CA1204585A - Method for making a concrete block - Google Patents
Method for making a concrete blockInfo
- Publication number
- CA1204585A CA1204585A CA000427553A CA427553A CA1204585A CA 1204585 A CA1204585 A CA 1204585A CA 000427553 A CA000427553 A CA 000427553A CA 427553 A CA427553 A CA 427553A CA 1204585 A CA1204585 A CA 1204585A
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- CA
- Canada
- Prior art keywords
- mix
- recited
- weight
- mold
- inches
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
ABSTRACT
A method for making metal fiber reinforced concrete block which comprises forming a mix of aggregates to which metal fibers and the cement are added. Water is added to the mix to form a mixture which is poured into a mold having two parallel spaced apart surfaces. A stripper is advanced through the mold and frictionally engages the inner surfaces of the two parallel walls and removes the concrete block.
A method for making metal fiber reinforced concrete block which comprises forming a mix of aggregates to which metal fibers and the cement are added. Water is added to the mix to form a mixture which is poured into a mold having two parallel spaced apart surfaces. A stripper is advanced through the mold and frictionally engages the inner surfaces of the two parallel walls and removes the concrete block.
Description
The invention relates to a method for making metal fiber reinforced concrete blocks used for cribbing for mine roof support systems.
PROBLEM
The mining industry searched for material to replace conventional wood cribbing to maintain positive roof support and at the same time reduce the cost of the support system.
Wood has a compressive strength of 500 PSI. The requirements of the material to replace the wood is that it must: have greater compressive strength; use less space to obtain greater support capacity; be non-flammable; be non-biodegradable; avoid adding to methane generation; be easier to handle and install;
have an indefinite storage lie; and have lower installation time. To meet these requirements a concrete block was prepared by the Bureau of Mines. Cribbing made of such block is able to take slack in the mine roof thereby greatly reducing the roof-to-floor closure without failure.
Cribs constructed of concrete blocks are cross stacked without mortar in square or rectangular columns similar to wooden cribs. The first layer of cribbing is leveled by locally excavating the floor. The crib is erected to distribute the load evenly. The outer physical dimensions of every block must have their contacting surfaces uniform to prevent stress points from buildiny within any block which would cause crumbling. Blocks can be made by hand which could maintain this uniformly however, this would make the cost prohibitive and limit supply.
The inventors developed a method of making the block which can be used to mass produce the block and which gives the necessary compressive strength and unlEormity o the critical surfaces of the block.
SUMMARY OF THE INVENTION
The invention provides a method for making metal fiber reinforced concrete block having a pair of opposite parallel surfaces in which the deviation from parallel through-out the spacing of the surfaces is not grea-ter than plus or minus 0.032 inches and when installed in a crib configuration the crib develops 3,000 PSI compressive streng-th comprising:
a. providing a mold having two parallel, aligned, spaced apart inner face walls wherein -the deviation from the parallel alignment of the inner face walls of the mold is not greater than plus or minus 0.032 inches;
b. providing a mix as follows:
(1) commencing with aggregates;
PROBLEM
The mining industry searched for material to replace conventional wood cribbing to maintain positive roof support and at the same time reduce the cost of the support system.
Wood has a compressive strength of 500 PSI. The requirements of the material to replace the wood is that it must: have greater compressive strength; use less space to obtain greater support capacity; be non-flammable; be non-biodegradable; avoid adding to methane generation; be easier to handle and install;
have an indefinite storage lie; and have lower installation time. To meet these requirements a concrete block was prepared by the Bureau of Mines. Cribbing made of such block is able to take slack in the mine roof thereby greatly reducing the roof-to-floor closure without failure.
Cribs constructed of concrete blocks are cross stacked without mortar in square or rectangular columns similar to wooden cribs. The first layer of cribbing is leveled by locally excavating the floor. The crib is erected to distribute the load evenly. The outer physical dimensions of every block must have their contacting surfaces uniform to prevent stress points from buildiny within any block which would cause crumbling. Blocks can be made by hand which could maintain this uniformly however, this would make the cost prohibitive and limit supply.
The inventors developed a method of making the block which can be used to mass produce the block and which gives the necessary compressive strength and unlEormity o the critical surfaces of the block.
