U.S. patent application number 12/841581 was filed with the patent office on 2011-01-20 for healing agent in cement-based materials and structures, and process for its preparation.
This patent application is currently assigned to Technische Universiteit Delft. Invention is credited to Hendrik Marius Jonkers.
Application Number | 20110011303 12/841581 |
Document ID | / |
Family ID | 39769331 |
Filed Date | 2011-01-20 |
United States Patent
Application |
20110011303 |
Kind Code |
A1 |
Jonkers; Hendrik Marius |
January 20, 2011 |
Healing Agent in Cement-Based Materials and Structures, and Process
for Its Preparation
Abstract
A healing agent in cement-based materials and structures,
wherein said healing agent comprises organic compounds and/or
bacteria-loaded porous particles, which porous particles comprise
expanded clay- or sintered fly-ash. Furthermore, said porous
particles are intact spheres, broken or crushed particles derived
from said intact spheres, having a specific density between 0.4 and
2 g cm.sup.-3. Finally, the present invention relates to a process
for the preparation of the healing agent.
Inventors: |
Jonkers; Hendrik Marius;
(Delgauw, NL) |
Correspondence
Address: |
PEACOCK MYERS, P.C.
201 THIRD STREET, N.W., SUITE 1340
ALBUQUERQUE
NM
87102
US
|
Assignee: |
Technische Universiteit
Delft
Delft
NL
|
Family ID: |
39769331 |
Appl. No.: |
12/841581 |
Filed: |
July 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/NL2009/050025 |
Jan 22, 2009 |
|
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12841581 |
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Current U.S.
Class: |
106/15.05 |
Current CPC
Class: |
C04B 20/1022 20130101;
C04B 2103/0001 20130101; C04B 2111/72 20130101; C04B 28/10
20130101; Y02W 30/92 20150501; Y02W 30/91 20150501; C12N 11/14
20130101; C04B 20/1022 20130101; C04B 14/12 20130101; C04B 20/1022
20130101; C04B 18/08 20130101; C04B 20/1022 20130101; C04B 20/002
20130101 |
Class at
Publication: |
106/15.05 |
International
Class: |
C09D 5/14 20060101
C09D005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2008 |
EP |
08100833.6 |
Claims
1. Healing agent in cement-based materials and structures, wherein
said healing agent comprises either porous particles loaded with
bacteria and organic compounds or a combination of porous particles
loaded with bacteria and porous particles loaded with organic
compounds.
2. The healing agent according to claim 1, wherein said porous
particles comprise expanded clay- or sintered fly-ash.
3. The healing agent according to claim 1, wherein said porous
particles are intact spheres, broken or crushed particles derived
from said intact spheres.
4. The healing agent according to claim 1, wherein the specific
density of said porous particles is between 0.4 and 2 g
cm.sup.-3.
5. The healing agent according to claim 1, wherein the surface pore
has a width of 0.01 to 100 .mu.m.
6. The healing agent of claim 5, wherein the surface pore width is
between 0.01 and 15 .mu.m.
7. The healing agent according to claim 1, wherein the size of the
bacteria-only loaded particles have a particle size with a diameter
of .gtoreq.0.02 mm.
8. The healing agent according to claim 1, wherein the size of the
bacteria-only loaded particles have a particle size preferably
0.02-8 mm.
9. The healing agent according to claim 7, wherein the particles
have a diameter of 0.05 to 1.0 mm and the particle surface pore a
width of 1.0 to 15 .mu.m.
10. The healing agent according to claim 1, wherein said bacteria
belong to the genera Bacillus or Sporosarcina and comprise either
vegetative bacteria or their spores or a combination of the
two.
11. The healing agent according to claim 10, wherein the bacteria
is Bacillus pseudofirmus or Sporosarcina pasteurii.
12. The healing agent according to claim 1, wherein the organic
compounds comprise an organic biomineral precursor compound and
organic bacterial growth factors.
13. The healing agent according to claim 12, wherein the organic
biomineral precursor compound comprises an organic calcium or
sodium salt and the organic bacterial growth factors comprise yeast
extract or peptone.
