CN111908857B

CN111908857B - Preparation method of one-time large-thickness molded spray sculpture concrete

Info

Publication number: CN111908857B
Application number: CN202010617900.6A
Authority: CN
Inventors: 刘喜军; 贺江波; 胡舜钦
Original assignee: Hunan Holy Land Environmental Art Engineering Co ltd
Current assignee: Hunan Holy Land Environmental Art Engineering Co ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2022-10-11
Anticipated expiration: 2040-06-30
Also published as: CN111908857A

Abstract

The invention discloses a preparation method of one-time large-thickness molded spray sculpture concrete, which relates to the technical field of materials and comprises the following steps: weighing an auxiliary agent: adding crack-resistant fibers, cellulose ether, starch ether, a concrete expanding agent, organic modified bentonite, an air entraining agent and a retarder into a stirrer and uniformly mixing; weighing portland cement, graded river sand, aggregate, fly ash and the mixed auxiliary agent, adding the mixture into a concrete mixer, and uniformly mixing; and adding water into the mixed materials in the concrete mixer, and uniformly stirring to finish the preparation of the sprayed concrete. The preparation method of the invention adopts a grading mode to add the river sand and the aggregate, controls the grain diameter of the river sand and the aggregate to be not less than 2.0 meshes, and uses the anti-crack fiber, the composite thickening agent, the expanding agent and the air entraining agent in a matching way to improve the water retention, the thixotropy and the forming consistency of the spray sculpture concrete and the good wire drawing characteristic, reduce the rebound rate and increase the one-time spray forming thickness.

Description

Preparation method of one-time large-thickness molded spray sculpture concrete

Technical Field

The invention relates to the technical field of material preparation, in particular to a preparation method of spray sculpture concrete capable of being formed in a large thickness at one time.

Background

The spray sculpture concrete is a material for building sculpture foundation, belonging to spray concrete series products. Shotcrete is concrete that is dynamically compacted at high speed under pneumatic pressure by cement, sand, stone, water and other aggregates. The sprayed concrete has the characteristics of short setting time, strong self-picking effect, high bonding strength, coordinated deformation, wide application range, quick construction and the like, is gradually applied and developed, has stable performance, is easy to store for a long time and is favorable for transportation, and is the main development direction of concrete materials when being prepared by adding water on site. In the sculpture market, the sprayed concrete is used as a bottom layer structure for constructing the sculpture, and the advantages of the sprayed concrete can be fully exerted and widely applied.

The sprayed sculpture concrete also has the defects of larger rebound resilience and serious sagging phenomenon in the application process. The rebound rate of the sprayed concrete is relatively discrete under the influence of construction factors such as the condition of a sprayed surface, the spraying condition and the like, and the Guanbao tree is reported in the sprayed concrete support technology of tunnels and underground engineering: the statistics of the relevant engineering of mass sprayed concrete reveal that: the range of resilience is approximately between 20-30%, which is a large value for the amount of concrete produced. When the spraying construction is adopted, in order to keep the spraying fluency, the water-cement ratio of the concrete is higher, so that a certain defect exists in a poured concrete structure, and the one-time spraying thickness cannot be too thick when the spraying construction is adopted is also limited. Around the above problems, related work on the mix ratio of shotcrete has been carried out to reveal: the rebound rate of the sprayed concrete can be reduced by adjusting the formula ratio of the concrete: (1) Chengquine (material composition and main performance of sprayed concrete [ J ]. Industrial building. 1986 (01)) reports that the initial setting speed of concrete is accelerated and the rebound is reduced by adding a proper accelerating agent into the concrete, but the spraying process is complicated by adding the accelerating agent; (2) In order to improve the performance of the sprayed concrete, reduce the rebound rate of the sprayed concrete and improve the forming quality of the sprayed concrete, the added mixed materials comprise mineral admixtures such as silica fume, fly ash, limestone micropowder and the like; however, for the production of sprayed concrete, the later strength loss of the sprayed concrete can be compensated by adding the silica powder, but the silica powder has small particle size, is easy to influence the bodies of operators, and is lack of environmental protection. (3) Germany adopts a method of adding an adhesive into sprayed concrete to improve the cohesiveness of the concrete and further reduce the rebound rate, japan also adopts an organic polymer as a tackifier, and the reports of Ching friend in China and the like adopt an acrylamide-sodium acrylate-acrylonitrile copolymer tackifier to obtain a certain effect of reducing the rebound rate; meanwhile, the addition of the adhesive can reduce the bleeding and rebound phenomena of the concrete; however, the addition of the tackifier increases the water cement ratio, so that the water yield is increased, and the later strength of concrete is reduced, therefore, the water reducing agent must be added, the addition of the water reducing agent causes the sagging phenomenon of sprayed concrete, the added adhesive and the water reducing agent must be reasonably blended, and the formulation of product production and the configuration complexity of the product formulation are increased.

The sprayed sculpture concrete is sprayed concrete with special purpose, and as a building sculpture base material, the sprayed sculpture concrete meets the performance of the sprayed concrete and also needs to meet certain sculpture performance requirements, wherein the most important thing is to meet the requirements of wire drawing operation on the surface of a sculpture product to generate continuous and smooth wire drawing.

Because the existing spraying sculpture concrete still needs to keep higher water cement ratio when spraying, the one-time spraying thickness of the existing spraying sculpture concrete is reduced, and the thickness formed by one-time spraying is not more than 3.0cm when the existing spraying sculpture concrete is used; when the sculpture concrete is sprayed and formed, the forming thickness exceeds 10.0cm according to the engineering requirement, so that the sculpture concrete can reach the thickness by multiple spraying operations.

Therefore, those skilled in the art have made efforts to develop a new scheme for preparing spray sculpture concrete so as to avoid adding a water reducing agent and a tackifier into the concrete and eliminate the influence of the addition of such additives on the later strength of the spray sculpture concrete; the problem of environmental protection caused by reducing the rebound rate of sprayed concrete by adding the silica powder is avoided; meanwhile, the addition of the auxiliary agent is matched to meet the requirements of the sculpture wire drawing performance, and the normal water-cement ratio during spraying is kept.

Disclosure of Invention

In view of the above defects of the prior art, the invention provides a novel preparation scheme of the sprayed sculpture concrete, which avoids adding a tackifier and a water reducing agent, eliminates the existence of additives, influences the later strength of the sprayed concrete and avoids the sagging phenomenon; no silica powder is added into the sprayed concrete so as to avoid influencing the production and the health of constructors; meanwhile, the addition of an auxiliary agent is matched to meet the requirements of the sculpture wire drawing performance of the sculpture wire drawing machine, and the normal water-cement ratio during spraying is kept.

In order to achieve the above object, the present invention provides a method for preparing spray sculpture concrete with one-time large thickness molding, comprising the steps of:

s100, weighing an auxiliary agent: adding crack-resistant fiber, cellulose ether, starch ether, concrete expanding agent, organic modified bentonite, air entraining agent and retarder into a stirrer and uniformly mixing;

s200, weighing portland cement, graded river sand, aggregate, fly ash and the mixed auxiliary agent, adding the mixture into a concrete mixer, and uniformly mixing;

s300, adding water into the mixed materials in the concrete mixer, uniformly stirring to finish the preparation of the shotcrete, and then preparing the shotcrete according to the water-cement ratio of 0.45-0.60.

Compared with the prior art, the invention has the advantages that:

(1) The preparation method of the one-time large-thickness molded spray sculpture concrete adopts the composite thickening agent, the expanding agent and the air entraining agent, improves the water retention and thixotropy of the spray concrete, and has good wire drawing property; meanwhile, the bleeding phenomenon is inhibited, the normal water consumption is kept, a water reducing agent is not required to be added, and the once spraying thickness is increased;

(2) According to the preparation method of the large-thickness spray sculpture concrete, the river sand and the aggregate are added in a grading mode, the particle sizes of the river sand and the aggregate are controlled to be not less than 2.0 meshes, the anti-crack fibers are used in a matching mode while the strength of the siliceous material is enhanced, the water in the spray product can be kept to enter the surface of the spray product through the capillary action, the consistency of the coagulation and hardening speeds of the surface and the interior of the spray product is ensured, and the cracking phenomenon after one-time molding is reduced;

(3) The invention adopts the air entraining agent, reduces the resistance of the sprayed concrete in the conveying process, eliminates the pipe blockage phenomenon, and simultaneously maintains the normal water-cement ratio during spraying;

(4) The concrete prepared by the technology of the invention is constructed by spraying with a jet pump, the one-step forming thickness can reach more than 10.0cm, and the rebound resilience value is lower than 5%.