SUMMARY OF THE INVENTION
The invention provides a method for making metal fiber reinforced concrete block having a pair of opposite parallel surfaces in which the deviation from parallel through-out the spacing of the surfaces is not grea-ter than plus or minus 0.032 inches and when installed in a crib configuration the crib develops 3,000 PSI compressive streng-th comprising:
a. providing a mold having two parallel, aligned, spaced apart inner face walls wherein -the deviation from the parallel alignment of the inner face walls of the mold is not greater than plus or minus 0.032 inches;
b. providing a mix as follows:
(1) commencing with aggregates;
(2) adding metal fibers to the aggregate and mixing them with the aggregates; and
(3) then adding cement to the aggrega-tes and metal fibers;
c. adding water to the mix and forming a mix-ture;
d. filling a mold with the mix-ture and compac-ting it in the mold -to form the concrete block; and e. advancing a stripper means through the mold wherein the stripper means frictionally engages the inner sur-faces of the two parallel walls and removes the concre-te block from the mold.
The invention will further be described,by way of example only, with reference to the accompanying drawing which shows a perspective view of a mold with a corresponding stripper member for removing a concrete block from the mold.
The figure shows a mold 10 which has two parallel, aligned and spaced apart inner face walls 12 and 14 which are 23 inches long and 7 5/8 inches high. The end walls 16 and 18 5~5 are 3 5/8 inches wide inside. The mold 10, therefore, produces a block 23 inches x 7 5/8 x 3 5/8. The blocks are stacked in such a manner that the planar dimensions oE 23 inches x 7 5/8 lay flat, one on top of the other. It is -therefore important that the surface defined by the 23 inches x 7 5/8 inches be flat and uniform to avoid any irregularities. It is also important that the thickness of the block, namely the 3 5/8 inches, remain constant to achieve uniformity. To achieve -the uniform -thickness of the block the deviation from parallel -throughout the spacing of the walls 12 and 14 should not be greater than plus or minus 0.032 inches and preferably should be not more than 0.010 inches.
In making the concrete block a mix is made using:
river sand having a fineness modulus in a range of 2.75 to 3.00 and which is in a weight range of between 30% to 60% by weight of the entire mix preferably 44% by weight of the mix; river gravel which is 1/2 inch x 1/8 inch and 25% to 50% by weight of the entire mix and preferably 36.7% by weight of the mix. These aggregates are designated as A.S.T.M. C-33. The mix also con-tains metal fibers which range in length between 20 mm. -to 50 mm. (or 0.7874 inches to 1.9685 inches) with a diameter of 2a.
~2~ 5~
0.50 mm. to 0.80 mm. (or 0.02 inches to 0.03 inches). The fibers form between 1% to 4% by weight oE the mix and preferably 1.95% by weight of the mix. These fibers are sold by Bekaert Steel Wire Corporation, Niles, Illinois under the mark DRAMIX. It is important to add these fibers discretely by separating them while adding them to the aggregates and mixing them before any cement is added. If the cement is added before or simultaneously with the metal fibers the proper dispersion of the fibers will not take place. Cement is then added and forms part of the mix. The cement comprises between 10% to 16 by weight of the mix and peferrably 14.8~ by weight of the mix. The cement is identified as A~S~ToM~ Type III C-150. Fly ash is added and forms part of the mix which is l to 5% by weight of the mix and preferably 2.4~ by weight of the mix.
plasticizer which forms part of the mix is added at a rate of 1.75 ounces per 100 pounds of cement.
Water is added to the mix to form a mixture which i5 poured into the mold 10. The mold 10 is filled and compacted over a time period not less than two seconds to achieve proper compaction.
A stripper means 20 having longitudinal faces 22 and 24 frictionally engages the inner surfaces 14 and 12 respectively and removes the cement block. This frictional engagement is necessary to achieve a uniformity of the corresponding block faces which are formed by walls 12 and 14 and avoid any protuding fibers on the surface.
After the block is removed from the mold it should sex between 1 to 4 hours and then steam heat is applied a-t a rate of increase of 60 F. per hour until a range of 120 F~ to 190 F. is reached. After the desired ternperature is reached x r r k ~25~85 the steam heat ;s maintained for 10 hours. Then dry heat at 180~ F. is applied for 22 hours. Heat is then removed from the block at a rate of 50 F. per hour.
This results in a block which has an individual compressive strength of 5,200 PSI and when installed in a crib configuration develops 3,000 PSI compressive strength. Each block weighs approximately 50 pounds and has post-failure toughness and will not easily crumble.
c. adding water to the mix and forming a mix-ture;
d. filling a mold with the mix-ture and compac-ting it in the mold -to form the concrete block; and e. advancing a stripper means through the mold wherein the stripper means frictionally engages the inner sur-faces of the two parallel walls and removes the concre-te block from the mold.
