GB2050854A - Method for supplying additives to concrete or cement - Google Patents
Method for supplying additives to concrete or cement Download PDFInfo
- Publication number
- GB2050854A GB2050854A GB8015208A GB8015208A GB2050854A GB 2050854 A GB2050854 A GB 2050854A GB 8015208 A GB8015208 A GB 8015208A GB 8015208 A GB8015208 A GB 8015208A GB 2050854 A GB2050854 A GB 2050854A
- Authority
- GB
- United Kingdom
- Prior art keywords
- concrete
- water
- additive
- cement
- mixing
- 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
- 239000000654 additive Substances 0.000 title claims abstract description 46
- 239000004567 concrete Substances 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 33
- 239000004568 cement Substances 0.000 title claims abstract description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 53
- 230000000996 additive effect Effects 0.000 claims abstract description 34
- 239000000203 mixture Substances 0.000 claims description 15
- 239000012895 dilution Substances 0.000 description 9
- 238000010790 dilution Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 239000011148 porous material Substances 0.000 description 6
- 238000007906 compression Methods 0.000 description 4
- 238000009434 installation Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000004576 sand Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 3
- 230000006835 compression Effects 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000009969 flowable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000025 natural resin Substances 0.000 description 1
- 239000011505 plaster Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28C—PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28C5/00—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions
- B28C5/02—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions without using driven mechanical means effecting the mixing
- B28C5/026—Mixing guns or nozzles; Injector mixers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/30—Injector mixers
- B01F25/31—Injector mixers in conduits or tubes through which the main component flows
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D11/00—Control of flow ratio
- G05D11/006—Control of flow ratio involving a first fluid acting on the feeding of a second fluid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F2101/00—Mixing characterised by the nature of the mixed materials or by the application field
- B01F2101/28—Mixing cement, mortar, clay, plaster or concrete ingredients
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Structural Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Preparation Of Clay, And Manufacture Of Mixtures Containing Clay Or Cement (AREA)
- On-Site Construction Work That Accompanies The Preparation And Application Of Concrete (AREA)
Abstract
A method for dosing and uniformly mixing additives in concrete or cement, wherein the additive is drawn in by a water stream in accordance with the principle of a water jet pump, mixed with the water and introduced into the concrete or cement together with the water stream. <IMAGE>
Description
SPECIFICATION
Method for supplying additives to concrete or cement
The invention relates to a method for dosing and uniformly mixing additives in the form of liquids, solutions, emulsions or dispersions or gases, into concrete or cement.
Various methods and devices or installations are available for the dosing of additives. Frequently, an electrically driven pump, e.g. a gear pump, is used together with a time control system. The functions of conveying and dosing are in such a case performed by a single unit. For control of the dosing, flow clocks, monitor lamps, visual cylinders and similar devices are used. A dosing pump is sensitive because of its moving parts, and disturbances or even failure of the pump can occur due to clogging up.
Occasionally, technically better but more expensive and uneconomic installations are used, in which instead of the dosing time, the dosing quantity is used, determined by a weighing device or in an analog manner by means of a potentiometer with a float, or by way of measurement electrodes.
Furthermore, arrangements are available which convey the additive by compressed air and which are less liable to disturbance, because of the lower number of moving parts.
These known arrangements and methods operate satisfactorily with sufficiently large dose amounts.
However, in many cases it is necessary to accurately dose only small or very small amounts, and to provide uniform mixing in low concentration, in a conveying medium for example in make-up water for concrete, cement, or their dry constituents. The dosing and mixing of such small amounts as additives is a problem, for example where large amounts of concrete must be prepared in a very short time, such as in motorway or airport construction, and most of all in large engineering works or in the concrete transporting or prefabricated concrete industries. The mixing times in such plants, which mix a number of cubic meters of concrete per charge, frequently lie considerably below 60 seconds.
The additives used in such cases in small doses, such as for example air-pore materials or liquid, are expensive and for reasons of concrete technology, must be accurately dosed and well mixed in.
The known installations are in such cases not usable or only usable under some conditions. Dosing by hand is technically inadequate.
It is an object of the invention to provide a method by which additives can be reliably dosed, even in small quantities, and rapidly and uniformly mixed in a conveying medium, whereupon the additive, fineiy distributed in the conveying medium, can be introduced into the material to be provided with the additive, namely concrete or cement, directly after the mixing, or later.
