CN104865156B - A kind of cement concrete isolation degree evaluation device and its evaluation method - Google Patents

Abstract

The invention discloses a cement concrete segregation degree evaluation device and an evaluation method thereof. The device includes a support part, a test part and a density measurement part; the support part includes a base, a vertical arm, a beam, a lifting device, and a bolt; the test The components include fixing screws, a vibrating device, and a material storage chamber; the density measuring components include a column, a density meter, a slide rail, a fixing device, and a guide rail. The invention can simulate the vibration situation of cement concrete in the process of transportation and vibration, and provide more realistic experimental data. It incorporates a density measuring device, which can accurately measure the density of cement concrete in real time. The test device of the invention is easy to operate, good in economy and high in practical value.

Description

A cement concrete segregation evaluation device and evaluation method

technical field

The invention belongs to the field of civil engineering concrete construction, and relates to a cement concrete segregation degree evaluation device and an evaluation method thereof, which are used for evaluating the cement concrete segregation degree and can provide reliable experimental data.

Background technique

Concrete segregation is a phenomenon in which the cohesion between the constituent materials of the concrete mixture is insufficient to resist the sinking of the coarse aggregate, and the components of the concrete mixture are separated from each other, resulting in uneven internal composition and structure. It usually shows that the coarse aggregate and the mortar are separated from each other, for example, the dense particles are deposited at the bottom of the large mixture, or the coarse aggregate is separated from the mixture as a whole.

The reasons for segregation may be pouring, improper vibration, excessive maximum particle size of aggregate, high proportion of coarse aggregate, low content of cementitious material and fine aggregate, and excessive density of coarse aggregate compared with fine aggregate. Large, or the mixture is too dry or too wet. The tendency to segregate can be reduced by using mineral admixtures or air-entraining agents.

The segregation of cement concrete is very harmful. The segregation of cement concrete affects the appearance of the concrete structure. Sand grains, exposed aggregates, and exposed steel bars appear on the concrete surface. The concrete strength will be greatly reduced, which will seriously affect the bearing capacity of the concrete structure, destroy the safety performance of the structure, and seriously cause rework and cause huge economic losses. The homogeneity of segregated cement concrete is poor, resulting in inconsistent shrinkage of various parts of the concrete, and concrete shrinkage cracks are easy to occur. Especially in the construction of concrete floors, due to concrete segregation, the cement slurry layer on the surface thickens, shrinkage increases sharply, and severe cracking occurs. It greatly reduces the durability of concrete such as concrete impermeability and frost resistance.

Currently there is no device to directly evaluate the segregation degree of cement concrete. What are used now are some indirect evaluation methods, mainly the slump method. The slump method indirectly reflects the segregation resistance of reactive concrete through cohesion. The slump method can only evaluate the initial concrete segregation degree and cannot reflect the final degree of segregation. The patent can directly evaluate the segregation degree of cement concrete, provide accurate and reliable experimental data, and has strong practicability.

Contents of the invention

The object of the present invention is to overcome the above-mentioned shortcomings of the prior art, and provide a cement concrete segregation degree evaluation device and evaluation method thereof.

The purpose of the present invention is achieved through the following technical solutions:

This cement concrete segregation degree evaluation device includes a supporting part, a test part and a density measuring part; the supporting part includes a base, a vertical arm, a beam, a lifting device, and a bolt; chamber; the density measuring components include a column, a densitometer, a slide rail, a fixture, and a guide rail;

One end of the base is fixed with a vertical arm, and the other end is horizontally fixed with a guide rail; a beam is installed on the upper end of the vertical arm through a lifting device, and an agitator is fixed on the beam; There is also a vibration device between them;

The guide rail is provided with a vertical slide rail that can slide horizontally along the guide rail. The column is fixed on the slide rail, and the density meter is fixed on the slide rail. Several round holes.

Further, the base and the bottom of the vibrating device are fixed by bolts and fixing screws.