14. The healing agent according to claim 1, wherein the particle
surface pore width is 0.01-1 .mu.m.
15. A process for the preparation of the healing agent according to
claim 1, wherein porous aggregate material, expanded clay or
sintered fly ash is loaded with bacteria and organic compounds by
contacting said porous particle with the bacteria or bacterial
spore-containing suspension or chemical biomineral precursor
compound solution, wherein first the porous particles are dried and
freed from the viable environmental bacteria by drying the same
overnight in an oven at a temperature of 120-200.degree. C.,
followed by cooling to room temperature, subjecting the particles
to vacuum treatment, while the porous particles still under vacuum
the bacteria or bacterial spore-containing suspension or chemical
biomineral precursor compound solution is supplied to the particles
and the particles are fully submerged, releasing the partial vacuum
followed by drying said suspension or solution-entrained particles
at room temperature and storing the same at room temperature until
further use.
16. A process for the preparation of the healing agent according to
claim 15, wherein porous aggregate material, expanded clay or
sintered fly ash is loaded with bacteria and organic compounds by
contacting said porous particle with the bacteria or bacterial
spore-containing suspension or chemical biomineral precursor
compound solution, wherein first the porous particles are dried and
freed from the viable environmental bacteria by drying the same
overnight in an oven at a temperature preferably 140.degree. C.
17. The process according to claim 15, wherein expanded clay
particles are loaded with Bacillus pseudofirmus.
18. The process according to claim 15, wherein expanded clay
particles are loaded with Sporosaxcina pasteurii spores.
19. The process according to claim 15, wherein two different types
of porous particles are used simultaneously, one loaded with
bacteria or their spores, and the other with a chemical biomineral
precursor compound.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of
International Patent Application Serial No. PCT/NL2009/050025
entitled "Heating Agent in Cement-Based Materials and Structures,
and Process for its Preparation", to Technische Universiteit Delft,
filed on Jan. 22, 2009, which is a continuation of European Patent
Application Serial No. 08100833.6, entitled "Healing Agent in
Cement-Based Materials and Structures, and Process for its
Preparation", to Technische Universiteit Delft, filed on Jan. 23,
2008, and the specification and claims thereof are incorporated
herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT
DISC
[0003] Not Applicable.
COPYRIGHTED MATERIAL
[0004] Not Applicable.
BACKGROUND OF THE INVENTION
[0005] 1. Field of the Invention
[0006] The present invention relates to a healing agent in
cement-based materials and structures, as well as to a process for
its preparation.
[0007] 2. Description of Related Art
[0008] Porous aggregate material (expanded clay- or sintered
fly-ash) loaded with bio-chemical compounds (bacteria and/or
organic compounds) can improve the durability of cement-based
structures when incorporated in the material matrix. Porous
materials such as different types of expanded clays (brand name,
e.g., Liapor.RTM., Argex.RTM.) and fly-ash (sintered pulverized
coal ash) (e.g., Lytag.RTM.) are commonly applied as aggregate
material in cement-based materials, specifically for the production
of lightweight concrete. So far, however, the potential storage
capacity of these porous materials for healing or repair agents,
such as chemical compounds or bacteria, have not been proposed or
applied yet.
[0009] In recent years, the application of bacteria for the
improvement and/or repair of cement-based materials, and concrete
in particular, have been investigated in several studies (Bang et
al . 2001; Ramachandran et al. 2001; DeMuynck et al. 2005 and 2007;
Jonkers & Schlangen 2007a+b; Jonkers 2007). In some of these
studies bacteria, or derived enzymes, were applied externally,
i.e., as a surface treatment system, to plug, seal, or heal cracks
in concrete through metabolic or enzymatic biomineral formation. In
only few reported studies bacteria were truly incorporated in the
concrete matrix (e.g. by mixing with the still fluid cement paste),
to investigate their potential for autonomous improvement of
concrete characteristics, e.g. to act as concrete-immobilized self-
healing agent (Jonkers & Schlangen 2007a+b; Jonkers 2007).