The invention consists in a method for dosing and uniformly mixing additives in concrete or cement, wherein the additive is drawn in by a water stream in accordance with the principle of a water jet pump, mixed with the water and introduced into the concrete or cement together with the water stream.
The additive may be mixed with the water stream in a suction and mixing chamber and is preferably swirled. The additive can be used in the form of a concentrated solution or a solution with predetermined dosing. It can be introduced into the concrete or cement directly after mixing in the water stream, and together therewith. In a preferred embodiment of the method, the mixture of additive and water is sprayed before being introduced into the concrete or cement. The mixture is advantageously introduced during the mixing of the concrete or cement. The water used for the water jet can be used at the same time as make-up water in the production of concrete or cement.
In the method according to the invention, a principle similar to a water jet pump is used, the additive being fed and dosed and combined with the stream of water and intensively mixed and swirled, preferably in high dilution.
Since the mixture of the additive and water can be introduced into the concrete or cement charge to be provided with the additive, directly after the mixing procedure, the additive can be distributed therein with little loss or can be sprayed with a large effective contact surface.
The method according to the invention can be performed with an installation which is economic and not liable to disturbance. By means of a water jet which can be regulated by a water pressure connection, additive can be drawn from an additive container through a line and fed into a suction and mixing chamber, which is followed by a supplementary air supply and a spray nozzle. If the additive-water mixture is to be furthermore introduced into a substance, then this can be done by way of a pipe leading into a mixer.
In this manner a very small, easily dosable amount of additive can be finely distributed and introduced into a mix substance present in a mixer, where it can be rapidly and uniformly mixed in.
It is particularly advantageous if the conveying medium can be make-up water for concrete or cement, which in this manner, in the total amount or in part can be introduced through a branch line and intensively swirled with the additive fed by the action of the water jet pump system, and subsequently sprayed.
Water jet pumps have a low efficiency. However, the potential available is sufficient for the dosing of small amounts of additive, this being for example ensured by make-up water conveying the additive. Make-up water is available at all concrete mixing plants.
The effectiveness of the method according to the invention will be further explained with reference to several examples which relate to the mixing of additives in various kinds of concrete and structural cement.
Example 1
Road concrete:
Consistency stiff (K1), Power mixer BHS 2m3
Concrete material B35 according to DIN 1045, with: 33% 0-2mm sand 26% 5-11 mm chippings 41% 1 1-22mm chippings
Required LP (air pore material) content 4.0%
LP material based on natural resins
The following table shows:
1.0 Null Row: simple mixing of air-pore former in
10% dilution with water, with shortened
mixing time,
1.1 Null Row: simple mixing ofairporeformerin 10% dilution with water, with normal
mixing time,
1.2 Row: with the method of the invention,
in 2.5% dilution with water, with
shortened mixing time.
LP medium dose Wet mix time present LP
(% by cement wt.) (seconds) (Vol, %) 1.0 0.08 50 3.2 1.1 0.08 75 4.1
1.2 0.06 50 4.2
Example 2
Compensation concrete
Consistency soft (K3), Mobile mixer 5m3
Concrete material-compression resistance 3NImm2 after 28 days
Grain: Exclusively sand 0-2mm
Required LP content 40 to 45%, LP material synthetically based.
The following table shows: 2.0 Null Row: simple mixing ofthe LP material undiluted, with shortened mixing time, 2.1 Null Row: simple mixing Df the LP material undiluted, with normal mixing time, 2.2 Row: with the method according to the invention, in 2.5% dilution with water, with shortened mixing time.
LP medium dose Wet mix time present LP (% by cement wt.) (seconds) (Vol.
2.0 0.30 120 -26
2.1 0.30 360 43 2.2 0.14 120 A3 Example 3
Protective concrete, fibre reinforced
Consistency flowable, Mobile mixer 5m3
Concrete material-compression resistance 6N/mm2 after 28 days bending resistance 5N/mm2 after 28 days
Grain: Sand 0.2mm
Fibre length 26mm
Required LP content 20 to 25%, delay based on organic means, LP medium synthetically based.
