is calculated, and the mass m of the test piece is weighed2。
Preferably, any of the above embodiments calculates the optimum water cutUsing the formula:
preferably, in any of the above schemes, the maximum dry density is calculated by using the formula:
the basic principle of the invention is that: and respectively filling the test molds for forming the cylindrical test piece into cement mixtures with different water contents for pressurization, measuring the height of the test piece when the pressure is increased to 500KN, and further calculating the volume of the test piece. And dividing the sum of the mass of the aggregate and the cement in the mixture by the volume of the test piece to obtain dry density, and dividing the difference between the mixing water amount and the mass loss of the test piece before and after forming by the mass of the test piece to obtain the water content. And establishing a quadratic relation curve with the water content on the horizontal axis and the dry density on the vertical axis, taking the extreme value of the dry density as the maximum dry density, and taking the water content corresponding to the maximum dry density as the optimal water content.
The method avoids the problem that the grading is changed due to the crushing of the mineral aggregate caused by the compaction test; the optimum water content and the maximum dry density are calculated by adopting the water content of the compacted test piece, so that the error of the water content caused by coring of the test piece is avoided. Drying is not needed, the optimal water content and the maximum dry density are obtained through rapid calculation, the workload is saved, and the test period is shortened. The maximum dry density determined by the method is slightly larger than the maximum dry density determined by the compaction test, the optimal water content is slightly smaller than the optimal water content determined by the compaction test, but the numerical value difference is not large, and the effectiveness of the method is proved.
Detailed Description
In order that the summary of the invention may be more clearly and accurately understood, the summary of the invention will be further explained and illustrated with reference to specific embodiments.
Example 1
A method for determining an optimum moisture content and a maximum dry density using a static pressure method, comprising the steps of:
A. selecting a test mold size according to the maximum nominal grain size of design gradation according to JTJ034-2000 technical specification of highway pavement base course construction: fine soil, the diameter of the test mould is multiplied by 50mm phi and 50mm high; the diameter of the test mould is multiplied by phi 100mm multiplied by 100 mm; coarse-grained soil, the diameter x height of a test mould is phi 150mm x 150 mm;
B. 7 samples were prepared by the method shown in T0804-1994, corresponding to 7 different water contents. For a test piece with the diameter of 50mm multiplied by 50mm, one test piece needs about 210g-240g of dry soil; for a test piece with the diameter of 100mm multiplied by 100mm, about 2000g-2200g of dry soil is needed for one test piece; for a test piece with the diameter of 150mm multiplied by 150mm, one test piece needs about 6000g-6400g of dry soil;
C. carrying out material sealing according to the method provided in T0843-2009, wherein the water adding amount of the material sealing is 1% -2% lower than the preset water content, and smearing engine oil on the inner wall of the test mold;
D. after the material sealing is finished, adding a preset amount of cement and uniformly mixing, adding reserved water in the mixing process, and forming a test piece within 1 hour after the mixing is finished;
E. placing a lower cushion block matched with the test mold at the lower part of the test mold, exposing for about 2cm, wherein the exposed size can be properly increased or decreased but not too small, otherwise, the test piece can be completely pressed into the test mold; the exposed dimension must not be too large, which would result in incomplete filling of the mix. And pouring the mixture into a test mold for 2-3 times, and slightly and uniformly inserting and compacting the mixture by using a tamper after each pouring. The mixture should approximately fill the test mold, so that the upper cushion block matched with the test mold can be just placed into the test mold, and the quality m of the filled mixture is recorded1；
F. Putting the whole test mold on a press, pressurizing to 500KN at a loading rate of 1mm/min (the test mold cannot be loaded too fast, the test mold is crushed too fast, and the test mold is unloaded after the test mold is maintained for 2 min;
G. demoulding the test mould, measuring the height h, calculating the volume V of the test piece, and weighing the mass m of the test piece2；
H. Calculating the water content omega and the dry density rho by taking the cement dosage as c and the water content of the mixture as w;
I. and establishing a quadratic relation curve by taking the water content omega as a horizontal axis and the dry density rho as a vertical axis, taking the extreme value of the dry density as the maximum dry density, and taking the water content corresponding to the maximum dry density as the optimal water content.
