GB2133000A - Mixture for the production of light-weight aggregates for building materials - Google Patents
Mixture for the production of light-weight aggregates for building materials Download PDFInfo
- Publication number
- GB2133000A GB2133000A GB08334167A GB8334167A GB2133000A GB 2133000 A GB2133000 A GB 2133000A GB 08334167 A GB08334167 A GB 08334167A GB 8334167 A GB8334167 A GB 8334167A GB 2133000 A GB2133000 A GB 2133000A
- Authority
- GB
- United Kingdom
- Prior art keywords
- weight
- mixture
- clay
- light
- mixture according
- 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.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/04—Silica-rich materials; Silicates
- C04B14/10—Clay
- C04B14/12—Expanded clay
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/02—Agglomerated materials, e.g. artificial aggregates
- C04B18/027—Lightweight materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Civil Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
A mixture which serves for the production of light-weight aggregates for building materials consists of between 10% and 80% by weight of expandable clay, between 1 % and 5% by weight of waste oil and as the residue, a filler, which can be formed by river and/or sea sediments, ashes or muds. The constituents of the mixture are made into a high quality product, which would otherwise have to be produced by the use of raw materials. The light-weight aggregate produced from the mixture is suitable for the production of building blocks with good thermal insulating capacities, as an additive for structural light-weight concrete and as an aggregate for insulating plaster for additional thermal insulation or for insulating mortar.
Description
SPECIFICATION
Mixture for the production of light-weight aggregates for building materials
The invention relates to a mixture for the production of light-weight aggregates for building materials.
Light-weight aggregates serve for reducing the weight and saving on quantities in the production of building materials, for example in the production of bricks, light-weight concrete, mortar and the like. However, for these light-weight aggregates, a high percentage of clay is required, for example at least approximately 85% by weight, which is a valuable raw material.
It is the object of the invention to provide a mixture of the above type so that the proportion of clay can be reduced.
The invention provides a mixture for the production of light-weight aggregates for building materials comprising between 1% and 5% by weight of waste oil, between 10% and 80% by weight of expandable clay, and a filler as the residue.
The constituents of such mixture are processed to form a high-quality product, which otherwise would have to be produced mainly by using up raw materials. In this case, materials even containing harmful substances, such as for example heavy metals, organic impurities and the like, can be used as fillers, which otherwise could only be stored on dumps, since the harmful content precludes the use of these substances for example in agriculture. With the mixture according to the invention, it is possible to produce a valuable light-weight aggregate, which has a low bulk weight, high resistance to compression and good thermal insulating properties.The lightweight aggregate produced from the mixture according to the invention is therefore eminently suitable for the production of building blocks with a good thermal insulating property, as an additive to light-weight structural concrete and as an aggregate for insulating plaster, for additional thermal inf ulation or for insulating mortar. The cost-incurring removal of waste products is replaced by the economic reincorporation of the waste products in the economic cycle of goods, in which case due to the goods produced, a raw material can be saved, which can be used elsewhere.
In a first embodiment of a mixture according to the invention, between 10% and 80% by weight of expandable clay, and between 1% and 5% by weight of waste oil, and river and/or sea sediments as the residue, are used. Opaline clay (Dogger a, Jura) or top speckled marl (central red marl, km 3) for example is used as good expandable clay. The river and/or sea sediments are obtained by the dredging of flowing and stagnant waters.
The sediments may be contaminated with
harmful substances. During subsequent pro
cessing of the mixture, the sediments are
surrounded by a sintered skin at the time of
cooling, so that they can no longer exert any
harmful effect. Insofar that the harmful sub
stances pass into the gaseous state before
reaching the expansion temperature, such as
for example cadmium, these harmful sub
stancas are discharged and collected in dust
filters or the like. It is therefore unnecessary to
remove the harmful substances from the sedi
ments produced when dredging the waters,
which would require complicated and expen
sive operations.
In a preferred embodiment, the mixture
consists of less than 30% by weight of clay,
between 68% and 88% by weight of river
and/or sea sediments, and substantially 2%
by weight of waste oil. With this mixture it is
possible to produce a light-weight aggregate
which has a particularly low bulk weight and
a high strength. In this mixture it is possible
to use exclusively river sediments or exclu
sively sea sediments or a mixture of river and
sea sediments. Preferably fine-grained river
and sea sediment is used.
