GB2161471A

GB2161471A - Manufacture of fire bricks

Info

Publication number: GB2161471A
Application number: GB08414955A
Authority: GB
Inventors: Yu Rin Hu
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-06-12
Filing date: 1984-06-12
Publication date: 1986-01-15
Also published as: GB8414955D0

Abstract

A process for manufacture of non-kiln fire bricks is disclosed in which clay (optionally with sand), water and bond, a mix of cement and hardening agent e.g. containing SiO2, Al2O3 and FE2O3, are mixed and pressed into molds for use without need to be fired.

Description

SPECIFICATION Process for manufacture of fire bricks This invention relates to fire bricks and the manufacture thereof.

This invention provides a process for manufacture of non-kiln fire bricks in which clay, sand, water and bond, a mix of cement and hardening agent containing SiO2, AI2O3 and Foe202, are mixed and pressed into molds for use without need to be fired.

Description of the drawings Figure 1 is a front elevation of the brick making machine employed in this invention.

Figure 2 is a top elevation of the said brick-making machine.

Figure 3 is a flow chart of the process of this invention.

Figure 4 is a grain size analysis of a clay.

Figure 5 is a graph of crushing strength against bond strength.

Figure 6 is a graph of water absorptivity v. bond strength.

This invention is to provide a process of non kiln fire bricks to eliminate the disadvantages of conventional fired bricks and to simplify the procedures of brick making. Conventionally, it takes a long time to processing the clay after it is dug. In the early stage, it was weathered in the open air so as to attain the desired property. Now special equipment is used to mix clay, sand, powdered brick and water into a plastic mass. This mass is pressed into molds by press. Dry-pressed molds are fired in periodic kilns or continuous kilns. Wet-pressed molds are first dried in drying rooms and then fired in kilns at 900 1100"C. After firing, the bricks are cooled. Their strength to resist crushing depends on the ingredients and the firing temperature. Usually the higher the temperature the harder the bricks.

From the above, it is clear that the common disadvantages of conventional methods of brick making are (a) complicated and time-wasting in process, (b) energy and labor-wasting, (c) expensive and specious in-equipment, (d) limited in clay, (e) vulnerable to weather and apt to pollute the air, and (f) easy to deform; In view of this, the inventor who has engaged in brick making for many years, developed a process of non kiln fire bricks after years of study and test. With this process we can not only eliminate the above mentioned disadvantages and also make high crushing strength bricks of clay, sand, cement, water and a little of cheap bond without need of firing.

Another object of this invention is to provide a simple process for mass production of bricks with simple machinery equipment in an integral operation.

Still another object of this invention is to provide a process of making bricks of common clay and sand so that bricks can be made in remote areas and offshore islands with local material at a low cost.

The methods, ingredients, operational conditions and brick making equipment of this invention are described as follows: In the process of non kiln fire bricks of this invention, crushed clay, bond and water are mixed and pressed into molds of desired sizes. The proportions of ingredients and the molding pressure are: Red clay . 70 - 93% Bond : 30- 7% Molding pressure (by the area of Brick) : 170 kgicm2 The clay does not need to be selected. It is allowed to contain a little of impurities. In other words, common clay (soil classification AASHTO A-7-6 (15) or LISCS ML) can be used. If it contains sand, the sand to be added to the mix can be relatively reduced. The sand used in this invention may be the pebbled sand from river bed, or the sand with gravel from the beach but the amount of sand can not be excessive or the sand would fall off after the mold is released.The said bond is a mixture of cement and hardening agent. The proportion of cement should be at least 90 - 95% or the binding strength would be too low. According to the test results, 95% is optimal. The content of cement can not be too high or the significance of making bricks with clay and sand will be reduced. The optimal content of hardening agent is 5 - 10%. Lower content of hardening agent will result in lower binding strength and lower crushing strength. Higher content of hardening agent is not necessary but to increase the cost. Water content is enough when the material has proper moisture. Excessive water will result in longer time to dry.The ingredients and their proportions are: SiO2 . 75% At203 18 - 20% Fe203 : 0.8% Test results show that a mix of 75% SiO2, 20% A12O2 and 0.8% Fe2O3 is most efficient.

