Protective mortar on top of external post-tension tendons

[ABA102]

Hi Experts,

We have this situation at our project site due to strengthening requirement of the building, external post-tension system is used as one of the strengthening systems. But there is a case that the tendons laid along the top of the driveway, refer to attached photo.
What suitable protective material can anyone suggest to protect the tendons on vehicular traffic condition?

 

[Ingenuity]

ABA102:

In my opinion, not an especially well thought out strengthening system if the issue of protecting/embedding the external PT is being considered in the construction phase rather in the documentation stage. Be that as it may!

Where is the fixed-end PT anchorage that is 'floating' to be placed?

If the existing reinforcement/PT in the slab below is such that it has sufficient cover, consider locally chipping and partially-routing the 2 new tendons in the top of slab and patching back with a cementitious matching material.

Based upon the photograph, looks like you need about 6+" thick of concrete to effectively embed the tendons - not sure how you can make that work for transitioning cars over unless you slope it over several feet.

 

[r13]

Bad design/construction. If no corrective action is considered at this time, suggest to grease the tendon, and box them for protection from traffic, and be ready for next repair. Note, the tendons shouldn't be left unprotected against the concrete though.

 

[Ingenuity]

suggest to grease the tendon

These are UNbonded tendons - already greased and sheathed in a HDPE extruded sheath - no need for further greasing.

 

[r13]

What suitable protective material can anyone suggest to protect the tendons on vehicular traffic condition?

I doubt. Can you suggest any protective material over greased tendon?

 

[Ingenuity]

Sure. Place concrete or a cementitious mortar (depending on applied thickness) over the tendons (and added rebar as required) and then cure and apply a waterproofing material.

Unbonded PT tendons are 7-wire strand coated with a corrosion inhibiting grease and protected by an extruded HDPE sheath (usually 50 mild thick). They are a pre-manufactured product. It is not like grease will be in direct contact with concrete.

 

[r13]

Thanks for the heads up. A quote from a manufacture.

Our unbonded systems feature 0.5” and 0.6” diameter strands coated with a layer of specially formulated grease. The outer layer is seamless plastic extruded in one continuous operation to provide protection against corrosion.

Encapsulated unbonded monostrand systems are used in areas that are subject to corrosive conditions. Strands are protected at the anchorages using greased plastic sleeves and grease-filled end caps. Additionally, anchorage components are fully encapsulated in a high density polyethylene plastic covering and an optional encapsulated intermediate coupler anchorage system can be used to protect the strand at construction joints.

 

[ABA102]

@Ingenuity

Thank you for your response.
The tendons actually laid crossing the existing slab section which around half of the length exposed on top and the other half exposed under the slab or soffit. Concrete cutting done by 25mm depth at driveway to concealed and protect the tendons with suitable high strength mortar but still under discussion for the right manufacturer.
One end of the tendons is fixed or dead end the other is live. At both concrete were cut and demolished as pan boxes, leaving reinforcement intact. That position of tendons on the photograph, tendons are not stressed yet because of the issues on correct depth of cutting in concrete so that sufficient thickness of mortar can be applied on top and the right manufacturer whose product can durably protect the tendons in the long run.