CN112479650A - Desert sand sprayed concrete and preparation method thereof - Google Patents
Desert sand sprayed concrete and preparation method thereof Download PDFInfo
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- CN112479650A CN112479650A CN202011317568.8A CN202011317568A CN112479650A CN 112479650 A CN112479650 A CN 112479650A CN 202011317568 A CN202011317568 A CN 202011317568A CN 112479650 A CN112479650 A CN 112479650A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00146—Sprayable or pumpable mixtures
- C04B2111/00155—Sprayable, i.e. concrete-like, materials able to be shaped by spraying instead of by casting, e.g. gunite
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/05—Materials having an early high strength, e.g. allowing fast demoulding or formless casting
Abstract
The invention discloses desert sand sprayed concrete and a preparation method thereof, wherein the desert sand sprayed concrete comprises the following raw materials in parts by weight: 230 portions of water 180-. The invention aims to provide the shotcrete which has high early strength, low cost and environmental friendliness.
Description
Technical Field
The invention relates to the technical field of concrete, in particular to desert sand shotcrete and a preparation method thereof.
Background
The sprayed concrete is a construction method for pouring fine stone concrete by spraying a pressure spray gun. It is commonly used for pouring linings of tunnel, linings of thin-wall structures such as wall and ceiling, or linings of other structures, and protective layers of steel structures. The sprayed concrete is formed by filling cement, sand, stones, water and a certain amount of additives which are prepared in advance into a spraying machine, sending the mixture to a spray head by utilizing high-pressure air, mixing the mixture with an accelerating agent and spraying the mixture to the surface of the rock or the concrete at a high speed.
The compressive strength is one of evaluation indexes of the sprayed concrete, and the compressive strength of the sprayed concrete is generally improved by adopting the following method at present: (1) and optimizing the mechanical sand grading. In actual construction, the consumption of concrete is large, the sand rate in sprayed concrete is usually over 45 percent, so that a large amount of machine-made sand needs to be consumed, and the gradation of the machine-made sand is adjusted, so that the standard of the machine-made sand is undoubtedly further improved, and the cost of the concrete is increased; (2) adding fly ash. The later-stage compressive strength of the concrete can be improved by the fly ash, but the early-stage compressive strength is reduced at the same time, which is contrary to the requirement of high early-stage strength requirement of sprayed concrete in actual construction.
Disclosure of Invention
The invention mainly aims to provide desert sand sprayed concrete and a preparation method thereof, and aims to provide the sprayed concrete with high early strength and low cost.
In order to achieve the purpose, the invention provides desert sand sprayed concrete which comprises the following raw materials in parts by weight: 230 portions of water 180-.
Optionally, the sand rate is 35% -45%; and/or the presence of a gas in the gas,
the fineness modulus of the desert sand is more than 0.2, and the mud content is less than 0.5%.
Optionally, the raw materials in parts by weight are as follows: 202 parts of water, 404 parts of cement, 959 parts of coarse aggregate, 314 parts of machine-made sand, 471 parts of desert sand, 32 parts of accelerating agent and 8 parts of water reducing agent.
Optionally, the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%.
Optionally, the coarse aggregate is crushed stone with the particle size of 5-10 mm, the content of needle and flaky particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%.
Optionally, the accelerator is an alkali-free accelerator or a low-alkali accelerator; and/or the presence of a gas in the gas,
the cement comprises one or more of Portland cement, ordinary Portland cement and composite Portland cement; and/or the presence of a gas in the gas,
the water reducing rate of the water reducing agent is 25-29%.
Optionally, the setting accelerator has an initial setting time of no more than 3min and a final setting time of no more than 12 min.
Optionally, 24-28 parts of micro silicon powder is further included.
In order to achieve the above object, the present invention further provides a method for preparing desert sand shotcrete as described above, comprising the steps of:
mixing cement, coarse aggregate, machine-made sand, desert sand and part of water, and stirring for 4-8 min at the rotating speed of 300-400 r/min to obtain a solid raw material;
uniformly mixing the accelerator, the water reducer and the rest part of water to form a water aqua raw material;
and adding the water aqua raw material into the solid raw material, and stirring for 5-8 min at the temperature of 20-40 ℃ and the rotating speed of 400-500 r/min to obtain the sprayed concrete.
