JPH02145490A - Production of high-strength heat-insulation material - Google Patents

Abstract

PURPOSE:To attain satisfactory workability as well as strength in the production of a high-strength heat-insulation material using a prepacked process by selecting the dimension of fibers in such a manner as to give a specific water/cement ratio. CONSTITUTION:A high-strength heat-insulation material is produced by preparatorily mixing a light-weight aggregate (e.g., obsidian particles having diameter of 0.6-1.2mm) with fibers such as glass fiber, filling the mixture into a mold and pouring a mixture of cement, water and a cement admixture or cement, water and a polymer emulsion into the mold, thereby impregnating the mixture between the light-weight aggregate and the fiber. The water/cement ratio is adjusted to <=0.7 in the case of a cement-water-cement admixture system or <=0.8 in the case of cement-water-polymer emulsion system by properly selecting the dimensions of the fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a high-strength heat insulating material by the pre-pect method.

(Prior Art) Conventionally, as a method for manufacturing lightweight concrete, a kneading method has been known in which lightweight aggregate is mixed with water and cement, and then poured into formwork. This manufacturing method has the drawback that the lightweight aggregate may break during kneading or separate after placement, making it impossible to obtain the desired strength and insulation performance, so a manufacturing method called the prevact method was developed.

The prevact method is a method of manufacturing lightweight concrete by filling the formwork or construction site with lightweight aggregate in advance, and injecting mortar into the gap and hardening it (for example,
"Concrete Industry Handbook" published by Asakura Shoten Co., Ltd., page 940 onwards). According to this pre-pect method, lightweight concrete with greater strength and insulation performance than the kneading method can be obtained, but in order to avoid reducing workability due to the time required for pouring mortar, the water/cement of the mortar to be injected is Is it necessary to increase the ratio (W/C)? However, as a result, there is a problem in that the specific gravity decreases and the compressive strength and bending strength decrease accordingly.

On the other hand, fiber-reinforced concrete or cement is known in which short fibers of steel or glass are added to improve the strength of the material. Among these short fibers, steel fibers have a length of about 20
~60ts, diameter 0.2~0.61cm, and glass fiber length 10~40+I1m, diameter 5~2
0Bm is used. In addition to mechanical mixing using a mixer, methods such as spray molding, in which the fibers and binder are directly sprayed onto a mold, are used to mix the fibers and binder.

Therefore, in an attempt to take advantage of both the Brepat method and fiber reinforcement, when glass fibers for fiber reinforcement are mixed and dispersed in the cement paste in advance, the viscosity of the injection agent becomes high and the workability of injection decreases significantly. If the W/C ratio of water (W) and cement (C) is increased in order to improve the properties, a problem arises in that the strength of the composite material decreases.

(Object and Structure of the Invention) The present invention has been made in view of the above points, and aims to manufacture a high-strength heat insulating material without sacrificing either workability or strength. When using an injection agent, the fiber dimensions were selected so that the W/C ratio was 0.7 or less, and when using a polymer emulsion type injection agent, the W/C ratio was 0.8 or less. The fibers having the dimensions thus selected are uniformly mixed with the weighed aggregate in advance (tri-blend) and filled into the mold, and then the injection agent is injected into the mold. The feasibility of the tri-blend method is determined by the fiber size, which affects the dispersion state of the fibers and the injection resistance of the aggregate packed bed. When using a polymer concrete type pouring agent, either a tri-blend or a wet blend with a W/C of 0.8 or less is possible. This is because the increase in viscosity due to the inclusion of fibers is not as noticeable in cement-based materials.

(Example) The present invention will be explained below based on the drawings.

FIG. 1 is a schematic diagram of an apparatus for manufacturing a high-strength heat insulating material by the method of the present invention.

In the figure, l is a formwork filled with lightweight materials and fibers in advance, and a lid 2 with an opening 2a is provided at the top of this formwork l, and wire meshes 3.4 are provided above and below inside the formwork l. is,
During this time, a mixed layer 5 of lightweight material and fibers is filled.

One end of an injection pipe 6 is connected to the center of the bottom of the formwork 2, and a cylindrical container 8 having a piston 7 is connected to the other end, and a cement-based or polymer emulsion-based injection agent 9 is placed inside the container 8. I'll keep it. Artificial lightweight aggregates (expanded perlite, expanded shale rock, fly ash, etc.) are examples of lightweight aggregates used in the lightweight concrete produced by the present invention.
and natural lightweight aggregates (volcanic rubble and its processed products) are used, and the fibers used include glass fibers, polycrystalline fibers, metal fibers, whiskers, and chemical fibers.

Next, the manufacturing method according to the present invention will be explained.

Lightweight aggregates and fibers such as those exemplified above are mixed uniformly in advance (in the case of wet blending, only lightweight aggregates are used),
The lid 2 at the top of the formwork 1 is removed and the space between the wire meshes 3 and 4 in the formwork l is filled. As a lightweight material, for example, a particle size of 0.6 to 1.
Using 2 m of helium particles, they are mixed with glass fibers at a density such that the weight per unit volume is, for example, 0.2 kg/l, and filled into a mold.

The injection agent is prepared in advance by accurately measuring and stirring cement, water, and admixture (and fibers in the case of a wet blend), and then transferred to a cylindrical container 8. The piston 7 is pushed in the direction of the arrow to, for example, 0. Injection agent 9 at a pressure of 6 kg/c112
is press-fitted into the mold l through the injection pipe 6 and from the injection port 6a. In this case, the mixing ratio of water and cement (W/C ratio) is an important factor that determines workability; if the W/C ratio is small, press-fitting requires a large force and takes time, resulting in poor workability. If the diameter is large, workability will be improved, but it will cause a decrease in strength later and corrosion of the concrete. Therefore, in practice, this W/C ratio is preferably 0.7 or less in the case of a cement-based injection agent, and 0.8 or less in the case of a polymer emulsion-based injection agent.

The injection agent rises uniformly from the bottom inside the mold 1, and the air inside the mixed layer 5 escapes to the outside through the opening 2a of the lid 2. After the injection agent has sufficiently penetrated into the mixed layer 5, the injection port 6a is closed to stop injection and the mixture is cured at 25°C. Released after 2 days, 25
When cured in an atmosphere of °C, a heat insulating material is completed.

Next, the present inventors conducted a large-scale experiment to produce a non-combustible and flame-retardant high-strength heat insulating material using the production method according to the present invention.

For the experiment, we used heliumite particles with an average particle size of 1 mm as a lightweight material, and glass fibers of various bridge lengths and diameters as reinforcing materials, and these were mixed uniformly in advance ( In the case of wet blending, fill only the lightweight material into the formwork shown in Figure 1.

Example-1 (Non-combustible high-strength insulation material) As an injection agent, cement (C) and water (W) are mixed and an admixture (naphthalene sulfonic acid type or arginine sulfonic acid type) is added, and a reinforcing material is used. fiber as 8
It was mixed into the heliumite particles at a volume percent ratio. Three types of fibers were used with different lengths and diameters d, and the W/C ratio and specific gravity were compared to when no fibers were used.The values are air-dried values, and bone-dry values are shown in parentheses. ), compressive strength, bending strength, and tensile strength were measured. The results of the experiment are shown in Table 1 below.

As can be seen from the experimental results, if the W/C ratio is set to 0.7 or less from the viewpoint of workability, the experimental number collapses.

In Example 4, a lightweight concrete with excellent compressive strength, particularly flexural strength, and tensile strength was obtained.

When combining the tri-blend method and the prepect method, the important factors that determine whether or not tri-blend can be used are the length and diameter of the fibers relative to the dimensions of the lightweight aggregate.If the fiber dimensions are significantly smaller than the appropriate range, the fibers may be Does not aggregate and disperse,
On the other hand, if it is large, tri-blend can be applied, but it is not uniform.
In addition, it is difficult to disperse the material in a high density, making it useless for reinforcement. Also,
If the mixed fibers are fine, the injection resistance of the packed bed will increase, making it necessary to increase the W/C ratio of the injection agent and lowering the viscosity of the injection agent, which will significantly reduce the strength of the manufactured concrete.

Table 1 shows a representative example of experiments conducted to find the appropriate size range of reinforcing fibers that would enable tri-blending. Experiment No. 2 is an example where the fiber length is long and the dispersion state of the fibers is unfavorable and the reinforcing effect does not appear much. Experiment No. 3 is an example where the fibers are short and the injection agent W/C.
This is an example where the ratio had to be increased, but as a result, the strength actually decreased. Experiment No. 4 had a fiber length intermediate between F.2 and F.3, and as mentioned above, excellent compressive strength and bending strength were obtained. Flkl 1, which is a standard for comparing these performances, is lightweight concrete made by the prepect method, which is made only of lightweight aggregate and binder without mixing reinforcing fibers, and has high strength due to the low W/C ratio. ing. By mixing fibers into this, lightweight,
The purpose of the triblend method can be achieved if strength can be improved without compromising thermal insulation as much as possible.Although a slight decrease in compressive strength is observed when comparing 4 with Nb and 1, bending and It can be seen that both tensile strength has significantly improved. In a similar manufacturing method, no improvement in strength was observed even when the amount of fibers was increased or the fiber length was increased.

Experiment 2 (Flame retardant high strength insulation material) Cement (C) and water (W) were mixed using acrylic emulsion and epoxy emulsion separately as fillers without using any admixtures. The fibers used as reinforcing materials were sufficiently fine whiskers (average diameter 0.4 μm, average length 1
5ILm), and the same performance measurements as in Experiment 1 were made in comparison with the case where no fiber was used. The experimental results are shown in Table 2 below.

As can be seen from the experimental results, lightweight concrete made with an epoxy emulsion injection agent is inferior to lightweight concrete made with an acrylic emulsion injection agent in terms of strength, but in either case, it is easy to work. With a W/C ratio of 0.8 or less, which does not cause any decrease in strength, lightweight concrete with a higher compressive strength was obtained than that without using any reinforcing material.

Above, we have illustrated the experimental results of producing lightweight concrete using a cement-based injection agent and a polymer emulsion-based injection agent.The cement-based lightweight concrete manufactured according to the present invention has excellent lightness and does not require the conventional simple method of forcibly removing air bubbles. It has much greater strength than the lightweight materials introduced, and does not have the problems of flame resistance, cost, weather resistance, etc. of polymeric materials that generally have excellent heat insulation properties, such as urethane.

Next, an experimental example will be described in which a heat insulating pillow for piping is manufactured according to the present invention by taking advantage of the feature of the prepect method, which is that complex shapes can be molded using a mold.

Actual Example 1-1 In this experiment, a heat insulating pillow 12 for a pipe 11 placed on a construction lO as shown in FIG. 2 was manufactured according to the present invention. 13 is a heat insulating material surrounding the pipe 11.

A lid form 15 having air holes 15a is fixed to the upper part of a metal box form 14 as shown in FIG. 3 with set screws 16, and the bottom surface is constituted by a slide base 17 which also serves as the form.

A number of holes 17a are bored in the bottom plate of the slide base 17, and fixing pins 18 are horizontally implanted inward in the surrounding vertical wall. A filling chamber 19 is arranged in the lower part of this formwork, and is fixed to the formwork 14 with a fixture 20. Several injection pipes 21 are provided on the side wall of the filling chamber 19.

Now, inside the formwork there is a lightweight aggregate and glass fiber as a reinforcing material (
(length: 31, diameter: lo ILm) and (
A cement-based injection agent having a W/C ratio of 0.7 is injected into the filling chamber 19 from the injection pipe 20 using an injection pump at an injection pressure of 0.6 kg/am''. The injection agent enters the formwork through the holes 17a of the slide base 17 and permeates between the lightweight aggregate and the glass fibers.During this time, the air in the formwork is released through the air holes 15a provided in the lid formwork 15. running away from

After two days, the filling chamber 19 and the molds 14 and 15 were released and cured in the air. As a result, the slide base 17 was integrated with the fiber-reinforced aggregate via the pins 18, and a heat insulating pillow 12 as shown in FIG. 4 was completed.