For the concreting of large surfaces, for example flat roofs, it is necessary for the setting time of the concrete to be considerably delayed without the LP content being substantially reduced. Too great a change in the LP content would mean that the solid concrete characteristics such as gross density and strength have changed too greatly. Also, the dimensional tolerance of the structure would be questionable.
The following table shows: 3.1 Null Row: simple mixing of the LP medium, undiluted, 3.2 Row: with the method of the invention, in 2.5% dilution with water.
LP medium Wet present present LP loss
dose mix LP LP within
(% by cement time (Vol %) after 12 hours
weight) 12 hours (Vol /O) (Vol %)
3.1 0.15 360 26 21 5
3.2 0.08 120 25 23 2
Example 4
Heavily delayed structural cement
Consistency soft (K3), Mobile mixer 5m3
Cement strength 6.5N/mm2 after 28 days
Grain: sand 0.2mm
Required LP content, at least 20% after 36 hours.
Delay organically based, LP medium synthetic.
The following table shows: 4.1 Null Row: simple mixing of the LP medium, undiluted, 4.2 Row: with the method of the invention, in 2.5% dilution with water.
LP medium Wet Present Present LP loss
dose mix LP LP within
(% by cement time (Vol %) after 36 36 hours
weight) seconds hours (Vol %) (Vol %) 4.1 0.17 360 28 17 11
4.2 0.09 120 29 23 6
The examples 1 to 4 relate to the mixing in of air pore formers. The considerably increased stability of the air pores according to the method of the invention is surprising. The use of concretes and cements with very high air pore content - up to 70% - which are economic and very workable, is made considerably more secure by the method of the invention.
The following example illustrates the method of the invention, using a liquifier.
Example 5
Concrete for the machine production of concrete plaster blocks:
Consistency soildamp-stiff (K1), drum mixer 1 m3
Concrete material: compression resistance 63N/mm2 after 28 days
Grain 0-16mm
Additive plasticising concrete liquifier (CL)
The following table shows: 5.1 Null Row: simple mixing of the CL in 10% dilution with water, 5.2 Row: with the method of the invention in 2.5% dilution with water.
CL dose Wet Compression Gross density
dose mix resistance after 28 days
time after28days
5.1 0.25% 120s 69.0N/mm2 2.27kg/l 5.2 0.15% 80s 71.2N/mm2 2.29kg/l
Even with the admixing of liquifier is the effectiveness of the method of the invention clearly shown, by which a uniform distribution and an activation of the additive reagents in the concrete, and an increased stability is obtained. A further important technical advance of the method of the invention is the surprising rapid uniform mixing in of the additive. The method is furthermore especially economic owing to the extensive utilisation, that is to say sparing use, of the additive.
The method of the invention can of course also be used for the dosed mixing of an additive into a liquid, the additive-liquid mixture being stored and only used when required.
In the drawing, an example of a device for performing the method of the invention is diagrammatically illustrated.
The device is connected to a pressure water connection 10, and the dosing and mixing arrangement D is disposed at the central part of the device. The arrangement comprises a branch line 6 which is immersed in an intermediate or additive container 13, from which a water stream coming from the pressure water connection 10 draws a dosed amount of the additive, through the branch line 6. The additive passes into a suction and mixing chamber 5 where it mixes with the water, and is sprayed from a spray nozzle 3 through a fine sieve 2 into a pipe 1 arranged at the outlet side of the device. This pipe 1 leads from the dosing arrangement D into a collecting container or mixer (not shown) in which the water provided with the additive collects, or is mixed into a material, for example concrete.In the wall of the pipe a plurality of air inlets 4 are provided which promote better swirling and enlargement of the surface of the additive-water mixture.
At the end of the dosing arrangement D remote from the delivery end, a water meter 7 and a magnetic valve 8 are arranged. Between the pressure water connection 10 and the magnetic valve 8, a manually operable valve 9 is interposed, bywhich the quantity of waterflowing can be further regulated.
The magnetic valve 8 is electrically controlled by way of a relay 11 connected to an electric supply 12, the relay having a time selection member. Thus, depending on the setting of the time selection, a given amount of water can be conducted through the dosing arrangement.
A plurality of such arrangements can be connected one after the other, in order to introduce not just one, but a plurality of additives.
