Post-tensioning concrete technology increases the resistance of flexural concrete members. This technology allows for the production of slenderer sections, and sequentially less usage of material preserving the sustainability concept in construction engineering. Post-tensioning process can be done using bonded or unbonded steel tendons. The unbonded tendons are thought to have better resistance to corrosion for structures exposed to severe environmental conditions. The unbonded tendon’s steel strands are painted with grease and covered with plastic sheathing to prevent the moisture from reaching the steel strands thus they can provide high corrosion resistance. According to the ACI 318-19 and other codes of practice, the stress in the unbonded tendon at the ultimate limit state is limited to less than or equal to the tendon’s yield stress. On the other hand, the bonded tendon’s stress at this state is determined to be more than or equal to the tendon’s yield stress. This limitation for the unbonded tendons restrained the widespread usage of the unbonded system. Through this research, six-simply supported one-way slabs; two with bonded tendons, two with unbonded tendons and two with unbonded tendons and non-prestressing steel reinforcement are tested in flexure to failure. The post-tension slabs are of 4.0-meters in span and the flexural tests are carried in the AUC structural engineering laboratory in a four-point loading scheme. The ultimate stress of the unbonded tendons are measured at the failure stage. The results of both systems are compared against each other and against the provisions of the ACI 318-19. The unbonded post-tension slabs with non-prestressing steel reinforcement showed higher failure loads than the bonded and unbonded slabs without reinforcement. The ACI 318-19 provisions were critically reviewed versus the results of the experimental investigation. The review reveals that the limitation of the unbonded tendon’s ultimate stress is not accurate and can be reviewed.


School of Sciences and Engineering


Construction Engineering Department

Degree Name

MS in Construction Engineering

Graduation Date

Spring 5-6-2021

Submission Date


First Advisor

Ezzeldin Yazeed

Committee Member 1

Cara Morton

Committee Member 2

Mohamed Abdel Mooty


131 p.

Document Type

Master's Thesis

Institutional Review Board (IRB) Approval

Not necessary for this item