CN113433032A - Test and evaluation method for pressure expansion degree variation of cement concrete mixture - Google Patents
Test and evaluation method for pressure expansion degree variation of cement concrete mixture Download PDFInfo
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- 239000004568 cement Substances 0.000 title claims abstract description 130
- 238000010998 test method Methods 0.000 title claims abstract description 13
- 238000011156 evaluation Methods 0.000 title description 9
- 238000005086 pumping Methods 0.000 claims abstract description 50
- 238000012360 testing method Methods 0.000 claims abstract description 24
- 238000001514 detection method Methods 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 22
- 238000006243 chemical reaction Methods 0.000 claims abstract description 9
- 230000009471 action Effects 0.000 claims abstract description 6
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 229910000831 Steel Inorganic materials 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
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- 238000010521 absorption reaction Methods 0.000 description 3
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- 238000011835 investigation Methods 0.000 description 2
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- 238000005259 measurement Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
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Abstract
The invention relates to a test method for the pressure expansion variation of a cement concrete mixture, which comprises the following steps: (1) determination of the expansion k of a cement concrete mixture by means of a slump cone0. (2) Performing a pressurization test on the same batch of cement concrete mixture obtained in the step (1), taking the pressurized cement concrete mixture as a detection object, and measuring the pressure expansion degree k of the cement concrete mixturemAnd k ismAnd said k0The detection time interval of (2) is not more than 10 min. (3) According to k1＝δk×kmIs given by the relationship ofmConversion to k1. (4) Calculating k0And k1The difference value between the two values is the pressure expansion loss value delta k of the cement concrete mixture, namely, delta k is k0－k1The larger the value of delta k, the greater the loss of fluidity of the corresponding cement concrete mixture under the action of pumping pressure, and the poorer the pumpability. This is the inventionThe method realizes the detection and quantitative analysis of the pumping pressure expansion loss value of the cement concrete mixture before construction.
Description
Technical Field
The invention relates to the technical field of cement concrete mixture fluidity test, in particular to a cement concrete mixture pressure expansion degree variation testing and evaluating method.
Background
The information disclosed in this background of the invention is only for enhancement of understanding of the general background of the invention and is not necessarily to be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
The expansion degree is a main technical index for representing the fluidity of the cement concrete mixture, and the larger the expansion degree is, the larger the corresponding fluidity is. The pumping construction is to carry the cement concrete mixture to the structural up end through concrete pump and pump line and pour the construction, and mobility is the main performance that characterizes the cement concrete mixture pumping construction degree of difficulty, and the expansion degree is bigger, and mobility is bigger, and corresponding cement concrete mixture is more easily the pumping construction, otherwise, the expansion degree is smaller, and mobility is smaller, is unfavorable for the pumping construction more, appears even that the pump line blocks up and can't carry out the casting construction. The practical findings are as follows: the fluidity of cement concrete mixtures tends to decrease and lose under the pumping pressure during pumping, mainly due to the following reasons:
on the first hand, under the action of pumping pressure, moisture enters the capillary pores of the aggregate, and the free water content of the slurry of the cement concrete mixture is reduced.
In a second aspect, lubricating bubbles between the aggregates are broken under the pumping pressure.
In the third aspect, mud powder and other substances with wet swelling property in the cement concrete mixture absorb water under pressure and wet swelling under the action of pumping pressure, so that the adsorption quantity of water reducing agent molecules with a fluidization effect is increased.
Above aspect all can cause cement concrete mixture to reduce at the pump sending extension, become thick, mobility descends, can appear cement concrete mixture when serious and appear segregation dry and astringent phenomenon.
At present, the expansion degree of the cement concrete mixture is measured by actual site construction, the expansion degree of the cement concrete mixture is measured when the cement concrete mixture enters a pump, the expansion degree of the cement concrete mixture at the mouth of a pouring surface delivery pump is measured, and the difference value of the expansion degree and the expansion degree is the loss value of the pumping pressure expansion degree of the cement concrete mixture. However, the detection control method is limited to on-site control, and the pumping pressure expansion loss value of the cement concrete mixture before pumping is unknown and uncontrollable, and can only be obtained by trial pumping detection in actual construction, so that unpredictability and risk of pumping construction are increased, and the pumping construction may not have any problem, and the casting difficulty is increased, even the pump blocking construction is interrupted, and large manpower and material resources are consumed for treatment, so that unnecessary quality and economic loss are caused.
