CA1139793A

CA1139793A - Glass fiber reinforced cements and process for manufacturing of same

Info

Publication number: CA1139793A
Application number: CA000322659A
Authority: CA
Inventors: Ernst H. Dereser
Original assignee: Owens Corning Fiberglas Corp
Current assignee: Owens Corning
Priority date: 1978-10-25
Filing date: 1979-03-02
Publication date: 1983-01-18
Also published as: BR7900611A; GR68707B; NZ189481A; NL7902295A; IT7829874A0; NO790227L; FI790213A; ZA79390B; AU4385579A; IT1101711B; FR2439758A1; JPS5560049A; AU527167B2; BE872304A; DK28879A; SE7900541L; DE2850868A1; GB2035286A; GB2035286B

Abstract

ABSTRACT OF THE DISCLOSURE
.
A fiber reinforced cementitious product comprising a cement as a continuous phase and fibers dispersed as reinforce-ment in the continuous phase, the product including a poly-electrolyte and a finely divided inorganic material having a high surface area. A process for producing the product and fibers comprising a size coating including the polyelectrolyte and the inorganic material are also disclosed.

Description

~3~ 3 This invention relates to reinforced cementitious products and -to a process ~or their manufacture.
It is now well known that various fibers can be used in the reinforcement of cementitious products. One of khe more well-known reinforced cementi~ious products is cement reinforced with asbestos fiber~. ~he asbestos fibers are combined with cement in khe form of a built-up laminate to provide a reinforced product, such as cemen~ pipes and cement sheets or boards and the like, having good strength chaxacteristics:
In the manufacture of such asbestos fiber reinforced cementitious products, two processes are well-known to those skilled in the art. The first is the so-called Hatschek process for the production of reinforced cementitious pipe and the second is the Magniani process for the production of boards formed of reinforced cemen~ In both of the processes, asbestos fibers ~re mixed with a cement slurry to form a pulp, and then the pulp is placed onto a foraminous forming member (a cylinder in the case of the Hatschek process and a flat, usually endless, belt in the Magniani process). Moi~ture from the slurry is re~oved by applying suction thereto whereby water is drawn through the foraminous forming member.
The mechanism underlying the effectiveness of as~estos fibers in khe manufacture of reinforced cementitious products is not fully understood at the present time. The asbesto~
reinforcement appears to maintain, to at least some degree, the retention of water as the reinforced cement product is being manufactured t~ prevent excessive dehydration or dewatering which would cause the cement product to crumble.

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I t l~d~ ~ell ~Iy~othe~iz~d that th~ hiyll s~lrfac~
activity of a~b~stos fibers makes them hl~hly r~clct1ve to retain small cement particles alony with wa-ter to prevent cement from being carried off with the water during dehydration or dewatering on the foraminous support. Th~t high reactivity is accentuated by the fact that the asbestos fibers have a high specific surface area (viz., of the order of 10-20 m2/g). Thus, the highly reactive surfaces of the asbestos fibers are believed to flocculate the cement ànd retain it to provide a reinforced cement product having good structural strength.
Various attempts have been made -to omit asbestos from such reinforced cementitious products but without success. In the absence of -the asbestos fibers dispersed in the cementitious materialg the rate at which water is removed so that the cementitious product can be cured is significantly increased.
In addition, the green strength of the reinforced cementitious product, before cure, is drastically reduced as a result of excessive dewaterin~ resulting in delamination .. , ..._... ,... ~ . , .
It has been proposed, in Fre~ch Patent No. 2,317,250, to partially replace asbestos fibers with glass fibers, Ev~n that technique has not met with any appreciable success. Glass fibers, when combined with cementitious materials in the manufacture of reinforced cementitious products have a tendency to adhere together, remaining in bundles, -thereby disturbing the rate at which water can be removed through the foraminous forming member. In general, the presence of glass fibers in such reinforced cement products makes such products~ in the hydrated state, too porous and causes the water present in the

