Use of CSH-seed modified fibers in oil field applications

Abstract

The present invention relates to the use of modified fibers in oilfield applications, particularly in borehole cementing. Said fibers have crystallization seeds attached to their surfaces thereby improving the mechanical strength and ductility of borehole cements.

Claims

1. A method of utilizing fibers in borehole cementing in the development, exploitation and completion of underground mineral oil and natural gas deposits and in wells, comprising: providing reinforcing fibers, wherein calcium silicate hydrate crystallization seeds are attached to said fibers via linker moieties, wherein the fibers are selected from polyvinyl alcohol fibers, polyolefin fibers, polysaccharide fibers and mixtures thereof, wherein the linker moieties comprise one or more functional groups selected from the group consisting of amine, ammonium, amide, nitrate, sulfate, sulfonate, sulfonamide, carboxylate, silanol, phosphate, phosphinate or phosphonate functional groups, providing a cement slurry incorporating the fibers, pumping the slurry into a borehole, and allowing the slurry to harden.

2. The method of claim 1, wherein the fibers are selected from polyvinyl alcohol fibers, polyethylene fibers, polypropylene fibers, cellulose fibers and mixtures thereof.

3. The method of claim 1, wherein the crystallization seeds are attached to the individual fiber bodies via covalently bound linker moieties in the presence of at least one comb polymer.

4. The method of claim 3, wherein the comb polymer has a main chain, wherein the comb polymer has side chains comprising polyether functions and acid functions, and wherein the side chains are present on the main chain.

5. The method of claim 1, wherein the linker moieties comprise one or more functional groups created from a reagent containing the amine, ammonium, amide, nitrate, sulfate, sulfonate, sulfonamide, carboxylate, silanol, phosphate, phosphinate or phosphonate groups.

6. The method of claim 5, wherein the reagent is an amphiphilic molecule.

7. The method of claim 1, wherein the size of the crystallization seeds is between 1 nm and 10 m.

8. The method of claim 7, wherein the size of the crystallization seeds is between 5 nm and 1.5 m.

9. The method of claim 7, wherein the size of the crystallization seeds is between 10 nm and 300 nm.

10. The method of claim 7, wherein the size of the crystallization seeds is between 10 nm and 100 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Heat flow curve for control fiber F1 and modified fiber F1-Seed1. Cumulated heat of hydration (HoH) is a measure of the activity of the seeds on the fiber (A=PVA Fiber; B=PVA Fiber modified by 3-(Aminopropyl)triethoxysilane; C=CSH-Seeds on PVA Fiber modified by 3-(Aminopropyl)triethoxysilane; y-axis=Normalized Heat Flow [mW/g(cement)]; x-axis=Time [h])

(2) FIG. 2: Scanning electron microscopy (SEM) micrograph of the CSH seed particle on a modified polypropylene fiber

(3) FIG. 3: Notched Coupon Test setup (left) and test specimen geometry (right)

(4) FIG. 4: Notched Coupon Test results of polypropylene fibers (A: PP fiber reference (coextruded with fumed silica); B: PP fiber (coextruded with fumed silica) and addition of an extra amount of CSH powder in the mortar (1 wt % with respect to the fiber content); C: PP fiber (coextruded with fumed silica) and addition of an extra amount of CSH powder in the mortar (2 wt % with respect to the fiber content); D: CSH modified PP fiber (coextruded with fumed silica);

(5) x-axis: crack opening [m], y-axis: load [N])

(6) FIG. 5: Notched Coupon Test results of polypropylene fibers with (E) and without (F) ettringite precipitate; x-axis: crack opening [m], y-axis: load [N])

(7) FIG. 6: SEM micrograph of the CSH seed particle on a modified polyvinylalcohol fiber

(8) FIG. 7: SEM micrograph of the gypsum calcium disulfate seed particle on a modified poyvinylalcohol fiber

(9) FIG. 8: Light microscopy image of CSH on sulfated PVA-fiber.

(10) FIG. 9: SEM image of CSH on sulfated PVA-fiber.

(11) FIG. 10: Light microscopy image of C-S-H on amino-functionalized PVA-fiber.

(12) FIG. 11 is a graph showing the heat flow calorimetry of amino-functionalized PVA-fiber (L2) and C-S-H modified amino-functionalized PVA-fiber (S2) measured in LaFarge cement at a w/z of 0.4, T=20 C.