The above-mentioned density meter is fixed on the slide rail through a fixing device.

The present invention also proposes a test method for measuring the segregation degree of cement concrete based on the above-mentioned cement concrete segregation degree evaluation device, comprising the following steps:

Remove the material storage room and vibrating device, then pour the mixed cement concrete into the material storage room evenly, tap ~ down lightly to make the concrete compact and reduce the experimental error, and then fix the material storage room and vibration device to the end seat;

Start the lifting device to lower the mixer into the material storage room, start the mixer to stir the cement concrete, and start the vibration device at the same time to simulate the state of cement concrete during construction and transportation under realistic conditions, and stop after mixing;

Adjust the density meter, measure the density of cement concrete through the round hole in the upper part of the storage room, which is recorded as ρ1, and measure the density of the cement concrete in the lower part through the round hole in the lower part of the storage room, and record it as _{ρ2 ;}

4 Calculate the degree of concrete segregation L=|ρ ₁ -ρ ₂ |/ρ, the greater the degree of segregation, the more obvious the segregation of concrete.

The present invention has the following beneficial effects:

1. The device of the present invention can simulate the vibration of cement concrete during transportation and vibration, and provide more realistic experimental data.

2. The device of the present invention adds a density measuring device, which can accurately measure the density of cement concrete in real time.

3. In the device of the present invention, the test part is placed on the base, which is more stable.

4. The device of the present invention adds a stirrer to simulate the actual conditions of concrete in the process of transportation and loading and unloading, and the experimental data is more reliable.

5. The evaluation method of the present invention proposes a new index segregation degree for evaluating the degree of concrete segregation.

6. The test device of the present invention has the advantages of convenient operation, good economy and high practical value.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Among them: 1 is the base; 2 is the vertical arm; 3 is the beam; 4 is the lifting device; 5 is the bolt; 6 is the agitator; 7 is the column; 8 is the density meter; 9 is the slide rail; Fixing screw; 12 is a vibrating device; 13 is a round hole; 14 is a material storage chamber; 15 is a guide rail.

detailed description

The present invention is described in further detail below in conjunction with accompanying drawing:

Referring to Fig. 1, the device for evaluating the segregation degree of cement concrete according to the present invention includes: a supporting part, a testing part and a density testing part. The support components include:

The base 1 stabilizes the upper structure and plays a supporting role;

Vertical arm 2, its function is to fix the crossbeam on the base to make room for placing experimental components;

Beam 3, its function is to fix the stirring device on the experimental part, to facilitate the experiment;

Lifting device 4, its function is to make stirring device enter or break away from 14 holding chambers;

Bolt 5, its function is to fix the test part on the base;

The test components include:

Fixing screw 11, its effect is to combine with fixing bolt 5 and test part is fixed on the base;

Vibration device 12, its effect is to provide the power of vibration to make 14 material storage chambers vibrate, imitate the construction site to vibrate cement concrete;

Circular hole 13, its effect is to make densitometer 8 can directly measure the density of cement concrete;

Material holding room 14, its effect is to hold cement concrete;

Described density testing device comprises:

Column 7, its effect is to play a supporting role;

Densitometer 8, its effect is to measure the density of cement concrete;

Slide rail 9, its function is to allow density meter 8 to slide along the vertical direction;

The fixing device 10 is used to fix the density meter 8 on the slide rail 9;

The guide rail 15 is used to allow the column 7 to stay away from or approach the experimental parts, so as to facilitate the measurement of cement concrete density.

The connection relationship of the above components is as follows:

One end of the base 1 is fixed with a vertical arm 2, and the other end is horizontally fixed with a guide rail 15; a beam 3 is set on the upper end of the vertical arm 2 through a lifting device 4, and an agitator 6 is fixed on the beam 3; a storage room is provided on the base 1 14. A vibration device 12 is also provided between the base 1 and the storage chamber 14; the guide rail 15 is provided with a vertical slide rail 9 that can slide horizontally along the guide rail 15, and the column 7 is fixed on the slide rail 9 , The density meter 8 is fixed on the slide rail 9, and a number of circular holes 13 are sequentially opened on the side wall of the storage chamber 14 from top to bottom. Further: the base 1 and the bottom of the vibration device 12 are fixed by bolts 5 and fixing screws 11 . The density meter 8 is fixed on the slide rail 9 through a fixing device 10 .