Disclosure of Invention
The loss value of the pumping pressure expansion degree of the cement concrete mixture cannot be detected and evaluated in advance, and the pumpability of the corresponding cement concrete mixture cannot be pre-controlled in advance, so that the method is a key problem which is urgently needed to be solved by the current concrete pumping construction control, and is particularly important for ultra-long and ultra-high pumping construction control. Therefore, the invention provides a test and evaluation method for the pressure expansion variation of the cement concrete mixture, which realizes the detection and quantitative analysis of the pumping pressure expansion loss value of the cement concrete mixture before construction. In order to achieve the above object, the technical solution of the present invention is as follows.
In a first aspect of the invention, a method for testing the pressure expansion variation of a cement concrete mixture is disclosed, which comprises the following steps:
(1) determination of the expansion k of a cement concrete mixture by means of a slump cone0。
(2) Performing a pressurization test on the same batch of cement concrete mixture obtained in the step (1), taking the pressurized cement concrete mixture as a detection object, and measuring the pressure expansion degree k of the cement concrete mixturemAnd k ismAnd said k0The detection time interval of (2) is not more than 10min to ensure the accuracy of the calculation result.
(3) According to k1＝δk×kmIs given by the relationship ofmConversion to k1Wherein: k is1Representing the slump cone converted spread, deltakRepresents a conversion coefficient, and k0、k1、dmThe units are the same; delta. thek＝2.3－0.1k0/300＋0.008dm。
(4) Calculating k0And k1The difference value between the two values is the pressure expansion loss value delta k of the cement concrete mixture, namely, delta k is k0－k1。
Further, in the step (1), k is0The test method comprises the following steps: preparing a cement concrete mixture and uniformly mixing, extracting a part of the cement concrete mixture, loading the cement concrete mixture into a slump cone, calculating the expansion k of the cement concrete mixture after the surface of the concrete mixture in the slump cone does not have large bubbles and does not sink any more0And (5) obtaining the product.
Further, will cement concrete mixture packs into behind the slump section of thick bamboo into, adopts the hammer to strike a slump section of thick bamboo outer wall, on the one hand to guarantee that concrete mixture can fill a slump section of thick bamboo completely and promote gaseous ground discharge wherein, on the other hand, prevent to adopt and smash the stick and insert excessive piling up of stone in slump section of thick bamboo bottom and appear great surface laitance and lead to the bottom to cause cement concrete mixture each component in the slump section of thick bamboo uneven phenomena such as layering settlement appear, thereby lead to great test error.
Further, in the step (2), the k is tested by a concrete pressure bleeding instrumentm. Preferably, a metal mesh, lower filter paper, a perforated steel plate and upper filter paper are sequentially placed in a bottom bin of the concrete pressure bleeding instrument from bottom to top, and water is injected into the bottom bin until the water is flush with the surface of the perforated steel plate.
Further, the k is tested by a concrete pressure bleeding instrumentmThe method comprises the following steps: vibrating the cement concrete mixture, pressurizing the vibrated cement concrete mixture, and measuring the expansion k of the pressurized cement concrete mixture by using a semi-slump conem。
Further, the method of vibrating a cement concrete mixture comprises: and (3) filling the cement concrete mixture into the pressure-bearing cylinder body in two layers, inserting and smashing each layer, and symmetrically and uniformly beating the outer wall of the pressure-bearing cylinder body by using a hammer until the inserting and smashing holes on the surface of the cement concrete mixture disappear and large bubbles are not found. Optionally, the tamping is performed by uniformly tamping the tamping bar from the edge to the center.
Further, the method for pressurizing the vibrated cement concrete mixture comprises the following steps: pressurizing the cement concrete mixture in the pressure-bearing cylinder body by a pressurizing device of a concrete pressure bleeding instrument, wherein the pressurizing pressure is 4-6 MPa and is kept for 20-30 s, preferably 5.5MPa and is kept for 30 s; and after pressurization is finished, taking out the cement concrete mixture, uniformly mixing, and recording as the cement concrete mixture to be measured.
Further, the expansion k of the pressurized cement concrete mixture is measured by adopting a semi-slump conemThe method comprises the following steps: screening aggregate with the size exceeding 31.5mm in the cement concrete mixture to be detected, loading the aggregate into a semi-slump cylinder, not inserting and tamping the aggregate during loading, knocking the semi-slump cylinder through a rubber hammer, and waiting for no large bubble on the surface of the concrete mixture in the semi-slump cylinder and no sinkingAnd calculating the expansion degree k of the cement concrete mixture to be measuredmAnd (5) obtaining the product. In general, the capacity of the semi-slump cone is limited, and when the aggregate with the size of more than 31.5mm is excessive, other materials in the mixture are difficult to add into the semi-slump cone or the proportion is small, so that the sample amount of the obtained mixture is insufficient.