(13) FIG. 12 is a graph showing the force displacement curves after 24 hours and 28 days for samples L1 and S1.

(14) FIG. 13 is a graph showing the force displacement curves after 24 hours and 28 days for samples L2 and S2.

(15) Table 1: Heat of hydration values (HoH) are represented as integrals of different heat flow measurements (see examples F1-F8) up to 6 h (HoH-6 h) and 10 h (HoH-10 h) (see FIG. 1). The modification of the fiber surface with different anchor groups or linkers influences the heat of hydration in most cases in a negative way. The CSH modification shows a shift of the heat flow measurements towards earlier hydration times in comparison with the reference system.

(16) Table 2: Summary of application tests. The F.sub.Max,2 increased after CSH modification. Also a significant improvement in the crack opening at this load can be recognized. (A: PP fiber reference (coextruded with fumed silica); B: PP fiber (coextruded with fumed silica) and addition of an extra amount of CSH powder in the mortar (1 wt % with respect to the fiber content); C: PP fiber (coextruded with fumed silica) and addition of an extra amount of CSH powder in the mortar (2 wt % with respect to the fiber content); D: CSH modified PP fiber (coextruded with fumed silica)

(17) TABLE-US-00002 TABLE 1 modified fiber with different linker modified fiber unmodified fiber moieties with stabilizer Route for HoH-6h HoH-10H HoH-6h HoH-10H HoH-6h HoH-10H Example Fiber Seeding (J/g) (J/g) (J/g) (J/g) (J/g) (J/g) F1 PVA Route 1 17.2 46.2 17.2 46.5 25.8 61.0 F2 PP Route 1 19.5 51.1 18.3 48.9 21.3 53.8 F3 PP Route 1 19.5 51.1 17.4 47.0 21.5 54.0 F4 PP Route 1 16.3 44.1 16.0 44.1 20.6 52.1 F5 Basalt Route 1 15.2 42.1 13.7 38.4 15.5 52.4 F6 cellulose Route 2 14.6 40.8 9.7 21.6 16.9 45.1 F7 cellulose Route 2 14.6 40.8 12.6 36.0 15.6 42.6 F8 cellulose Route 2 14.6 40.8 13.8 40.1 16.0 44.0

(18) TABLE-US-00003 TABLE 2 Fiber F.sub.Max,2 .sub.Max,2 W.sub.Max,2 A 564 422 284 D 861 760 261 B 531 420 259 C 581 363 214

EXAMPLES

Example F1

(19) 4 L Ethanol, 8 g 3-aminopropyltriethoxysilane and 10 mL conc. ammonium hydroxide solution were put in a reaction vessel and stirred. 80 g polyvinylalcohol fiber were suspended in this as prepared mixture. After storing for 5 h at room temperature the fibers were separated from the liquid, washed and dried at 70 C. for 16 h.

Example F2

(20) 1.5 g Phosphonated polypropylene, prepared from triethylphosphit and chlorinated polypropylene followed by acidic hydrolysis, was dissolved in 500 mL methyl-tertbutyl ether. Then 25 g polypropylene (PP) fibers were added and stored for 5 h in the mixture at room temperature before the fibers were separated from the liquid, washed and dried at 70 C. for 16 h.

Example F3

(21) 20 g PP fibers were suspended in 1.4 L chloroform, 15 g n-bromo succinimide and 2.0 g dibenzoyl peroxide were added and the mixture was heated to 60 C. to maintain a gentle reflux. After 1 h the mixture was cooled down to room temperature for 2.5 h. The fibers where then separated from the liquid compounds, washed with methyl-tertbutyl ether and dried at room temperature.

(22) Then, the fibers were mixed with 500 mL diethylene triamine and heated for 5 h at 90 C. Afterwards, the fibers were washed with methyl-tertbutyl ether and dried at room temperature.

Example F4

(23) 20 g PP fibers were suspended in a solution of polyvinylamine-polypropylene copolymer (VP PR 8358 X; BASF) in 600 g water and heated to 60 C. for 8 h. The mixture was then allowed to cool down to room temperature slowly. The fibers were separated, washed with water and dried at 60 C.