Optionally, the raw material of the desert sand shotcrete further comprises 24-28 parts of silica fume;
the method comprises the following steps of mixing cement, coarse aggregate, machine-made sand, desert sand and part of water, stirring for 4-8 min at the rotating speed of 300-400 r/min, and obtaining a solid raw material:
mixing cement, coarse aggregate, machine-made sand, desert sand, micro-silica powder and part of water, and stirring for 4-8 min at the rotating speed of 300-400 r/min to obtain the solid raw material.
In the technical scheme provided by the invention, the desert sand with wide sources is selected to replace machine-made sand, so that the sand rate is reduced, the cost of concrete spraying is greatly reduced, and the environmental and economic benefits are extremely high; by coordinating the amounts of the desert sand, the machine-made sand and the coarse aggregate and the water-cement ratio, the 1d compressive strength of the desert sand sprayed concrete is not less than 18MPa, and the 28d compressive strength meets the requirements of application scenes, so that the early strength of the sprayed concrete is improved while the later strength is ensured.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other related drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of an embodiment of a preparation method of desert sand shotcrete according to the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments.
It should be noted that those whose specific conditions are not specified in the examples were performed according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially. In addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B" including either A or B or both A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The sprayed concrete is a construction method for pouring fine stone concrete by spraying a pressure spray gun. It is commonly used for pouring linings of tunnel, linings of thin-wall structures such as wall and ceiling, or linings of other structures, and protective layers of steel structures. The sprayed concrete is formed by filling cement, sand, stones, water and a certain amount of additives which are prepared in advance into a spraying machine, sending the mixture to a spray head by utilizing high-pressure air, mixing the mixture with an accelerating agent and spraying the mixture to the surface of the rock or the concrete at a high speed.
The compressive strength is one of evaluation indexes of the sprayed concrete, and the compressive strength of the sprayed concrete is generally improved by adopting the following method at present: (1) and optimizing the mechanical sand grading. In actual construction, the consumption of concrete is large, the sand rate in sprayed concrete is usually over 45 percent, so that a large amount of machine-made sand needs to be consumed, and the gradation of the machine-made sand is adjusted, so that the standard of the machine-made sand is undoubtedly further improved, and the cost of the concrete is increased; (2) adding fly ash. The later-stage compressive strength of the concrete can be improved by the fly ash, but the early-stage compressive strength is reduced at the same time, which is contrary to the requirement of high early-stage strength requirement of sprayed concrete in actual construction.
In order to achieve the purpose, the invention provides desert sand sprayed concrete which comprises the following raw materials in parts by weight: 230 portions of water 180-.
In the technical scheme provided by the invention, the desert sand with wide sources is selected to replace machine-made sand, so that the sand rate is reduced, and the cost of sprayed concrete is greatly reduced; by coordinating the amounts of the desert sand, the machine-made sand and the coarse aggregate and the water-cement ratio, the 1d compressive strength of the desert sand sprayed concrete is not less than 18MPa, and the 28d compressive strength meets the requirements of application scenes, so that the early strength of the sprayed concrete is improved while the later strength is ensured.
The machine-made sand is sand processed by the sand making machine and other accessory equipment, the finished product is more regular, and the sand can be processed into sand with different rules and sizes according to different process requirements, so that the daily requirement can be better met. Therefore, the cost of the machine-made sand is also more expensive. And the desert resources in China are abundant, and the inventor discovers that the Guerbantong Gute desert sand, the Mao Wusu desert sand, the Ulan cloth and the desert sand, the Tenggery desert sand or the Ku cloth and the same desert sand replace machine-made sand in a certain proportion by researching and comparing various desert sands, so that the sand rate of the concrete can be reduced, and the early compressive strength of the concrete can be further improved while the later compressive strength is ensured. Specifically, the selection criteria for desert sand can be quantified as a fineness modulus greater than 0.2 and a mud content less than 0.5 wt%.
As an optimal embodiment, the fineness modulus of the desert sand is further 0.3-1.2, and the desert sand with the fineness modulus of 0.3-1.2 is selected to partially replace machine-made sand, so that the aggregate grading of the concrete is further improved, the pore structure in the concrete is optimized, and the early compressive strength is improved.
In addition, the embodiment adjusts the sand rate of the concrete, controls the sand rate of the concrete to be between 35% and 45%, greatly reduces the sand rate compared with common sprayed concrete, reduces the using amount of fine aggregate and the cost on one hand, and also rationalizes the grading of the concrete aggregate on the other hand.