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cement slurry -to be removed too rapidly, carrying with it large quantities oE the cement itself. Because glas fibers have quite low surface areas (of the order of 0.1-0.2 m2/g), they do not share in the ability of asbestos to retain either cement or water. Thus, it has not been possible, by prior art methods to form, on a Hatschek machine, reinforced cement products contain-ing more than 2% by weight of glass fibers.
Accordingly, a broad object of the present invention is to provide a glass fiber reinforced cementitious product and a process for the manufacture thereof which obviate or mitigate the above identified disadvantages of -the prior art.
According to an aspect of the present lnvention there is provided a fiber reinforced cementitious product comprising a cement as a continuous phase and fibers dispersed as reinforce-ment in the continuous phase, the product including a poly-electrolyte and a finely divided inorganic material having a high surface area.
According to a further aspect of the present invention there is provided a process for preparing the above described product comprising forming a pulp from the cement and the fibers; contacting the pulp with a foraminous forming member and removing water therefrom to produce a green product; and curing the green product.
According to a still further aspect of the present invention there is provlded a fiber for reinforcing a cementitious product, the fiber comprising a size coating including a poly-electrolyte and a finely divided inorganic material having a high surface area.
In one embodiment this invention can be applied to the filter press process for manufacturing reinforced cementitious C~ .

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products, besides the above mentioned Hatschek and Magniani processes.
The concepts of the present invention reside in the discovery that glass fibers can be employed as reinforcement in the manufacture of reinforced cementitious products when the cement system includes, as a component of the size on the glass fiber surfaces or as a component of the cement slurry (or both), an inorganic, finely divided particulate material having a high surface area in combination with polyelectrolytes.
It has been unexpectedly found that the presence of the inorgan-ic material and the polyelectrolyte serve to markedly increase the amount of cement particles and water retained by the glass fibers. It is therefore possible to produce, when desired, a glass fiber reinforced cement procluct containing as much as 30%
glass fibers by weight, all without adversely affecting the structural properties of the reinforced product.
In the preferred practice of the invention, glass fibers which may or may not have been previously sized (as in forming) are sized with a size composition containing, as the essential ingredien~s, the inorganic material and the polyelec-trolyte. The glass fibers are then laid down on a foraminous support member with a cement slurry which has also been formu-lated with the inorganic material and polyelectrolyte(s).
Water isthen removed in a conventional manner (as by applying a vacuum to the foraminous support) to effect partial dehydration or dewatering of the glass fiber-cement composite, after curing the result is a fiber reinforced-cement product having high structural strength.
As the inoryanic material, use is preferably made of a finaly divided siliceous material having a small par'cicle ..~