When the step A is implemented, the medium value of the grading range specified by the specification is used as the design grading, and the specific grading is shown as the following table:
the size of the test mold is selected according to the maximum nominal particle size.
When the step B is implemented, 7 samples are prepared by adopting a method in specification T0804-1994, wherein the 7 samples correspond to 7 different water contents (2.6%, 3.6%, 4.1%, 4.6%, 5.1%, 5.6% and 6.6%), 240g of 210-sand-containing soil with the grain size of 0-9.5mm is weighed in the gradation, and 2200g of 2000-sand-containing soil with the grain size of 9.5-26.5mm is weighed; 6000-6400g of coarse-grained soil with the grain diameter of 26.5-31.5mm is weighed.
And C, when the step C is implemented, independently sealing the samples prepared in the step B by adopting a method provided in specification T0843-2009, wherein the water adding amount of the sealed materials is 1% -2% lower than the preset water content, and coating engine oil on the inner wall of the test mold. If the aggregate is clay soil, the material sealing time is 12-24 h; if the soil is silty soil, the material sealing time is 6-8 h; if the soil is sandy soil, gravel soil, laterite gravel, graded gravel and the like, the material sealing time can be shortened to 4 hours; the unsieved broken stones, gravels and sands with little soil are contained, and the material sealing time can be shortened to 2 hours.
And D, respectively mixing 3% (in percentage by weight of the aggregate and the cement) of No. 42.5 ordinary portland cement with 3% of c and 7 samples subjected to blank filling to form 7 parts of mixed materials, adding 1% -2% of the residual preset water content in the mixing process, and forming a test piece within 1 hour after the mixing is finished, wherein the shorter the test piece forming time is, the better the test piece forming time is.
When the step E is implemented, 7 parts of mixture are respectively filled into the test molds, and each part of mixture is filled for 2 to 3 times, andrecording the filled mix mass m1。
And F, pressurizing to 500KN at a loading rate of 1mm/min, maintaining the pressure for 2min, and then unloading.
When step H is implemented, each parameter is substituted into a formula
The 7 water contents ω of 0.04131, 0.04247, 0.04324, 0.04452, 0.04528, 0.04634 and 0.04748 were calculated.
And substituting the parameters into the formula
In the above, 7 corresponding dry densities (unit g/cm) were calculated3)ρ＝2.0436，2.1043，2.2948，2.3328，2.3304，2.3146，2.3029。
Wherein omega is the water content of the cement stabilized macadam mixture;
rho is the dry density of the cement stabilized macadam mixture;
w-water content of the mixture;
m1-the mass of mix filled into the mould before applying pressure;
c-the amount of cement added when blending the mix;
m2the quality of the test piece after pressure application and demoulding;
v is the volume of the test piece after pressure is applied and demoulding.
And (3) when the step I is implemented, establishing a quadratic curve by taking the 7 water contents obtained in the step H as a horizontal axis and the corresponding 7 dry densities as a vertical axis, and taking a dry density mechanism as the maximum dry density, wherein the corresponding water content is the optimal water content. The extreme dry density (i.e., maximum dry density) is 2.33g/cm3Corresponding to an optimum water content of 4.4%.
The compaction test is carried out under the condition that the cement dosage is 3 percent, and the optimal water content is 4.6 percent and the maximum dry density is 2.32g/cm when the cement dosage is 3 percent3。
It can be seen that the error between the maximum dry density determined by the hydrostatic method for the cement-stabilized macadam of the present invention and the result of the compaction test is (2.33-2.32)/2.32 × 100% ═ 0.43%, and the error between the optimum water content is (4.6-4.4)/4.6 × 100% > -4.35%, both of which are within 5%, which indicates the effectiveness of the method for determining the optimum water content and the maximum dry density of the cement-stabilized macadam provided by the present invention.