The invention will further be described,by way of example only, with reference to the accompanying drawing which shows a perspective view of a mold with a corresponding stripper member for removing a concrete block from the mold.
The figure shows a mold 10 which has two parallel, aligned and spaced apart inner face walls 12 and 14 which are 23 inches long and 7 5/8 inches high. The end walls 16 and 18 5~5 are 3 5/8 inches wide inside. The mold 10, therefore, produces a block 23 inches x 7 5/8 x 3 5/8. The blocks are stacked in such a manner that the planar dimensions oE 23 inches x 7 5/8 lay flat, one on top of the other. It is -therefore important that the surface defined by the 23 inches x 7 5/8 inches be flat and uniform to avoid any irregularities. It is also important that the thickness of the block, namely the 3 5/8 inches, remain constant to achieve uniformity. To achieve -the uniform -thickness of the block the deviation from parallel -throughout the spacing of the walls 12 and 14 should not be greater than plus or minus 0.032 inches and preferably should be not more than 0.010 inches.
In making the concrete block a mix is made using:
river sand having a fineness modulus in a range of 2.75 to 3.00 and which is in a weight range of between 30% to 60% by weight of the entire mix preferably 44% by weight of the mix; river gravel which is 1/2 inch x 1/8 inch and 25% to 50% by weight of the entire mix and preferably 36.7% by weight of the mix. These aggregates are designated as A.S.T.M. C-33. The mix also con-tains metal fibers which range in length between 20 mm. -to 50 mm. (or 0.7874 inches to 1.9685 inches) with a diameter of 2a.
~2~ 5~
0.50 mm. to 0.80 mm. (or 0.02 inches to 0.03 inches). The fibers form between 1% to 4% by weight oE the mix and preferably 1.95% by weight of the mix. These fibers are sold by Bekaert Steel Wire Corporation, Niles, Illinois under the mark DRAMIX. It is important to add these fibers discretely by separating them while adding them to the aggregates and mixing them before any cement is added. If the cement is added before or simultaneously with the metal fibers the proper dispersion of the fibers will not take place. Cement is then added and forms part of the mix. The cement comprises between 10% to 16 by weight of the mix and peferrably 14.8~ by weight of the mix. The cement is identified as A~S~ToM~ Type III C-150. Fly ash is added and forms part of the mix which is l to 5% by weight of the mix and preferably 2.4~ by weight of the mix.
plasticizer which forms part of the mix is added at a rate of 1.75 ounces per 100 pounds of cement.
Water is added to the mix to form a mixture which i5 poured into the mold 10. The mold 10 is filled and compacted over a time period not less than two seconds to achieve proper compaction.
A stripper means 20 having longitudinal faces 22 and 24 frictionally engages the inner surfaces 14 and 12 respectively and removes the cement block. This frictional engagement is necessary to achieve a uniformity of the corresponding block faces which are formed by walls 12 and 14 and avoid any protuding fibers on the surface.
After the block is removed from the mold it should sex between 1 to 4 hours and then steam heat is applied a-t a rate of increase of 60 F. per hour until a range of 120 F~ to 190 F. is reached. After the desired ternperature is reached x r r k ~25~85 the steam heat ;s maintained for 10 hours. Then dry heat at 180~ F. is applied for 22 hours. Heat is then removed from the block at a rate of 50 F. per hour.
This results in a block which has an individual compressive strength of 5,200 PSI and when installed in a crib configuration develops 3,000 PSI compressive strength. Each block weighs approximately 50 pounds and has post-failure toughness and will not easily crumble.
Claims (18)
1. A method for making metal fiber reinforced concrete block having a pair of opposite parallel surfaces in which the deviation from parallel throughout the spacing of the surfaces is not greater than plus or minus 0.032 inches and when installed in a crib configuration the crib develops 3,000 PSI compressive strength comprising:
a. providing a mold having two parallel, aligned, spaced apart inner face walls wherein the deviation from the parallel alignment of the inner face walls of the mold is not greater than plus or minus 0.032 inches;
b. providing a mix as follows:
(1) commencing with aggregates;
(2) adding metal fibers to the aggregate and mixing them with the aggregates; and (3) then adding cement to the aggregates and metal fibers:
c. adding water to the mix and forming a mixture;
d. filling a mold with the mixture and compacting it in the mold to form the concrete block; and e. advancing a stripper means through the mold wherein the stripper means frictionally engages the inner surfaces of the two parallel walls and removes the concrete block from the mold.
