Papers by Author: Ting Yu Hao

Abstract: An experimental investigation was conducted on behavior of high performance steel-fiber concrete subjected to high temperature, in terms of explosive spalling and permeability. A series of concretes incorporated steel fiber at various dosages were prepared, and further processed to have a series of moisture contents. Explosive spalling tests were conducted on control plain concrete and steel fiber concrete. After explosive spalling tests, each of the specimens that didn’t encounter spalling was sawn into two pieces. Crack observations and permeability tests were conducted on the sawn surfaces. The results prove that steel fiber is efficient to avoid spalling concrete under high temperature. The permeability increases significantly after thermal exposure, while it also exhibits an ascending trend with the increase of moisture content. Therefore it is concluded that steel fiber can play a positive effect on explosive spalling of high performance concrete under high temperature, as well as on permeability after thermal exposure.

Abstract: By comparing the permeability test results between the autoclam method introduced by Queens University Belfast and the seepage method specified in China standard, it was found that water permeability index given by autoclam test had a better correlation with seepage value than air permeability index and water absorption index.

Abstract: This paper presents an experimental investigation on fire resistance of densified normal strength concrete (DNSC), at water/binder (W/B) ratios of 0.45, 0.36, and 0.32, of which compressive strength of 28-days ranged from 42.5 MPa to 56.3 MPa. The results of the spalling test reveal that DNSC encountered explosive under high temperature. Polymer fiber can be used to improve fire resistance of DNSC. DNSC subjected to high temperature lost its mechanical properties in a similar manner to that of high-strength concrete.

Abstract: Concrete permeability has been an important part of durability assessment of existing structures. The preliminary application of in-situ permeation assessment by Autoclam system was reported in this paper. The reliability of this nondestructive method has been preliminary proved.

Abstract: Two Reinforcement Concrete (RC) roof slabs, with a size of 1.5 m×6 m, suddenly dropped from the roof after 32 years service in a steel rolling workshop of a steel mill. By in-situ inspection and lab investigation, it was found that the failure of the roof slabs were due to the severe corrosion of the prestressed steel bar, which was induced by concrete degradation connected closely with the service environments of the slabs.

Abstract: In-situ inspection and lab study were combined to analyze the prestressed concrete girders of an existing railway bridge built in 1976 in North China. The reactive components in aggregates and the alkali content of concrete were investigated. Typical reaction product was found in site and was analyzed in lab. Residual expansion of concrete cores drilled from some girders was measured. From test results, it can be deducted that alkali silica reaction had affected the concrete girders and would continue to cause expansion in the future.