Example F5

(24) 4 L Ethanol, 8 g 3-aminopropyltriethoxysilane and 10 mL conc. ammonium hydroxide solution were put in a reaction vessel and mixed. 25 g basalt fiber were suspended in this mixture. After storing for 5 h at room temperature the fibers were separated from the liquid, washed with ethanol and dried at 70 C. for 16 h.

Example F6

(25) 700 mL THF and 5 g ammonium polyphosphate were put in a reaction vessel and stirred. 42.5 g viscose fibers were suspended in this prepared mixture. After stirring for 5 h in boiling THF the fibers were separated from the liquid, washed and dried at 70 C. for 16 h.

Example F7

(26) 1.5 L acetone, 4.5 g 1,4-butanosultone and 4.5 g sodium hydroxide were put in a reaction vessel and stirred. 45 g viscose fibers were suspended in this prepared mixture. After stirring for 5 h in boiling acetone the fibers were separated from the liquid, washed and dried at 70 C. for 16 h.

Example F8

(27) 1.5 L isopropanol, 5.8 g sodium chloroacetate and 2-1 g sodium hydroxide were put in a reaction vessel and stirred. 30 g cellulose fibers were suspended in this prepared mixture. After stirring for 5 h in boiling isopropanol the fibers were separated from the liquid, washed and dried at 70 C. for 16 h.

Example F9

(28) 96 g tetrahydrofurane, 0.5 g sulforylchloride and 5 g polyvinylalcohol fiber was stirred for 8 h at room temperature. Afterwards the fibers were filtered, washed with toluene and water and dried for 1 h at 60 C.

Example F10

(29) 150 g cyclohexane, 1 g aminoacetaldehyde dimethylacetale and 0.2 g methansulfonic acid mixed together, 10 g polyvinylalcohol fibers were added. The mixture was heated in a Dean-Stark apparatus (water separator) for 3 h and 120 mL cyclohexane containing small amounts of methanol-byproduct was distilled off and same amount of cyclohexane was freshly added to the fibers continuously. Then the fibers were filtered and washed with water, saturated sodium carbonate solution, again washed with water and dried at 60 C. for 16 h.

Example F11

(30) 96 g tetrahydrofurane, 0.5 g phosphorous oxychloride and 5 g polyvinylalcohol fiber was stirred for 8 h at room temperature. Afterwards the fibers were filtered, washed with toluene and water and dried at 60 C. for 1 h.

Example F12

(31) 100 g tetrahydrofurane, 0.25 g sulforylchloride and 5 g cellulose fiber (Lyocell) was stirred for 8 h at room temperature. Afterwards the fibers were filtered, washed with toluene and water three times each and dried for 16 h at 60 C.

Example F13

(32) 5 g of glass fiber were dispersed in 100 mL ethanol. Then, 0.5 mL of aminopropyltriethoxysilane were added together with 0.1 microliter of 33 wt % ammonia solution. The Mixture was stirred for 16 h at room temperature. Then the fibers were filtered off and dried at 40 C. for 16 h.

(33) Attachment of Seed Particles to Fibers

(34) The modification of fibers may be carried out in two different ways: 1. synthesis of seeding material separately, followed by storage of fibers in suspension containing seeding material, or 2. direct synthesis of seeding material in suspension containing modified fibers.

Example SP1

(35) Production of Modified Fibers after Route 1:

(36) As seeding material polymer stabilized CSH was produced after following procedure:

(37) Polymer 1: MVA 2500 (BASF):

(38) Polymer 1 is a comb shaped polymer based on the monomers maleic acid, acrylic acid and vinyl-O-butyl polyethyleneglycol5800. The molar ratio acrylic acid/maleic acid is 7. Mw=40.000 g/mol determined by gel permeation chromatography (GPC). The solid content is 45.1 weight-% (wt %). The charge density is 930 eq/g polymer.

(39) Polymer 2: Polyarylether

(40) The comb polymer Polymer 2 is produced by polycondensation of phenol-polyethyleneglycol 5000 and phenoxyethanolphosphate. The molecular weight is 23.000 g/mol as determined by GPC. The solid content is 35 wt %. The charge density is 745 eq/g polymer.

(41) 40.3 g Calciumacetate (100%) was dissolved in 231 g H.sub.2O resulting in solution 1. Solution 2 was obtained by dissolving 47.2 g Na-metasilicate-pentahydrate in 133.2 g H.sub.2O.