In a further embodiment, the mixture ac
cording to the invention consists of between
10% and 80% by weight of expandable clay,
between 1% and 5% by weight of waste oil,
and of ashes and/or muds as the residue.
As the ash, fly ash for example is available,
which consists essentially of very fine mineral
substances, which occur in modern filter and
separating plants of coal fired power stations.
As the mud, red mud for example can be
used, as it occurs in the production of alumi
nium from bauxite. The light-weight aggregate
produced from this mixture is characterised by
low bulk weights. Above all, the addition of
fly ash increases the strength of the light
weight aggregate considerably, even with re
spect to the first embodiment of the mixture.
In the second embodiment, the mixture may
contain solely fly ash or solely mud or a
mixture of ash and mud. In a preferred em
bodiment, between 10% and 30% by weight
of clay, between 68% and 88% by weight of
ash and/or mud, and substantially 2% by
weight of waste oil are used. Opaline clay or
top speckled marl for example can once again
be used as expandable clay.
In a third embodiment of the mixture ac
cording to the invention, between 10% and
80% by weight of clay, between 1% and 5%
by weight of waste oil, and river and/or sea
sediments as the residue and ashes and/or
muds in any ratio with respect to each other
are used. A preferred composition of this
mixture is between 10% and 30% by weight
of clay, substantially 2% by weight of waste
oil, and between 68% and 88% by weight of
fine-grained river and/or sea sediments mixed
with ashes and/or muds in any ratios. The mixing ratios of river and/or sea sediments and ashes and/or muds depends on the desired strength of the light-weight aggregate. If high strengths are required, such as for example for light-weight concrete, a greater proportion of ashes and/or muds is used.
Accordingly, the strength of the light-weight aggregate is reduced, if the proportion of ash and/or mud is low.
In all the embodiments, the sediments, ashes and muds are fine-grained, in order to obtain a homogeneous mixture. With the mixtures described, the proportion of clay is reduced, so that this valuable raw material can be saved. In particular, in the mixtures according to the invention, the major part consists of waste products, which consequently do not need to be deposited, but can be used immediately for the production of light-weight aggregates.
Preferably, each of the mixtures described contains a proportion of red mud, which is present in a concentration of between 1% and 10% by weight in the mixtures.
In a particularly advantageous embodiment, as an additional constituent, the mixture contains an auxiliary expanding agent. According to the quantity of auxiliary expanding agent added, the proportion of clay in the mixture can be reduced. For example, if 3% auxiliary expanding agent is added to a mixture of 70% filler, for example sediments, 25% clay and 5% other additives, then the proportion of clay can be reduced to approximately 15% and the proportion of filler increased to approximately 77%. With the auxiliary expanding agent, a high and satisfactory expansion capacity is achieved in the expanded clay production from the mixture. The individual components of the mixture are mixed with water and granulated and then dried and preheated. After drying, the granulated material is burnt and thus expanded.During this expansion process, each granule obtains its light-weight properties. The expansion operation is controlled so that the granules already have a closed sintered skin, when the expansion operation begins. The gases necessary for the expansion are thus prevented from escaping. As a result of the auxiliary expansion agent, despite the reduced proportion of clay, an extremely high and good expansion capacity is achieved, so that the expanded granulated material has a very low bulk weight and very high resistance to compression. The light-weight aggregate produced from the ix- ture is therefore eminently suitable for the production of building blocks with a good thermal insulating capacity, as an addition to structural light-weight concrete and as an aggregate for insulating plaster for additional thermal insulation or for insulating mortar.
Waste products are likewise used extensively for the mixture, so that these waste products no longer need to be removed in an expensive manner. This removal is replaced by economic reincorporation of the waste products into the economic cycle of goods, in which case due to the goods produced, other raw materials can be saved for processing elsewhere.
River and/or sea sediments can be used as fillers. These fillers, which otherwise would have to be removed in an expensive manner, such as for example sediments contaminated with heavy metals from storage dams and reservoirs, can now be used for the production of a high quality light-weight aggregate for building materials. Due to the addition of the auxiliary expanding agents, even larger quantites of these fillers can be made into a high quality light-weight aggregate, together with less use of the valuable raw material clay. Instead of river and/or sea sediments or together with the latter, ashes and muds can also be used. The expanded clay has a closed, smooth sintered skin, fine uniformly distributed pores and high strength.
