Concrete Cracks Of Huairou District Highway Bridges: Causes And Prevention

For the country’s bridges in service, especially those built before1980’s,various defects and problems, including the structure crack, rust corrosion,concrete erosion and aging, have appeared during their service life. Amongthe defects and problems, cracking of concrete structure is the most seriousone and there is an urgent need to address the technically difficult problem.Many bridges encountered premature failure and were not able to sustain fortheir designed serive life; others are still in service but already existedcertain safety imperiments.Let’s take highway bridges in Huairou District as an example. By theend of2010, altogether there are269highway bridges at or above thecounty level, among which220were built s before1980, about200out ofthe220bridges exists different degree of concrete cracking. Considering thestructural characteristics, technical conditions and actual cases of HuairouDistrict highway bridges, this thesis analyzed the reasons of the structurecracking for the30Level III bridges, and put forward the suitable repairplan as well as prevention measures.Possible causes of concrete cracks exist during the entire process ofdesign, construction and operation management. In order to facilitateidentifing different engineering cracks, common cracks can be divided intoseven classes, that is, cracks caused by loading, cracks caused by foundationdeformation, cracks caused by frost heaving, cracks caused by rust corrosion,cracks caused by concrete shrinkage, cracks caused by temperature change,and cracks caused by construction.Although concrete cracks are inevitable, their degree of harmfulness ispossible to be controlled. During the process of operation management, it isnecessary to inspect those Level III bridges regularly, and concrete cracksshould be identified and dealt with as soon as possible. To prevent suchcracks from occurring and to safeguard the durability of future bridges, allrelevant state standards and technical standard should be strictly adheredduring the design, construction and inspection of new bridges. Expererience gained by highway bridges in Huairou Districtdemonstrated that by adopting advanced technology and appropriatematerials, concrete cracks can be repaired and the service life of the bridgebe prolonged.