Drawings

FIG. 1 is a flow chart of a method of making a preferred embodiment of the present invention.

Detailed Description

In order to facilitate an understanding of the invention, the invention will be described more fully and in detail with reference to the following description and preferred embodiments, but the scope of the invention is not limited to the specific embodiments described below.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specifically stated, various raw materials, reagents and the like used in the present invention are commercially available or can be prepared by existing methods.

As shown in fig. 1, a flow chart of a method for preparing a high-thickness sprayed sculpture concrete according to a preferred embodiment of the present invention includes the following steps:

On one hand, the preparation method of the one-time large-thickness formed spray sculpture concrete adopts the composite tackifier, improves the water retention property and thixotropy of the spray sculpture concrete, enables the spray sculpture concrete to have good wire drawing property, simultaneously inhibits the bleeding phenomenon, keeps normal water consumption, does not need to add a water reducing agent, and increases the one-time spray thickness;

secondly, the preparation method of the one-time large-thickness molded spray sculpture concrete adopts a grading mode to add the river sand and the aggregate, controls the particle size of the river sand and the aggregate to be not less than 2.0 meshes, and can keep the water in the spray product to enter the surface of the spray product through the capillary action by using the anti-crack fiber while exerting the reinforcing strength of the siliceous material, thereby ensuring the consistency of the coagulation and hardening speed of the surface and the interior of the spray product;

finally, the invention adopts the air entraining agent, reduces the resistance in the process of conveying the sprayed concrete and eliminates the phenomenon of pipe blockage.

In a preferred embodiment, the raw materials comprise the following components in percentage by weight: 20-30% of ordinary portland cement, 60-70% of graded river sand and aggregate, 5-10% of fly ash, 0.05-0.12% of organic modified bentonite, 0.1-0.2% of anti-crack fiber, 0.02-0.05% of air entraining agent, 0.05-0.12% of starch ether, 0.05-0.15% of cellulose ether, 0-1.0% of retarder and 1.0-3.0% of expanding agent.

In a preferred embodiment, the Portland cement is 32.5 or 42.5 Portland cement; the grain sizes of the graded river sand and the aggregate are less than 2.0 meshes, and the aggregate is broken stone and pebbles; the anti-crack fiber is organic flocculent fiber substance or synthetic fiber; the cellulose ether is hydroxypropyl methyl cellulose ether; the starch ether is a starch modified ether compound; the retarder is sodium gluconate or sodium citrate, the air entraining agent is an alcohol ether composite air entraining agent and comprises but is not limited to Yashilan RN8018, and the expanding agent is calcium sulphoaluminate and calcium aluminate expanding agent and comprises but is not limited to U-shaped expanding agent.

In a preferred embodiment, the Portland cement and the fly ash are used as inorganic cementing materials of concrete, and can be hardened in the air and can firmly bond sand, stone and the like together after being stirred by adding water.

In a preferred embodiment, the retarder is used to adjust the setting time of the cement, and can be maintained for several hours according to the requirements of specific sculpture stringing.

In a preferred embodiment, the anti-cracking fibers are used to enhance the consistency of the surface of the sprayed product with the internal cement setting and hardening processes to reduce cracking.

In a preferred embodiment, the organically modified bentonite, the starch ether or the cellulose ether and the swelling agent simultaneously achieve the aims of bleeding, water retention and no increase of water consumption.

In a preferred embodiment, the air entraining agent is used for eliminating pipe blockage and maintaining a normal water-cement ratio during spraying.

Hereinafter, preferred embodiments of the present invention will be described to make the technical contents thereof clearer and easier to understand. The present invention may be embodied in many different forms of embodiments and the scope of the invention is not limited to the embodiments set forth herein.

