Composition comprising at least one microorganism and use thereof

Abstract

A composition contains at least one microorganism which can form a phosphate or carbonate precipitate in an alkaline medium, and at least one calcium source. The composition has at least one silicon compound having at least one Si-atom, at least one C-atom, and at least one H-atom. The composition can be used in a method for producing a construction product.

Claims

1: A composition comprising at least one microorganism capable of forming a phosphate or carbonate precipitate in an alkaline medium, and optionally at least one calcium source, wherein the composition comprises at least one silicon compound comprising at least one Si atom, at least one C atom, and at least one H atom.

2: The composition according to claim 1, wherein the at least one microorganism is selected from a bacterium, a lyophilized bacterium, and a bacterial spore of a bacterium.

3: The composition according to claim 1, wherein the at least one microorganism is selected from a bacterial spore or a bacteria of the genera Enterococcus, Diophrobacter, Lysinbacillus, Planococcus, Bacillus, Proteus or Sporosarcina.

4: The composition according to claim 1, wherein a weight ratio of the at least one microorganism capable of forming a phosphate or carbonate precipitate in an alkaline medium to the at least one silicon compound comprising at least one Si atom, at least one C atom, and at least one H atom is from 100:1 to 1:100.

5: The composition according to claim 1, wherein a mass fraction of the at least one microorganism capable of forming a phosphate or carbonate precipitate in an alkaline medium, based on the total mass of the composition, is from 0.0001% to 10% by weight.

6: The composition according to claim 1, wherein the composition contains at least one mineral building material.

7: The composition according to claim 1, wherein the composition contains at least one enrichment medium (growth medium) for enrichment of the at least one microorganism.

8: The composition according to claim 1, wherein the at least one silicon compound comprising at least one Si atom, at least one C atom, and at least one H atom has hydrophobizing properties.

9: The composition according to claim 1, wherein the at least one silicon compound comprising at least one Si atom, at least one C atom, and at least one H atom is selected from silane compounds, siloxane compounds, silicone oils, siliconates, organosilane compounds, or organosiloxane compounds.

10: The composition according to claim 1, wherein the composition contains at least one silicon compound which comprises at least one Si atom, at least one C atom, and at least one H atom, and conforms to a formula (I), (IIa), or (IIb); wherein formula (I) is represented by R—SiR.sup.1.sub.xR.sup.2.sub.z, in which R is a linear or branched alkyl group having 1 to 20 C atoms, R.sup.1 is a linear or branched alkyl group having 1 to 4 C atoms, R.sup.2 is a linear or branched alkoxy group having 1 to 4 C atoms or a hydroxyl group, wherein the radicals R.sup.1 and R.sup.2 may each be identical or different, x equals 0, 1, or 2, z equals 1, 2, or 3, and x+z=3; and wherein formula (IIa) is represented by (R′).sub.3Si—O—[Si(R′).sub.2—O].sub.m—Si(R′).sub.3 and formula (IIb) is represented by ##STR00004## in which the individual radicals R′, independently of one another, represent hydroxyl alkoxy, alkoxyalkoxy, alkyl, alkenyl, cycloalkyl, and/or aryl, and wherein m is an integer from 2 to 30, n is an integer from 3 to 30, and with the proviso that a sufficient number of the individual radicals R′ in the compounds of formulae (IIa) and (IIb) are an alkoxy radical, to ensure that a quotient of the molar ratio of Si to alkoxy radicals in the compounds of formulae (IIa) and (IIb) is at least 0.3.