~L~3g'7~3 size, prQferably less than 10 microns, and a high specific surface area (i.e., surface areas greater than 20m /g and most preferably in the range of 75-500 m2/g~. Best results have been obtained with a specially treated bentonite known as ALTON I T .
Good results can also be achieved with fumed silica, diatomaceous earth or like silicas.
The term "polyelectrolyte" includes flocculating agents, such materials which have been found to provide good results are the flocculating agents HARCOFLOC 900 or DEFLOC 50-V, both of which are commercially available. Surfactants and wett-ing agents may be used together with the polyelectrolytes.
The total amount of inorganic material employed is not critical, and can be varied within relatively wide limits.
Best results are usually obtained when the inorganic material constitutes from 5 to 50% by weight, based on the weight of the cement employed, and preferably 10 to ~5~ by weight. Similarly, the amount of the polyelectrolyte can be varied, usually within the range of 0.01 to 1% by weight based on the weight of the cement employed.
Where, in the preferred embodiment, the inorganic material is present in a size applied to the glass fibers, the size composition is formulated, on a solids basis, to include from 10 to 75~ inorganic material and 1 to 25% polyelectrolyte.
It is sometimes preferred to formulate the size with film-former which is compatible with the polyelectrolyte. Suitable are starches or similar film formers and/or vinyl resins. One vinyl resin which provides goo~ results is polyvinyl alcohol such as MOWIOL ~.88 from ~loechst ~G, Germany.
In addition, the size can be formulated to include other conventional additives such as glass fiber lubricants, * a trade mark ~L~3~7~3 wetting agents, etc. Suitable lubricants include SODAMINE* or E~RLUBE*7484. The amount of the film-former generally ranges from 5-35% by weight and the lubricant from 1.0 to 15%, based on the solids content of the size. The size is applied to the glass fibers in amounts ranging from 0.1 to 25% solids by weight based on the weight of the glass fibers. If the fibers are used without additives to the cementitious slurry, the solids of glass sizing will be in the range of 5 to 200% or more of glass weight.
1~ In the application of the size composition to glass fibers, use can be made of any of a variety of known applica-tion techniques. For example, the glass fibers can be passed in contact with a roller wet with one of the size compositions.
Alternatively, the size compositions can be sprayed onto the glass fibers.
Glass fibers used herein can include "E" glass fibers, well known to those skilled in the art; such fibers are described in U.S. Patent No. 2,334,961. Preferred glass fibers, however, are alkali resistant glass fibers. Such glass fibers are now well known to those skilled in the art and are described in U.S. Patent Nos. 3,840,379, 3,861,927 and 3,861,926.
In combining glass fibers treated as taught herein with cementitious material, use can be made of any of a number of cements of the same type employed in the art. Suitable cementitious materials include cement, Portland cement, concrete, mortar, gypsum, hydrous calcium silicate, etc. The treated glass fibers, generally in an amoun-t ranging from 1 to 25 by weight based upon the weight of the cement are blended with a cement slurry, either with or without the addition of other fibers such as asbestos fibers. When such other fibers * a trade mark ~,, ~39'~ 3 are used, -they are generally present in an amount ranging from l-lG% by weight based upon the weight of the cementi-tious material. The pulp resulting from blending the fibers and the cementitious material is then placed in contact with a foraminous forming member in accordance with the well known Hatschek or Magniani processes and a vacuum applied to the forminous member to remove water from the fiber reinforced cementitious product. The product is then cured in accordance wi~h convention-al techniques.
The resulting fiber reinforced cementitious product is characteriæed by high strength, and can be used as various building materials in accordance with will known principles of the prior art.
The following examplesPurther lllustrates the invention.

This example illustrates the preparation and use of a size com~osition as described herein, A size composition was formulated as follows:
Parts by Weight Polyvinyl alcohol ~MOWIOL 4.88) 14.0 ALTONIT 18.0 Lubricant (EMERLUBE 7484) 4.3 Flocculating Agents: DELFLOC 50-V 5.0 HERCOFLOC 900 1.0 The above size composition was combined with water to make up a suspension having a solids content of 2.9~ by weight solids~
The foregoing size composition was applied to glass fibers by roller coating. The resulting ibers coated with the size composition had a gel-like coating on the surfaces thereof, * a trade mark 7 _ r~

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the coating exhibited good adhesion to the glass fiber surfaces.
EXAMPI~ 2 This example illustrates the use of glass fibers treat-ed as described herein in the manufacture of glass fiber-reinfor-ced cementitious pipe or sheet.
Glass fibers treated in accordance with Example 1 were blended with a cement composition having the following composi-tion:
Cement Composition Parts by Weight Cement 800 *

HERCOFLOC 900 0.4 Water 8,000 The glass fibers, chopped to lengths of about 1/8 to

3 inches, were employed in an amount corresponding to about 10%
by weight based upon the weight of the cement. The pulp thus formed was then processed conventionally in a Hatschek machine to form fiber reinforced cement pipes or sheets having good strength characteristics. This may include the use of additional polyelectrolytes.
While the foregoing description is based on the use of glass fibers as reinforcement, it will be understood that the concepts of the present invention lend themselves to the use of other fibers, including natural and synthetic organic and inorga-nic fibers, such as wool,~ACRON*, nylon, polyester fibers, metal etc.
The invention may be practiced to allow the use of mineral fibers, particularly glass fibers in paper-making systems and in wet process board and mat systems by improving the processability characteristics of such inorganic fibers.