Utilize above cement concrete segregation degree evaluation device, the present invention tests cement concrete segregation degree measuring method, comprises the following steps:

(1) Remove the material holding chamber 14 and the vibrating device 12, then pour the mixed cement concrete evenly into the material holding chamber 14, tap lightly 4 to 5 times to make the concrete compact and reduce the experimental error, and then place the It is fixed to the base 1 .

(2) Start the lifting device 4 and lower the agitator into the material holding chamber, start the agitator 6 to stir the cement concrete, and start the vibrating device 12 simultaneously to simulate the state of the cement concrete in the construction and transportation process under actual conditions, and stir and vibrate for 10 Minutes later stop.

(3) Adjust the density meter 8 to measure the density of the cement concrete through the upper round hole 13, denoted as ρ ₁ , and measure the density of the lower cement concrete through the lower round hole 13, denoted as ρ ₂ .

(4) Calculate the degree of concrete segregation L=|ρ ₁ -ρ ₂ |/ρ, the greater the degree of segregation, the more obvious the segregation of concrete. where ρ is the density of the reference concrete.

Claims (2)

1. A cement concrete segregation degree evaluation device is characterized in that, comprising: support component, test component and density measuring component; Described support component comprises base (1), vertical arm (2), crossbeam (3), lifting device (4), bolt (5); Described test part comprises fixing screw (11), vibrating device (12), material holding chamber (14); Described density measurement part comprises column (7), densitometer (8), Slide rail (9), fixture (10), guide rail (15); One end of the base (1) is fixedly provided with a vertical arm (2), and the other end is horizontally fixedly provided with a guide rail (15); the upper end of the vertical arm (2) is provided with a crossbeam (3) through a lifting device (4), and the crossbeam (3) A stirrer (6) is fixed on it; a material holding chamber (14) is arranged on the base (1), and a vibration device (12) is also arranged between the base (1) and the material holding chamber (14); The guide rail (15) is provided with a vertical slide rail (9) that can slide horizontally along the guide rail (15), the column (7) is fixed on the slide rail (9), and the density meter (8) is fixed on the slide rail (9). On the rail (9), a number of round holes (13) are sequentially opened on the side wall of the material chamber (14) from top to bottom; and fixing screws (11); the density meter (8) is fixed on the slide rail (9) through the fixing device (10). 2. a method for measuring cement concrete segregation degree according to the cement concrete segregation degree evaluation device of claim 1, is characterized in that, comprises the following steps: (1) Remove the material storage chamber (14) and the vibrating device (12), then pour the mixed cement concrete into the material storage chamber (14) evenly, tap lightly 4-5 times to make the concrete dense, Reduce the experimental error, then fix the material holding chamber (14) and the vibrating device (12) on the base (1); (2) Start the lifting device (4) lower the agitator (6) into the material storage chamber (14), start the agitator (6) to stir the cement concrete, and start the vibration device (12) at the same time to simulate construction under realistic conditions And the state of cement concrete during transportation, stop after mixing; (3) Adjust the density meter (8), measure the density of cement concrete through the round hole (13) on the upper part of the stock chamber ( ₁₄ ), denote it as ρ1, and measure it through the round hole (13) on the bottom of the stock chamber (14) Density of cement concrete in the lower part, denoted as _ρ2 ; (4) Calculate the degree of concrete segregation L=|ρ ₁ -ρ ₂ |/ρ, where ρ is the density of the reference concrete; the greater the degree of segregation, the more obvious the segregation of concrete.