[0010] Major disadvantage of direct addition of bacteria or their
spores to cement paste is that this procedure may strongly decrease
their viability [Jonkers & Schlangen 2007b]. Reason for the
limited life-time of bare concrete immobilized bacteria is most
likely a combination of high concrete matrix alkalinity (pH>12)
and ongoing reduction in matrix pore-size diameter (<1 .mu.m)
during continued cement hydration.
BRIEF SUMMARY OF THE INVENTION
[0011] The object of the present invention is to provide a healing
agent in cement-based materials and structures, wherein the
above-mentioned disadvantages are eliminated.
[0012] This goal has been achieved by the present invention by
providing a healing agent in cement-based materials and structures
wherein said healing agent comprises organic com-pounds and/or
bacteria-loaded porous particles.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0013] Not Applicable.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Usually the porous particles comprise expanded clay- or
sintered fly-ash and they can occur as intact spheres, broken or
crushed particles derived from intact spheres.
[0015] The specific density of said porous particles is between 0.4
and 2 g cm.sup.-3.
[0016] Furthermore, the surface pore has a width of 1.0 to 100
.mu.m, and preferably between 1.0 and 15 .mu.m.
[0017] It is advantageous according to the invention when the size
of the bacteria-only loaded particles have a particle size with a
diameter of >0.02 mm, preferably 0.02-8 mm. Commonly, the
particle size of the bacteria-only loaded particles is 0.05 mm.
[0018] Usually, the bacterial spores or species according to the
invention belong to the genera Bacillus and Sporosarcina, whereas
preferably as bacteria Bacillus pseudofirmus is used.
[0019] On the one hand, bacteria belonging to the genus
Sporosazcina are ureolytic bacteria, such as Sporosarcina
pasteurii.
[0020] On the other hand, the organic compound is a chemical
biomineral precursor compound, preferably calcium formate, calcium
acetate, or other carboxylic acid calcium salt.
[0021] Last but not least it is advantageous that the particle
surface pore has a width of 0.01-1 .mu.m for biomineral precursor
compound-loaded particles.
[0022] It appeared surprisingly according to the invention that
when protecting the bacteria or their spores by immobilization
inside expanded clay- or sintered fly-ash particles prior to
addition to cement paste can result in almost full preservation, or
significantly diminished decrease in viability, and thus to a
longer-term potential as healing or repair agent in concrete and
other cement-based materials.
[0023] In addition to bacteria, porous expanded clay- or expanded
fly-ash particles can also be loaded with a suitable organic
biomineral precursor compound to increase the healing or repair
potential of these particles in concrete and cement-based
materials.
[0024] In order to obtain a favorable result, the porous particle
characteristics such as specific density, size, surface pore-size
and applied density in cement-based materials are as follows.
[0025] Usually, expanded clay- or sintered fly-ash particles can be
intact spheres.
[0026] Furthermore, the surface pore width dimensions are important
as these should be large enough to allow bacteria to enter.
[0027] The choice of applied particle size, its surface pore width
and applied density in the cement-based material depends mainly on
the intended functionality of the loaded particle. A particle can
be small when loaded with bacteria (i.e., catalyst for biomineral
production) only, but needs to be rather large when additionally
loaded with the chemical biomineral precursor compound needed for
healing of the cement-based material. The first option is feasible
when the biomineral precursor compound will be applied externally,
i.e., will be provided to the bacteria via intrusion through cracks
in the material. In this case, bacteria-only loaded particles can
be small and the distribution and applied density of the particles
should be such that the chance that a newly formed micro-crack in
the cement-based material encounters a matrix embedded porous
bacteria-loaded particle is significant. For this application,
porous particle surface pore width should not be too large, i.e.,
to prevent substantial leakage of previously intruded bacteria
before setting of the cement paste. Therefore, surface pore width
should be between 1.0 and 100 .mu.m, or more ideally between 1.0
and 15 .mu.m. The size of bacteria-only loaded particles should be
large enough to accommodate and protect a substantial number of
bacteria or bacterial spores, i.e., a particle size with a diameter
of minimally 0.02 mm. The chance that a newly formed crack with a
crack width of 0.1 mm and a length of 2 mm encounters a 0.05 mm
diameter bacteria-loaded particle is close to one when the
particles are homogeneously distributed through the material. The
volumetric ratio of 0.05 mm sized particles to the cement-based
material would then be in the order of 1:240. However, particle
sizes may also be larger, i.e., in the range of 0.02 to 8 mm.
Furthermore, when the porous particles should also function as a
reservoir for chemical biomineral precursor compounds, sizes should
be substantially larger than 0.02 mm, as the volumetric healing or
repair potential of such chemicals are directly related to their
own volume. The healing, or crack-filling, potential is limited to
the amount of healing agent loaded in porous particles, i.e., the
larger the to-be-healed crack volume, the larger the porous
particle reservoir volume must be. Note that less volume is needed
when the conversion reaction of precursor compound to produced
biomineral is an expansive reaction. Also, partial biomineral crack
plugging may already result in a substantial reduction, thus
healing, of crack permeability. Reservoir particles should
therefore not be too small as this would limit their healing or
repair potential. However, their size should also not be too large,
as the distribution and amount of the particles should be such that
the compressive strength and related functionality of the
cement-based material is not negatively affected to a major extend.
The particle surface pore width of chemical biomineral precursor
compound-loaded particles should be similar to those of
bacteria-loaded particles when both are simultaneously loaded.
However, particle surface pore width can be substantially smaller,
i.e., in the range of 0.01 to 1 .mu.m, when the suitable chemical
biomineral precursor compound is loaded to the porous particles
without additional bacteria. For the latter material healing or
repair application two different types of porous particles may thus
be applied simultaneously, i.e., one loaded with bacteria or their
spores, and the other with a suitable chemical biomineral precursor
compound.
[0028] Furthermore, the present invention relates to a process for
the preparation of the healing agent as described above.
[0029] Accordingly, the present invention relates to a process for
the preparation of the healing agent characterized in that the
porous aggregate material, expanded clay- or sintered fly-ash, is
loaded with bacteria and/or organic compounds by contacting said
porous particle with the bacteria or bacterial spore-containing
suspension or chemical biomineral precursor compound solution,
wherein first the porous particles are dried and freed from the
viable environmental bacteria by drying the same overnight in an
oven at a temperature of 120-200.degree. C., preferably 140.degree.
C., followed by cooling to room temperature, subjecting the
particles to vacuum treatment, while the porous particles still
under vacuum the bacteria or bacterial spore-containing suspension
or chemical biomineral precursor compound solution is supplied to
the particles and the particles are fully submerged, releasing the
partial vacuum followed by drying said suspension or
solution-entrained particles at room temperature and storing the
same at room temperature until further use.
[0030] The above process is suitable for loading the porous
particles with the bacteria- or bacterial spore-containing
suspension or chemical biomineral precursor compound solution. It
should be noted when the partial vacuum is subsequently released,
the suspension or solution will efficiently intrude the porous
particles.
[0031] According to the present process, especially bacterial
spores of species related to the genera Bacillus and Sporosarcina
can be kept viable for several years. Also, bacterial spores of
species of these genera will remain viable for months up to several
years when incorporated in cement-based materials such as concrete
when immobilized inside porous particles prior to mixing with fresh
(non-set) cement paste.
[0032] It is noted that for a long-term (several years) healing
potential, the number of porous particle-immobilized bacterial
spores should be in the range of 10.sup.4 to 10.sup.9 spores
cm.sup.-3 concrete.
[0033] Herein after the present invention will be further
illustrated by the following not-limitative examples.
EXAMPLE 1
[0034] Application of expanded clay particles loaded with Bacillus
pseudofirmus spores and calcium lactate solution to decrease
permeability of cracked concrete.
[0035] The produced spores of a Bacillus pseudofirmus DSM 8715
culture in its late exponential growth phase are harvested by
centrifugation (20 minutes at 10000 g). The obtained pellet,
containing cells and spores, is washed once by re-suspension of the
pellet in tap water followed by an additional centrifugation step.
The washed pellet is subsequently re-suspended in an aliquot of tap
water to obtain a suspension with a density of 310.sup.10 spores
ml.sup.-1. A batch of crushed expanded clay particles (e.g.
