JPH029737A - Heat-resistant concrete - Google Patents

Abstract

PURPOSE:To improve the high-temp. characteristic of concrete by heat-treating tar pitch in a reducing atmosphere, grinding the raw coke obtained by growing mesophase microbeads, and incorporating the obtained powdery heat resistance improver into cement. CONSTITUTION:Tar pitch is heated at a specified temp. in a reducing atmosphere for a specified time to grow mesophase microbeads so that the volatile matter content of the tar pitch is controlled to >=10%. The obtained raw coke is then ground to produce a powdery heat resistance improver, the improver is incorporated into cement, water is added, and the mixture is kneaded to produce heat-resistant concrete. When the heat-resistant concrete is exposed to high temps., mesophase microbeads are grown from around the powdery raw coke grains dispersed in the concrete, and integrated to form a continuous carbon phase having excellent high-temp. strength. Consequently, high mechanical strength is maintained even under high-temp. conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to heat-resistant concrete to which a heat-resistant reinforcing agent is added to improve the high-temperature properties of concretes.

[Prior art and its problems] Concrete, mortar, and other concrete types, especially cement concrete, are widely used as structural materials, but they have insufficient fire resistance and heat resistance, and when exposed to high temperatures, they deteriorate. There is a drawback that mechanical strength etc. decrease rapidly.

As a result of intensive studies aimed at improving the heat resistance of concrete, the inventor discovered a new fact that heat resistance can be greatly improved by adding and dispersing a certain type of powdered coke to concrete. However, the present invention was obtained.

"Means for Solving the Problems" The heat-resistant concrete of the present invention contains powdered raw coke that can form mesoface spheres when heated.

Menface spherules are an "intermediate phase" in the transition state from a liquid phase to a solid phase that is produced in the intermediate process of carbonization, in which heavy oil, tar pitch, etc. are thermally decomposed and carbonized. It is a type of liquid crystal.It exhibits optical anisotropy and is known to take on the shape of a single sphere when observed under a polarizing microscope.

Furthermore, it is recognized that the memphithic sphere has a lamellar structure in which lamellae mainly composed of aromatic condensed rings are stacked.

350% straight-run heavy oil, pyrolysis heavy oil, tarbi, etc.
When heated between ~550°C, a thermal decomposition reaction occurs,
Gas and light fractions escape, and the residue undergoes polycondensation and eventually solidifies. Cool the residue heat-treated in the above temperature range (initial stage of carbonization).

When the resulting sample is molded with resin and well polished and observed under a reflective polarizing microscope, an optically oriented phase is observed in Sample 1. That is, optical n
Optically anisotropic mesophasic spheres, which are seed liquid crystals, emerge from the tropic matrix.

Mesophase spheroids grow like normal crystals.

The resulting mesophase spheroids grow when the temperature is increased or the holding time is increased.

- Once grown, the mesoface spheroid is surrounded by the surrounding mud J y
It gradually grows by attracting aromatic condensed rings etc. from the camphorax.

Thereafter, coalescence of the menface spheres progresses.

While one spherical body is growing, the nucleus of a new spherical body is generated around it [7], and the spherical bodies coalesce due to these reactions, and meso7 ace is formed and formed.

The present invention is characterized in that powdered cow coke, which can form such mesoface spherical bodies by heating, is used as a heat-resistant reinforcing agent for concrete necks.

Powdered raw coke that can form mesophase spheres by such heating is prepared by, for example, raw coke obtained by thermally decomposing Ishiura city oil at a temperature of 550'C or less in a reducing atmosphere for 1 to 30 minutes. 1! ] I? There is crushed raw coke in powder form.

"Function" Powdered raw coke as described above can be mixed with latent hydraulic cements such as self-hardening cement such as Portland cement, lime slag cement, and blast furnace slag cement, cement such as mixed cement, slaked lime, volcanic ash, burnt stone cola, etc. Hydraulic materials are mixed with old materials such as sand, sand fil, crushed stone, etc., water is added, kneaded, and hardened to form heat-resistant concrete. The mixing ratio of powdered raw coke and cement is not particularly limited, but it is desirable that the volume ratio is less than 2 parts of powdered raw coke to 1 part of cement, and is usually in the range of 0.1 to 1 liter. Selected based on usage, characteristics, etc.

