It depends on the types of abnormaility. If you are talking about the genetic anomaloes such as mutations etc then fertilization will takes place but actual problem will be during the gestation period.
As in sperm DNA demage the gestation period may not be completed and leads to miscarriage.
It depends on the type of abnormality of the sperm. In several cases, the fertilization could be done,but there would be problems in embryo development.
In some cases, morphologically abnormal sperm may fertilize the oocyte (in farm animals). Fertilization possibility depends on the type and degree of the sperm defect.