Example 2.1
A method for determining optimum water content and maximum dry density by hydrostatic pressure, substantially as in example 1, except that the cement content is 4%, and that, when step H is carried out by the method of the present invention, water contents 0.04239, 0.04328, 0.04453, 0.04547, 0.04636, 0.04712, 0.04846 are calculated; dry Density (units g/cm)3) 1.9948, 2.0564, 2.2463, 2.3438, 2.3396, 2.3046 and 2.2946. When the step I is implemented, the established secondary relation curve of the water content and the dry density obtains the maximum dry density rho of 2.34g/cm obtained by the method for determining the optimal water content and the maximum dry density of the cement stabilized macadam3The optimum water content omega is 4.5%.
The compaction test is carried out under the condition that the cement dosage is 4 percent, and the maximum dry density rho is 2.34g/cm3The optimum water content ω is 4.7%.
Therefore, the error between the maximum dry density determined by the static pressure method and the result of the compaction test is 0, and the error between the optimal water content is 4.26 percent and is within 5 percent, which shows the effectiveness of the method for determining the optimal water content and the maximum dry density of the cement stabilized macadam provided by the invention.
Example 2.2
A method for determining optimum water content and maximum dry density by hydrostatic pressure substantially as described in example 1, except that the cement content is 5%, and that, when step H is carried out by the method of the present invention, the water content is 0.04239, 0.04328, 0.04453, 0.04634, 0.04753, 0.04838, 0.04926 and the dry density (in g/cm) are calculated3) 1.8924, 2.1035, 2.1754, 2.3548, 2.3494, 2.3406 and 2.3357. When step I is carried out, the quadratic relation curve of the water content and the dry density is established to obtain the water-soluble organic fertilizerThe maximum dry density rho obtained by the method for determining the optimal water content and the maximum dry density of the cement stabilized macadam is 2.35g/cm3The optimum water content omega is 4.6%.
The compaction test is carried out under the condition that the cement dosage is 5 percent, and the maximum dry density rho is 2.33g/cm3The optimum water content ω is 4.7%.
Therefore, the error between the maximum dry density determined by the cement-stabilized macadam and the result of the compaction test is 0.86%, and the error between the optimum water content is 2.13%, which are both within 5%, so that the effectiveness of the method for determining the optimum water content and the maximum dry density of the cement-stabilized macadam provided by the invention is demonstrated.
Example 2.3
A method for determining the optimum water content and the maximum dry density by the hydrostatic method, substantially as in example 1, except that the cement content is 6%, step H is carried out with a water content of 0.04216, 0.04348, 0.04406, 0.04613, 0.04733, 0.04806, 0.04943 and a dry density (in g/cm)3) 1.9235, 2.1154, 2.1853, 2.3503, 2.3414, 2.3391 and 2.2347. When the step I is implemented, the established secondary relation curve of the water content and the dry density obtains the maximum dry density rho of 2.35g/cm obtained by the method for determining the optimal water content and the maximum dry density of the cement stabilized macadam3The optimum water content omega is 4.6%.
The compaction test is carried out under the condition that the cement dosage is 6 percent, and the maximum dry density rho is 2.34g/cm3The optimum water content omega is 4.8%.
Therefore, the error between the maximum dry density determined by the cement-stabilized macadam and the result of the compaction test is 0.43%, and the error between the optimum water content is 4.17%, which are both within 5%, so that the effectiveness of the method for determining the optimum water content and the maximum dry density of the cement-stabilized macadam provided by the invention is demonstrated.
Example 3.1
A method for determining the optimum water content and the maximum dry density by the hydrostatic method is substantially the same as in example 1 or 2.1 or 2.2 or 2.3, except that step F is carried out by pressurizing to 500KN at a load rate of 1mm/min and unloading after maintaining the pressure for 5min, with the result that the water content and the maximum dry density are not changed.
Example 3.2
A method for determining the optimum water content and the maximum dry density by the hydrostatic method is substantially the same as in example 1 or 2.1 or 2.2 or 2.3, except that step F is carried out by pressurizing to 500KN at a load rate of 1mm/min and unloading after maintaining the pressure for 3min, with the result that the water content and the maximum dry density are not changed.