(42) In a reactor solution 3 was obtained by mixing 65.4 g of Polymer 1 (polymer suspension with 45.1 wt % solid content), 22.8 g of Polymer 2 (polymer suspension with 35 wt % solid content) and 460 g water. Within 50 minutes solution 1 and solution 2 were slowly added to solution 3 in the reactor. The suspension was stirred constantly at 400 rpm.

(43) After production of the suspension containing CSH seed particles stabilized by polymers 1.5 g of fiber (non-modified or modified with different functionalities) were stored in 250 g of the CSH seed particle suspension (solid content 11 wt %). The beaker was sealed with a film. Storage time was varied between 1 hour and 24 hours. After storage fibers were separated from the suspension by filtration and washed 2 times with 50 ml of 0.005 n Ca(OH).sub.2-solution. Finally fibers were dried at 60 C. in a drying oven.

(44) Production of Modified Fibers after Route 2:

(45) The synthesis of CSH seed particles as described in Route 1 was done in a comparable way with the exception that the modified fiber was present in solution 3 during the synthesis of the CSH seed particle suspension. 1.5 g of fibers were added to solution 3.

(46) Additionally, the synthesis of the CSH seed particle suspension was done without usage of comb polymer as stabilizers. In this case the solution 3 contains only 180.5 g water.

(47) After synthesis of the CSH seed particles fibers were separated from the suspension by filtration and washed 2 times with 50 ml of 0.005 n Ca(OH).sub.2-solution each. Finally fibers were dried at 60 C. in a drying oven.

(48) Results

(49) The effects of the CSH seed particles were studied by isothermal heat flow calorimetry. For the investigation 1.5 wt % of the fibers by weight of cement were mixed with cement with a water/cement ratio of 0.4. The measurements were performed at 20 C. The measurements were done with the original fiber as control and with the modified fiber and with added CSH seed particles.

(50) FIG. 1 and table 1 present and summarize the results for the heat flow calorimetry comparing control vs. seed particle modified fibers.

Example SP2

(51) Production of Modified Fibers after Route 2:

(52) 5 g of polypropylene Masterfibers 100 (BASF) coextruded with 1 wt % of amorphous fumed silica (diameter: 40 m; length: 12.7 mm) were deposited in 600 mL 0.005 m Ca(OH).sub.2 solution for 2 hours. The treated fiber was filtered and redispersed in 965.72 g water and 129.96 g MVA 2500 (BASF).

(53) 543, 41 g of solution 1 (120.12 g calcium acetate dissolved in 695.00 g water) and 360.96 g of solution 2 (141.84 g Na.sub.2SiO.sub.3*5 H.sub.2O+399.60 g water) were, in the course of 100 minutes slowly added to solution 1.

(54) After synthesis of CSH seed particles fibers were separated from the suspension by filtration and washed 2 times with 200 mL ethanol. Finally fibers were dried at 60 C. in a drying oven. The increase in weight caused by CSH crystallization on the fibers was round 1 wt %. Scanning electron microscopy (SEM) verified that CSH seed particles were attached to the fiber surface (FIG. 2).

Comparative Example

(55) For the preparation of ettringite coated fiber (E) 30 g polypropylene fibers (30 micrometer diameter; 12.7 mm length) were deposited in 30 mL water, initially stirred for 30 min at 200 rpm, followed by the addition of 5.4 g Ca(OH)2 and further stirring of the suspension for another 20 min. For ettringite precipitation a solution of 8.1 g Al.sub.2(SO.sub.4).sub.3*18 H.sub.2O was dissolved in 60 g water and added to the fiber-suspension and stirred at 150 rpm for 30 min. The resulting suspension was filtered through a paper-filter and the wet fibers dried under ambient conditions.

(56) The Notched-Coupon-Test is used as mechanical test method to demonstrate fiber adhesion and pull-out behavior of fiber in cementitious binder systems. The test specimens, prisms with specific dimensions (see FIG. 3) were prepared with mortar containing control fibers and seed particle modified fibers. 10 test specimens have been prepared for each individual fiber composition tested. The fiber dosage was 1 vol % if nothing else is explicitly mentioned. The prepared specimen are stripped after one day and stored under water at 20 C. for another 27 days to provide a total hydration time of 28 days. The prisms are then polished and a notch of only 0.5 mm is introduced. The test specimens were then tested in the tensile test apparatus. Within the measurement, the test prism is pulled apart and the notch simulates a single crack. The results of the measurements are diagrams showing the load (N) at a specific crack opening (m). 5-10 specimens have been tested for each system.