Claims (7)
1. A method for dosing and uniformly mixing additives in concrete or cement, wherein the additive is drawn in by a water stream in accordance with the principle of a water jet pump, mixed with the water and introduced into the concrete or cement together with the water stream.
2. A method according to claim 1, wherein the additive is mixed and swirled with the water stream in a suction and mixing chamber.
3. A method according to claim 1 or 2, wherein the additive is used in the form of a concentrated solution or in the form of a solution with predetermined dosing.
4. A method as claimed in claim 1,2 or 3, wherein the additive is introduced into the concrete or cement directly after the mixing in the water stream and together therewith.
5. A method as claimed in claim 4, wherein the mixture of additive and water is sprayed before introduction into the concrete or cement.
6. A method as claimed in claim 4 or 5, wherein the concrete or cement to be supplied with the additive is mixed during the introduction of the mixture of additive and water.
7. A method as claimed in any one of claims 1 to 6, wherein the water stream serving as conveying medium is used at the same time as make up water for the concrete or cement.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2918451A DE2918451C2 (en) | 1979-05-08 | 1979-05-08 | Process for dosing and evenly mixing admixtures in the form of liquids into concrete or mortar |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2050854A true GB2050854A (en) | 1981-01-14 |
| GB2050854B GB2050854B (en) | 1983-06-02 |
Family
ID=6070188
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8015208A Expired GB2050854B (en) | 1979-05-08 | 1980-05-08 | Method for supplying additives to concrete or cement |
Country Status (6)
| Country | Link |
|---|---|
| AT (1) | AT390397B (en) |
| BE (1) | BE883177A (en) |
| CH (1) | CH646093A5 (en) |
| DE (1) | DE2918451C2 (en) |
| GB (1) | GB2050854B (en) |
| NL (1) | NL8002527A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1992000138A1 (en) * | 1990-06-22 | 1992-01-09 | Fosroc International Limited | Apparatus for delivering a rapidly setting composition |
| EP0506421A1 (en) * | 1991-03-27 | 1992-09-30 | Elkem A/S | Method for shotcreting |
| FR2684326A1 (en) * | 1991-11-29 | 1993-06-04 | Bonnavion Pierre | Double-flow spraying of mortar or concrete by dry means |
| WO2019034476A1 (en) * | 2017-08-17 | 2019-02-21 | Basf Se | Process for producing liquid formulations containing fibers |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3436813C1 (en) * | 1984-10-06 | 1986-05-07 | Elba-Werk Maschinen-Gesellschaft Mbh & Co, 7505 Ettlingen | Device for flushing an additive balance in concrete preparation |
| GB8614486D0 (en) * | 1986-06-13 | 1986-07-16 | Young Robert Co Ltd | Liquid mixer |
| DE19626312A1 (en) * | 1996-07-01 | 1998-01-08 | Wilhelm Haase | Colouring fine plaster to obtain body coloured mortar |
| DE19628315A1 (en) * | 1996-07-13 | 1998-01-15 | Wilhelm Haase | Colourant adding apparatus to produce coloured plaster |
| DE29714379U1 (en) * | 1997-03-27 | 1998-01-02 | Haase, Andreas, 68753 Waghäusel | Membrane switch operated by propellant |
| DE19757734C2 (en) * | 1997-12-23 | 2000-09-14 | Bug Betriebs & Grundbesitz | Process and mixer for producing colored mortar compounds |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1690891U (en) * | 1954-08-17 | 1955-01-05 | Max Schmid | METERING PUMP FOR ADDITIVES DURING THE PREPARATION OF CONCRETE OR MORTAR WITH A MIXING MACHINE. |
| BE795086A (en) * | 1972-09-22 | 1973-05-29 | Grohe Kg Hans | SUCTION AND MIXING DEVICE FOR ADDITIVES IN A FLOW OF LIQUID |
| GB1519442A (en) * | 1975-09-29 | 1978-07-26 | Trans Vac Process Equipment Lt | Mixing apparatus |
| US4123800A (en) * | 1977-05-18 | 1978-10-31 | Mazzei Angelo L | Mixer-injector |