Example 3.3
A method for determining the optimum water content and the maximum dry density by the hydrostatic method is substantially the same as in example 1 or 2.1 or 2.2 or 2.3, except that step F is carried out by pressurizing to 500KN at a load rate of 1mm/min and unloading after maintaining the pressure for 7min, with the result that the water content and the maximum dry density are not changed.
Example 3.4
A method for determining the optimum water content and the maximum dry density by the hydrostatic method is substantially the same as in example 1 or 2.1 or 2.2 or 2.3, except that step F is carried out by pressurizing to 500KN at a load rate of 1mm/min and unloading after maintaining the pressure for 10min, with the result that the water content and the maximum dry density are not changed.
Example 3.5
A method for determining the optimum water content and the maximum dry density by the hydrostatic method is substantially the same as in example 1 or 2.1 or 2.2 or 2.3, except that step F is carried out by pressurizing to 500KN at a load rate of 1mm/min and unloading after maintaining the pressure for 30min, with the result that the water content and the maximum dry density are not changed.
Example 3.6
A method for determining the optimum water content and the maximum dry density by the hydrostatic method is substantially the same as in example 1 or 2.1 or 2.2 or 2.3, except that step F is carried out by pressurizing to 500KN at a load rate of 1mm/min and unloading after maintaining the pressure for 50min, with the result that the water content and the maximum dry density are not changed.
Example 3.7
A method for determining the optimum water content and the maximum dry density by the hydrostatic method is substantially the same as in example 1 or 2.1 or 2.2 or 2.3, except that step F is carried out by pressurizing to 500KN at a load rate of 1mm/min, and unloading after maintaining the pressure for 120min, with the result that the water content and the maximum dry density are not changed.
Examples 1 and 3.1 to 3.7 show that when step F is carried out, the test piece is kept under a load of 500KN for 2min or more, so that the test piece is prevented from rebounding, and the accuracy of the measurement result is ensured. Meanwhile, the inventor also maintains the test piece for 1min under the load of 500KN, and the result shows that after the load is unloaded, the test piece rebounds, so that the height measurement of the time after demolding is inaccurate, and the volume calculation of the test piece is inaccurate, so that the calculation results of the water content and the dry density are influenced, and the finally obtained maximum dry density and the optimum water content have larger difference with the compaction test.
Example 4.1
A method for determining the optimum moisture content and the maximum dry density by the hydrostatic method was substantially the same as in example 1, except that in the case of carrying out the step B, 6 samples were prepared corresponding to moisture contents of 2.6%, 3.6%, 4.1%, 4.6%, 5.1%, 5.6%.
Example 4.2
An optimum moisture content and maximum dry density determination method by hydrostatic pressure was carried out substantially the same as in example 1 except that in carrying out step B, 8 samples were prepared corresponding to moisture contents of 2.6%, 3.6%, 4.1%, 4.6%, 5.1%, 5.6%, 6.6%, 7.6%.
Example 4.3
A method for determining the optimum moisture content and the maximum dry density by the hydrostatic method was substantially the same as in example 1, except that in the case of carrying out the step B, 5 samples were prepared corresponding to moisture contents of 3.6%, 4.1%, 4.6%, 5.1%, 5.6%.
Examples 4.1-4.3 are intended to illustrate the number of sample portions prepared, and the amount of water contained therein is not limited and can be selected by one skilled in the art.
It should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (15)
1. A method for determining optimum water content and maximum dry density by static pressure method comprises applying pressure to a molded test piece, pressurizing to 500KN at a loading rate of 1mm/min, and maintaining unloading for more than 2 min; calculating the water content omega and the dry density rho; establishing a quadratic relation curve by taking the water content omega as a horizontal axis and the dry density rho as a vertical axis, taking a dry density extreme value as a maximum dry density, taking the water content corresponding to the maximum dry density as an optimal water content, and calculating the water content by adopting a formula:
the dry density is calculated by the formula:
wherein m is1For the mass of mix filled into the mold before applying pressure,
m2for the quality of the test piece after applying pressure and demoulding,
v is the volume of the test piece after pressure is applied and demoulding;
the preparation of the molded test piece comprises the following steps:
A. preparing 5-8 parts of samples with different preset water contents w;
B. stuffing a test material;
C. and after the material sealing is finished, adding cement with a preset quantity c, uniformly mixing, and forming a test piece within 1 hour after the mixing is finished.