Considering that the concrete strength is reduced due to the fact that the desert sand is excessively mixed, the sand rate is reduced and the water-cement ratio is controlled on the basis of increasing the desert sand mixing amount, so that the desert sand mixing amount is stabilized to be 55% -65%, the concrete can still have high compressive strength under the mixing amount, and the cost is greatly reduced while the compressive strength of the concrete is ensured. Based on the optimization of the parts of the raw material components, the desert sand shotcrete of the embodiment comprises the following raw materials in parts by weight: 202 parts of water, 404 parts of cement, 959 parts of coarse aggregate, 314 parts of machine-made sand, 471 parts of desert sand, 16 parts of an accelerator and 28 parts of a water reducer.
In addition, the other components should meet the following criteria: the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%; the coarse aggregate is crushed stone with the thickness of 5-10 mm, the content of needle and sheet particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%; the accelerator is an alkali-free accelerator or a low-alkali accelerator, the initial setting time of the accelerator is not more than 3min, and the final setting time is not more than 12 min; the cement comprises one or more of Portland cement, ordinary Portland cement and composite Portland cement; the water reducing agent is preferably a water reducing agent having a water reducing ratio of 25% to 29%, for example, a high-performance polycarboxylic acid water reducing agent or the like.
In another embodiment of the present invention, the raw material of the desert sand shotcrete further comprises silica fume, and 24-28 parts of silica fume is correspondingly added to every 402-460 parts of cement by weight, for example, the desert sand shotcrete may comprise the following raw materials by weight: 230 parts of water 180-class, 460 parts of cement 402-class, 1000 parts of coarse aggregate 900-class, 24-28 parts of silica fume, 314 parts of machine-made sand 225-class, 475 parts of desert sand 307-class, 20-36 parts of accelerator and 4-8 parts of water reducer. The micro silicon powder can fill gaps among cement particles, so that the particle size distribution of a cementing material system is more reasonable, and the compactness of the internal structure of the concrete is improved.
In addition, the invention also provides a preparation method of the desert sand shotcrete, which is used for preparing the desert sand shotcrete. Fig. 1 is an embodiment of a preparation method of desert sand shotcrete according to the present invention.
Referring to fig. 1, the preparation method of the desert sand shotcrete comprises the following steps:
and step S10, mixing the cement, the coarse aggregate, the machine-made sand, the desert sand and part of water, and stirring for 4-8 min at the rotating speed of 300-400 r/min to obtain the solid raw material.
And step S20, uniformly mixing the accelerator, the water reducer and the rest part of water to form the water aqua raw material.
Wherein the weight parts of the components are as follows: 230 portions of water 180-. The weight ratio of the "part of water" in the step S10 to the "rest of water" in the step S20 may be 0.8-1.2: 1; the fineness modulus of the desert sand is more than 0.2, and the mud content is less than 0.5 wt%; the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%; the coarse aggregate is crushed stone with the thickness of 5-10 mm, the content of needle and sheet particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%; the accelerator is an alkali-free accelerator or a low-alkali accelerator, the initial setting time of the accelerator is not more than 3min, and the final setting time is not more than 12 min; the cement comprises one or more of Portland cement, ordinary Portland cement and composite Portland cement; the water reducing agent is preferably a water reducing agent having a water reducing ratio of 25% to 29%, for example, a high-performance polycarboxylic acid water reducing agent or the like.
And step S30, adding the water aqua raw material into the solid raw material, and stirring for 5-8 min at the temperature of 20-40 ℃ and the rotating speed of 400-500 r/min to obtain the sprayed concrete.
In an embodiment of the present invention, the raw material of the desert sand shotcrete further includes silica fume. In this embodiment, the preparation method of the desert sand shotcrete comprises the following steps:
and step S100, mixing cement, coarse aggregate, machine-made sand, desert sand, micro silicon powder and part of water, and stirring for 4-8 min at the rotating speed of 300-400 r/min to obtain a solid raw material.
And step S200, uniformly mixing the accelerator, the water reducer and the rest part of water to form an aqueous agent raw material.
And step S300, adding the water aqua raw material into the solid raw material, and stirring for 5-8 min at the temperature of 20-40 ℃ and the rotating speed of 400-500 r/min to obtain the sprayed concrete.