Powdered raw coke can also be dispersed in a polymer dispersion (resin emulsion) and then added to a cement-aggregate mixed wire system. Furthermore, common cement admixtures such as AE agents, dispersants, hardening accelerators, and setting retarders can also be added.

The powdered raw coke added to the cement mixture is chemically stable even under strong alkalinity caused by eluates from cement, etc., and is easily and uniformly dispersed in the mixture.

As is clear from the description of the examples below, the heat-resistant concrete thus obtained has high strength when cut with a knife.
It has excellent high temperature properties.

Here, by adding powdered raw coke that forms mesophase spherical bodies by heating, it is possible to increase the strength of
The reason why the intersection increases will be explained. When concrete is heated, it usually gradually deteriorates and becomes brittle due to the thermal decomposition reaction of cement hydrate, but countless particles of powdered raw coke as described in 1. If the raw coke powder is mixed with the raw coke particles, mesoface spherules grow from around the powdered raw coke particles, and these mesoface spherules coalesce with each other and combine with aggregate particles. By penetrating into the voids in the pores generated by decomposition, a continuous carbon matrix layer that is stable even at high temperatures is formed, resulting in the formation of a carbon phase with excellent high-temperature strength.

It is known that when the powdered raw coke is heated in the presence of oxygen (in air), the oxidation reaction begins gradually at around 550°C. In the case of FMD, the amount of oxygen is extremely small, and no oxidation reaction is observed at all, and no decrease in the strength of the concrete fleet due to oxidation of powdered raw coke is observed.

"Example" Below, as an example of the heat-resistant concrete of the present invention, several specimens were prepared by mixing powdered raw coke in cement mortar at different mixing ratios, and the strength of each specimen and the strength of each specimen were evaluated. The strength at high temperature heating i was measured.The results are shown in Example 1 and Example 2, respectively, and will be specifically explained.

[Example IJ Powdered raw coke having the characteristics shown in Table 1 was used. Incidentally, the powdered raw coke shown in Table 1 is obtained by heating coal tar at 435°C, and the powdered raw coke that is added as a heat-resistant reinforcing material to the heat-resistant concrete of this invention may be coal tar heat-treated at 400 to 150'C. In addition, this powdered raw coke is sold separately for 500 yen.
It has been confirmed by polarizing microscopy that mesophase spheres are formed by heating at ℃].

Table 1 This powdered coke was mixed with cement mortar according to the mixing ratio shown in Table 2 to prepare a 4X4X16Cjl specimen specified in JIS-R-5201, and air-cured (
20°C 550% R [() or water curing (J l5-
R-5201), and the compressive strength and bending strength were measured. The results are shown in FIGS. 1 and 2.

Table 2 All water/cement ratios (W/C) are 65%.

Toyoura standard sand was used for the sand.

Sotsu Portland cement was used as the cement.

As is clear from Figures 1 and 2, when the volume ratio of powdered raw coke to cement is between 01 and 05, the compressive and bending strength is equal to or higher than that of ordinary mortar without powdered raw coke. In particular, the strength improvement is particularly remarkable when powdered raw coke is used at a volume ratio of 0.11. Further, at a volume ratio of 01 to 0.5, the powdered raw coke was uniformly dispersed in the mortar. This result shows that the heat-resistant concrete of the present invention exhibits an excellent reinforcing effect even at room temperature.

[Example 2] Each specimen prepared and cured in the same manner as in Example I was heated to 500"C.
The mixture was heated at 1700°C and 1900°C for 90 minutes, and then cooled to room temperature.

Here, as shown in Table 1, the powdered raw coke contains as much as 1000% volatile content, that is, oil content, but
This indicates that the production reaction of mesophase spherules in the raw coke powder has not been completely completed, and that the mesophase spherules will grow further when heated again at a high temperature.