Example 1

S100, adding 0.1kg of organic modified bentonite, 0.06kg of starch ether, 0.1kg of hydroxymethyl cellulose ether, 0.1kg of organic flocculent fibrous matter, 0.03kg of Asia-strawberry RN8018, 0.06kg of sodium gluconate and 2.5kg of U-shaped expanding agent into a stirrer, and uniformly mixing in a premixing bin;

s200, feeding the materials in the stirrer into a concrete mixer, adding 25kg of 42.5 common Portland cement, 65kg of graded river sand and aggregate and 7.5kg of fly ash into the concrete mixer, and uniformly mixing;

s300, adding 16.2kg of water into the materials in the concrete mixer, and uniformly mixing to finish the preparation of the sprayed concrete. And (3) preparing the prepared shotcrete into the shotcrete according to the water cement ratio of 0.50.

Example 2

S100, adding 0.06kg of organic modified bentonite, 0.1kg of starch ether, 0.2kg of synthetic fiber, 0.04kg of methylene blue RN8018, 0.1kg of sodium citrate and 2.5kg of U-shaped expanding agent into a stirrer, and uniformly mixing in the stirrer;

s300, adding 14.7kg of water into the stirrer, and uniformly mixing to finish the preparation of the shotcrete. And (3) preparing the prepared shotcrete into shotcrete according to the water cement ratio of 0.45.

The shotcrete prepared in the above 2 examples was used for construction using an Italian TURBOSOL shotcrete machine at a delivery pressure of 3.0MPa and a wind pressure of 0.6MPa, and the properties thereof were compared:

table 1 comparison of properties of shotcretes prepared in example 1 and example 2

As can be seen from the above table, the shotcrete prepared in example 1 has a thickness of 10cm and a rebound resilience of 5% or less; the thickness of the shotcrete prepared in example 2 is 13cm, and the rebound resilience is less than or equal to 5%; the initial setting time of the shotcrete prepared in example 1 was 360 minutes, the initial setting time of the shotcrete prepared in example 2 was 380 minutes, the final setting time of the shotcrete prepared in example 1 was 540 minutes, the final setting time of the shotcrete prepared in example 2 was 550 minutes, the 28-day strength of the shotcrete prepared in example 1 was 32.0MPa, and the 28-day strength of the shotcrete prepared in example 2 was 37.0MPa.

After the surface of the product formed by spraying the two examples is subjected to wire drawing operation, the generated drawn wires are continuous and smooth, and the construction and operation requirements of the subsequent sculpture process are met.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the prior art according to the concepts of the present invention should be within the scope of protection determined by the claims.

Claims

1. A method for preparing one-time large-thickness formed spray sculpture concrete, which comprises the following steps:

s100, adding 0.1kg of organic modified bentonite, 0.06kg of starch ether, 0.1kg of hydroxymethyl cellulose ether, 0.1kg of organic flocculent fibrous matter, 0.03kg of RN8018 of methylene blue, 0.06kg of sodium gluconate and 2.5kg of U-shaped expanding agent into a stirrer, and uniformly mixing in a premixing bin;

s200, feeding the materials in the stirrer into a concrete mixer, adding 25kg of 42.5 common Portland cement, 65kg of graded river sand and aggregate and 7.5kg of fly ash into the concrete mixer, and uniformly mixing; wherein the aggregate is broken stone and pebble;

s300, adding 16.2kg of water into the materials in the concrete mixer, and uniformly mixing to finish the preparation of the sprayed concrete; wherein, the prepared shotcrete is prepared according to the water cement ratio of 0.50;

the construction is carried out by using an Italian TURBOSOL concrete sprayer under the conditions that the conveying pressure is 3.0Mpa and the wind pressure is 0.6Mpa, and the performance of the concrete sprayer is characterized as follows:

the once spraying thickness is 10cm, the rebound rate is less than or equal to 5%, the initial setting time is 360 minutes, the final setting time is 540 minutes, the 28 balance average strength is 32MPa, and after the wire drawing operation is performed on the surface of the product formed after spraying, the generated wire drawing is continuous and smooth, so that the construction and operation requirements of the subsequent sculpture process are met.

2. The method of claim 1, wherein the graded river sand and aggregate have a particle size of not less than 2.0 mesh; the starch ether is an ether compound modified by starch.