11: The composition according to claim 1, wherein the at least one silicon compound comprising at least one Si atom, at least one C atom, and at least one H atom is selected from the group consisting of CH.sub.3Si(OCH.sub.3).sub.3, CH.sub.3Si(OC.sub.2H.sub.5).sub.3, C.sub.2H.sub.5Si(OC.sub.2H).sub.3, i-CH.sub.7Si(OC.sub.2H.sub.5).sub.3, C.sub.2H.sub.5Si(OCH.sub.3).sub.3, i-C.sub.3H.sub.7Si(OCH.sub.3).sub.3, n-C.sub.3H.sub.7Si(OCH.sub.3).sub.3, n-C.sub.3H.sub.7Si(OC.sub.2H), i-C.sub.3H.sub.7Si(OCH).sub.3, n-C.sub.4H.sub.9Si(OCH.sub.3).sub.3, n-C.sub.4H.sub.9Si(OC.sub.2H.sub.5).sub.3, i-C.sub.4H.sub.9Si(OCH.sub.3).sub.3, n-C.sub.4H.sub.9Si(OC.sub.2H.sub.5).sub.3, n-C.sub.5H.sub.11Si(OCH.sub.3).sub.3, n-C.sub.5H.sub.11Si(OC.sub.2H.sub.5).sub.3, i-C.sub.5H.sub.11Si(OCH.sub.3).sub.3, i-C.sub.5H.sub.11Si(OC.sub.2H.sub.5).sub.3, n-C.sub.6H.sub.13Si(OCH.sub.3).sub.3, n-C.sub.6H.sub.13Si(OC.sub.2H.sub.5).sub.3, i-C.sub.6H.sub.13Si(OCH.sub.3).sub.3, i-C.sub.6H.sub.13Si(OC.sub.2H.sub.5).sub.3, n-C.sub.8H.sub.17Si(OCH.sub.3).sub.3, n-C.sub.8H.sub.17Si(OC.sub.2H).sub.3, i-C.sub.7H.sub.17Si(OCH.sub.3).sub.3, i-C.sub.8H.sub.17Si(OC.sub.2H.sub.5).sub.3, n-C.sub.10H.sub.21Si(OCH.sub.3).sub.3, n-C.sub.10H.sub.21Si(OC.sub.2H.sub.5).sub.3, i-C.sub.10H.sub.21Si(OCH.sub.3).sub.3, i-C.sub.10H.sub.21Si(OC.sub.2H.sub.5).sub.3, n-C.sub.16H.sub.33Si(OCH.sub.3).sub.3, n-C.sub.16H.sub.33Si(OC.sub.2H.sub.5).sub.3, i-C.sub.16H.sub.33Si(OCH.sub.3).sub.3, i-C.sub.16H.sub.33Si(OC.sub.2H.sub.5).sub.3, a partial condensate of one or more of the recited compounds, a mixture of the recited compounds, a mixture of the partial condensates, and a mixture of the compounds and the partial condensates.

12: A process for producing a building product, the process comprising: mixing the composition of claim 1 with a building material.

13: The process according to claim 12, wherein the building product is mortar, a mortar-based component or product, steel-reinforced concrete, concrete, a steel-reinforced concrete part, a concrete part, a concrete block, a roof tile, a brick, or a porous concrete block.

14: The process according to claim 12, wherein the composition is employed before completion of the building product or of a built structure.

15: The process according to claim 12, wherein the composition is employed after completion of the building product or of built structure.

16: The composition according to claim 3, wherein the at least one microorganism is a bacterial spore or a bacteria selected from the group consisting of Bacillus cohnii, Bacillus megaterium, Bacillus pasteurii, Bacillus pseudofirmus, Bacillus sphaericus, Bacillus spp., Bacillus subtilis, Proteus vulgaris, Bacillus licheniformis, Diophrobacter sp., Enterococcus faecalis, Lysinbacillus sphaericus, Proteus vulgaris, and Sporosarcina pasteurii.

17: The composition according to claim 3, wherein the at least one microorganism is a bacterial spore or a bacteria of Bacillus subtilis or Bacillus cohnii.

18: The composition according to claim 3, wherein the at least one microorganism is a bacterial spore or a bacteria of Bacillus subtilis.

19: The composition according to claim 6, wherein the at least one building material is cement.

20: The composition according to claim 7, wherein the at least one enrichment medium is tryptic soy broth.

Description

[0066] The subject-matter of the present invention is more particularly elucidated with reference to FIGS. 1 to 4, without any intention that the subject-matter of the present invention be restricted thereto.

[0067] The image in FIG. 1 shows a 200-times magnification of the side view of the test specimen comprising a crack, 18 days after the block from example 4a was broken in two. It is apparent that the crack has been healed.

[0068] The image in FIG. 2 shows a 100-times magnification of a top-down view onto the fracture surface, 69 days after the block from example 4a was broken in two. It is apparent that Ca carbonate has formed in the crack.

[0069] The image in FIG. 3 shows a 100-times magnification of a top-down view onto the fracture surface, 0 days after the block from example 4b was broken in two. It is apparent that healing has not yet occurred.

[0070] The image in FIG. 4 shows a 100-times magnification of the side view of the test specimen from example 4c, 69 days after the block from example 4c was broken in two. It is apparent that Ca carbonate has formed in the crack.

[0071] The images in FIGS. 5a and 5b show in 30- and 100-times magnification the crack in the test specimen of example 3 (E). The images in FIGS. 6a and 6b show in 30- and 100-times magnification the crack in the test specimen of example 3 (S). In both cracks the formation of filling material (crack healing) is readily apparent after one day.

[0072] The subject-matter of the present invention is elucidated in detail in the examples which follow, without any intention that the subject-matter of the present invention be restricted to these.

Measurement Methods:

[0073] The healing of the cracks was determined optically using a microscope. [0074] Flexural tensile strengths were determined based on DIN EN 12390-5 (3-point flexural test with central loading). [0075] Karsten tube test: Water absorption was measured using a water penetration tester, also known as a Karsten tube as described in “MEASUREMENT OF WATER ABSORPTION UNDER LOW PRESSURE; RILEM TEST METHOD NO. 11.4, horizontal application” (https://www.m-testco.com/files/pages/Rilem%20Test.pdf)

Substances Used:

[0076] Spores of Bacillus subtilis (DSM 32315), also referred to hereinbelow as spores 32315, 8×10.sup.10 spores/g (spore number determined according to the standard DIN EN 15784). [0077] Spores of Bacillus subtilis (DSM 10) [0078] Spores of Bacillus pseudofirmus (DSM 8715) [0079] Tryptic Soy Broth (Sigma Aldrich, product number 22092), also referred to hereinbelow as TSB [0080] Milke® Classic CEM I 52.5 N cement (Heidelberg Cement AG), also referred to hereinbelow as cement [0081] CEN standard sand according to DIN EN 196-1 (Normensand GmbH), also referred to hereinbelow as standard sand, [0082] Liquid Repair System-ER7 (Basilisk-Contracting BV), also referred to hereinbelow as LRS [0083] Protectosil® WS 405 (Evonik Resource Efficiency GmbH), an aqueous silane emulsion also referred to hereinbelow as WS 405 [0084] Protectosil® WA CIT (Evonik Resource Efficiency GmbH), an aqueous emulsion of multifunctional silanes also referred to hereinbelow as WA CIT [0085] Meat extract (Merck KGaA) [0086] Peptone from casein (Merck KGaA) [0087] Concrete cubes, sawn similarly to ISO 13640, method 1 concrete quality according to EN 196 CEM I 42.5, edge length 5 cm, from Rocholl GmbH [0088] Kuraray Poval® 4-88 (Kuraray), polyvinyl alcohol [0089] Kuraray Elvanol® 8018 (Kuraray), polyvinyl alcohol copolymer with lactone

EXAMPLES

Example 1: Testing of Compatibility of Microorganisms with Hydrophobizing Agent and Shrinkage Reducer

[0090] The strains Bacillus subtilis (DSM 10) and Bacillus pseudofirmus (DSM 8715) were investigated for compatibility with hydrophobizing agents and shrinkage reducers.

[0091] A mixture of 3 g of meat extract, 5 g of peptone from casein and 1000 mL of distilled water adjusted to pH 7 using HCl/NaOH for Bacillus subtilis (DSM 10) and adjusted to pH 7 using Na sesquicarbonate for Bacillus pseudofirmus (DSM 8715) was used as the medium.

[0092] A pre-culture was initially produced for each of the two strains: To this end, an inoculation dose of the spores was in each case placed into a culture tube with 8 mL of the respective medium and left overnight in a laboratory shaker at 30° C. and 200 revolutions per minute. Furthermore, aqueous stock solutions respectively having a concentration of Protectosil® WS405 (hydrophobizing agent) of 500 g/L and a concentration of neopentyl glycol (shrinkage reducer) of 280 g/L were produced.

[0093] For the main cultures two 6-well spot plates were each filled with 8 mL of medium. Then, 10 μL of the first pre-culture were added to each well of the first plate and 10 μL of the second pre-culture were added to each well of the second plate. Aqueous PROTECTOSIL® WS405 stock solution was added to three wells of both plates in amounts such that the concentration of PROTECTOSIL® WS405 was 5 g/L, 20 g/L or 30 g/L. Neopentyl glycol stock solution was added to the other three wells of the two plates in amounts such that the concentration of neopentyl glycol was 0.7 g/L, 7 g/L or 14 g/L.

[0094] The main cultures were subsequently left in a laboratory shaker for 4 days at 30° C. and 200 revolutions per minute. Observation of turbidity changes were used to determine whether the microorganisms grow in the presence of hydrophobizing agent and/or shrinkage reducer.

[0095] It was found that the growth of neither organism was impaired by the addition of hydrophobizing agent or shrinkage reducer in the recited concentrations.

[0096] For spores of the strain Bacillus subtilis DSM 32315 compatibility with neopentyl glycol (7 g/L) and Protectosil® WS405 (20 g/L) was investigated on agar plates. A mixture of 3 g of meat extract, 5 g of peptone from casein and 1000 mL of distilled water adjusted to pH 7 using HCl/NaOH was used as medium. Formation of colonies was observed in all cases. This shows that the additives do not influence the growth of the strain.

Example 2: Production of Test Specimens

[0097] Test specimens were produced using the formulation for producing standard mortar having a mortar composition according to EN 480-1. To this end, 450 g of Milke® classic CEM I 52.5 N cement and 1350 g of CEN standard sand according to EN 196-1 were homogenized to afford a dry mixture using a mortar mixer from Hobart.

[0098] The homogenized dry mixture was added to the mortar mixer over 30 seconds at a slow mixing speed (setting 1). 450 g of water were then added over 30 seconds and the total mortar mixture was stirred for a further 60 seconds at the slow setting. The amount of water was chosen such that the weight ratio of water to cement was 1 to 2.

[0099] The mortar was then stirred for 60 seconds at high speed (setting 2). The total mixing time ran to 3 minutes and 30 seconds.

[0100] Steel moulds for three prisms in each case (4 cm×4 cm×16 cm) were filled to an overfill of 0.5 to 1.0 cm using a box attachment and subsequently compacted on a vibration table for 120 seconds at 50 Hz. The mortar in the mould was then smoothed and covered with a glass sheet. After 48 hours the prisms were carefully demoulded, labelled and stored under standard climatic conditions until testing after 28 days.

Example 3: Testing of the Healing Effect of Compositions

[0101] A number of test specimens from example 2 were broken apart in the middle and treated at the fracture edges either with a prior art composition (S) or with an inventive composition (E) which, however, lacked hydrophobizing agent and subsequently joined together again.

[0102] The treatment with the Liquid Repair System-ER7 (prior art product) is carried out such that 90 g of the component A in 500 mL of water (temperature of the water 40° C.) was converted into solution A and 50 g of component B in 250 mL of water (temperature of the water 40° C.) was converted into solution B in accordance with the use instructions. Then, according to the use instructions, the fracture edges were sprayed twice with solution A and then once with solution B.

[0103] The treatment with the composition according to the invention was carried out such that initially 15 g of tryptic soy broth were stirred with 50 g of spores of Bacillus subtilis DSM 32315 in 500 mL of water and this solution was sprayed onto the fracture edges.

[0104] After joining the test specimens were secured with a Teflon tape. The test specimens were stored in a water bath at room temperature. The test specimens were immersed into the water bath to a depth of 0.5 cm and the crack was not below the water level. The crack was sprayed with water at regular intervals of 2 days.

[0105] Crack healing was observed for both test specimens (FIGS. 5a, 5b, 6a and 6b) even after a time of 1 day. It was possible to exert a vertical downward force of at least 1.23 N on the healed crack in each case. This force corresponds to the mass of the lower part of the test specimen multiplied by the acceleration due to gravity of 9.81 m/s.sup.2. As a reference one test specimen was brush coated with exclusively tryptic soy broth. No healing of the crack was observable here after the same time had elapsed.

Example 4: Production of Test Specimens with Addition of Healing Additives

[0106] The production of the test specimens was performed as described in example 2. However, the aqueous proportion of the added compositions was considered as forming part of the mixing water and thus accounted for and all mixtures for producing test specimens were therefore produced with the same water to cement ratio to ensure comparability of results. The employed substances and the appearance of the mortar mixtures during processing are reported in table 1a.

TABLE-US-00001 TABLE 1a Mortar mixtures (without water fraction) and appearance thereof Standard 32315 Example Cement sand LSR spores TSB WS 405 WA CIT Appearance 4a 450 g 1350 g 13.5 g 4.5 g — — normal viscosity 4b 450 g 1350 g 13.5 g 4.5 g 18 g normal viscosity 4c 450 g 1350 g 13.5 g 4.5 g 18 g normal viscosity

[0107] To assess the hydrophobizing effect of the silane addition (silicon compound comprising at least one Si atom, at least one C atom and at least one H atom) the reduction in capillary water absorption over a period of 24 h and 14 days was determined. Test specimen 4a (only biomass) was used as a reference.

[0108] Before commencement of water absorption the dry mass of each test specimen was determined. Each test specimen was then stored vertically with the 40 mm×40 mm base surface in a constant water depth of 3 mm in a suitable container. Suitable blocks or linings (glass inserts or glass beads) are to be used to ensure unhindered access of the water to the immersed base surface. The individual test specimens must not contact one another and the container is to be closed for the duration of the test. The masses of the individual test specimens are to be determined and noted in the test protocol after the specified time intervals. In order to remove adherent water at the test specimens are lightly dabbed with a dry cloth (test setup analogous to EN 480-5 but with other measurement periods and without triplicate determination). The percentage reduction in water absorption was determined by the following method:

[00001]$100-\frac{\begin{array}{c}[\left(\mathrm{mass}.Math..Math.\left(\mathrm{ex}\right).Math..Math.\mathrm{after}.Math..Math.\mathrm{UWS}-\mathrm{mass}.Math..Math.\left(\mathrm{ex}\right).Math..Math.\mathrm{before}.Math..Math.\mathrm{UWS}\right)/\\ \mathrm{mass}.Math..Math.\left(\mathrm{ex}\right).Math..Math.\mathrm{before}.Math..Math.\mathrm{UWS}*100]\end{array}}{\begin{array}{c}[\left(\mathrm{mass}.Math..Math.\left(\mathrm{ref}\right).Math..Math.\mathrm{after}.Math..Math.\mathrm{UWS}-\mathrm{mass}.Math..Math.\left(\mathrm{ref}\right).Math..Math.\mathrm{before}.Math..Math.\mathrm{UWS}\right)/\\ \mathrm{mass}.Math..Math.\left(\mathrm{ref}\right).Math..Math.\mathrm{before}.Math..Math.\mathrm{UWS}*100]\end{array}}*100$

ref=reference example (4a); ex=examples (4b/4c)

[0109] The results after 24 hours are shown in table 1b, the results after 14 days are shown in table 1c.

TABLE-US-00002 TABLE 1b reduction in capillary water absorption after 24 h Water Reduction Mass before Mass after 24 h absorption in WA after Example UWS [g] UWS [g] [g] 24 h [%] 4a 518.3 555.1 36.8 — 4b 531.3 534.6 3.3 91.3 4c 535.3 540 4.7 87.6 UWS—underwater storage; WA—water absorption

TABLE-US-00003 TABLE 1c reduction in capillary water absorption after 14 d Water Reduction Mass before Mass after 14 d absorption in WA after Example UWS [g] UWS [g] [g] 14 d [%] 4a 518.3 557.0 38.7 — 4b 531.3 539.4 8.1 79.7 4c 535.3 546.5 11.2 72.1 UWS—underwater storage; WA—water absorption

[0110] As is apparent from tables 1b and 1c addition of a silicon compound comprising at least one Si atom, at least one C atom and at least one H atom (of a hydrophobizing agent) markedly reduces the water absorption of the test specimens.

[0111] The test specimens were then broken into two parts, placed on top of one another again at the fracture edges and subsequently stored standing upright in a bowl of water (about 5 mm water fill height) for 69 days so that the fracture was immersed in the water on one side.

[0112] In 200-times magnification a side view of the test specimen comprising the crack showed that 18 days after the block from example 4a was broken in two the crack was healed (filled) (FIG. 1). In 100-times magnification a top-down view onto the fracture surface showed that 69 days after the block from example 4a was broken in two Ca carbonate had formed in the crack (FIG. 2). The 100-times magnification of the side view of the test specimen from example 4c showed that 69 days after the block from example 4a was broken in two Ca carbonate had formed in the crack.

Example 5: Influence of Microorganism Concentration and Ca Source

[0113] The aim was to determine the influence of the mass of microorganisms and additional Ca source on flexural strength and water absorption of the test specimen. To this end, test specimens with different combination options of biomass, tryptic soy broth, Ca source and hydrophobizing agent (WS405) were employed.

[0114] The production of the test specimens was performed as described in example 2. However, the components and concentrations reported in table 2a were used. The Ca source employed was calcium lactate hydrate. Example Si is the reference sample.

[0115] For simpler metering of the microorganisms 0.68 g of 32315 spores were initially diluted with 50 mL of tap water to produce a spore mixture which accordingly had a concentration of 0.0136 g (spores 32315)/mL.

TABLE-US-00004 TABLE 2a Employed formulations for producing the test specimens Standard Spore Example Cement sand Water solution TSB Ca source WS405 5a 450 g 1350 g 224.0 g 1 mL 4.5 g 0 g 0 g 5b 450 g 1350 g 222.9 g 1 mL 4.5 g 0 g 2.25 g    5c 450 g 1350 g 224.0 g 1 mL 4.5 g 3.15 g    0 g 5d 450 g 1350 g 222.9 g 1 mL 4.5 g 3.15 g    2.25 g    5e 450 g 1350 g 224.9 g 0.1 mL   4.5 g 0 g 0 g 5f 450 g 1350 g 223.8 g 0.1 mL   4.5 g 0 g 2.25 g    5g 450 g 1350 g 224.9 g 0.1 mL   4.5 g 3.15 g    0 g 5h 450 g 1350 g 223.8 g 0.1 mL   4.5 g 3.15 g    2.25 g    5i 450 g 1350 g 225.0 g 0 mL   0 g 0 g 0 g

[0116] After 28 days of storage of the test specimens at 23° C. and 50% relative humidity (standard climatic conditions) the flexural tensile strength of the test specimens and the reduction in the water absorption after 24 h were measured. To determine water absorption after 24 h the test specimens were stored standing upright in a water bath. They were immersed into the water to a depth of about 5 cm. After 24 h the amount of water absorbed by the test specimens was determined by gravimetric means. The results are shown in Table 2b.

TABLE-US-00005 TABLE 2b Results of testing Example S.sub.fracture Reduction in water absorption Rating 5a 836.6N −22.5% − 5b 3016.3N  65.3% ++ 5c 294.6N −36.4% −− 5d 2547.2N  65.7% + 5e 565.9N −40.8% −− 5f 2808.6N  68.2% ++ 5g 727.3N 6.8% − 5h  2553N 69.1% + 5i 3849.4 N.sup.  0.0%

[0117] It is apparent from the results shown in table 2b that markedly higher strengths are achievable with addition of TSB, microorganisms and hydrophobizing agent than without the addition of hydrophobizing agent. In addition, compared to the untreated test specimen water absorption increases (negative % values) without addition of hydrophobizing agent but with addition of TSB and spore solution. The further addition of a Ca source appears to result in a slight improvement in the reduction in water absorption but also to a slightly lower flexural strength.

Example 6: Effect of Surface Treatment

[0118] The aim of this experiment is to investigate the effect of a surface treatment with a solution of hydrophobizing agent, spores, tryptic soy broth, calcium lactate and water.

[0119] To this end, commercially available concrete cubes from Rocholl GmbH were treated with formulations containing distilled water and optionally WS 405, spores. TSB and/or Ca-Lactat*H.sub.2O. The compositions of the formulations employed in the examples 6a to 6e are reported in table 3a. Example 6e is the reference sample.

TABLE-US-00006 TABLE 3a Formulations employed in example 6 Formulation Application Ca lactate Dist. quantity Example WS405 Spores TSB H2O water [g/m.sup.2] 6a 60 g 0 g   0 g 0 g 90 g 204 6b 60 g 0 g 4.5 g 4.5 g   90 g 202.7 6c 60 g 15 g  4.5 g 4.5 g   90 g 204 6d 60 g 15 g  4.5 g 0 g 90 g 209.3 6e  0 g 0 g   0 g 0 g  0 g —

[0120] The cubes were initially immersed in the corresponding formulations until an approximate application quantity of 200 g/m.sup.2 was achieved. The actual amount of the formulation applied was determined by gravimetric means and is likewise reported in table 3a. After 14 days the reduction in water absorption was determined with the Karsten tube test. To this end, the water absorption was determined after 24 h and related to the water absorption of the reference sample 6e. The results are reported in table 3b.

TABLE-US-00007 TABLE 3b Reduction in water absorption without fracture Water absorption [ml] Reduction in water Product 0.5 h 2 h 6 h 24 h absorption [%] 6a 0 0 0 0.05 97.0 6b 0 0 0 0.05 97.0 6c 0 0 0 0.05 97.0 6d 0 0 0 0.05 97.0 6e 0.2 0.5 0.9 1.7 —

[0121] The cubes (including 6e) were then fractured and the fracture surface was brush coated with the respective formulation in the application quantity reported in table 3c. The cubes were then placed on top of one another again at the fracture edges, secured with Teflon tape and then stored in a bowl of water (about 5 mm water fill height) for 14 days so that the crack was immersed in the water on one side. The reduction in water absorption was determined as follows: The cubes were dried and weighed. They were then stored under water for 24 h. From the difference between the masses before and after underwater storage the reduction in water absorption was determined according to the following formula:

Reduction in water absorption %=[(mass after−mass before)/mass before]/[(mass_reference after−mass_reference before)/mass_reference before]*100

[0122] The results of reduction in water absorption are shown in the following table 3c.

TABLE-US-00008 TABLE 3c Reduction in water absorption after fracture Application Reduction in water Example [g/m.sup.2] absorption [%] 6a 201.3 94.9 6b 199.3 91.6 6c 210.7 93.2 6d 202.7 93.8 6e — 4.2* *= water absorption after 24 h in %, (mass after − mass before)/mass before *100 = absolute water absorption

[0123] As is apparent from table 3c a reduction in water absorption compared to the untreated test specimen is observable even after fracture of the test specimen (cube) and subsequent treatment with the inventive composition.

[0124] A Karsten tube test was performed after a storage of 8 weeks. To this end, the tubes were attached above the crack. The side that was stored below the water surface was during the 8 weeks was used. For example 6d no water absorption was observed during a measurement duration of 0.5 h. This means that the crack has closed for this formulation without Ca lactate.

Example 7: Encapsulation with Polyvinyl Alcohol (PVA)

[0125] In this experiment the stability of uncoated and PVA-coated spores of the strain Bacillus subtilis DSM 32315 was analyzed during concrete mixing.

[0126] Coating of Bacillus subtilis Spores with Polyvinyl Alcohol:

[0127] The apparatus employed for coating/encapsulation was a Hüttlin coater (Bosch) fitted with a fluidized bed attachment. To achieve coating/encapsulation the biomass was initially charged into the Hüttlin coater, sprayed with an aqueous PVA solution and subsequently dried. The biomass employed was a mixture of 50% by weight of Bacillus subtilis DSM 32315 spores and 50% by weight of lime. The PVA solution employed was a solution of 5% by weight of Kuraray Poval® 4-88 PVA and 5% by weight of Kuraray Poval® 8018 PVA in water. The total concentration of PVA was accordingly 10% by weight based on the total mass of the solution. To produce the PVA solution, a mixture of Kuraray Poval® 4-88 PVA and Kuraray Poval® 8018 PVA was initially sprinkled into cold water with stirring and heated to 90° C. to 95° C. in a water bath until fully dissolved before the solution was cooled with stirring to avoid skin formation. Subsequently the biomass was initially charged into the fluidized bed unit, heated with a temperature-controlled nitrogen stream and fluidized. As soon as the fluidized bed had reached the required temperature the PVA solution was added via a peristaltic pump. The relevant process settings are summarized in table 4.

TABLE-US-00009 TABLE 4 Settings for fluidized bed process Parameter Unit Value N.sub.2 temperature ° C. 60-65 Bed temperature ° C. 45-48 N.sub.2 flow rate m.sup.3/h 20 Spraying air pressure bar 0.5 Microclimate mbar 150 Pump speed % 5 PVA spraying rate g/h 92 ± 23

[0128] In the coating/encapsulation of the biomass 750 g of the aqueous PVA solution (10% by weight PVA) were applied to 500 g of biomass. This corresponds to a proportion of 13% by weight of PVA based on the total mass of the dried product.

[0129] Determination of Stability:

[0130] To determine stability, equivalent amounts of coated (78 g per 50 l concrete batch, corresponds to 0.5% by weight based on cement) and uncoated spores (46 g per 50 l concrete batch, corresponds to 0.29% by weight based on cement), said amounts being adjusted to the spore concentration CFU/g in the feedstock, were placed in a cement mixer together with the growth medium (92 g of TSB). After 1 min of dry mixing samples were taken before the appropriate amount of water (7.2 kg) was added to the concrete batch. Samples were taken again after a total of 3 min. 20 min. 60 min and 120 min. The samples taken were immediately and in duplicate diluted to about 1:100 in water, shaken and subsequently aliquoted and stored at −20° C. until further processing.

[0131] To determine the spore count of the samples the samples were thawed and in a serial dilution diluted in polysorbate peptone salt solution (pH=7) such that after plating-out of the samples and incubation at 37° C. a countable number of colonies on TSA agar plates was to be expected.

TABLE-US-00010 TABLE 5 Stability of coated and uncoated DSM 32315 spores during concrete mixing Sample Spore count in formulation Mixing time Sample concrete CFU/g uncoated — expected CFU/g 1.39E+08 concrete PVA-coated — expected CFU/g 1.39E+08 concrete uncoated  1 min 1-1 5.25E+07 PVA-coated (dry mixing) 1-2 4.52E+07 1-1 6.57E+07 1-2 7.01E+07 uncoated  3 min 2-1 9.53E+07 PVA-coated (following 2-2 9.84E+07 addition 2-1 9.28E+07 of water) 2-2 1.28E+08 uncoated 20 min 3-1 9.82E+07 PVA-coated 3-2 6.89E+07 3-1 9.08E+07 3-2 1.18E+08 uncoated 60 min 4-1 8.10E+07 PVA-coated 4-2 7.91E+07 4-1 9.01E+07 4-2 9.29E+07 uncoated 120 min  5-1 5.39E+07 PVA-coated 5-2 5.28E+07 5-1 8.91E+07 5-2 1.07E+08

[0132] The results reported in table 5 show that the spores in the concrete batch are probably not yet homogeneously distributed after one minute, thus initially resulting in a lower spore count than expected. After mixing for three minutes the spore count was close to the expected spore count both in the batch comprising coated spores and in the batch comprising uncoated spores. In the course of mixing up to 2 h it was apparent from the spore count data that no loss greater than one log step was incurred either with coated spores or with uncoated spores.