Ema Kato

Experimental Investigation of the Influence of Moisture on the Bond Behavior of FRP to Concrete Interfaces

The effects of moisture on the initial and long-term bonding behavior of fiber reinforced polymer (FRP) sheets to concrete interfaces have been investigated by means of a two-year experimental exposure program. The research is focused on the effects of (1) moisture at the time of FRP installation, in this paper termed “construction moisture,” consisting of concrete substratum surface moisture and external air moisture; and (2) moisture, in this paper termed “service moisture,” which normally varies throughout the service life of concrete. Concrete beams with FRP bonded to their soffits were prepared. Before bonding, concrete substrates were preconditioned with different moisture contents and treated with different primers. The FRP bonded concrete beams were then cured under different humidity conditions before being subjected to combined wet/dry (WD) and thermal cycling regimes to accelerate the exposure effects. Adhesives with different elastic moduli were used to investigate the long-term durability of ...

Chloride-induced corrosion of reinforcement and its effect on performance of structures

This paper discusses the chloride-induced corrosion of reinforcement in marine concrete structures focusing on the variability in the progress of deterioration. Through tests and analyses of reinforced concrete slabs taken out from existing open-type piers that have been in service for 30 to 40 years, the following are particularly discussed: variation in chloride ion profiles of concrete, variation in corrosion properties of reinforcement embedded in concrete and influence of the reinforcement corrosion on the load-carrying capacity of the concrete slabs. As a result, their variability was found to be very large even in one reinforced concrete slab under almost the same conditions. It was also discussed how to determine the calculation parameters for the prediction of decreasing in load-carrying capacity of concrete members with chloride-induced corrosion of reinforcement.

Structural performance evaluation of heavily deteriorated RC members based on simplified inspection results

Port and harbour structures are generally affected by harsh marine environmental actions. Material deterioration and damage to structural components are likely to occur throughout structure’s service period. In order to select suitable methods of countermeasures for such structures, structural evaluation by using simplified inspection results shall be necessary. The methodology and accuracy of structural performance evaluation based on simplified inspection results, however, are not made clear to evaluate structural performance by using simplified inspection results so far. This paper reports the evaluated results of structural performance of heavily deteriorated RC members serviced in marine environments for 44 years based on simplified inspection. The RC members were extracted from an existing port structure, and loading tests were conducted after simplified inspection. The method of simplified inspection was selected to be used in the field. The accuracy of evaluation with simplified inspection was discussed.

FACTUAL INVESTIGATION ON DECLINE IN FUNCTIONAL PERFORMANCE OF MOORING FACILITIES

Non-structural components of mooring facility such as yard apron and ancillaries are important equipment for ensuring safe and smooth operation in the facility. They often suffer deterioration and deformation under severe environmental and usage conditions, however, quantitative evaluation method of decline in their functional performance has not been developed to date. The decline in functional performance of ancillaries would consequently become one of main causes of decrease in safe and serviceability of the mooring facility. This paper reports the results of the factual investigation on the decline in functional performance of mooring facilities in Japanese ports with focusing on deterioration and/or deformation observed in face-line of wharf, yard apron and ancillaries, such as bollard and fender. The problems for developing quantitative evaluation method of functional performance from the viewpoint of safe and smooth operation in the facility were made clear from the investigated results.

APPLICABILITY OF CONCRETE WITH HIGH VOLUME OF SLAG FINE AGGREGATE TO PORT CONCRETE STRUCTURES

It is required to apply concrete with high volume slag fine aggregate without special quality improvement (HVSA concrete) to appropriate concrete structures from the viewpoint of benefiticial utilization of industrial by-products. This paper reports the mechanical properties and durability of HVSA concrete. As a result, the effect of bleeding on the mechanical properties of HVSA concrete was small when the bleeding content was less than 0.5cm/cm. It was confirmed that the long-term durability of HVSA concrete was almost the same as normal concrete. The results implied that port concrete structures can be produced with HVSA concrete when the bleeding of HVSA concrete is less than 0.5cm/cm.

EVALUATION OF LIFE-CYCLE SCENARIO OF DETERIORATED OPEN-TYPE WHARF CONSIDERING DECREMENT IN LOAD CARRING CAPACITY

While lots of harbor structures have been constructed, some of them are reaching the ends of design service life. The number of structures at which remedial actions are required will be increasing rapidly. To meet the increasing number of degraded structures, strategic maintenance and repair methods should be implemented to realize life extension and structural performance recovery, resulting in minimization of life-cycle costs.In this paper, the method is proposed to evaluate proper life-cycle scenario of deteriorated open-type wharf from the viewpoint of life-cycle cost. The change in load carrying capacity of RC members due to rebar corrosion is taken into account. Based on the calculated results, life-cycle scenarios with different repair plans were discussed from the viewpoints of recovery of load carrying capacity and the relevant life-cycle cost.