(57) Preparation of Microfiber/Mortar Composites for Testing:

(58) 430 g Portland cement, 880 g fly ash, 150 g quartz sand (0-0.3 mm), 150 g quartz flour, 300 g water and 4.3 g superplastiziser (Melflux 2641; BASF) as well as 0.5 g stabilizer are mixed. followed by the addition of the respective fibers. The mortar quality is tested optically for the existence of lumps or if the fibers are screwed around the mixer. A subsequent slump tests shows the flow behavior of the fiber filled mortar paste and finishes the workability test. The prepared composite blocks all have shown good to acceptable behavior in the workability test.

(59) Results of the Application Tests:

(60) The CSH modified polypropylene fiber (coextruded with amorphous fumed silica) showed an increase in FMax,2, Max,2 and WMax,2 in comparison to the unmodified fiber (FIG. 4 and Table 2). The increase of the FMax,2, Max,2 and WMax,2 values was due to the CSH seed particles on the fiber surface, since the application test with the pristine polypropylene fibers (coextruded with fumed silica) and additional CSH powder (1 wt % referring to the fiber content) did not show any improvement. Moreover an increase of the CSH powder content to 2 wt % also did not result in any benefit. Ettringite coated fibers (E) performed even worse when compared to unmodified fiber (FIG. 5)

Example SP3

(61) Production of Modified Fibers after Route 2:

(62) 2.5 g of polyvinylalcohol fibers modified with phosphate anchor groups (F 11(diameter: 13 m; length: 6 mm) were dispersed in 482.94 g water and 64.98 g MVA 2500 (BASF). 271.7 g of solution 1 (70.9 g Calciumacetat dissolved in 199.81 g water) and 180.6 g of solution 2 (60.1 g Na2SiO3*5 H2O+347.5 g water) were slowly dosed into solution 1 in a period of 50 minutes.

(63) After synthesis of CSH seed particle fibers were separated from the suspension by filtration. Afterwards fibers were washed for 2 times with 100 mL ethanol. Finally fibers were dried at 60 C. in a drying oven. The increase in weight caused by CSH crystallization on the fibers was round 3 wt %. SEM micrograph (FIG. 6) also verifies that CSH seeds were attached to the fiber surface.

Example SP4

(64) Calcium sulfate dehydrate seed particles on the surface of a polyvinylalcohol (PVA) fiber modified with sulfate anchor groups (F9) 2.5 g of the fibers (modified with phosphate groups) were dispersed in 200 mL of a 0.1 m MgSO.sub.4 solution and in 200 mL of a 0.1 m CaCl.sub.2 solution. 300 g of a 0.15 molar MgSO.sub.4 solution and 300 g of a CaCl.sub.2 solution were dosed in parallel to the fiber in 45 minutes. After the addition of 100 g of the 0.15 molar solutions 0.46 g Melflux 2650 L (BASF; SC=32.5 wt %) are added. After a further addition of 100 g of the 0.15 molar solutions accessory 0.40 g Melflux 2650 L (BASF; SC=32.5 wt %) were dosed to the reaction.

(65) After synthesis of gypsum seeds on the PVA fibers they were separated from the suspension by filtration. Afterwards fibers were washed for 2 times with 100 mL ethanol. Finally fibers were dried at 40 C. in a drying oven. SEM micrograph FIG. 7 shows gypsum seeds on the fiber surface. So far our yet unpublished PCT/EP2014/067807.

(66) After the hardening of borehole cements, these cements sometimes exhibit cracks. These cracks can lead to the migration of gas and/or oil into underground water reservoirs and/or the migration of water into the oil. Previous attempts were made to reinforce borehole cements with fibers. These fibers, however, often exhibit very weak bonding to the cementitious matrix, leading to an insufficient sealing performance. There was thus a need for a system exhibiting sufficient sealing performance even under cracking, i.e., an increased flexural strength of the reinforced cement.

(67) This problem was solved by the use of modified fibers in oilfield applications, particularly in borehole cementing, said fibers having crystallization seeds attached to their surface thereby improving the mechanical strength and ductility of borehole cements.

