Evaluation of freeze-thaw damage on concrete material and prestressed concrete specimens. (30th October 2016)

• Record Type: Journal Article
• Authors: Qin, Xiao-chuan; Meng, Shao-ping; Cao, Da-fu; Tu, Yong-ming; Sabourova, Natalia; Grip, Niklas; Ohlsson, Ulf; Blanksvärd, Thomas; Sas, Gabriel; Elfgren, Lennart
• Is Part Of: Construction & building materials. Volume 125(2016)
• Page Start: 892
• Page End: 904
• Publication Date: 2016-10-30
• Subjects: Concrete structures -- Durability -- Assessment -- Deterioration -- Damage; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2016.08.098
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: We study the microscopic and macroscopic freeze-thaw damage on concrete material. We investigate the freeze-thaw prestress loss of the bonded and unbonded specimens. Severe microscopic damages occur after 200 freeze-thaw cycles. Prestress loss from the intact to the completed damaged status is about 5% of σ con . Influence of grouting on freeze-thaw prestress loss depends on grout damage status. Abstract: The pore structure of the hardened concrete and the microscopic changes of a few selected pores throughout the freeze-thaw test were investigated by a method combining RapidAir and digital metalloscope. Traditional tests were also performed to evaluate the macroscopic change caused by freeze-thaw cycles (FTCs). The investigation shows that the concrete material, of which the spacing factor is 0.405 mm and the air content is 2.38%, can still withstand more than 300 FTCs. Severe microscopic damages occurred after approximately 200 FTCs and the freeze-thaw damage were gradually aggravated afterwards. Prestress forces have a remarkable impact on the failure pattern under FTCs. It was further found that the compressive strength as an indicator is more reliable than the relative dynamic modulus of elasticity in evaluating the freeze-thaw damage on concrete material. In addition, the test and analysis show that the measured prestress losses of bonded specimen are larger than that of unbounded specimen under the attack of FTCs due to the duct grouting effect. The ultimate freeze-thaw prestress loss is about 5% of σ con for both the bonded and unbonded specimens because the grouting cement paste will eventually be completely destroyed.