Guide to Concrete Repair - bestmaterials.com

1 Preface This Guide contains the expertise ofnumerous individuals who havedirectly assisted the author on manyconcrete Repair projects or freelyshared their Concrete repairknowledge whenever requested. Their substantial contributions to thepreparation of this Guide areacknowledged and appreciated. Someof the material in this Guide originatedin the various editions ofReclamation s Concrete Manual. Theauthor edited, revised, or updated thisinformation for inclusion who have been especiallyhelpful to the author include James , former Reclamationengineer, mentor, and friend,deceased; Edward M.

2 Harboe, Reclamation engineer, retired; Cash, Reclamation technician,deceased; Dennis O. Arney,Reclamation technician, retired; DePuy, Reclamation engineer,former supervisor and friend, retired; andKurt D. Mitchell, Reclamationtechnician. Dr. Dave Harris,Manager, Materials Engineering andResearch Laboratory, obtained muchof the funding to prepare this Guide ;Kurt F. Von Fay, Civil Engineer,Materials Engineering and ResearchLaboratories, performed the peerreview; James E. McDonald,Structures Laboratory, WaterwaysExperiment Station, Army Corpsof Engineers, provided editorialreviews of selected information andmany useful sug-gestions andparticipated with the author in severalcooperative Reclamation Corpsof Engineers Concrete Repair programs.

3 The assistance of these and numerousother engineers and technicians isgratefully PageChapter I Repair of Concrete .. of Requirements for Quality 3 Chapter II A Concrete Repair the Cause(s) of the Extent of the Need to the Repair the Old Concrete for the Repair the Repair 18 Chapter III Causes of Damage to Concrete Mix Caused by Cyclic Freezing and of Reinforcing 43 Chapter IV Standard Methods of Concrete Cement Pack and Epoxy-Bonded Dry Aggregate Epoxy Replacement Polymer Concrete Molecular Weight Methacrylic Sealing Surface Fume

4 Siloxane Sealing 96iiPageChapter V Nonstandard Methods of of Nonstandard Repair 101 Appendix AFiguresFigurePage1 Lack of maintenance has resulted in near loss of this irrigation 22 Deferred maintenance has allowed freezing and thawing deterioration to seriously damage this 23 Freezing and thawing deterioration to the downstream face of this dam does not require Repair for safe operation of the 94 This freezing and thawing deterioration should have been repaired before it advanced to the point that wall replacement or removal is the only 95 Absorptive aggregate popout on a spillway 106 Spillway damage requiring repairs at some future 107 This Concrete damage was found to be a serious threat to the structural integrity of this 118 Saw cut patterns for the perimeters of Repair 129 Corners of Repair areas should be rounded whenever 1310 Shot blasting equipment used to remove shallow Concrete 1411 Scrabbler

5 Equipment used to remove shallow Concrete 1512 Multiple bits on the head of a scrabbler pound and pulverize the Concrete surface during the removal 1613 Correct preparation of a Concrete delamination. Perimeter has been sawcut to a minimum depth of 1 inch, and Concrete has been removed to at least 1 inch beneath exposed reinforcing 1614 Preparation of a Concrete deterioration that extends completely through a Concrete 1715 Preparation of a shallow defect on a highway bridge 1716 Relation between durability and water-cement ratio for air entrained and nonair- entrained 2017 Delamination caused by solar 2218 Gel resulting from alkali-aggregate reaction causes expansion and tension cracks in a Concrete 2419 Severe

6 Cracking caused by alkali-aggregate 2520 Freezing and thawing deterioration on small irrigation gate 2721 Freezing and thawing deterioration on spillway 2722D-cracking type of freezing and thawing 2823 Abrasion-erosion damage in a Concrete stilling 2924 Abrasion-erosion damage caused by sand or 2925 Early stages of abrasion-erosion 3026 Placing silica fume Concrete to Repair a spillway floor damaged by cyclic freezing and thawing and 3127 Typical Christmas tree pattern of progressive cavitation 3228 Extensive cavitation damage to Glen Canyon 33iiiFigurePage29 Concrete damage caused by chloride-induced corrosion of reinforcing steel.

7 The waters contained within this flume had high chloride 3530 Concrete deterioration caused by acidic 3631 The depth of acidic water on this Concrete wall is very 3632 Typical appearance of drying shrinkage 3833 Plastic shrinkage cracking caused by high evaporative water loss while the Concrete was still in a plastic 3934 Inadequate crack Repair techniques often result in poor appearance upon 4035 Improper crack Repair techniques often result in short service 4036 Crack gage installed across a crack will allow determination of progressive widening or movement of the crack.

8 It may be necessary to monitor such gages for periods up to a year to predict future crack 4137A large reflective crack has formed in a Concrete overlay which also exhibits circular drying shrinkage 4238 Multiple causes of damage are apparent in this photograph. Poor design or construction practices placed the electrical conduit too near the surface. A combination of freezing and thawing deterioration and alkali-aggregate reaction is responsible for the cracking and surface spalling on the parapet 4439A portland cement mortar patch seldom matches the color of the original Concrete unless special efforts are taken to blend white cement with normal portland 4740A small size pneumatic gun can be used to apply portland cement mortar.

9 Regular shotcreting equipment would be too large for this 4741 Saw-tooth bit used to cut slot for dry 4942 The downstream face of Barker Dam, near Boulder, Colorado, was resurfaced with prepacked aggregate 5143 Dry mix shotcrete equipment being used in the Denver Concrete 5444 Dry mix shotcrete equipment showing the nozzle and water injection 5445 Wet mix shotcrete equipment. The premixed shotcrete is delivered to the shotcrete pump by a transit 5546 Wet mix shotcrete is propelled by compressed 5547 Preparation of a wall for placement of replacement Concrete 5948 Detail of forms for Concrete replacement in 6049A gas-fired forced air heater is being used to heat Concrete prior to application of epoxy 6450An enclosure has been constructed over an area to be repaired with epoxy mortar to keep the Concrete 6651A bucket mixer can be used

10 To mix epoxy mortar for small Repair 6652 Epoxy mortar is consolidated and compacted by hand 6853 Applying the steel trowel finish required by epoxy mortar 6854 Postcuring heating enclosure installed over an epoxy mortar Repair 6955If forms are required for epoxy-bonded Concrete repairs, they should be installed at least once prior to application of the epoxy bond coat to ensure that they fit as planned and that they can be installed and filled before the bond coat 7156 The placement techniques for epoxy-bonded Concrete are essentially the same as for conventional 7257 Placing polymer Concrete in a Repair area.