Further, after the cement concrete mixture to be tested is filled into the semi-slump cylinder, the outer wall of the semi-slump cylinder is knocked by a hammer to promote the settlement of the concrete mixture and the gas discharge of the concrete mixture.
Further, in step (3), k in the following table proposed by the present invention can also be used0、dm、δkObtaining k from the conversion relation of1The numerical value of (c). Relative to according to k1＝δk×km，δk＝2.3－0.1k0/300＋0.008dmCalculating the k1And the table look-up mode is more convenient and faster.
k0、dm、δkThe units of the numerical values in the table are mm.
Further, in the step (3), k is0、k1、dmAre all accurate to 1mm, deltakTo the nearest 0.01 mm.
In a second aspect of the present invention, a method for evaluating pumpability of a cement concrete mixture is disclosed: and evaluating the pumpability of the cement concrete mixture according to the delta k: the larger the value of Δ k, the greater the loss of fluidity of the corresponding cement concrete mixture under the action of pumping pressure, and the worse it can be pumped.
Furthermore, the pumping performance of the cement concrete mixture is qualified, good and excellent respectively when the delta k is less than or equal to 120, the delta k is less than or equal to 90 and the delta k is less than or equal to 60.
Compared with the prior art, the invention has the following beneficial effects:
(1) the testing method provided by the invention realizes the detection and quantitative analysis of the pumping pressure expansion loss value of the cement concrete mixture before construction, provides a method for evaluating the pressure expansion loss value delta k of the cement concrete mixture and the pumpability of the cement concrete mixture, and the corresponding technical requirements of different pumping heights on the pressure expansion loss value delta k of the cement concrete mixture, and realizes the scientific and objective advance pre-control and evaluation of the pumpability of the cement concrete mixture. So that: the method realizes the purpose of predicting whether the constructed concrete meets the pouring requirement of pumping construction in advance, avoids the problems of pump blockage and pouring quality, has great significance for avoiding and reducing pumping construction and quality risks and reducing and avoiding economic loss, and particularly realizes effective control and smooth construction of ultra-long and ultra-high pumping construction. In addition, data support and basis can be provided for the evaluation and improvement of the design performance of the mixing proportion, so that the construction quality of the cement concrete is improved.
(2) Testing the k by a concrete pressure bleeding instrumentmWhen the invention is used, the filter paper, the perforated steel plate and the metal net are combined and placed in the bottom bin, and the bottom bin is filled with water, and the invention has the advantages that: on one hand, the cement concrete sample can be prevented from pressing excessive water and cement paste into the bottom bin under the action of piston pressure. On the other hand, due to the function of the filter paper, excessive water in the bottom bin can be prevented from migrating into concrete during charging and vibrating; the actual pumping pressure state of the cement concrete mixture can be well reflected, and the effectiveness and accuracy of detection are improved.
(3) Because of being limited by the capacity of the concrete pressure bleeding instrument, the sample amount of the cement concrete mixture in the cylinder body after the pressure test is finished cannot meet the sample amount required by the expansion degree detection of the primary slump cone, the test times are increased, the test workload and time are increased, and the test efficiency is reduced; and a correlation mathematical formula and a recommendation table of the expansion degree of the semi-slump detection and the expansion degree of the slump cone detection are provided, so that the expansion degree of the semi-slump detection and the expansion degree of the slump cone detection are converted, the test workload and time are obviously saved, and the test work efficiency is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic structural view of a tapered slump cone in an embodiment of the present invention, wherein: the slump cone is a cylindrical structure with a cone body communicated up and down, and the inner diameter of the upper end surface of the slump coned 1 Is 100mm, and the inner diameter of the lower bottom surfaced 2 Is 200mm in heighth 1 Is 300 mm.
Fig. 2 is a schematic structural diagram of a concrete pressure bleeding instrument in the embodiment of the invention.
FIG. 3 is a schematic view of the combination of filter paper, perforated steel plate, filter paper and metal mesh in the embodiment of the present invention.
FIG. 4 is a schematic structural view of a tapered semi-slump cone in an embodiment of the invention, wherein: the slump cone is a cylindrical structure with a cone body communicated up and down, and the inner diameter of the upper end surface of the slump coned 3 Is 50mm, and the inner diameter of the lower bottom surfaced 4 Is 100mm in heighth 2 Is 150 mm.