a. providing a mold having two parallel, aligned, spaced apart inner face walls wherein the deviation from the parallel alignment of the inner face walls of the mold is not greater than plus or minus 0.032 inches;
b. providing a mix as follows:
(1) commencing with aggregates;
(2) adding metal fibers to the aggregate and mixing them with the aggregates; and (3) then adding cement to the aggregates and metal fibers:
c. adding water to the mix and forming a mixture;
d. filling a mold with the mixture and compacting it in the mold to form the concrete block; and e. advancing a stripper means through the mold wherein the stripper means frictionally engages the inner surfaces of the two parallel walls and removes the concrete block from the mold.
2. A method as recited in claim 1 wherein the aggregates include:
a. sand having a fineness modulus in a range of 2.75 to 3.00 and which is between 30% and 60% by weight of the mix; and b. gravel which is between 25% to 50% by weight of the mix.
a. sand having a fineness modulus in a range of 2.75 to 3.00 and which is between 30% and 60% by weight of the mix; and b. gravel which is between 25% to 50% by weight of the mix.
3. A method as recited in claim 1 wherein the aggregates include:
a. sand having a fineness modulus in a range of 2.75 to 3.00 and which is between 30% and 60% by weight of the mix; and b. gravel 1/2 inch by 1/8 inch which is between 25%
to 50% by weight of the mix.
a. sand having a fineness modulus in a range of 2.75 to 3.00 and which is between 30% and 60% by weight of the mix; and b. gravel 1/2 inch by 1/8 inch which is between 25%
to 50% by weight of the mix.
4. A method as recited in claim 1 wherein the aggregates include:
a. sand having a fineness modulus in a range of 2.75 to 3.00 and which is 44% by weight of the mix;
and b. gravel which is 36.7% by weight of the mix.
a. sand having a fineness modulus in a range of 2.75 to 3.00 and which is 44% by weight of the mix;
and b. gravel which is 36.7% by weight of the mix.
5. A method as recited in claim 1 wherein the metal fibers are in the range of 0.787 inches to 1.9685 inches in length and the fibers are between 1% to 4% by weight of the mix.
6. A method as recited in claim 1 wherein the metal fibers are in the range of 0.787 inches to 1.9685 inches in length and the fibers are 1.96% by weight of the mix.
7. A method as recited in claim 1 wherein the metal fibers are discretely added to the aggregates before the cement is added to the mix.
8. A method as recited in claim 1 wherein the cement is type III and between 10% to 16% by weight of the mix.
9. A method as recited in claim 1 wherein the cement is type III and is 14.8% by weight of the mix.
10. A method as recited in claim 1 including adding fly ash to the mix which is between 1% to 5% of the weight of the mix.
11. A method as recited in claim 1 including adding fly ash to the mix which is 2.4% by weight of the mix.
12. A method as recited in claim 1 including adding a plasticizer to the mix.
13. A method as recited in claim 1 including adding a plasticizer to the mix at a rate of 1.75 ounces per 100 pounds of cement.
14. A method as recited in claim 1 including filling the mold with the mixture and compacting it in the mold to form the concrete block, the filling and compacting is accomplished in a time period of not less than two seconds.
15. A method as recited in claim 1 including allowing the block which is removed from the mold to set for 1 to 4 hours.
16. A method as recited in claim 1 including applying steam heat to the block after it is removed from the mold at a rate of increase of 60° F. per hour until a range of 120°F. to 190° F. is reached and then continuing to apply the stream for 10 hours.
17. A method as recited in claim 1 including applying dry heat to the block at 180° F. for 22 hours.
18. A method as recited in claim 1 including removing heat from the block at a rate of 50° F. per hour.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000427553A CA1204585A (en) | 1983-05-05 | 1983-05-05 | Method for making a concrete block |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000427553A CA1204585A (en) | 1983-05-05 | 1983-05-05 | Method for making a concrete block |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1204585A true CA1204585A (en) | 1986-05-20 |
Family
ID=4125182
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000427553A Expired CA1204585A (en) | 1983-05-05 | 1983-05-05 | Method for making a concrete block |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1204585A (en) |
-
1983
- 1983-05-05 CA CA000427553A patent/CA1204585A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |