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Pre-stressed S&P Laminates CFK

Manual for applicators

January 2010

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1. Pre-stressing system 1.1 Set up of pre-stressing system 1.1.1 Pre-stressing side (the pre-stress force is only applied on this side): Remark: The pre-stressing can also be done on both sides.

1.1.2 Fixed side: Remark: In case the pre-stressing is only done on one side.

Hydraulic cylinder

Clamping unit

Frame

Anchor plate

Hydraulic hose

Fixing unit long

Anchor plate

Frame

Distance plate

Clamping unit Fixing unit short

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1.1.3 Required tools: Anchor plate with anchor bolts and screws

Fixing unit: short (fixed side)

Fixing unit: long (pre-stressing side)

6 Hilti HST-R M16x140/25

Almec 79, 200x12-272 mm

2 Hilti HSA M12x150/55/75

4 M8 x 25 mm, hexagon socket

Fixing unit, 70x40x15-160 mm

1 M8 setscrew, 40 mm

Fixing unit, 70x40x15-250 mm

3 M8 setscrews, 40 mm

2 Hilti HSA M12x150/55/75

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Frame

Clamping unit

Manual hydraulic pump

Frame 220x79-340 mm

Security cylinder

8 M12 x 25 mm

2 Distance plates on fixed side

Bottom of clamping unit

Cap of clamping unit

2 aluminium plates

2 M16 x 80 mm (10.9)

Manometer

Release valve

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Hydraulic pump

Hydraulic hoses

Hydraulic cylinder

Hydraulic hose

Manometer

Remote control

Rotating head of the cylinder

Release valve

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2. Guideline for the application

2.1 Marking of the internal steel rebars

The internal steel rebars shall be found and marked. The anchor plate shall be positioned in a way that the anchor bolts will not be placed on the internal steel rebars. In case of insufficient space, it is possible to drill through the internal steel rebars with special drilling equipment.

2.2 Positioning of S&P Laminates CFK

The position of the S&P Laminates CFK and anchor plates is marked on the sub base.

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2.3 Preparation of sub base

The minimum demand of the tensile strength of sub base is 1.5 N/mm2 (pull off test) in areas where the S&P Laminate CFK and the end anchor plate is applied. The sub base is locally sandblasted or grinded. The minimum demand for the concrete compressive strength is 30 N/ mm2. If the compressive strength is insufficient, the transformation of force through the anchor bolts is not possible. Under the FRP Laminate a maximum unevenness of 5 mm/2m is allowed. Otherwise, the levelling with S&P Resin 230 is required. The unevenness of the sub base shall never be convex. Under such circumstance, the transformation of force into the sub base is not possible.

2.4 Placing of anchor bolts (Hilti HST-R M16)

The anchor plate shall be placed in the centre line of the S&P laminate CFK. This has to be considered already during the marking of the anchor plate. The anchor plate is used as a template during the marking. The drilling must be done vertical into the concrete. The dust during the drilling shall be vacuum cleaned. Also the drill hole shall be cleaned out with air. The anchor bolt shall be placed vertically so that the anchor plate can be applied without any problems.

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2.5 Preparation of clamping units

The aluminium plates are slightly grinded with a sand paper (180).

The clamping units and the aluminium plates are cleaned and degreased with S&P Cleaner.

The fast setting adhesive (Loktite) is filled in the cavity of the clamping unit cap.

The rectangular aluminium plate is pressed against the sub base for a couple of seconds.

The fast setting adhesive (Loktite) is filled in the cavity of the clamping unit bottom.

The rounded aluminium plate is pressed against the sub base for a couple of seconds.

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2.6 Fixing of the clamping unit

After the anchor plate is positioned, the fixing unit is mounted with the Hilti HAS M12 x 150/55/75. Note that on the fixed respectively pre-stressing side different fixing units are used. The short fixing unit is used on the fixed side and the long fixing unit on the pre-stressing side. For the marking of the anchor bolts, the following drawing for the drilling can be used:

2.6.1 Fixed side:

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2.6.2 Pre-stressing side:

If the strain during the pre-stressing is < 50 mm, 4 anchor bolts are sufficient. If the strain during the pre-stressing is > 50 mm, 6 anchor bolts are recommended.

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2.6.3 Positioning of the clamping units

After the fixing units are mounted provisorily, the clamping units are shifted between the fixing units. See the following 2 pictures!

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2.6.4 Definitive mounting of the fixing units

The fixing units shall be fixed strongly with the anchor bolts so that the clamping unit will not twist while the screws in the clamping unit are closed. The hexagon sockets in the fixing unit shall be opened so that the fixing unit is pressed over the entire section against the clamping unit.

2.7 Definition of the length of the S&P laminate CFK

As soon as both clamping units are in position, the final length of the S&P laminate CFK can be determinated. The measuring starts and ends at the edges of the cap of the clamping unit.

Measure point = edge of the cap

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2.8 Preparation of anchor plates, frame and aluminium plates

2.8.1 The aluminium plates are slightly grinded with a sand paper (180). The clamping units and the aluminium plates are cleaned and degreased with S&P Cleaner.

2.8.2 The holes for the bolts M12 (8 pces.) are covered locally with a tape. This is important so that the holes are not filled later by the S&P resin 220. The M8 hexagon sockets are placed and screwed in so that the over-standing is approx. 4 – 5 mm.

2.8.3 The bottom side of the frame shall be covered with a tape. Thanks to this, the cleaning from adhesive will be less.

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2.8.4 Before the S&P laminate CFK is placed finally, the aluminium plate shall be cleaned and degreased once more with S&P Cleaner.

2.9 Gluing of the S&P laminate CFK

2.9.1 The cutted S&P laminate CFK shall be cleaned with S&P Cleaner.

2.9.2 Mixing of S&P Resin 220 to a smooth, constant grey colour.

2.9.3 The glue is applied on the S&P laminate CFK with the S&P gluing set.

Attention: - on the fixed side: the last 22 cm of the laminate shall be left without glue! - on the pre-stressing side: the last 24 cm of the laminate shall be left without glue! 2.9.4 The S&P laminate CFK is applied provisorily on the cleaned concrete sub base.

2.10 The clamping units are closed and the screws M16 (black) of the clamping units are tighten with the dynamometric key M16 (position black). The torsional moment is 170 Nm.

2.11 After the fixing unit is lightly opened, the hexagon sockets have to be positioned in a way that a small opening between clamping unit and fixing unit remains.

Small opening required!

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2.12 Fixing of anchor plates

2.12.1 S&P Resin 220 is applied on the clean anchor plate; afterwards the anchor plate is mounted. The M16 anchor bolt shall be closed until the screws are flush with the sub base. The adhesive pressed out under the anchor plate shall be removed immediately.

2.13 Fixing of the frame

The frame is placed with 8 screws M12x25 mm on top of the anchor plate.

On the fixed side, the distance pieces shall be mounted so that the sliding of the S&P laminate CFK between the frame and anchor plate is possible.

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3. Pre-stressing

3.1 Positioning of the hydraulic cylinder

3.1.1 The hydraulic cylinder is fixed with the existing bolts by twisting.

3.1.2 The hydraulic cylinder is fixed additionally with the retaining clip. The retaining clip is fixed with 2 screws into the frame.

Security cylinder shall be closed!

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3.1.3 After the hydraulic hoses and - pumps are mounted, the pre-stressing can be started. An initial tension is added so that the S&P laminate CFK is stretched completely and clamping units are flush to the aluminium frame.

3.2 Quality control

3.2.1 Visual control

A reference distance for the final strain in the laminate shall be measured and marked. Example: If the S&P laminate CFK 150/2000, length 5 m, shall be pre-stressed at the strain level of 6‰, 5 m x 6 mm/m = 30 mm distance is marked. Thanks to this visual control, the strain in the laminate during the pre-stressing is recognised. The pre-stressing force is shown on the manometer fixed at the pump.

The theoretical pre-stressing force can be calculated as follows: S&P Laminate CFK 150/2000, 100x1.2 mm, pre-stressing strain 6‰, therefore: 120 mm2 x 1000 N/mm2 (pre-stressing tension in laminate) = 120 kN

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3.2.2 Electronical control

If required, an additional electronical control is offered. Strain gauges are glued on the S&P laminate CFK. The strain in the laminate will be shown directly on the laptop. A strain measurement report can be printed out.

Print of measurement report

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3.3 Blocking of the pre-stressing force

3.3.1 Fixing of distance screws:

3 types of fixing screws depending on the strain (70-84 mm, 84-112 mm, 109-162 mm) are available. The fixing screw is mounted between the frame and the clamping set.

The screws are tightened manually or with a screw wrench.

After the screws are tightened, the cylinder is moved off the frame. The same cylinder is used to apply the pre-stressing force in the next laminate.

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4. Removing

4.1 Pre-stressing side

The hydraulic cylinder shall be put in again. The pre-stressing force is applied carefully until the distance screws get loose. Now the distance screws can be removed.

The hexagon sockets of the fixing unit shall be opened so that the M12 can be tightened.

The M16 of the clamping set can be opened now with the dynamometric key.

After the M12 are loose, the clamping set can be taken away.

Also fixing units and frames are demounted.

The laminate standing out behind the anchor plate is cutted off.

The M12 anchor bolts can be cutted off flush to the concrete sub base.

4.2 Fixed side

The hydraulic cylinder shall be put in again. The pre-stressing force is applied carefully until the distance screws get loose. Now the distance screws can be removed.

The M16 of the clamping set can be opened now with the dynamometric key.

After the M12 are loose, the clamping set can be taken away.

Also fixing units and frames are demounted.

The laminate standing out behind the anchor plate is cutted off.

The M12 anchor bolts can be cutted off flush to the concrete sub base.