* a trade mark 8

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fiber reinforced cementitious product comprising a cement as a continuous phase and glass fibers dispersed as reinforcement in said continuous phase, said product including a polyelectrolyte and a finely divided inorganic material having a high surface area.

2. A product as defined in claim 1, wherein said polyelectrolyte is a flocculating agent and said inorganic material has a surface area greater than 20 m2/g.

3. A product as defined in claim 2, wherein said flocculating agent and said inorganic material are present in admixture with said cement.

4. A product as defined in claim 2, wherein said flocculating agent and said inorganic material are present as a size coating on said fibers.

5. A product as defined in claim 2, wherein said flocculating agent and said inorganic material are present in admixture with said cement and as a size coating on said fibers.

6. A product as defined in claim 3, 4 or 5, wherein said inorganic material has an average particle size Less than 10 microns and a surface area in the range of 75 to 500 m 2/g.

7. A product as defined in claim 3, 4 or 5, wherein said inorganic material is selected from the group consisting of:
a silica, a bentonite and a diatomaceous earth.

8. A product as defined in claim 3, 4 or 5, wherein said inorganic material is ALTONIT (a trade mark).

9. A product as defined in claim 3, 4 or 5, wherein said inorganic material comprises from 5 to 50 weight percent and said flocculating agent comprises from 0.01 to 1 weight percent each relative to the weight of said cement.

10. A product as defined in claim 3, 4 or 5, wherein said inorganic material comprises from 10 to 25 weight percent and said flocculating agent comprises from 0.01 to 1 weight percent each relative to the weight of said cement.

11. A product as defined in claim 3, 4 or 5, wherein said fibers are glass fibers.

12. A product as defined in claim 3, 4 or 5, wherein said fibers are "E" glass fibers.

13. A product as defined in claim 3, 4 or 5, wherein said fibers are alkali resistant glass fibers.

14. A product as defined in claim 3, 4 or 5, wherein said fibers are selected from the group consisting of: wool fibers, DACRON (a Trade Mark) fibers, nylon fibers, polyester-fibers, metal fibers and mixtures thereof.

15. A product as defined in claim 3 t 4 or 5, wherein said fibers are glass fibers and said glass fibers comprise up to 30 weight percent of said product.

16. A product as defined in claim 3, 4 or 5, wherein said fibers are glass fibers coated with a conventional size.

17. A product as defined in claim 3, 4 or 5, wherein said flocculating agent is selected from the group consisting of:
HARCOFLOC 900 (a trade mark), DELFLOC 50-V (a trade mark) and mixtures thereof.

18. A product as defined in claim 3, 4 or 5, wherein said flocculating agent is used in combination with an auxilliary agent selected from the group consisting of: a surfactant, a wetting agent and mixtures thereof.

19. A product as defined in claim 4 or 5, wherein said size coating comprises, on a solids basis, from 10 to 75 percent of said inorganic material and from 1 to 25 percent of said flocculating agent.

20. A product as defined in claim 4 or 5, wherein said fibers are glass fibers and said size coating comprises auxilliary agents selected from the group consisting of: from 5 to 35 weight percent of a film former compatible with said flocculating agent, from 1 to 15 weight percent of a glass fiber lubricant, a wetting agent and mixtures thereof; said weight percent ranges being based on the solids content of said size coating.

21. A product as defined in claim 4 or 5, wherein said fibers are glass fibers and said size coating comprises, on a solids basis, from 0.1 to 25 weight percent of said glass fibers.

