METHOD OF MANUFACTURING A CONCRETE ELEMENT

Abstract

In a method of manufacturing a concrete element having a functional layer, a rear side of the functional layer being bonded to the concrete element by an adhesive, the roughness of the rear side of the functional layer is increased by sand blasting, wherein the sand blasting is carried out for obtaining a surface roughness Ra of the rear side of the functional layer of between 1.5 m and 6 m.

Claims

1. A method of manufacturing a concrete element having a functional layer, a rear side of the functional layer being bonded to the concrete element by means of an adhesive, comprising: increasing the roughness of the rear side of the functional layer by means of sand blasting, providing a mould, placing the functional layer at the bottom or at a side wall of the mould with the rear side facing the interior of the mould, applying an adhesive layer on the rear side surface of the functional layer, pouring fresh concrete into the mould, thereby at least partially covering the rear side of the functional layer with concrete, allowing the concrete to harden, demoulding the hardened concrete element, wherein the sand blasting is carried out for obtaining a surface roughness Ra of the rear side of the functional layer of between 1.5 m and 6 m.

2. A method according to claim 1, wherein the functional layer is configured as a flexible layer and the sand blasting is carried out for obtaining a surface roughness Ra of the rear side of the functional layer of between 3 and 5.2 m.

3. A method according to claim 1, wherein the functional layer is configured as a rigid layer and the sand blasting is carried out for obtaining a surface roughness Ra of the rear side of the functional layer of between 1.6 and 3.4 m.

4. A method according to claim 1, wherein the functional layer is a photovoltaic panel.

5. A method according to claim 1, wherein the adhesive layer is applied onto the rear side of the functional layer so as to form a layer thickness of 0.5-1.5 mm.

6. A method according to claim 1, wherein an epoxy resin based adhesive is used as said adhesive.

7. A method according to claim 1, wherein the sand blasting is carried out over a time period of 5-60 sec.

8. A method according to claim 1, wherein the sand blasting is carried out by using compressed air having a pressure of 4 bar-8 bar.

9. A method according to claim 1, wherein the sand blasting is carried out at a blasting distance of 15-25 cm.

10. A method according to claim 1, wherein the sand blasting comprises using sand having a particle size distribution, which is characterized by a D90 of <900 m.

11. A method according to claim 1, wherein the sand blasting comprises using silica sand of medium grade according to ISO 14688-1:2002 having a particle size between 0.2 and 0.63 mm.

12. A method according to claim 11, wherein the sand blasting comprises using silica sand having a particle size distribution, which is characterized by a D50 of 310 m and a D10 of 250 m.

13. A method according to claim 1, wherein the sand blasting comprises using sand of fine grade according to ISO 14688-1:2002.

14. A method according to claim 10, wherein the sand blasting is carried out over a time period of >25 sec.

15. A method according to claim 1, wherein the sand blasting comprises using sand having a particle size distribution, which is characterized by a D90 of >900 m.

16. A method according to claim 15, wherein the sand blasting comprises using sand comprising >80 wt.-% aluminum silicate crystals.

17. A method according to claim 15, wherein the sand blasting is carried out over a time period of <10 sec.

18. A method according to claim 1, wherein the concrete is a ultra-high performance concrete (UHPC) having a compressive strength of >100 MPa at 28 days, a high performance concrete (HPC) having a compressive strength of >80 MPa at 28 days, or an earth-binder based concrete.

19. Concrete element having a functional layer, a rear side of the functional layer being bonded to the concrete element by means of an adhesive, wherein the construction element is obtained by the method of claim 1.

20. A method comprising utilizing a concrete element obtained by the method of claim 1, as a construction element.

21. A method according to claim 1, wherein the functional layer comprises a carrier and a functional element arranged on the carrier, and wherein the carrier forms the rear side of the functional layer and is made of a polymer.

Description

EXAMPLES

[0105] In the following examples, concrete elements having a functional layer, namely a photovoltaic layer, were produced according to the method of the invention.

[0106] The Following Materials were Used for Producing the Concrete:

[0107] The cement used is a cement of the CEM I 52.5N strength class, according to the classification given in EN 197-1 of February 2001.

[0108] The silica fume has a D50 of 1+/0.1 m.

[0109] The components used for the preparation of ultrahigh performance concrete are:

[0110] (1) Portland cement: white cement produced at the Le Teil Lafarge plant in France, CEM I 52.5N

[0111] (2) Ground limestone filler: DURCAL 1 supplied by Omya

[0112] (3) Silica fume: MST supplied by SEPR (Socite Europenne des Produits Rfractaires)

[0113] (4) Sand: BE01 supplied by Sibelco France (Carrire Sifraco Bedoin)

[0114] (5) Admixture: Ductal F2 supplied by Chryso (a polycarboxylate type water reducer)

[0115] The components used for the preparation of high performance concrete are:

[0116] (1) Portland cement: white cement produced at the Le Teil Lafarge plant in France, CEM I 52.5N

[0117] (2) Fly ash: CV Carling T6 supplied by Surschiste

[0118] (3) Sand 0/5 mm: Lafarge France, produced at St Bonnet La Petite Craz

[0119] (4) Gravel 3/6 mm: Lafarge France, produced at Cassis

[0120] (5) Admixture: Adva Flow 450 supplied by Grace Pieri

[0121] The components used for the preparation of the earth-binder concrete are:

[0122] (1) Pauzat earth

[0123] (2) Rammed earth 0/1 mm

[0124] (3) Sand 0/2 mm: Lafarge France, produced at St Bonnet La Petite Craz

[0125] (4) Sand 0/1.6 mm: Lafarge France, produced at Cassis

[0126] (5) Sand 1.6/3 mm: Lafarge France, produced at Cassis

[0127] (6) Sand 3/6 mm: Lafarge France, produced at Cassis

[0128] (7) Portland cement: CEM I 52.5N (according to the standard EN 197-1 of February 2001) produced at the Lafarge France cement plant of Saint Pierre La Cour

[0129] Photovoltaic Panels and Adhesive:

[0130] The photovoltaic panels and the adhesive for bonding the panels to the concrete surface are all polymer based. The references of the materials used in the examples of this invention are:

[0131] (1) The rigid photovoltaic panels, with an epoxy matrix and using polycrystalline silicium: Solarmodul 4V/250 mA, supplied by Conrad

[0132] (2) The flexible photovoltaic panels, with a ETFE base PVL-68 and using amorphous silica 12V/4.1 A, are supplied by Solariflex

[0133] (3) The epoxy based glue is supplied by Chryso, and sold under the commercial name Chrysor C6123.

[0134] Sand Used for Sand Blasting:

[0135] The sand blasting of the rear side or the photovoltaic panels was done using 3 types of sand grains:

[0136] (1) quartz sand supplied by Sibelco France (Carrire Sifraco Bedoin) having a medium grade according to ISO 14688-1:2002

[0137] (2) Samenaz RUGOS 2000, 0.4-1.6 mm (http://www.semanaz.com) This sand is produced from melted glass of aluminium silicate, and is composed of hard and angular crystals of brown to topaz colour. The sand contains 50.8% silica, 27.3% alumina, and 9.7% iron oxide.

[0138] (3) White Corundum F100

[0139] White Corundum F100 sand is essentially composed of crystals of aluminum oxide (99.7%) obtained by high temperature fusion of bauxite. Once ground, the sand grains are angular and shiny and have a high abrasion coefficient. Their hardness according to the Mohs scale is of 9.

[0140] Concrete Mix Designs:

[0141] Ultra-High Performance Concrete (UHPC):

[0142] The ultrahigh performance concrete used for producing the photovoltaic concrete panels of the present invention has the composition given in the table below.

TABLE-US-00001 Proportion (wt.-% of the Component entire composition) CEM I 52.5 N - White cement 31.0 from Le Teil Lafarge plant in France Ground limestone filler - 9.3 DURCAL 1 Silica fume - MST 6.8 Sand - medium grade 44.4 Total added water 7.1 Admixture - Ductal F2 1.4

[0143] The water cement ratio is 0.26 and the compressive strength after 28 days is above 100 MPa.

[0144] The components were mixed in a RAYNERI mixer at 20 C., and the mixing procedure was done according to the following steps: [0145] at T=0 seconds, the cement, limestone filler, silica fume and sand were added to the mixing bowl and mixed for a duration of 7 minutes at 15 rpm [0146] at T=7 minutes, water and half the amount of admixture were added, and the composition was mixed for another minute at 15 rpm [0147] at T=8 minutes, the rest of the admixture was added, and the composition was mixed for another minute at 15 rpm [0148] at T=9 minutes, the mixer speed was set at 50 rpm, and the composition was mixed for another 8 minutes [0149] at T=17 minutes, the mixer speed was set at 15 rpm, and the composition was mixed for another minute [0150] at T=18 minutes, the concrete was poured into the moulds

[0151] High Performance Concrete (HPC):

[0152] The high performance concrete used for producing the photovoltaic concrete panels of the present invention has the composition given in the table below.

TABLE-US-00002 Proportion (wt.-% of the Component entire composition) CEM I 52.5 N - White cement from Le 21.75 Teil Lafarge plant in France Fly Ash 6.55 Sand 0/5 mm 38.57 Gravels 3/6 mm 26.4 Total added water 6.5 Admixture - Adva Flow 450 0.23

[0153] The water cement ratio is of 0.30 and the compressive strength after 28 days is above 80 MPa.

[0154] The components were mixed in a RAYNERI mixer at 20 C., and the mixing procedure was done according to the following step: [0155] at T=0 seconds, the sand, gravels and pre-wetting water were added to the mixing bowl and mixed for a duration of 1 minute at 30 rpm; [0156] at T=1 minutes, sleeping period for a duration of 3 minutes and 45 seconds; [0157] at T=4 minutes 45 seconds, addition of the cement and fly ash during 15 seconds; [0158] At T=5 minutes, mixing for a duration of 1 minute at 30 rpm; [0159] at T=6 minutes, addition of the water and mixing for a duration of 30 seconds at 30 rpm; [0160] at T=6 minutes and 30 seconds, mixing for a duration of 90 seconds at 30 rpm; [0161] at T=8 minutes, mixing for a duration of 120 seconds at 40 rpm; [0162] at T=10 minutes, the concrete was poured into the moulds.

[0163] Earth-Binder Based Concrete:

[0164] The composition (1) of earth-binder mortar is described in the table below.

TABLE-US-00003 Proportion (wt.-% of the Component entire composition) CEM I 52.5 N - Saint Pierre la 11.0 Cour Sand 0/1.6 mm - Lafarge France 36.0 (Cassis) Sable 1.6/3 mm -Lafarge France 15.0 (Cassis) Sable 3/6 mm - Lafarge France 18.0 (Cassis) Rammed earth 10.0 Total water added 10.0

[0165] The water cement ratio is 0.91. The earth-binder mortar according to composition (1) was prepared using a RAYNERI mixer at 20 C., and the mixing procedure was done according to the following steps: [0166] at T=0 second, the cement, sands and the rammed earth were added to the mixing bowl and mixed for a duration of 3 minutes at 15 rpm [0167] at T=3 minutes, the water was added, and the composition was mixed for another 2 minutes at 15 rpm [0168] at T=5 minutes, the mixer was stopped and the bottom of bowl was scraped, for a duration of 30 seconds [0169] at T=5 minutes and 30 seconds, the mixer was turned back on and the composition was mixed for another 2 minutes at 15 rpm

[0170] The composition (2) of earth-binder mortar is described in the table below.

TABLE-US-00004 Proportion (wt.-% of the Component entire composition) CEM I 52.5 N - Saint Pierre la 5.0 Cour Sand 0/2 mm - Lafarge France 52.0 (St Bonnet) Pauzat earth 36.0 Total water added 7.0

[0171] The water cement ratio is 1.4. The earth-binder mortar according to composition (1) was prepared using a RAYNERI mixer at 20 C., and the mixing procedure was done according to the following steps: [0172] at T=0 second, the cement, sands and the Pauzat earth were added to the mixing bowl and mixed for a duration of 3 minutes at 15 rpm [0173] at T=3 minutes, the water was added, and the composition was mixed for another 2 minutes at 15 rpm [0174] at T=5 minutes, the mixer was stopped and the bottom of bowl was scrapped, for a duration of 30 seconds [0175] at T=5 minutes and 30 seconds, the mixer was turned back on and the composition was mixed for another 2 minutes at 15 rpm

[0176] Casting Procedure:

[0177] Panels were prepared by casting fresh concrete in wood moulds covered with Bakelite, without addition of any demoulding agent. On the inner surfaces of the moulds, rigid, flexible or a combination thereof, of photovoltaic panels were positioned horizontally.

[0178] On the back of each photovoltaic panel, the epoxy-based adhesive was placed with a brush, and evenly spread with a comb. The thickness of the epoxy-based glue was about 1 mm, corresponding to between 400 and 900 g/m2 of adhesive, preferably between 400 and 600 g/m2 of adhesive relating to the rear side surface of photovoltaic panel.

[0179] The concrete was then poured into the moulds that contain the photovoltaic panels and the adhesive 15 minutes after the adhesive was spread with the comb.

[0180] In some cases, the rear side surface of the photovoltaic panel had been sand blasted beforehand. Different sand blasting procedures were tested, where the following parameters were tested: [0181] 3 durations of sand blasting were tested: 5, 30 and 60 seconds. [0182] 3 types of sand grains were tested as mentioned above [0183] the sand blasting was always done from a distance of 20 cm of the rear side surface of the photovoltaic panel, [0184] The pressure and airflow was constant, wherein compressed air at 5 bars was used.

[0185] The concrete panels were demoulded 18 hours after the concrete was casted and then subjected to the following accelerated testing procedures, in order to test the durability of the layered concrete element, in particular to study the durability of the adhesion between the concrete, the adhesive and the photovoltaic panels.

[0186] Water Condensation Accelerated Ageing Test (QCT)

[0187] The test was carried out using a QCT condensation tester supplied by Q-Lab which simulates the damaging effects of outdoor moisture by condensing warm water directly onto test specimen. In a few days or weeks, the QCT tester can reproduce the damage due to moisture that occurs over months or years outdoors.

[0188] The specimen were positioned in a way to form a wall of the condensation chamber, at an inclination angle of 15. Deionised water was heated to generate steam, wherein the steam filled the chamber in order to obtain 100% of relative humidity and a temperature of 38 C.+/2 C. The specimen were positioned in such a way that a part was exposed to the environment of the chamber, and another part to ambient air. The temperature difference between the surface of the specimen and the atmosphere of the chamber caused water to condense continuously, and water to flow downwards on the surface of the specimen. The concrete-adhesive-solar panel specimen usually separates at the adhesive-solar panel interface.

[0189] Freeze-Thaw Accelerated Aging Test

[0190] The specimen were stored in a freeze-thaw chamber to perform a 4-step cycle: (i) 45 min at +9 C. under water, (ii) decrease of temperature during 3 h until 18 C., (iii) 35 min at 18 C. under air, (iv) increase of temperature during 40 min until reaching +9 C.

[0191] The following example shows the results of the testing as a function of the sand blasting method used. The type of concrete is not mentioned, because the results were irrespective of whether the ultrahigh performance concrete (UHPC), the high performance concrete (HPC), or the earth-binder composition (1) or the earth-binder composition (2) was used. The first table indicates the results obtained when using flexible photovoltaic panels and the second table indicates the results obtained when using rigid photovoltaic panels.

[0192] Results with Flexible Photovoltaic Panels

[0193] Based on the results in the table below, the best sand blasting process for achieving optimal durability of the concrete photovoltaic panels of the invention was determined in having a surface roughness Ra of above 3.0 m and below 5.2 m. This was achieved by sand blasting for 5 seconds with the Semanaz RUGOS 2000 sand, 30 seconds with the quartz sand, or 60 seconds with the Corundum F100 sand. Furthermore, sand blasting more than 30 seconds with the quartz sand did not significantly improve the surface roughness, nor the adhesion of the specimen after accelerated ageing. When the surface roughness was too high, such as 9.1 or above, the photovoltaic panels were structurally damaged.

TABLE-US-00005 Roughness Ra of the rear Adhesion of the Adhesion of the Damage visible side of the concrete - adhesive - concrete - adhesive - on the rear photovoltaic photovoltaic panel photovoltaic panel surface of the panel after Sand blasting process specimen after water specimen after freeze photovoltaic sand blasting (type of sand and condensation thaw accelerating panels after [m] duration) accelerated ageing ageing sand blasting 1.2 (+/0.1) Without sand blasting Poor adhesion, the Poor adhesion, the No photovoltaic panels photovoltaic panels peeled off after 1 day peeled off after 1 cycle 4.9 (+/0.3) Semanaz 5 sec Good adhesion, no Good adhesion, no No RUGOS 2000 peeling off after 1 peeling off after 150 month cycles 9.1 (+/0.2) Semanaz 30 sec Yes RUGOS 2000 10.7 (+/0.8) Semanaz 60 sec Yes RUGOS 2000 1.8 (+/0.1) Quartz sand 5 sec Poor adhesion, the Poor adhesion, the No photovoltaic panels photovoltaic panels peels off after 1 day peels off after 1 cycle 3.4 (+/0.4) Quartz sand 30 sec Good adhesion, no Good adhesion, no No peeling off after 1 peeling off after 150 month cycles 4.2 (+/0.4) Quartz sand 60 sec Good adhesion, no Good adhesion, no No peeling off after 1 peeling off after 150 month cycles 1.0 (+/0.2) Corundum 5 sec Poor adhesion, the Poor adhesion, the No F100 photovoltaic panels photovoltaic panels peels off after 1 day peels off after 1 cycle 2.5 (+/0.3) Corundum 30 sec Poor adhesion, the Poor adhesion, the No F100 photovoltaic panels photovoltaic panels peels off after 1 day peels off after 1 cycle 3.4 (+/0.2) Corundum 60 sec Good adhesion, no Good adhesion, no No F100 peeling off after 1 peeling off after 150 month cycles

[0194] Results with Rigid Photovoltaic Panels

[0195] Based on the results in the table below, the best sand blasting process for achieving optimal durability of the concrete photovoltaic panels of the present invention consists in having a roughness Ra of above 1.6 m and below 3.4 m. This may be achieved by sand blasting for 5 seconds with the Semanaz RUGOS 2000 sand, 30 seconds with quartz sand, or 30 seconds with the Corundum F100 sand. When the surface roughness is too high, such as 9.1 m or above, the photovoltaic panels are structurally damaged. Sand blasting with the Semanaz RUGOS 2000 sand for 30 seconds or more results in structural damages of the photovoltaic panels, and the measured roughness is of about 4.2.

TABLE-US-00006 Roughness of Adhesion of the Adhesion of the Damage visible the back of the concrete - adhesive - concrete - glue - on the rear photovoltaic photovoltaic panel photovoltaic panel surface of the panel after Sand blasting process specimen after water specimen after freeze photovoltaic sand blasting (type of sand and condensation thaw accelerating panels after [m] duration) accelerated ageing ageing sand blasting 0.4 (+/0.2) Without sand blasting Poor adhesion, the Poor adhesion, the No photovoltaic panels photovoltaic panels peels off after 1 day peels off after 1 cycle 2.3 (+/0.4) Semanaz 5 sec Good adhesion, no Good adhesion, no No RUGOS 2000 peeling off after 1 month peeling off after 150 cycles 4.4 (+/0.2) Semanaz 30 sec Yes RUGOS 2000 4.2 (+/0.1) Semanaz 60 sec Yes RUGOS 2000 1.2 (+/0.3) BE01 5 sec Poor adhesion, the Poor adhesion, the No photovoltaic panels photovoltaic panels peels off after 1 day peels off after 1 cycle 1.8 (+/0.2) BE01 30 sec Good adhesion, no Good adhesion, no No peeling off after 1 month peeling off after 150 cycles 2.6 (+/0.5) BE01 60 sec Good adhesion, no Good adhesion, no No peeling off after 1 month peeling off after 150 cycles 1.0 (+/0.1) Corundum 5 sec Poor adhesion, the Poor adhesion, the No F100 photovoltaic panels photovoltaic panels peels off after 1 day peels off after 1 cycle 2.4 (+/0.3) Corundum 30 sec Good adhesion, no Good adhesion, no No F100 peeling off after 1 month peeling off after 150 cycles 3.0 (+/0.4) Corundum 60 sec Good adhesion, no Good adhesion, no No F100 peeling off after 1 month peeling off after 150 cycles