Abstract
A statistical evaluation on crack reduction in reinforced concrete beams by using expansive concrete is studied. Crack reduction effects of reinforced concrete beam by using expansive concrete are shown by flexural strength tests with 24 specimens having different effective height. The effects of reduction in chemically pre-stressed concrete（CPC）by using expansive concrete are discussed by view points of flexural crack width, frequency and spacing of cracks. And, experiment values of maximum crack width are compared with calculated values. The calculated values are evaluated by fiber model with concept of Work-done that is able to evaluate chemical pre-stress and chemical pre-strain in CPC beam by based on length change of standard specimen defined as JIS A 6202 annex 2.
Cracking moment of CPC is increased in comparison with normal reinforced concrete（RC）due to introduced chemical pre-stress. Under the same bending moment, flexural crack width in CPC beam is clearly decreased in comparison with RC due to introduced chemical pre-strain in tensile rebars. Cracks in CPC beam are occurred at same intervals due to introduced chemical pre-stress and chemical pre-strain. In addition, measurements of maximum flexural crack width in CPC beam are judged more safety side than evaluation values calculated by the Concrete Standard Specification of Japan Society of Civil Engineer.