2. The method of determining the optimum moisture content and maximum dry density of claim 1, wherein: in the case of performing step A, 6 to 7 samples having different predetermined water contents w are prepared.
3. The method for determining the optimum moisture content and the maximum dry density according to claim 1 or 2, wherein: and B, implementing the step B, and smearing engine oil on the inner wall of the test mold during material sealing.
4. A method for determining the optimum moisture content and maximum dry density of claim 3, wherein: and B, implementing the step B, wherein the water adding amount is 1-2% lower than the preset water content when the materials are subjected to material sealing.
5. The method of determining the optimum moisture content and maximum dry density of claim 4, wherein: and C, implementing the step C, wherein the size of the test mold is selected according to the maximum nominal grain size of the design gradation when the test piece is formed.
6. The method of determining the optimum moisture content and maximum dry density of claim 5, wherein: and C, adding reserved water in the mixing process when the step C is carried out.
7. The method of determining the optimum moisture content and maximum dry density of claim 6, wherein: when a test piece is formed, a lower cushion block matched with a test mold is placed at the lower part of the test mold and exposed for 2cm, the mixture is poured into the test mold for 2 to 3 times, a tamping rod is used for lightly and uniformly inserting and compacting after each pouring, the test mold is approximately filled with the mixture, an upper cushion block matched with the test mold can be just placed into the test mold, and the mass m of the filled mixture is recorded1。
8. The method of determining the optimum moisture content and maximum dry density of claim 1, wherein: when the pressure is applied, the pressure is maintained for 3min under the condition of 500KN, and then the unloading is carried out.
9. The method of determining the optimum moisture content and maximum dry density of claim 1, wherein: when the pressure is applied, the pressure is maintained for 5min under the condition of 500KN, and then the unloading is carried out.
10. The method of determining the optimum moisture content and maximum dry density of claim 1, wherein: when the pressure is applied, the pressure is maintained for 7min under the condition of 500KN, and then the unloading is carried out.
11. The method of determining the optimum moisture content and maximum dry density of claim 1, wherein: when the pressure is applied, the pressure is maintained for 10min under the condition of 500KN, and then the unloading is carried out.
12. The method of determining the optimum moisture content and maximum dry density of claim 1, wherein: when the pressure is applied, the pressure is maintained for 30min under the condition of 500KN, and then the unloading is carried out.
13. The method of determining the optimum moisture content and maximum dry density of claim 1, wherein: when the pressure is applied, the pressure is maintained for 50min under the condition of 500KN, and then the unloading is carried out.
14. The method of determining the optimum moisture content and maximum dry density of claim 1, wherein: when the pressure is applied, the pressure is maintained for 120min under the condition of 500KN, and then the unloading is carried out.
15. The method for determining the optimum water content and the maximum dry density according to any one of claims 8 to 14, after the pressure is unloaded, removing the test mold, measuring the height h of the test piece, calculating the volume V of the test piece, and weighing the mass m of the test piece2。
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| CN106977148B (en) * | 2017-04-24 | 2019-03-29 | 广州大学 | A kind of cement stabilized recycled concrete aggregate rubble proportion design method |
| CN107219151A (en) * | 2017-05-08 | 2017-09-29 | 长安大学 | A kind of test method for determining roadbed soil-stone material maximum dry density |
| CN108101479A (en) * | 2017-11-22 | 2018-06-01 | 北京建筑大学 | A kind of lime based on small specimen, fine coal ash broken stones shrinkage performance test method |
| CN108225967B (en) * | 2017-12-26 | 2021-02-12 | 徐忠卫 | Method for testing stone content in cement stable gravel material |
| CN108593391A (en) * | 2018-07-23 | 2018-09-28 | 四川正达检测技术有限责任公司 | A kind of forming method of the engineering geotechnique carrying than test specimen |
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