The equipment employed in this invention is very simple. As show in Figs. 1 & 2, the dug clay is filled in the clay hopper 1 and after dropping onto the chain conveyer 2, is carried to the H hopper 4. After it drops from the H hopper 4 onto the belt conveyer 5, the clay. is carried to the clay mill 6 and crushed therebt. The crushed clay is filled in the clay bin 7 and with the sand from the sand bin 8, filled in the belt feeder 9. On the other hand, the cement from the cement bin 10 and the bond (or binding agent) from the bond bin 11 are mixt in the paddle type mixer 12. The mix of cement and bond from the mixer 12 and the clay and sand from the belt feeder 9 are filled in the bucket elevator 13 which carries the clayr sand and bond to the fine material hopper 14. The fine material is then filled in the pan type mixer 15 -and mixed there with the water from the water pump.The mix of clay, sand, bond and water is pressed into molds by the molding press 16 with a pressure of 300 tons. The molded bricks with high crushing strength and water absorptivity are taken out and stacked on the ground. They are ready for use without need to be fired at high temperature.

The brick samples made in compliance with the process of this invention have found to have a crushing strength of 150kg/cm2 and a water absorptivity of 10 - 15%. So it is really a breakthrough in brick making and a useful process to the industry.

The following tests demonstrate the effectiveness of the invention..

Test report Content of non kiln fire brick 1. Bond: Cement (REBAR) 9.5% and hardening agent 0.5% - by weight 2. Kind of soil and its physical property: Grain size Natural Soil analysis Moisture Liquid Plastic Specific classification Soil content limit index gravity No, description # #4 #200 (%) (%) AASHTO - USCS +4 #200 or less B Red clay 0 7.2 92.8 16.3 -44.2 14.7 2.69 A-7-6(15) ML See Fig. 4 3..Sample making steps: (5) Soil and bond were mixed in the proportion as sho.wn in chart 1.

Chart 1 Red clay Proportions Weight of sand Weight of bond Soil by total mix & clay mix (gr) moisture Remarks No. {%} content Weight of Weight of Cement Hardening { /O) Soil Bond dry soil wet soil agent B-1 93 7 2139 2579.6 153 8.0 20.6 B-2 90 10 2070 2496.4 218.5 11.5 20.6 B-3 80 20 1840 2305.5 437.0 23.0 25.3 B-4 70 30 1610 2049.5 655.5 34.5 27.3 (2) Three samples were made for each No. (proportion) totaling 12 samples.

(3) The samples were pressed only once at the static pressure of 170Kg/cm2 and taken out four curing.

4. Sample curing: They were cured in the room for 21 days.

5. Test methods and items: (1) The test was made in accordance with ASTM C67.

(2) Test items: (a) Crushing strength and (b) Water absorptivity.

(3) Test results: See Table 2 and Figs. 5 & 6.

TABLE 2 Test Results of Compressive Strength (21 days) and Water Absorptivity No. Specific compressive Water gravity strength in 21 absorptivity Remarks days {Kgiom2) (%) B-1-1 2.14 133.1 15.0 B-1-2 2.13 140.1 14.2 B-1-3 2.15 143.9 13.6 B-2-1 2.15 153.3 13.6 B-2-2 2.15 176.5 16.9 B-2-3 2.15 196.7 16.7 B-3-1 2.18 234.0 14.7 B-3-2 2.17 213.4 14.4 B-3-3 2.17 265.3 13.7 B-4-1 2.15 287.3 14.2 B-4-2 2.15 268.6 13.8 B-4-3 2.14 259.4 13.1

Claims

1. A process of manufacturing fire bricks in which crushed clay, bond (a mix of cement and hardening 3gent) and some water are mixed and pressed into bricks under the below specified pressure: Clay : 70-93% Bond (a mix of cement 90-95% & : 30-7% hardening agent 5-10%) Molding pressure (by the brick area) : 170kg/cm2

2. A process according to claim 1 wherein the clay is red clay of soil classification AA SHTO A-7-6 (15) Df LISCS ML.

3. A process according to either of claims 1 or 2 wherein the hardening agent contains mainly: SiO2 . 75% At203 : 18-20% Fe2O3 . 0.8%

4. A process according to claim 1 of manufacturing fire bricks substantially as hereinbefore described.

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5. Fire bricks manufactured by a process according to any one of claims 1 to 4.