Liapor.RTM., Liapor GmbH & Co. KG Hallendorf, Germany) with an
average particle size of 0.05 mm is dried overnight at a
temperature of about 140.degree. C. followed by cooling to room
temperature. An amount of this batch is subsequently brought under
partial vacuum, after which 1 ml of a 310.sup.10 spores ml.sup.-1
spore suspension is added per 16.5 g of evacuated particles, where
after the vacuum is released. The spore suspension-intruded porous
particles are subsequently dried at a temperature of 30.degree. C.
until no further weight loss occurs. A second batch of intact
expanded clay spheres (e.g. Aquaclay.RTM., Okotau Easy Green GmbH,
Germany) in the size range of 4-8 mm is dried overnight at a
temperature of about 140.degree. C. followed by cooling to room
temperature. An amount of this batch is subsequently brought under
partial vacuum, after which a 150 mM calcium lactate solution is
added until all evacuated particles are submerged, where after the
vacuum is released. The calcium lactate solution-intruded porous
intact spheres are subsequently dried at a temperature of
30.degree. C. until no further weight loss occurs. Aggregate
fractions, cement and water are mixed according to the following
specifications.
TABLE-US-00001 Aggregate size Density Weight Volume (mm) Type
(g/cm.sup.3) (g) cm.sup.3 4-8 Aquaclay .RTM. + 1.1 687 624
Ca-Lactate 2-4 Sand 2.7 1133 420 1-2 Sand 2.7 848 314 0.5-1.sup.
Sand 2.7 848 314 0.25-0.5 Sand 2.7 730 270 0.125-0.25 Sand 2.7 396
147 0.05 Liapor .RTM. + 1.3 17 13 B. pseudofirmus spores OPC CEMI
32.5R Cement 3.15 1170 371 Water Water 1.0 585 585
[0036] The crushed Liapor.RTM.-Immobilized B. pseudofirmus spores
in this type of concrete are characterized by a long-term viability
(months to years). Germinating spores, activated by water
penetrating freshly formed cracks, can mediate the production of
calcite by the metabolic conversion of calcium lactate and concrete
matrix portlandite according to the following reaction:
Ca(C.sub.3H.sub.5O.sub.3).sub.2+5Ca(OH).sub.2+6O.sub.2.fwdarw.6CaCO.sub.-
3+10H.sub.2O
[0037] The produced calcite decreases concrete permeability by
sealing freshly formed cracks.
EXAMPLE 2
[0038] Application of expanded clay particles loaded with
Sporosarcina pasteurii spores as healing agent in concrete.
[0039] In this example expanded clay particle-immobilized spores of
ureolytic bacteria such as Sporosarcina pasteurii DSM 33 act as
healing catalyst in cracked concrete, while the calcite precursor
compound mixture (a mixture of urea, calcium acetate and peptone)
is applied externally. The produced spores of a Sporosarcina
pasteurii DSM 33 culture are immobilized in expanded crushed clay
(e.g., Liapor.RTM.) particles using the procedure as described
under example 1. The 0.05 mm sized S. pasteurii spore-containing
particles (1.810.sup.9 spores/gram particles) are added to the
concrete mixture in a proportion of 5.4 kg per 1 m.sup.3 concrete
mixture. Surface cracks in set and aged concrete can subsequently
be healed by immersion or spraying the concrete surface with the
urea, calcium acetate, peptone mixture (10, 27 and 0.5 g/L water
respectively). The organics acetate and peptone of this mixture
will activate (germinate) the S. pasteurii spores which ureolytic
activity will subsequently result in the hydrolysis of urea. The
carbonate ions produced by this reaction will spontaneously
precipitate with the solution's calcium ions to produce a dense and
relatively impermeable calcite layer within cracks and on the
concrete surface. Instead of applying the calcite precursor
compound mixture externally, it can also be absorbed into porous
expanded clay particles which are added to the concrete mixture,
analogous to the procedure described in Example 1, in order to
obtain an autonomous bacterially-mediated calcite producing
system.
[0040] It should be noted that the present invention is not limited
to the above examples and that other embodiments within the skill
of the ordinary men in the art belong to the invention as well.
* * * * *