(68) A first subject matter of the present invention is thus the use of fibers in the development, exploitation and completion of underground mineral oil and natural gas deposits and in deep wells, wherein calcium silicate hydrate crystallization seeds are attached to said fibers via linker moieties.

(69) Moreover, the fibers are preferably used in borehole cementing, comprising the steps of providing a cement slurry incorporating the fibers, pumping the slurry into the borehole and allowing the slurry to harden. The fibers can be added to the cement slurry after mixing the cement (preferably a Portland Cement) with water. However, it is also possible to mix a premixed cement/fiber composition with water.

(70) According to the invention, the fibers are preferably selected from polyvinyl alcohol fibers, polyolefin fibers, polysaccharide fibers and mixtures thereof. More preferably, they are selected from polyvinyl alcohol fibers, polyethylene fibers, polypropylene fibers, cellulose fibers and mixtures thereof.

(71) It is a preferred embodiment of the present invention that the crystallization seeds are attached to the surfaces of the individual fiber bodies via covalently bound linker moieties in the presence of at least one comb polymer.

(72) According to the invention, the comb polymer should have a main chain as well as side chains comprising polyether functions and acid functions (or salts thereof), wherein the side chains are present on the main chain. Examples of suitable comb polymers are the well-known polycarboxylate ethers.

(73) The linker moieties, as far as the present invention is concerned, should be selected to comprise one or more functional groups containing an amine, amide, phosphate or phosphonate functionality, preferably any type of amphiphilic molecule containing amine, ammonium, amide, nitrate, sulfate, sulfonate, sulfonamide, carboxylate, silanol, phosphate, phosphinate or phosphonate groups.

(74) Finally, the size of the crystallization seeds should be between 1 nm and 10 m, preferably between 5 nm and 1.5 m, more preferably between 10 nm and 300 nm and most preferably between 10 nm and 100 nm.

(75) The present invention is now illustrated in more detail with reference to the examples, figures and tables hereinbelow.

EXAMPLES

(76) Modification of Fibers with Linker Groups

Sulfate Groups on PVA: Example Linker: Example L1

(77) Fibers PVA (PVA 13/6, Kuraray) were modified as described in Example F9 (above)

Amino Groups on PVA: Example Linker: Example L2

(78) Fibers PVA (PVA 13/6, Kuraray) were modified as described in Example F1

Unspecific Hydrophilic Linker on PP Via Oxidation Recation: Example L3

(79) 25.0 g short cut PP-fiber with 30 micrometer diameter and 12.7 mm length has been dispersed in a solution of 90.9 g potassium persulfate in 1.7 L water via mechanical stirrer. The bath was then heated to 80 C. and kept for 2 h while stirring carefully/slowly. Then the fibers were removed using a sieve, washed peroxide-free with water and dried in an oven at 60 C. for 16 h.

(80) Attachment of Seeds to Linker Group Modified Fiber

(81) Calcium Silicate Hydrate (CSH-Seeds) on Fiber with Sulfate Groups: Example Seed on Fiber S1

(82) Three solutions have been prepared. Solution 1: 45 g fibers L1 were dispersed in 3863 g deionized water plus 520 g Polymer 1. Solution 2: 384.4 g calcium acetate was dissolved in 2228.0 g deionized water. Solution 3: 453.9 g of Na.sub.2SiO.sub.3*5H.sub.2O was dissolved in 1278.8 g deionized water. 2173.8 g of Solution 2 and 1443.9 g of Solution 3 were dosed simultaneously into Solution 1 with constant rates to the fiber suspension within 200 minutes, while constantly stirring at 50 rpm. Fibers were collected by filtering through a sieve. Fibers were redispersed twice in 600 ml ethanol and sieved again. Fibers were dried in an oven at 40 C. FIG. 8 exhibits CSH-particles fiber deposited onto sulfated PVA-fibers L1.

(83) Polymer 1: MVA 2500 (BASF):

(84) Polymer 1 is a comb shaped polymer based on the monomers maleic acid, acrylic acid and vinyl-O-butyl polyethylene glycol5800. The molar ratio acrylic acid/maleic acid is 7. Mw=40.000 g/mol determined by gel permeation chromatography (GPC). The solid content is 45.1 wt %. The charge density is 930 eq/g polymer.