The scores in the above figures represent: 1-a pressure gauge; 2-an oil pump; 3-a piston; 4-a pressure-bearing cylinder body; 5-bottom bin; 6-upper filter paper; 7-perforated steel plate; 8-lower layer filter paper; 9-metal screen; 10-fastening bolts.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and the specific meaning of such terms in the present invention can be understood as appropriate to one of ordinary skill in the art. The description will be further described with reference to the drawings and specific examples.
First embodiment
A test and evaluation method for the pressure expansion variation of a cement concrete mixture comprises the following specific steps:
(1) and (3) preparing a C30 cement concrete mixture for pumping, wherein the sampling quantity is 20L, the maximum nominal particle size of the aggregate is 25mm, and uniformly mixing the samples to obtain a cement concrete mixture sample for later use.
(2) A portion of the sample is extracted from the cement concrete mixture sample and is filled into a slump cone as shown in figure 1 to determine the cement concrete mixture spread k0Found to be 650 mm.
(3) Because the quantity of the cement concrete mixture sample required by the slump cone cannot be obtained at one time due to the limit of the capacity of the concrete pressure bleeding instrument, the test time is too long due to the fact that the pressure is applied for multiple times, and the cement concrete mixture sample obtained for multiple times has a variable quantity, in this embodiment, part of the cement concrete mixture sample prepared in the step (1) is extracted at the same time, the concrete pressure bleeding instrument shown in the figure 2 is used for carrying out a pressurization test, and the pressure expansion k of the part of the cement concrete mixture is measured on the basis of the pressure expansion kmFound as 200mm, and kmAnd said k0The detection time interval of (2) is within 10min, and the time can change after the samples are taken out, so even if the same sample is taken out, if one of the two samples is just taken out for testing, and the other sample is placed for a period of time for testing, the tested data can be inaccurate. k is a radical ofmThe specific determination steps are as follows:
(i) placing the concrete pressure bleeding instrument on a flat ground, keeping the concrete pressure bleeding instrument horizontal, opening the concrete pressure bleeding instrument, as shown in figures 2 and 3, sequentially placing an upper layer filter paper 6, a perforated steel plate 7, a lower layer filter paper 8 and a metal mesh 9 from top to bottom in a bottom bin 5 of the concrete pressure bleeding instrument, and then injecting water into the bottom bin 5 until the water is flush with the upper surface of the perforated steel plate 7.
(ii) The cement concrete mixture sample is loaded into a pressure-bearing cylinder 4 of a pressure bleeding instrument in two layers, the number of times of inserting and tamping is 6 when one layer is loaded, a tamping rod is uniformly inserted and tamped from the edge to the center, and the outer wall of the cylinder is symmetrically and uniformly beaten for 6 times by a rubber hammer gently until the inserting and tamping holes on the surface of the mixture disappear and no large bubbles are found.
(iii) After the cover body of the concrete pressure bleeding instrument is covered, the fastening bolt 10 is screwed down, air impermeability is guaranteed, the oil pump 2 is started, the band-pass piston 3 is pressurized to 5.5MPa and kept for 30s, the pressurizing pressure can be read out from the pressure gauge, the cover body is opened after the pressurization is completed, the cement concrete mixture sample is taken out, and then the mixing is uniform, so that the cement concrete mixture sample to be tested is obtained.
(iv) Before charging, screening aggregate with the size exceeding 31.5mm in the cement concrete mixture sample to be measured by using a sieve with the aperture of 31.5mm, then putting the cement concrete mixture sample to be measured into a semi-slump cylinder shown as 4, gently and uniformly beating the outer wall of the cylinder body for 6 times by using a rubber hammer until no large bubble is found on the surface of the concrete mixture in the semi-slump cylinder and the concrete mixture does not sink any more, and then determining the expansion k of the cement concrete mixturemAn actual measurement value of 200mm was obtained.
(4) Measuring the slump constant k obtained in the step (2)0Measured value of 650mm and maximum nominal particle diameter d of coarse aggregate of cement concrete mixture samplemMeasured value of (d) is substituted into the conversion coefficient delta by 25mmkIn the calculation formula (2): deltak= 2.3－0.1k0/300＋0.008dmTo obtain a conversion coefficient deltak=2.28。
(5) Substituting the measured value of the expansion degree km of the half-slump cone into the formula of the slump cone converted expansion degree k1, wherein the measured value is 200 mm: k is a radical of1＝δk×kmTo obtain k1=456mm。
(6) Calculating the spread k of a slump cone determination0Measured value of 650mm and slump cone converted spread k1Is recorded as the difference between the measured values of (delta k) and (k) of (d)0－k1(ii) a And the delta k is the pressure expansion loss value of the cement concrete mixture, and the obtained delta k =194 mm.