When using the mixture according to the invention, considerably improved pelletability of the expanded clay is also achieved.
In one mixture between 10% and 80% by weight of expandable clay, between 1% and 5% by weight of auxiliary expanding agent, between 1% and 5% by weight of waste oil and between 10% and 88% by weight of river and/or sea sediments as the residue are used. The river and/or sea sediments are obtained when dredging flowing and stagnant waters and may contain harmful substances.
These harmful substances are enclosed by the sintered skin during the production of expanded clay, so that they can no longer exert any harmful effect. Insofar that these harmful substances pass into the gaseous state before reaching the expansion temperature, such as for example cadmium, they are discharged and collected in dust filters or the like. It is therefore unnecessary to remove harmful substances from the sediments produced when dredging waters, which would necessitate complicated and expensive processes.
In another mixture, between 10% and 80% by weight of clay, between 1% and 5% by weight of auxiliary expansion agent, between 1% and 5% by weight of waste oil and between 10% and 88% by weight of ashes and muds as the residue are used. Fly ashes can be used for example as the ashes, the latter consisting essentially of mineral substances in the form of a fine dust, which occur in modern filtering and separating plants of coal fired power stations. Communal waste water muds or industrial muds of organic, metallic or mineral nature can be used as mud. The light-weight aggregate produced from this mixture is characterised by low bulk weights. Above all the addition of fly ash clearly increases the strength of the lightweight aggregate. The mixture may contain solely ash or solely mud or a mixture of ash and mud.
In a further embodiment between 10% and 80% by weight of expandable clay, between 1% and 5% by weight of auxiliary expansion agent, between 1% and 5% by weight of waste oil and between 10% and 88% by weight of river and/or sea sediments and ashes and/or muds as the residue are used.
The river and/or sea sediments can be mixed in any proportions with respect to each other with ashes and/or muds. The proportions of the mixture depend on the desired strength of the light-weight aggregate. If high strengths are required, such as for example for lightweight concrete, a greater proportion of ashes and/or muds is used. The proportion of ashes and/or muds is correspondingly less, if the strength of the light-weight aggregate is intended to be lower. In all embodiments, the sediments, ashes and muds are fine-grained, in order to obtain a homogeneous mixture.
An alkaline binder is preferably used as the auxiliary expanding agent, by which the constituents of the mixture can be held together firmly. Cements, for example Portland cement, are preferably used as auxiliary expanding agents.
Claims (11)
1. A mixture for the production of lightweight aggregates for building materials, comprising between 1% and 5% by weight of waste oil, between 10% and 80% by weight of expandable clay, and a filler as the residue.
2. A mixture according to claim 1, comprising less than 30% by weight of clay, between 68% and 88% by weight of filler and substantially 2% by weight of waste oil.
3. A mixture according to claim 1 or claim 2, wherein opaline clay (Dogger a, Jura) is used as said clay.
4. A mixture according to claim 1 or claim 2, wherein top speckled marl (middle red marl, km 3) is used as said clay.
5. A mixture according to any one of claims 1 to 4, wherein ashes and mud mixed together are used as the filler.
6. A mixture according to any one of claims 1 to 4, wherein river and/or sea sediments are used as the filler.
7. A mixture according to any one of claims 1 to 4, wherein the mixture contains river and/or sea sediments and ashes and/or muds in any ratio with respect to each other.
8. A mixture according to claim 5 or claim 7, comprising red mud in a concentration of between 1% and 10% by weight.
9. A mixture according to claim 1, comprising between 1% and 5% by weight of auxiliary expanding agent.
10. A mixture according to claim 9, wherein the auxiliary expanding agent is an alkaline binder.
11. A mixture according to claim 9 or claim 10, wherein the auxiliary expanding agent is cement.
1 2. A mixture according to any one of claims 9 to 11, comprising an auxiliary expanding agent in the range of 2% to 4% by weight.
1 3 A mixture for the production of lightweight aggregates for building materials substantially as hereinbefore described.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19833300052 DE3300052C2 (en) | 1981-12-23 | 1983-01-04 | Light aggregate for use in building materials and mixtures |
| DE19833339575 DE3339575A1 (en) | 1983-11-02 | 1983-11-02 | Mix for producing light aggregates for building materials |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8334167D0 GB8334167D0 (en) | 1984-02-01 |
| GB2133000A true GB2133000A (en) | 1984-07-18 |
| GB2133000B GB2133000B (en) | 1986-06-04 |
Family
ID=25807390
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8334167A Expired GB2133000B (en) | 1983-01-04 | 1983-12-22 | Mixture for the production of light-weight aggregates for building materials |
Country Status (3)
| Country | Link |
|---|---|
| FR (1) | FR2539125A1 (en) |
| GB (1) | GB2133000B (en) |
| NL (1) | NL8400003A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0411052A1 (en) * | 1988-04-27 | 1991-02-06 | Ceramic Bonding, Inc. | Process for the chemical bonding of heavy metals from sludge in the silicate structure of clays and shales and the manufacture of building and construction materials therewith |
| EP0471132A1 (en) * | 1990-08-13 | 1992-02-19 | Societa Meridionale Argille Espanse S.P.A | A thermic lithosynthesis process for disposal of liquid and solid industrial wastes |
| GB2264943A (en) * | 1991-01-25 | 1993-09-15 | Eth Umwelttechnik Gmbh | Brickwork products |
| WO2006056197A1 (en) * | 2004-11-23 | 2006-06-01 | Danmarks Tekniske Universitet | A method of manufacturing building materials and use thereof |
| RU2455248C2 (en) * | 2010-03-22 | 2012-07-10 | Государственное образовательное учреждение высшего профессионального образования "Самарский государственный университет" | Composition for producing porous aggregate |
| RU2481282C1 (en) * | 2011-12-29 | 2013-05-10 | Юлия Алексеевна Щепочкина | Mixture for producing porous aggregate |
| RU2532230C1 (en) * | 2013-08-13 | 2014-10-27 | Юлия Алексеевна Щепочкина | Mixture for making porous aggregate |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113696306A (en) * | 2021-09-10 | 2021-11-26 | 上海百奥恒再生资源有限公司 | High-efficiency reinforcing process for autoclaved aerated concrete block |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1400854A (en) * | 1972-07-25 | 1975-07-16 | Sherwen Eng Co Ltd | Manufacture of synthetic aggregates |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH490289A (en) * | 1966-02-03 | 1970-05-15 | Haniel Ag Franz | Process for the production of a porous non-capillary active ceramic material |
| DE1284348C2 (en) * | 1966-03-17 | 1975-08-21 | Elmolit GmbH, Basel (Schweiz) | Process for the production of expanded clay with improved properties |
| DE1571602A1 (en) * | 1966-03-28 | 1970-12-17 | Krause Heinz Josef | Process for the production of granules from red mud as additives for the construction industry |
| FR1574731A (en) * | 1967-04-12 | 1969-07-18 | ||
| BE759521A (en) * | 1969-11-28 | 1971-04-30 | Albright & Wilson | GRAVILON MANUFACTURING PROCESS |
| FR2034069A5 (en) * | 1970-02-24 | 1970-12-04 | G N | Keramzite filler production |
| GB1406250A (en) * | 1971-11-23 | 1975-09-17 | Redland Technology Ltd | Road-making material |
| US3909283A (en) * | 1974-03-04 | 1975-09-30 | Wilbert E Warnke | Producing lightweight aggregate |
| AT366019B (en) * | 1975-05-27 | 1982-03-10 | Kreutzer Wilhelm Dipl Kfm Dr | METHOD FOR PRODUCING BURNED BLOCKS |
| SU692806A1 (en) * | 1977-01-12 | 1979-10-25 | Всесоюзный научно-исследовательский институт по креплению скважин и буровым растворам | Raw mixture for preparing porous clay filler |
| SU692807A1 (en) * | 1977-08-03 | 1979-10-25 | Минский научно-исследовательский институт строительных материалов | Raw mixture for preparing aggloporous material |
| DE2945061A1 (en) * | 1979-11-08 | 1981-05-21 | Pfister Gmbh, 8900 Augsburg | Expanded or foamed solid particles prodn. - from clays slags etc. using foaming agent in a slurry, then drying by heating |
| DE3150993A1 (en) * | 1981-12-23 | 1983-06-30 | Ed. Züblin AG, 7000 Stuttgart | METHOD FOR THE DISPOSAL OF FLOWING AND STANDING WATERS OF FINE-GRAINED SEDIMENTS |
-
1983
- 1983-12-22 GB GB8334167A patent/GB2133000B/en not_active Expired
-
1984
- 1984-01-02 NL NL8400003A patent/NL8400003A/en not_active Application Discontinuation
- 1984-01-03 FR FR8400056A patent/FR2539125A1/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1400854A (en) * | 1972-07-25 | 1975-07-16 | Sherwen Eng Co Ltd | Manufacture of synthetic aggregates |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0411052A1 (en) * | 1988-04-27 | 1991-02-06 | Ceramic Bonding, Inc. | Process for the chemical bonding of heavy metals from sludge in the silicate structure of clays and shales and the manufacture of building and construction materials therewith |
| EP0411052A4 (en) * | 1988-04-27 | 1991-07-03 | Ceramic Bonding, Inc. | Process for the chemical bonding of heavy metals from sludge in the silicate structure of clays and shales and the manufacture of building and construction materials therewith |
| EP0471132A1 (en) * | 1990-08-13 | 1992-02-19 | Societa Meridionale Argille Espanse S.P.A | A thermic lithosynthesis process for disposal of liquid and solid industrial wastes |
| GB2264943A (en) * | 1991-01-25 | 1993-09-15 | Eth Umwelttechnik Gmbh | Brickwork products |
| WO2006056197A1 (en) * | 2004-11-23 | 2006-06-01 | Danmarks Tekniske Universitet | A method of manufacturing building materials and use thereof |
| RU2455248C2 (en) * | 2010-03-22 | 2012-07-10 | Государственное образовательное учреждение высшего профессионального образования "Самарский государственный университет" | Composition for producing porous aggregate |
| RU2481282C1 (en) * | 2011-12-29 | 2013-05-10 | Юлия Алексеевна Щепочкина | Mixture for producing porous aggregate |
| RU2532230C1 (en) * | 2013-08-13 | 2014-10-27 | Юлия Алексеевна Щепочкина | Mixture for making porous aggregate |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2133000B (en) | 1986-06-04 |
| NL8400003A (en) | 1984-08-01 |
| GB8334167D0 (en) | 1984-02-01 |
| FR2539125A1 (en) | 1984-07-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3720609A (en) | Process for treating aqueous chemical waste sludges and composition produced thereby | |
| US4266980A (en) | Expansive solidifying material | |
| CN110357538B (en) | Regenerated self-compacting concrete and preparation method thereof | |
| GB2133000A (en) | Mixture for the production of light-weight aggregates for building materials | |
| CN107673738A (en) | A kind of iron ore tailings haydite and preparation method | |
| KR20200125141A (en) | High strength lightweight mortar composition comprising pre-wetted artificial lightweight fine aggregate with recycled water of ready mixed concrete | |
| JP2008036532A (en) | The effective use method for construction sludge | |
| CN115073093A (en) | Low-shrinkage high-strength self-compacting recycled concrete and preparation method thereof | |
| Alsadey et al. | Effect of superplasticizers to enhance the properties of concrete | |
| CN111943545B (en) | Artificial sand and preparation method thereof | |
| US3096188A (en) | Structural composition material and process for making same | |
| US4304674A (en) | Method of disposing of a washing water sludge from filtering systems | |
| KR20000072111A (en) | Composition for lightweight aggregate and method for manufacturing the same | |
| JP2006298730A (en) | Method of firing incineration ash and sintered compact obtained by the same method | |
| CN112242182A (en) | Reverse design method, preparation method and application of recycled lightweight concrete | |
| JP3569696B2 (en) | Concrete production method | |
| JPS59131558A (en) | Mixture for producing aggregate for construction material | |
| JP4358359B2 (en) | Low shrinkage concrete | |
| EP0657397A1 (en) | Light aggregates for low-density structural concrete compositions | |
| JP3216034B2 (en) | Porous sintered body and method for producing the same | |
| JPS5836965A (en) | Improved lightweight aggregate and manufacture | |
| US2077374A (en) | Concrete mixture and method of making the same | |
| JP7185994B2 (en) | Cement-based solidifying material and its manufacturing method | |
| Rahman | A comparative study of the potentials of rice husk ash on cohesive and cohesionless soils | |
| CN1139025A (en) | Dry process processing caustic sludge to produce earth for earthwork |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19961222 |