Comparing the insulating pillow manufactured in this way with the insulating pillow mechanically reinforced with a conventionally widely used polymeric material with excellent heat insulating properties such as polyurethane, the specific gravity and compressive strength are as shown in Table 3. It has been found that the thermal conductivity is excellent in all respects, and the cost is also less than 1/2, which is advantageous. Furthermore, it is advantageous in terms of fire resistance. Considering that insulation pillows for piping are required to have higher strength than insulation performance, they have great practical value.

In the manufacturing method according to the present invention, the binder is injected after tri-blending fibers in an appropriate size range with lightweight aggregate, or the injecting is carried out by a tri-blend method in which fibers are mixed in the injecting agent in advance. It has been found that it is possible to improve the strength of the layer. In terms of workability and developed strength, the introduction of the triblend method is a very effective method for reinforcing Brevact materials. This experiment confirmed improvements in bending and tensile strength, so the use of cement-based prepact composites reinforced with triblend fibers is wide-ranging.

(Effect of the invention) As explained above, in the present invention, when using a cement-based injection agent, the W/C ratio is set to 0.7 or less, and when using a polymer concrete-based injection agent, the W/C ratio is set to 0.7 or less. A tri-blend of fibers and lightweight aggregate whose dimensions are selected so that the /C ratio is 0.8 or less is filled in a formwork, and then a cement-based injection agent or a polymer concrete-based material is poured into the formwork. Lightweight concrete can be manufactured by injecting a pouring agent, or lightweight aggregate can be filled in the formwork in advance, and the W/C ratio of the polymer emulsion type pouring agent can be set to 0.
Lightweight concrete was manufactured by mixing fibers with dimensions of 8 or less with cement, water, and an injecting agent (wet blend) and injecting them into the formwork, so that the aggregate could be used as a binder and as a binder. The advantages of the pre-vacuum method, which allows for close packing without separation and provides lightweight concrete with excellent strength and heat insulation performance, can be enjoyed as is, and in addition, greater compressive strength and bending strength can be obtained without reducing workability. It has the effect of being

In the present invention, when dispersing and mixing lightweight aggregate and fibers, we adopt the so-called tri-blend method in which they are mixed in advance before injecting the injection agent. Therefore, by appropriately selecting dimensions such as fiber length and fiber diameter, high density A high density distribution of fibers is possible between the filled lightweight aggregates. In addition, by adopting the tri-blend method, fibers are mixed in the filler in advance and injected into the packed layer of lightweight aggregate, which is unique to the so-called wet blend method. This solves the problem that the W/C ratio has to be increased due to an increase in injection workability, and is expected to improve compressive strength and bending strength due to the fiber reinforcement effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the basic configuration of an apparatus used for manufacturing a high-strength heat insulating material according to the present invention, and FIG. 2 is a perspective view showing a state in which a heat insulating pillow for piping manufactured by the manufacturing method of the present invention is used. FIG. 3 is a perspective view showing the manufacturing equipment for the heat insulating pillow shown in FIG. 2;
FIG. 4 is a perspective view of a heat insulating pillow manufactured by the manufacturing method of the present invention.

Claims (3)

[Claims] (1) Lightweight aggregate and fiber are mixed in advance and filled into the formwork, so that the W/C ratio of the injection agent consisting of cement (C), water (W), and admixture is 0.7 or less. A method for manufacturing a high-strength heat insulating material, characterized in that the dimensions of the fibers are determined as follows, and the injection agent is injected into the mold to infiltrate between the lightweight aggregate and the fibers. (2) The lightweight aggregate and fibers are mixed in advance and filled into the formwork, so that the W/C ratio of the injection agent consisting of cement (C), water (W), and polymer emulsion is 0.8 or less. A method for manufacturing a high-strength heat insulating material, characterized in that the dimensions of the fibers are determined as follows, and the injection agent is injected into the mold to infiltrate between the lightweight aggregate and the fibers. (3) Fill the weighed aggregate into the formwork in advance and cement (C)
The fiber dimensions are determined so that the W/C ratio of the injecting agent consisting of water (W), polymer emulsion, and fibers is 0.8 or less, and the injecting agent is injected into the mold, and the aggregate particles are measured. A method for producing a high-strength insulation material, which is characterized by infiltrating the material between the layers.