Referring to Table 1, the pressure expansion loss value Deltak is greater than 120, which is not qualified, so that the cement concrete mixture can not meet the construction requirements after being pumped.
TABLE 1 technical requirements of different pumping heights for pressure expansion loss value Delta k of cement concrete mixture
| Pumpability rating | Qualified | Good wine | Superior food |
| Pumping height (mm) | <100 | 100~200 | >200 |
| Loss value of degree of pressure expansion Δ k (mm) | ≤120 | ≤90 | ≤60 |
The investigation and analysis show that the reason for the large loss value of the pressure expansion is that: the sand has low strength and water absorption rate of particles with the particle diameter of more than 5mm, and the crushing index value is 33 percent.
The improved adjustment measures are as follows: sieving the sand by adopting a 4.75mm square-hole sieve, preparing concrete according to the same mixing proportion, and detecting the pressure expansion loss value according to the same method, wherein the detection result is as follows: maximum nominal particle diameter d of aggregatemIs 25mm, k0Found 638mm, kmFound 258 mm. Calculated, deltakIs 2.29, k1590mm and 47mm as Δ k.
The analysis and evaluation are continued by referring to the table 1, and it can be seen that the pressure expansion loss value delta k after the improvement and the adjustment meets the requirements, the concrete pumping construction with the pumping height of more than 200mm is met, and the pumping grade is excellent.
Further, putting the cement concrete mixture meeting the requirements into pumping construction, and detecting that: the pump-in expansion degree is 650mm, the expansion degree of the pump-out pipe orifice after pumping is 595, the pressure expansion loss value delta k is 55mm, the pumping and pouring construction is smooth, and the construction technical quality requirement is met.
Second embodiment
(1) Preparing a C50 cement concrete mixture for pumping, wherein the maximum nominal particle size of the aggregate is 20mm, and the mixture is used for pumping construction and is detected as follows: the pump-in expansion degree is 660mm, the expansion degree of the pump-out pipe orifice after pumping is 400, the pressure expansion loss value delta k is 260mm, the pressure expansion loss is large, the pumping and pouring speed is low, and the pump is blocked during pouring.
(2) The investigation and analysis show that the loss of the pressure expansion is large because: the crushing index value of the particles with the particle diameter of more than 5mm in the sand is 32 percent, and the strength is low; the stones are granite, and the saturated surface dry water absorption is 3.2%. The improved adjustment measures are as follows: sieving the sand by using a 4.75mm square hole sieve; the stones are replaced by limestone materials, the saturated surface dry water absorption is 0.8%, and the concrete is prepared according to the same mixing ratio.
(3) The adjusted and prepared C50 cement concrete mixture is subjected to pressure expansion loss value detection, and the detection method is referred to the first embodiment. The detection result is as follows: maximum particle diameter d of aggregatemIs 20mm, k0Is 645mm, kmFound 263 mm.
(4) Look up δ according to Table 2k=2.24, calculated, k1589mm, Δ k 56mm, and an analytical evaluation made in comparison with Table 1 above, it can be seen that: improved adjusted pump height compliance>The pumping grade of the concrete with the thickness of 200mm is excellent. Putting the cement concrete mixture into pumping construction, and detecting: the pump-in expansion degree is 640mm, and the pump-out pipe orifice expansion degree after pumping590, the pressure expansion loss value delta k is 50mm, the pumping pouring construction is smooth, and the construction technical quality requirement is met.
TABLE 2 k0、dm、δkThe units of the numerical values in the table are mm.
The testing method provided by the invention can be used for detecting and quantitatively analyzing the expansion loss value of the pumping pressure of the cement concrete mixture in a laboratory before construction, and realizes scientific and objective advance pre-control and evaluation on the pumpability of the cement concrete mixture. Therefore, the purpose of predicting whether the constructed concrete meets the pouring requirement of pumping construction or not in advance is achieved, the problems of pump blockage and pouring quality are avoided, pumping construction and quality risks are avoided and reduced, economic loss is reduced and avoided, and the method has great significance for effectively controlling and smoothly constructing ultra-long and ultra-high pumping construction.
Finally, it should be understood that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (10)
1. A test method for the pressure expansion variation of a cement concrete mixture comprises the following steps:
(1) determination of the expansion k of a cement concrete mixture by means of a slump cone0；
(2) Performing a pressurization test on the same batch of cement concrete mixture obtained in the step (1), taking the cement concrete mixture after pressurization as a detection object,measuring its pressure spread kmAnd k ismAnd said k0The detection time interval of (2) is not more than 10 min;
(3) according to k1＝δk×kmIs given by the relationship ofmConversion to k1Wherein: k is1Representing the slump cone converted spread, deltakRepresents a conversion coefficient, and k0、k1、dmThe units are the same; delta. thek＝2.3－0.1k0/300＋0.008dm；
(4) Calculating k0And k1The difference value between the two values is the pressure expansion loss value delta k of the cement concrete mixture, namely, delta k is k0－k1。
2. The cement concrete mixture pressure spread variation test method according to claim 1, wherein in step (1), k is0The test method comprises the following steps: preparing a cement concrete mixture and uniformly mixing, extracting a part of the cement concrete mixture, filling the cement concrete mixture into a slump cone, and testing to obtain the expansion k of the cement concrete mixture after no air bubble is found on the surface of the concrete mixture in the slump cone and the concrete mixture does not sink any more0(ii) a Preferably, after the cement concrete mixture is loaded into the slump cone, the outer wall of the slump cone is knocked by a hammer.
3. The cement concrete mixture pressure spread variation testing method according to claim 1, wherein in the step (2), the k is tested by a concrete pressure bleeding instrumentm(ii) a Preferably, a metal mesh, lower filter paper, a perforated steel plate and upper filter paper are sequentially placed in a bottom bin of the concrete pressure bleeding instrument from bottom to top, and water is injected into the bottom bin until the water is flush with the surface of the perforated steel plate.
4. The method for testing the pressure expansion variation of a cement concrete mixture as claimed in claim 3, wherein a concrete pressure bleeding tester is adoptedK ismThe method comprises the following steps: vibrating the cement concrete mixture, pressurizing the vibrated cement concrete mixture, and measuring the expansion k of the pressurized cement concrete mixture by using a semi-slump conem。
5. The cement concrete mixture pressure spread variation test method of claim 4, wherein the method of pressurizing the vibrated cement concrete mixture comprises: loading the cement concrete mixture into a pressure-bearing cylinder body and ensuring complete filling, pressurizing the cement concrete mixture in the pressure-bearing cylinder body through a pressurizing device of a concrete pressure bleeding instrument, taking out the cement concrete mixture and uniformly mixing, and marking as the cement concrete mixture to be tested; preferably, the pressurizing pressure is 4 to 6MPa and is maintained for 20 to 30s, and more preferably, the pressurizing pressure is 5.5MPa and is maintained for 30 s.
6. The method for testing the pressure expansion variation of a cement concrete mixture as claimed in claim 5, wherein said method for measuring the expansion k of a pressurized cement concrete mixture by using a semi-slump conemThe method comprises the following steps: screening aggregate with the size exceeding 31.5mm in the cement concrete mixture to be measured, loading the aggregate into a semi-slump cylinder, not inserting and tamping during loading, knocking the semi-slump cylinder through a rubber hammer, calculating the expansion k of the cement concrete mixture to be measured when the surface of the concrete mixture in the semi-slump cylinder does not have large bubbles and does not sink any moremObtaining the product;
preferably, after the cement concrete mixture to be tested is filled into the semi-slump cone, the outer wall of the slump cone is knocked by adopting a hammer.
7. The cement concrete mixture pressure spread variation test method according to any one of claims 1 to 6, wherein in step (3), k in the following table is used0、dm、δkObtaining k from the conversion relation of1The units of the values in the table are mm:
8. the cement concrete mixture pressure spread variation test method according to claim 7, wherein in step (3), k is0、k1、dmAre all accurate to 1mm, deltakTo the nearest 0.01 mm.
9. A method for evaluating the pumpability of a cement concrete mixture, characterized in that the pumpability of a cement concrete mixture is evaluated according to Δ k calculated by the test method according to any one of claims 1 to 8: the larger the value of Δ k, the greater the loss of fluidity of the corresponding cement concrete mixture under the action of pumping pressure, and the worse it can be pumped.
10. The method for evaluating the pumpability of a cement concrete mixture as claimed in claim 9, wherein said Δ k ≦ 120, Δ k ≦ 90, and Δ k ≦ 60 are acceptable, good, and excellent, respectively, for the pumpability of the cement concrete mixture.
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