Title:
Concrete Q&A
Author(s):
Publication:
Concrete International
Volume:
37
Issue:
4
Appears on pages(s):
76
Keywords:
DOI:
10.14359/51687787
Date:
4/1/2015
Abstract:
Q. I understand that ACI 546R recommends limiting chipping hammers to 15 lb to prevent bruising and microcracking of the concrete around a repaired zone. Can you confirm that this limit refers to the weight of the hammer itself and is not a measure of the energy imparted to the concrete (that is, could the value be 15 ft-lb rather than 15 lb)? It seems that different types of hammers (for example, electric, pneumatic, and hydraulic) could impart different amounts of energy to the concrete even if they have identical weights. Is the weight of the hammer the major factor that affects microcracking?
Related References:
1. ACI Committee 546, “Guide to Concrete Repair (ACI 546R-14),” American Concrete Institute, Farmington Hills, MI, 2014, 70 pp.
2. Manning, D.G., “Removing Concrete from Bridges,” NCHRP Synthesis of Highway Practice 169, Transportation Research Board, Washington, DC, 1991, 42 pp.
3. “Guidelines for Partial-Depth Spall Repair,” American Concrete Pavement Association, Skokie, IL, 1998, 15 pp.
4. Vorster, M.C.; Merrigan, J.P.; Lewis, R.W.; and Weyers, R.E., “Techniques for Concrete Removal and Bar Cleaning on Bridge Rehabilitation Projects,” SHRP-S-336, National Research Council, Washington, DC, Dec. 1992, 121 pp.
5. Bissonnette, B.; Courard, L.; Vaysburd, A.M.; and Belaire, N., “Concrete Removal Techniques,” Concrete International, V. 28, No. 12, Dec. 2006, pp. 49-55.
6. Popp, D., “Spotlight—Pavement Breakers,” Highway & Heavy Construction, V. 131, No. 8, 1988, pp. 66-70.
7. “Rebel with a Cause in Milan,” International Construction, V. 27, No. 9, 1988, p. 87.