One of the biggest problems impacting the long-term performance of concrete
\nrepairs and bonded overlays is cracking of the repair material and repair material
\ndebonding from the concrete substrate. There are many purposes for concrete
\nrepair, including prolonging the useful service life of a deteriorated or distressed
\nstructure or element, restoring the load carrying capacity and the stiffness, and
\nstrengthening the structure. In most cases, for the repair to be successful,
\nmonolithic action (acting as one unit) between the repair material and the
\nsubstrate concrete (the composite repair system) is needed. A prerequisite for
\nmonolithic action is long lasting bond between the existing concrete substrate and
\nthe repair material.
\nThe mechanisms and characteristics of bond between existing concrete and repair
\nmaterials have been researched in the past. It is a very broad and generic
\nengineering task. Thus, the scope of existing guidance and specifications on
\nmethods to ensure obtaining long-term bond is limited. This is mainly due to the
\nlack of understanding of some of the factors that affect bond strength and
\ndurability of in situ repairs. Despite the relatively large pool of theoretical
\nknowledge, the practical issues related to surface preparation of existing concrete
\nto achieve long lasting bond are still inadequately addressed. This is
\ndemonstrated by the small number of ongoing research projects in the field, the
\ncurrent state of limited knowledge, the codes of practices, and in some cases the
\ncontinued poor performance of repairs and overlays. <\/p>\n","protected":false},"excerpt":{"rendered":"