Research status and future directions of defect detection in grouted splice sleeves: A review

••A review of grout defect detection techniques for grouted splice sleeves (GSSs) is presented.••The causes and types of grout defects are summarized.••The principles, detection mechanisms, and advantages and disadvantages of various detection techniques are analyzed and compared.••A concept of full life cycle monitoring of grout defects for GSSs is introduced.••The future prospects of grout defect detection for GSSs are discussed.