Study on Development of Rehabilitation Systems for Reinforced Concrete Slabs

1)首次对日本东北地区典型冰雪寒冷地区在役钢筋混凝土板(RC板)进行了观测调查。根据调查结果，将钢筋混凝土楼板劣化的原因分为以下四类：a)材料；b)建筑；c)结构；d)周边条件；2)钢筋混凝土楼板劣化的对策。建议的方法如下：a)裂缝注入；b)粘结钢板；c)粘结碳纤维板；d)安装附加纵梁；e)增加桥面厚度。3)70 mm以上的钢筋混凝土板覆盖层厚度大于70 mm，钢筋混凝土板表面涂覆环氧聚合物涂层可以有效地保护钢筋免受盐蚀、冻融等恶劣条件的影响。4)钢筋混凝土板的使用寿命和功能应始终进行比较和平衡。从环境问题的角度来看，生命周期成本也是影响新混凝土结构施工的重要因素。提出了考虑上述因素和条件的钢筋混凝土楼板加固体系。5)总结了1998~2000年两年的成果，并完成了报告。

1) The observation survey of reinforced concrete slabs (RC slabs) in service in the north-east district of Japan corresponding to the typical snow and cold region was performed first. Based on the survey results, the factors of deterioration of RC slabs were classified into the following four group: a) Materials b) Construction c) Structures d) Surrounding Conditions.2) Countermeasures for the deteriorated RC slabs were investigated. The proposed methods are described as follows ; a) Crack injection b) Bonding steel plate c) Bonding carbon fiber sheets d) Installation of additional stringer e) Increasing the deck thickness.Some characteristics of polymer mortars as repair and restoration materials were clarified. Particularly the setting shrinkage stress and deformation of the repaired concrete members due to polymer mortars were main subject of this part.3) Cover depth of RC slabs more than 70 mm and the epoxy polymer coating over the surface of RC slabs were effective to protect the reinforcing bars from severe condition such as salt attack, and freezing and thawing.4) Service life and functions of RC slabs should be always compare and balanced. Life cycle cost is also an important factor at the construction of new concrete structures from the view point of environmental problem. Rehabilitation systems of RC slabs considering above factors and conditions were proposed.5) All results of two years from 1998 to 2000 were summarized and the repot was completed.