Study on Development of Rehabilitation Systems for Reinforced Concrete Slabs

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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.