22. A product as defined in claim 4, wherein said fibers are glass fibers and said size coating comprises, on a solids basis, from 5 to 200 weight percent of said glass fibers.

23. A product as defined in claim 3, 4 or 5, wherein said fibers are glass fibers and said glass fibers comprise from 1 to 25 weight percent of said cement.

24. A product as defined in claim 3, 4 or 5, wherein said fibers are glass fibers and said glass fibers comprise from 1 to 25 weight percent of said cement; said product further comprising from 1 to 10 weight percent of said cement of fibers other than glass fibers including asbestos fibers.

25. A product as defined in claim 3, 4 or 5, wherein said cement is selected from the group consisting of: cement, Portland cement, concrete, mortar, gypsum and hydrous calcium silicate.

26. A process for forming a fiber reinforced cementi-tious product comprising a cement as a continuous phase and fibers dispersed as reinforcement in said continuous phase, said product including a polyelectrolyte and a finely divided inorga-nic material having a high surface area; said process comprising forming a pulp from said cement and said fibers; contacting said pulp with a foraminous forming member and removing water there-from to produce a green product; and curing said green product.

27. A process as defined in claim 26, wherein said product is formed by the Hatschek process.

28. A process as defined in claim 26, wherein said product is formed by the Magniani process.

29. A process as defined in claim 26, 27 or 28, where-in the removal of water from said pulp is achieved by applying a vacuum to said foraminous forming member.

30. A process as defined in claim 26, wherein said product is formed by the filter press process.

31. A fiber for reinforcing a cementitious product, said fiber comprising a size coating including a polyelectrolyte and a finely divided inorganic material having a high surface area.

32. A fiber as defined in claim 31, wherein said polyelectrolyte is a flocculating agent and said inorganic material has a surface area greater than 20 m2/g.

33. A fiber as defined in claim 32, wherein said inorganic material has an average particle size less than 10 microns and a surface area in the range of 75 to 500 m /g.

34. A fiber as defined in claim 33, wherein said inorganic material is selected from the group consisting of: a silica, a bentonite and a diatomaceous earth.

35. A fiber as defined in claim 34, wherein said inorganic material is ALTONIT (a trade mark).

36. A fiber as defined in claim 32, 33 or 34, wherein said fiber is a glass fiber.

37. A fiber as defined in claim 32, 33 or 34, wherein said fiber is an "E" glass fiber.

38. A fiber as defined in claim 32, 33 or 34, wherein said fiber is an alkali resistant glass fiber.

39. A fiber as defined in claim 32, 33 or 34, wherein said fiber is selected from the group consisting of: a wool fiber, a DACRON (a Trade Mark) fiber, a nylon fiber, a metal fiber and mixtures thereof.

40. A fiber as defined in claim 32, 33 or 34, further comprising a conventional size coating.

41. A fiber as defined in claim 32, 33 or 34, wherein said flocculating agent is selected from the group consisting of:
HARCOFLOC 900 ( a trade mark), DELFLOC 50 V (a trade mark) and mixtures thereof.

42. A fiber as defined in claim 32, 33 or 34, wherein said size coating comprises, on a solids basis, from 10 to 75 percent of said inorganic material and from 1 to 25 percent of said flocculating agent.

43. A fiber as defined in claim 32, 33 or 34, wherein said fiber is a glass fiber and said size coating comprises auxilliary agents selected from the group consisting of: from 5 to 35 weight percent of a film former compatible with said flocculating agent, from 1 to 15 weight percent of a glass fiber lubricant, a wetting agent and mixtures thereof; said weight percent ranges being based on the solids content of said size coating.

44. A fiber as defined in claim 32, 33 or 34, wherein said fiber is a glass fiber and said size coating comprises, on a solids basis, from 0.l to 25 weight percent of said glass fiber.

45. A fiber as defined in claim 32, 33 or 34, wherein said fiber is a glass fiber and said size coating comprises, on a solids basis, Prom 5 to 200 weight percent of said glass fiber.