| DE7817913U1 (en) * | 1978-06-15 | 1978-10-12 | Oloflex - Flexible Spezialfolie Gmbh & Co Kg, 7712 Blumberg | DEVICE FOR THE OPTIONAL MIXING OF TWO LIQUID SUBSTANCES TO A PRESSURIZED LIQUID |
-
1979
- 1979-05-08 DE DE2918451A patent/DE2918451C2/en not_active Expired
-
1980
- 1980-04-28 CH CH325280A patent/CH646093A5/en not_active IP Right Cessation
- 1980-05-01 NL NL8002527A patent/NL8002527A/en not_active Application Discontinuation
- 1980-05-07 AT AT0243880A patent/AT390397B/en not_active IP Right Cessation
- 1980-05-08 GB GB8015208A patent/GB2050854B/en not_active Expired
- 1980-05-08 BE BE0/200518A patent/BE883177A/en not_active IP Right Cessation
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1992000138A1 (en) * | 1990-06-22 | 1992-01-09 | Fosroc International Limited | Apparatus for delivering a rapidly setting composition |
| US5320424A (en) * | 1990-06-22 | 1994-06-14 | Fosroc International Ltd. | Apparatus for delivering a rapidly setting composition |
| EP0506421A1 (en) * | 1991-03-27 | 1992-09-30 | Elkem A/S | Method for shotcreting |
| FR2684326A1 (en) * | 1991-11-29 | 1993-06-04 | Bonnavion Pierre | Double-flow spraying of mortar or concrete by dry means |
| WO2019034476A1 (en) * | 2017-08-17 | 2019-02-21 | Basf Se | Process for producing liquid formulations containing fibers |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2918451A1 (en) | 1980-11-20 |
| NL8002527A (en) | 1980-11-11 |
| BE883177A (en) | 1980-09-01 |
| GB2050854B (en) | 1983-06-02 |
| AT390397B (en) | 1990-04-25 |
| CH646093A5 (en) | 1984-11-15 |
| ATA243880A (en) | 1989-10-15 |
| DE2918451C2 (en) | 1982-02-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4039170A (en) | System of continuous dustless mixing and aerating and a method combining materials | |
| CN1910025B (en) | Method for processing gunned concrete by means of a spraying machine, and spraying machine | |
| GB2050854A (en) | Method for supplying additives to concrete or cement | |
| US6415824B2 (en) | Method and composition for grouting water-flooded conduits | |
| CN105298131A (en) | Grouter with spray mechanism and concrete spraying method thereof | |
| US5512093A (en) | Hot mix asphalt and method of preparation thereof | |
| US3547412A (en) | Production of lightweight concrete | |
| CN103924785B (en) | Multiviscosisty cement premixing mortar green construction method | |
| CN108177252B (en) | Using method of three-in-one stirring complete device for producing three engineering materials | |
| CN102619538A (en) | Wet type high-pressure hydraulic spraying device | |
| CN105274993A (en) | Novel stirring type grouter, and control system and stirring method thereof | |
| CN209224289U (en) | A kind of Ardealite concrete production system | |
| CN114800877A (en) | Concrete mixing plant and mixing plant without inclined belt and mixing method thereof | |
| CN102922605B (en) | Mixing plant | |
| SU1203242A1 (en) | Method of constructing monolithic concrete roof | |
| JPH07180355A (en) | Pressure conveying device and method for hydraulic fluid and spraying method using the same | |
| JPS62185922A (en) | Expanded mortar injection work in shield tunnel | |
| KR101216593B1 (en) | Mixed branch pipe for shotcrete construction equipment | |
| SU1694556A1 (en) | Method of producing light concrete mix | |
| RU2040627C1 (en) | Device for preparation of waterproofing emulsion mastic or paste | |
| DE4118536C1 (en) | Light plaster mixt. for spraying - consisting of water and cement with light aggregate mfd. by mixing foaming agent with cement and injecting into mixing chamber | |
| DE3831951C2 (en) | Dry spray process for processing mortar or concrete | |
| RU13382U1 (en) | MINI-FACTORY CONTAINER TYPE FOR THE PRODUCTION OF DRY CONSTRUCTION MIXTURES | |
| SU919890A1 (en) | Method of preparing a solution of pulverulent components of concrete mix | |
| SU943380A1 (en) | Method of feeding concrete mix |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |