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Duct Grouting Material for Prestressed Tendon of Bridge Girder

DUCT GROUTING MATERIAL FOR PRESTRESSED TENDON OF BRIDGE GIRDER TS-168G DUCT GROUTING MATERIAL FOR PRESTRESSED TENDON OF BRIDGE GIRDER is a dry material premixed with high-grade cement and a variety of inorganic and organic materials. It has the technical properties of non-segregation,......

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DUCT GROUTING MATERIAL FOR PRESTRESSED TENDON OF BRIDGE GIRDER

TS-168G DUCT GROUTING MATERIAL FOR PRESTRESSED TENDON OF BRIDGE GIRDER is a dry material premixed with high-grade cement and a variety of inorganic and organic materials. It has the technical properties of non-segregation, non-bleeding, micro-expansion and high fluidity. After add certain proportion water and stir evenly at the construction site, this product is used for the duct grouting material of the post-tensioned prestressed tendon of the bridge beam. The implementation standard is JTG/T F50-2011 Technical Specification for Construction of Highway Bridge and Culverts.


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Test item

National standard

TS-168G

Water-binder ratio(%)

0.26-0.28

0.28

Setting time(h)

initial setting

≥5

≥5

Final setting

≤24

≤24

Fluidity(s)

Initial fluidity

10-17

13.5

30min fluidity

10-20

16

60min fluidity

10-25

20

Bleeding rate(%)

3h Inter-wire bleeding rate

0

0

24h free bleeding rate

0

0

Pressure bleeding rate(%)

0.22MPa

≤2.0

≤0.8

0.36MPa

≤2.0

≤0.9

 

Compressive strength(MPa)

3d

≥20

≥35.2

7d

≥40

≥52.1

28d

≥50

≥68.5

 

Flexural strength(MPa)

3d

≥5

≥9.8

7d

≥6

≥12.1

28d

≥10

≥14.3

Free expansion rate(%)

3h

0-2

0.8

24h

0-3

1.1

Filling degree

qualified

qualified

Corrosion of steel bars

Non corroding

Non corroding


Scope of application:

This product is suitable for grouting of post-tensioned prestressed tendon duct of various beam bodies. It can also be used for anchoring of equipment foundations, anchor rods, spikes and other components, as well as defects repair such as concrete looseness, holes, etc.


Product features:

Low water-to-binder ratio: This water-to-binder ratio of product is 0.27±0.01; 

High fluidity: The fluidity value of the slurry can reach 13s, and after 60min it still can remain less than 25s; 

Suitable condensation time: Initial setting time ≥5h, final setting time≤ 24h;

Good stability and no bleeding: The slurry test value of 3h Inter-wire bleeding rate and the 24h free bleeding rate are both 0;

Micro-expansion and no shrinkage: The slurry test expansion rate value after 3h is 0 ~ 2% and24h it is 0~ 3%; 

High durability: The test value of 28d anti-freeze level is greater than F50 and 28d chloride ion diffusion coefficient is 1.25 × 10~ 12 m2 / s;


Construction preparation:

1.1 The supply water and electricity for grouting must be reliable. If necessary, special pipelines should be provided and there should be spare water and power sources.

1.2 Check the measuring system and work status of the automatic slurry making machine, and carry out related maintenance in time

1.3 Select the appropriate grouting pump according to the height, length and shape of the grouting duct and the grouting equipment should work continuously. The slurry pump shall be equipped with a qualified pressure gauge. Then check the reliability of the slurry pipe, valve and supporting equipment before grouting.

1.4 It is advisable to use automatic recorder for grouting construction.

1.5 Establish suitable environmental and labor safety measures and make sure the sewage and waste slurry should not be discharged at will.

1.6 Inspect the conformity and inspection certificate of the duct material, no matter it is metal or plastic. Protective measures should be taken for the duct to prevent the entry of debris such as maintenance water. Before the prestressing tendons are threaded, the tunnels should be cleaned and better use compressed air to blow out the impurities in the dust channel.

1.7 After the final tension is completed, the channel shall be grouted within the specified time. Before the grouting, the exposed excess steel strand shall be cut off and the anchor need be sealed. Then set the valves of grout pipe, slurry outset pipe and air outlet hole, ensure the slurry outset valve is set at the highest place of the duct.

1.8 The slurry temperature should be kept between 5°C and 30°C in grouting process. The beam and ambient temperature should not be lower than 5°C during the grouting period and within 48 hours after the grouting completed. Otherwise, maintenance measures should be taken and the requirements for winter construction should be adopted. The appropriate amount of air entraining agent can be added to the slurry but antifreeze must not be used. If the ambient temperature is higher than 35°C, the grouting treatment is preferably carried out at night.

1.9 Before construction, it is necessary to set a test hole in the place where is  possible to lead insufficient grouting.This way is used for endoscopic inspection of grouting fullness, it is a means of checking process reliability and quality supervision.

1.10 The pipes which are connected with grout valve, slurry outset valve and air outlet valve should adopt the pressure pipe and diameter more than 20mm. The free length of the slurry and air outlet pipe should be more than 1m and the pipes must maintain vertical before and after grouting. The grouting pipe should adopt the positioning measure. When the prestressing tendon is W-shaped, an exhaust hole should be set in between the decurved position (the highest point) and the position  of 0.5 m. Before grouting,ensure the airtightness in the dust and keep the grouting pipe vertical and sealed.


Making slurry process:

1.1 Slurry feeding sequence for stirring: Add the amount of all the slurry water consumption in the mixer → Start the mixer → Evenly add all the grouting agent (material) → Evenly add all the cement → Stir for another 2 min till uniform 

1.2 Pour the evenly mixed slurry into the storage tank through the filter and keep the slurry stirring in storage tank to ensure the fluidity.


Grouting process: 

1.1 Before injecting the slurry into the beam duct, first turn on the grouting pump and discharge a small amount of slurry from the grouting nozzle to remove the air, water and thin slurry inside the grouting pipe. After the fluidity of discharged slurry and the fluidity of the slurry in the stirring tank keep same, then start pressuring slurry into the duct.

1.2 For the curved and the vertical duct, slurry should enter from the lowest point of grouting hole into the duct; For the ducts of components or structure which are made in the upper and lower layers, slurry should be grouted from the lower layer to the upper layer. The grouting of the same duct should be carried out slowly, evenly, continuously and in one time. Open and close all the air outlet holes at the highest points one by one to make the air in the dust can exhaust without obstacle.

1.3 The slurry should be continuously stirring before use and during the injection process and the duration time from complete the slurry mixing to start the injection should not exceed 40 minutes. For the slurry with reduced fluidity due to delay, it is forbidden to try to add water to increase the fluidity and the slurry must be discarded.

1.4 For the horizontal or curved ducts, the injection pressure should be 0.5-0.7 MPa; For the ultra-long ducts, the maximum pressure should not exceed 1.0 MPa; For the vertical ducts, the pressure should be 0.3-0.4 MPa. Check the filling degree of the slurry, make sure the duct outlet is full of slurry and the fluidity of exhaust slurry is same with the specified fluidity, then close the slurry outlet and hold for another 3 ~5 minutes under the stable pressure of more than 0.5 MPa.

1.5 The duct injection of multi-span continuous prestressing tendon which is connected by connectors shall be carried out immediately after each section is tensioned, and shall not be taken in one time after all the sections have been stretched.

1.6 Vertical duct grouting should be carried out from bottom to top, and a valve should be installed to prevent the cement slurry from flowing back. 

1.7 When adopt the vacuum-assisted grouting way, first need close the injection valve and air exhaust valve. Then open the vacuum pump at the discharge end and make sure the vacuum degree inside the duct reaches 0.06~-0.08MPa and keep stable. Then open the grout pump and start injection. During the injection process, the vacuum pump should work continuously. When the slurry passes through the vacuum end, close the vacuum pump valve and open the slurry discharge valve which is located above the slurry discharge end. After a small amount of slurry is discharged, close the valve and continue the injection in usual way.

1.8 After injection, check the slurry compaction through the inspection hole. If anywhere is not compact, replenish immediately and take standard curing operation for 28 days.

1.9 Transportation and hoist can only be taken after the slurry strength reaches the specified value.


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