Therefore, in this way, each specimen mixed with powdered raw coke with residual volatile content of about 0% or more (preferably about 20% or less) was heated at a high temperature of 500°C or higher. In some cases, mesoface spherules grow from around countless powdered raw coke particles dispersed in concrete, and these mesoface spherules coalesce with each other and combine with aggregate particles. By penetrating into the voids in the pores generated by the thermal decomposition of cement water (0), a continuous carbon matrix layer that is stable even at high temperatures is formed, and a carbon phase with excellent high-temperature strength is formed. The Rukoto.

Next, the bending strength and compressive strength of each specimen heated at each of the above-mentioned grades were measured, and the results are shown in Figures 3 and 4.
Shown in the figure.

The results shown in Figures 3 and 4 do not directly indicate the strength of each specimen at that temperature because the strength was not measured at the valley temperature, but if this data is taken as the residual strength after heating, The reinforcing effect of raw coke powder is observed. Also,
At a heating temperature of 500"C, the volume ratio of powdered raw coke is 0.1
The reinforcing effect is large in the range of 03 to 700°C and 9
It can be seen that the reinforcing effect tends to be high in the range of 03 to 1.0 at 00°C.

"Effects of the Invention" As explained above, according to the heat-resistant concrete of the present invention, by heating tar pitch at a predetermined temperature for a predetermined time in a reducing atmosphere, more than 10% of the volatile content in the tar pitch remains. A powdered heat-resistant reinforcing agent made by grinding raw coke obtained by growing mesoface spheres in cement was mixed into cement, and water was added to the mixture and kneaded. When exposed to concrete, mesoface spherules grow around the countless powdery raw coke particles dispersed in the concrete.
These membrane spherical bodies coalesce into JL, combine with aggregate particles, and penetrate into the voids in the pores generated by the thermal decomposition of cement water fO, thereby creating a stable continuous structure even under high temperatures. Forms a carbon matrix layer, which forms a carbon phase with excellent high temperature strength,
High mechanical strength etc. will be maintained even at high temperatures.

Therefore, this heat-resistant concrete not only improves fire resistance and heat resistance, but also loses strength when exposed to high temperatures, so when used as a structural material 1) for building structures, etc. , it is possible to construct fire-resistant architectural structures. In addition, when this heat-resistant concrete is made into precast concrete, it can also be used as a base material for enamel concrete, which is useful as decorative panels for houses and walls. Since it is possible to prevent cracks from occurring in the base material even under high temperatures during the process, high quality enameled concrete can be produced.

Moreover, this heat-resistant concrete has an excellent reinforcing effect even at normal temperatures. In other words, when pulverized raw coke is uniformly dispersed in concrete, it exerts a kind of stress relaxation function, which reduces the mechanical anisotropy (the change in mechanical strength depending on the direction of concrete placement) observed in conventional concrete. difference)
This will relieve and eliminate the problem and give uniform strength.

Furthermore, raw coke, which is the raw material for the heat-resistant reinforcing agent added to this heat-resistant concrete, is produced in large quantities as a by-product during crude oil rectification, so the cost is low, and the cost of concrete by adding the heat-resistant reinforcing agent is low. It has the advantage that the increase is only slight.

[Brief explanation of the drawing]

Figures 1 to 4 are graphs showing the relationship between concrete strength and powdered fresh coke addition. Figure 1 is a graph showing compressive strength at room temperature, and Figure 2 is a graph showing bending strength at room temperature. FIG. 3 is a graph showing the bending strength after heating at a predetermined temperature, and FIG. 4 is a graph showing the compressive strength after heating at a predetermined temperature.

Claims (1)

[Claims] By heating tar pitch at a predetermined temperature for a predetermined time in a reducing atmosphere, the volatile content in the tar pitch is reduced to 1
A powdered heat-resistant reinforcing agent made by grinding the raw coke obtained by growing mesoface spheres so that 0% or more remains is mixed into cement, and then mixed with water. Features of heat-resistant concrete.