(85) Calcium Silicate Hydrate (CSH)-Seeds on Fiber with Amino Groups: Example Seed on Fiber S2:

(86) 80 g amino-functionalized PVA-fibers (V8) were dispersed in 4000 g of a 1:1-diluted solution of NHA 2100 L NF X-SEED BASF and water for 5 hours. Fibers were collected by filtering through a sieve. Fibers were washed with ethanol twice and dried in an oven at 40 C. The CSH-content is at 18 wt %. FIG. 10 exhibits CSH-particles fiber deposited onto amino-functionalized PVA-fibers. Isothermal heat flow calorimetry is shown in FIG. 11.

(87) Calcium Silicate Hydrate (CSH) Seeds on Fiber with Nonspecific Oxidized Surface: Example Seed on Fiber S3:

(88) Three solutions have been prepared. Solution 1: 42 g fibers L3 were dispersed in 4000 g deionized water. Solution 2: 2.37 g calcium acetate was dissolved in 100.0 g deionized water. Solution 3: 2.72 g of Na2SiO3*5H2O was dissolved in 100.0 g deionized water. 66.68 g of Solution 2 and 66.70 g of Solution 3 were dosed simultaneously into Solution 1 with constant rates to the fiber suspension within 10 minutes, while constantly stirring at 50 rpm. After 3.3 minutes of dosage for Solutions 2 and 3, at once 8.94 g of Polymer 1 were also added. Fibers were collected by filtering through a sieve. Fibers were redispersed twice in 500 ml ethanol and sieved again. Fibers were dried in an oven at 40 C.

(89) Polymer 1: MVA 2500 (BASF):

(90) Polymer 1 is a comb shaped polymer based on the monomers maleic acid, acrylic acid and vinyl-O-butyl polyethyleneglycol5800. The molar ratio acrylic acid/maleic acid is 7. Mw=40.000 g/mol determined by gel permeation chromatography (GPC). The solid content is 45.1 weight-% (wt %). The charge density is 930 eq/g polymer.

(91) Application Test of Seed-Linker-Fiber Systems in Mortar:

(92) General:

(93) Three-point-bending-tests have been carried out using the following recipe:

(94) 1 kg LaFarge Cement (Class G Cement)

(95) 5 g thickener (Polytrol FL34)

(96) 380 g water (w/z=0.38)

(97) 4.7 g fibers

(98) Cement preparation for prisms of 2416 cm.sup.3, storage at 23 C. and 50% rel. humidity for 28 days measurement was carried out. Early strength measurements were also carried out after 24 h. Bending strength was measured in 3-point bending on a Zwick Z250 SN with constant crosshead speed.

(99) Results for Example S1:

(100) Seed modified fiber shows more flexible behavior in early stage and results in higher bending strength after 28 days, see FIG. 12 and Table 1.

(101) TABLE-US-00004 TABLE 1 Statistical summary of bending measurements for samples L1 and S1 24 h hours 28 days F.sub.max .sub.max .sub.max F.sub.max .sub.max .sub.max N N/mm.sup.2 mm N N/mm.sup.2 mm Unmodified Mean 395.3 3.7 1.6 311.6 3.1 0.8 reference Standard 23.6 0.3 0.1 36.4 0.4 0.1 fiber deviation L1 Mean 282.4 2.6 2.3 340.8 3.3 0.8 Standard 65.1 0.6 0.4 29.8 0.3 0.02 deviation S1 Mean 248.1 2.3 3.5 248.1 2.3 3.5 Standard 33.1 0.3 0.4 33.1 0.3 0.4 deviation
Results for Example S2:

(102) Seed modified fiber shows higher bending strength after 28 days, see FIG. 6 and Table 2.

(103) TABLE-US-00005 TABLE 2 Statistical summary of bending measurements for samples L2 and S2 24 h hours 28 days F.sub.max .sub.max .sub.max F.sub.max .sub.max .sub.max N N/mm.sup.2 mm N N/mm.sup.2 mm Unmodified Mean 395.3 3.7 1.6 311.6 3.1 0.8 reference Standard 23.6 0.3 0.1 36.4 0.4 0.1 fiber deviation L2 Mean 236.2 2.2 2.8 212.2 2.0 0.4 Standard 25.3 0.2 0.6 deviation S2 Mean 125.3 1.2 0.7 543.5 5.1 0.8 Standard 19.4 0.2 0.03 83.6 0.8 0.1 deviation