Wherein the weight parts of the components are as follows: 230 parts of water 180-class, 460 parts of cement 402-class, 1000 parts of coarse aggregate 900-class, 24-28 parts of silica fume, 314 parts of machine-made sand 225-class, 475 parts of desert sand 307-class, 16-18 parts of accelerator and 28-40 parts of water reducer.
The technical solutions of the present invention are further described in detail with reference to the following specific examples, which should be understood as merely illustrative and not limitative.
Example 1
Weighing 404 parts of cement, 959 parts of coarse aggregate, 314 parts of machine-made sand, 475 parts of desert sand and 102 parts of water, adding into a mixing stirrer, uniformly stirring, controlling the rotating speed of the mixing stirrer to be 300r/min, stirring for 4min, and obtaining the solid raw material after stirring. Wherein the cement is portland cement; the coarse aggregate is 4.75-9.5 continuous graded broken stone, the content of needle and flaky particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%; the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%; the fineness modulus of the desert sand is 0.3-1.2, and the mud content is less than 0.5%.
Weighing 36 parts of accelerator, 4 parts of water reducer and 100 parts of water, and uniformly stirring to obtain the water aqua raw material. Wherein the accelerator is an alkali-free accelerator, the initial setting time is not more than 3min, and the final setting time is not more than 12 min; the water reducing agent is a polycarboxylic acid water reducing agent and has a water reducing rate of 28 percent.
Adding the water agent raw material into a mixing stirrer filled with solid raw materials, controlling the rotating speed of the mixing stirrer to be 400r/min, stirring for 5min, and stirring at the temperature of 20 ℃, and obtaining the desert sand shotcrete after stirring.
Example 2
Weighing 402 parts of cement, 900 parts of coarse aggregate, 240 parts of machine-made sand, 360 parts of desert sand and 80 parts of water, adding the materials into a mixing stirrer, uniformly stirring, controlling the rotating speed of the mixing stirrer to be 350r/min, stirring for 7min, and obtaining the solid raw material after stirring. Wherein the cement is ordinary portland cement; the coarse aggregate is 4.75-9.5 continuous graded broken stone, the content of needle and flaky particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%; the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%; the fineness modulus of the desert sand is 0.3-1.2, and the mud content is less than 0.5%.
Weighing 26 parts of accelerator, 4 parts of water reducer and 100 parts of water, and uniformly stirring to obtain the water aqua raw material. Wherein the accelerator is an alkali-free accelerator, the initial setting time is not more than 3min, and the final setting time is not more than 12 min; the water reducing agent is a polycarboxylic acid water reducing agent and has a water reducing rate of 28 percent.
Adding the water agent raw material into a mixing stirrer filled with solid raw materials, controlling the rotating speed of the mixing stirrer to be 450r/min, stirring for 7min at the stirring temperature of 30 ℃, and obtaining the desert sand shotcrete after stirring.
Example 3
Weighing 460 parts of cement, 1000 parts of coarse aggregate, 225 parts of machine-made sand, 307 parts of desert sand and 115 parts of water, adding into a mixing stirrer, uniformly stirring, controlling the rotating speed of the mixing stirrer to be 400r/min, stirring for 8min, and obtaining the solid raw material after stirring. Wherein the cement is composite portland cement; the coarse aggregate is 4.75-9.5 continuous graded broken stone, the content of needle and flaky particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%; the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%; the fineness modulus of the desert sand is 0.3-1.2, and the mud content is less than 0.5%.
Weighing 28 parts of accelerator, 7 parts of water reducer and 115 parts of water, and uniformly stirring to obtain the water aqua raw material. Wherein the accelerator is an alkali-free accelerator, the initial setting time is not more than 3min, and the final setting time is not more than 12 min; the water reducing agent is a polycarboxylic acid water reducing agent and has a water reducing rate of 28 percent.
Adding the water agent raw material into a mixing stirrer filled with solid raw materials, controlling the rotating speed of the mixing stirrer to be 500r/min, stirring for 8min, and stirring at the temperature of 40 ℃, and obtaining the desert sand shotcrete after stirring.
Example 4
Weighing 404 parts of cement, 959 parts of coarse aggregate, 24 parts of silica fume, 314 parts of machine-made sand, 475 parts of desert sand and 102 parts of water, adding into a mixing stirrer, uniformly stirring, controlling the rotating speed of the mixing stirrer to be 300r/min, and stirring for 4min, and obtaining the solid raw material after stirring. Wherein the cement is portland cement; the coarse aggregate is 4.75-9.5 continuous graded broken stone, the content of needle and flaky particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%; the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%; the fineness modulus of the desert sand is 0.3-1.2, and the mud content is less than 0.5%.
Weighing 30 parts of accelerator, 5 parts of water reducer and 100 parts of water, and uniformly stirring to obtain the water aqua raw material. Wherein the accelerator is an alkali-free accelerator, the initial setting time is not more than 3min, and the final setting time is not more than 12 min; the water reducing agent is a polycarboxylic acid water reducing agent and has a water reducing rate of 28 percent.
Adding the water agent raw material into a mixing stirrer filled with solid raw materials, controlling the rotating speed of the mixing stirrer to be 400r/min, stirring for 5min, and stirring at the temperature of 20 ℃, and obtaining the desert sand shotcrete after stirring.
Example 5
Weighing 402 parts of cement, 900 parts of coarse aggregate, 25 parts of silica fume, 240 parts of machine-made sand, 360 parts of desert sand and 80 parts of water, adding the materials into a mixing stirrer, uniformly stirring, controlling the rotating speed of the mixing stirrer to be 350r/min, stirring for 7min, and obtaining a solid raw material after stirring. Wherein the cement is a mixture of Portland cement and ordinary Portland cement; the coarse aggregate is 4.75-9.5 continuous graded broken stone, the content of needle and flaky particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%; the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%; the fineness modulus of the desert sand is 0.3-1.2, and the mud content is less than 0.5%.
Weighing 28 parts of accelerator, 4 parts of water reducer and 100 parts of water, and uniformly stirring to obtain the water aqua raw material. Wherein the accelerator is a low-alkali accelerator, the initial setting time is not more than 3min, and the final setting time is not more than 12 min; the water reducing agent is a polycarboxylic acid water reducing agent and has a water reducing rate of 25%.
Adding the water agent raw material into a mixing stirrer filled with solid raw materials, controlling the rotating speed of the mixing stirrer to be 450r/min, stirring for 7min at the stirring temperature of 30 ℃, and obtaining the desert sand shotcrete after stirring.
Example 6
Weighing 460 parts of cement, 1000 parts of coarse aggregate, 28 parts of silica fume, 225 parts of machine-made sand, 307 parts of desert sand and 115 parts of water, adding into a mixing stirrer, uniformly stirring, controlling the rotating speed of the mixing stirrer to be 400r/min, and stirring for 8min to obtain a solid raw material after stirring. Wherein the cement is portland cement; the coarse aggregate is 4.75-9.5 continuous graded broken stone, the content of needle and flaky particles is not more than 12.0%, the content of mud is not more than 1.0%, and the content of mud blocks is not more than 0.5%; the fineness modulus of the machine-made sand is 2.8-3.1, the mud content is not more than 3.0%, the mud block content is not more than 1.0%, the MBV value is not more than 1.4, the stone powder content is not more than 3%, and the water content is not more than 6%; the fineness modulus of the desert sand is 0.3-1.2, and the mud content is less than 0.5%.
Weighing 24 parts of accelerator, 7 parts of water reducer and 115 parts of water, and uniformly stirring to obtain the water aqua raw material. Wherein the accelerator is an alkali-free accelerator, the initial setting time is not more than 3min, and the final setting time is not more than 12 min; the water reducing agent is a polycarboxylic acid water reducing agent and has a water reducing rate of 29 percent.
Adding the water agent raw material into a mixing stirrer filled with solid raw materials, controlling the rotating speed of the mixing stirrer to be 500r/min, stirring for 8min, and stirring at the temperature of 40 ℃, and obtaining the desert sand shotcrete after stirring.
Comparative example 1
The procedure was the same as in example 1 except that the amount of the desert sand was changed to 158 parts.
Comparative example 2
The procedure was as in example 1 except that the amount of the desert sand was changed to 703 parts and the amount of the machine-made sand was changed to 469 parts.
Comparative example 3
The procedure was the same as in example 1 except that 404 parts of cement was changed to 350 parts of cement and 54 parts of fly ash.
Comparative example 4
The procedure was as in example 1 except that the amount of the accelerator was changed to 40 parts and the amount of the water-reducing agent was changed to 7 parts.
The concrete of examples 1 to 6 and comparative examples 1 to 4 were subjected to performance tests, which included: slump, normal pressure bleeding rate, air content and compressive strength. The results are shown in Table 1.
The test method is as follows:
slump: the slump is detected according to GB/T50080-2016 Standard test method for the Performance of common concrete mixtures.
Normal-pressure bleeding rate: the bleeding rate is detected according to GB/T50080-2016 Standard test method for the Performance of common concrete mixtures.
Gas content: the gas content is detected according to GB/T50080-2016 Standard test method for the Performance of common concrete mixtures.
Compressive strength: the compressive strength of the concrete was measured on day 28 according to the method of appendix C of JGJ/T372-2016 sprayed concrete application Specification. The compressive strength of the concrete in the railway engineering structure is detected on the 1 st day according to a nail shooting method of TB/T10426 and 2019, namely, the concrete strength detection regulations of the railway engineering structure, and the result is only used for reference.
Table 1 results of performance testing
As can be seen from table 1 above, each example not only satisfied the 28d compressive strength to the design requirements of shotcrete, but also had a higher 1d compressive strength than comparative examples 2 to 3; compared with the comparative example 1, the compressive strength of each example 1d and the compressive strength of each example 28d are both equivalent to the comparative example, but the mixing amount of the desert sand in each example is obviously higher than that in the comparative example 1, namely, the cost of each example is lower; compared with comparative example 4, each example has equivalent 1d compressive strength, and 28d strength is more suitable for construction requirements.
The above is only a preferred embodiment of the present invention, and it is not intended to limit the scope of the invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the scope of the present invention.
Claims (10)
1. The desert sand sprayed concrete is characterized by comprising the following raw materials in parts by weight: 230 portions of water 180-.
2. The desert sand shotcrete as claimed in claim 1, wherein the sand rate is 35% to 45%; and/or the presence of a gas in the gas,
the fineness modulus of the desert sand is more than 0.2, and the mud content is less than 0.5%.
3. The desert sand shotcrete as claimed in claim 1, comprising the following raw materials in parts by weight: 202 parts of water, 404 parts of cement, 959 parts of coarse aggregate, 314 parts of machine-made sand, 471 parts of desert sand, 32 parts of accelerating agent and 6 parts of water reducing agent.
4. The desert sand shotcrete as claimed in claim 1, wherein the machine-made sand has a fineness modulus of 2.8-3.1, a mud content of not more than 3.0%, a mud cake content of not more than 1.0%, an MBV value of not more than 1.4, a stone powder content of not more than 3%, and a water content of not more than 6%.
5. The desert sand shotcrete as claimed in claim 1, wherein the coarse aggregate is crushed stone of 5-10 mm, and has a needle and flake particle content of not more than 12.0%, a mud content of not more than 1.0%, and a mud cake content of not more than 0.5%.
6. The desert sand shotcrete as claimed in claim 1, wherein the accelerator is an alkali-free accelerator or a low-alkali accelerator; and/or the presence of a gas in the gas,
the cement comprises one or more of Portland cement, ordinary Portland cement and composite Portland cement; and/or the presence of a gas in the gas,
the water reducing rate of the water reducing agent is 25-29%.
7. The desert sand shotcrete as claimed in claim 6, wherein the setting accelerator has an initial setting time of not more than 3min and a final setting time of not more than 12 min.
8. The desert sand shotcrete as claimed in claim 1, further comprising 24-28 parts of silica fume.
9. A method for preparing desert sand shotcrete as claimed in any one of claims 1-7, comprising the steps of:
mixing cement, coarse aggregate, machine-made sand, desert sand and part of water, and stirring for 4-8 min at the rotating speed of 300-400 r/min to obtain a solid raw material;
uniformly mixing the accelerator, the water reducer and the rest part of water to form a water aqua raw material;
and adding the water aqua raw material into the solid raw material, and stirring for 5-8 min at the temperature of 20-40 ℃ and the rotating speed of 400-500 r/min to obtain the sprayed concrete.
10. The method for preparing the desert sand shotcrete as claimed in claim 9, wherein the raw material of the desert sand shotcrete further comprises 24-28 parts of silica fume;
the method comprises the following steps of mixing cement, coarse aggregate, machine-made sand, desert sand and part of water, stirring for 4-8 min at the rotating speed of 300-400 r/min, and obtaining a solid raw material:
mixing cement, coarse aggregate, machine-made sand, desert sand, micro-silica powder and part of water, and stirring for 4-8 min at the rotating speed of 300-400 r/min to obtain the solid raw material.
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