Q.: What is your opinion of the mudjack method of repairing sunken sidewalks? We are considering repairing approximately 1596 square feet of sunken sidewalks by having 2-inch holes drilled in the concrete, then using a mudjack to pump in a mixture of lime, water and cement in order to bring the sidewalk level with others and then filling the 2-inch holes with concrete.

A.: The mudjacking process, more properly referred to nowadays as slabjacking, is an effective, well established method of repairing pavements, floors and other flatwork on ground. The most recent article on slabjacking published by Concrete Construction is "Slabjacking Art and Science," February 1969, page 53. The state of the art has improved considerably since that time and we anticipate publishing an updated article in the near future. Two recent publications on the subject are "Slabjacking—State-of-the-Art," Journal of the Geotechnical Engineering Division, American Society of Civil Engineers (ASCE), Volume 103, Number GT9, September 1977, pages 987-1005 (probably the most up-todate and authoritative paper on the subject), and a paper by James Warner and Tom Fera, "Rehabilitation of Concrete Pavement," Journal of the Construction Division, ASCE, Volume 103, Number CO3, September 1977, pages 395-403.