A WATER RESOURCES TECHNICAL PUBLICATION ENGINEERING MONOGRAPH No. 34 Control of Crackingin Mass Concrete Structures UNITED STATES DEPARTMENT REVISED REPRINT - 1981 OF THE INTERIOR BUREAU OF RECLAMATION A WATER RESOURCESTECHNICAL PUBLICATION EngineeringMonograph No. 34 Control of Cracking in Mass Concrete Structures bY C. L. TOWNSEND Dams Branch Division of Design Engineeringand ResearchCenter UNITED STATES DEPARTMENT OF THE INTERIOR Bureau of Reclamation As the Nation’s principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, pre- serving the environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department assessesour energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsi- bility for American Indian reservation communities and for people who live in Island Territories under U.S. administration. ENGINEERING MONOGRAPHS are published in limited editions for the technical staff of the Bureau of Reclamation and interested technical circles in Government and private agencies. Their purpose is to record developments, innovations, and progress in the engineering and scientific techniques and practices that are employed in the planning, design, construction, and operation of Reclamation struc- tures and equipment. First Printing: October 1965 Revised Reprint: May 1981 UNITED STATES GOVERNMENT PRINTING OFFICE DENVER: 1981 - For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC., 20402, and the Bureau of Reclamation, Engineering and Research Center, Denver Federal Center, P 0 Box 25007, Denver CO 80225, Attn D-922. Pre Face VARIOUS BUREAU OF RECLAMATION papers and artificial cooling and the results obtained. Be- memoranda on heat flow and temperature control cause of the limited availability of these &t,a and of mass concrete have been written during the past memoranda and because *additional experiences in 25 years. Several of these writings were con-. cooling of mass concrete structures have modified, cerned only with the mathematical relationships in some instances, the application of temperature of heat flow. Others either gave general consid- control measures, this Engineering Monograph eratdons TV be taken into account in design and was written to summarize studies and procedures construction, or described a particular instance of as they relate to present day practice. iii Contents Pap2 . 111 Introductbn--------- _______----___---_--__---_-- ____------_--_ Volumetric Changes in Mass Concrete- _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ ___ ___ _ _ The Temperature Control Problem- _ _ _ - - - _ _ _ _ _ _ _ _ _ - - _ _ _ _ _ _ _ _ _ _ Applications-___________-_____--------_-----____--------____ Costs_--_---______--____________________------------------- Temperaturecontrol Studies------------------------------------ 9 General___-_-___________________________------------------- 9 Range of Mean Concrete Temperatures----------....------------ 9 Diffusivityof concrete----- ___________________ -_-___-_-__ 10 Amplitudes of air temperatures-------------------------- 10 Amplitudes of concrete temperatures- - - - - _ - - - - - _ _ _ _ _ _ _ _ _ _ _ 15 Reservoir water temperatures- _______ - _________ ----_---_-- 19 Solarradiation effect ___________ ---___--_----_- ___________ 22 ClosureTemperature_--- ______ -_--_--_-_--__---- ____________ 23 Temperatures in Mass Concrete-- _____ -__----__-__--__-_-_____ 39 Heat of hydration----....--- ___________________ --_---__-- 40 Schmidt’sMethod__---________-____________________----- 41 Carlson’sMethod------ _______ ---- ______ -_--- ____-_____- 48 Temperature distributions_ - _ _ _ _ _ - - _ _ _ _ _ _ _ - - - _ - _ _ _ _ _ _ _ _ _ _ - 49 Removal of heat by cooling pipe- - - _ _ _ _ _ _ - - _ - - - _ _ _ _ _ _ _ _ - _ _ 49 57 Length of Construction Block_-------------------- ____________ 57 Width of Construction Block_------- ____ ---_------__-___- _____ 58 Control of Temperature Drop-------- _________ -__- ___._______- 60 Rate of Cooling ______. -- ______ ---_---~~~----~---- ___________- 63 Joints-______-__________________________-------------------- 65 Temperature Reinforcement-General- - _ _ _ -.- _ - - _ -__ _ _ _ _ _ _ _ _ _ _ - 65 Temperature Reinforcement-Frames Attached to Mass Concrete- 66 V vi CONTENTS Page Construction Requirements _____ ._...... - - -..-. _ - ______ ____ ._. ______ 67 SurfaceTreatments__------_-___-.__-._--.----------- ___._____ 67 SurfaceGradients--------------------- _____. -_.--__------ ____ 68 Foundation Irregularities___--_----_______-_---_-_-----------_ 69 Relaxation of Initial Cooling--- _ _ _ - - _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ - _ 69 FinalCooling---_---- ____ --_---_-- _._____ -_- _._____ --------- 70 Height Differerltial-__---_--_-_--- ____. -___-___-- __._ --------- 70 Openings in Dam---------- _____ -- _.__ -_-__-_-_---__--------- 71 Extended Exposure of Horizontal Construction Joints- _ _ _ _ _ _ _ _ _ _ _ 7 1 FIGURES NUTObt7 1 Glen Canyon Dam-cooling pipe layout-------_---- ____________ 5 2 Glen Canyon Dam-concrete cooling details- - - - - - - - _ _ _ - _ _ _ - _ _ _ _ 6 3 MonticelloDam-coolingpipelayout--- _________ -_-_-___----__ 7 4 Hungry Horse Dam-location and general layout_- _ _ _ _ - _ _ _ _ _ _ _ _ _ 11 5 Hungry Horse Dam-climatic and mean concrete temperatures- _ _ _ 12 6 Monticello Dam-general layout-. __ _ _ - _ _ _ _ -_ - _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ 13 7 Monticello Dam-climatic and mean concrete temperatures- _ _ _ _ _ _ 14 8 Computation form (Sheet 1 of 2)-range of mean concrete tempera- tures_---_--_-___--_____________________---------------- 15 9 Computation form (Sheet 2 of 2)-range of mean concrete tempera- tures____--_______-___-_-------_-_-_-_-------------------------- 16 10 Glen Canyon Dam-air and water temperatures- _ _ _ - _ _ - - - _ _ _ - _ _ - 17 11 Temperature variations of flat slabs exposed to sinusoidal tempera- ture variation on both faces-------_-------_______________ 20 12 Range of actual reservoir temperatures under operating conditions (Sheet 1 of 2)---- _________ -- _____ -__-- _________ --_-__-__ 21 13 Range of actual reservoir temperatures under operating conditions (Sheet2of2) _____ -_- ____ -__-----_--_- ______ --__-___--_- 22 14 Range of actual reservoir temperatures under operating conditions- Salt River Project dams--- ____ -___-___-__- ________ -___-__ 23 15 Reservoir temperatures-Grand Coulee Dam_---_-----_-___-_--- 24 16 Reservoir temperatures- HooverDam _____ ---_-__-_----_-__-_- 25 17 Reservoir temperatures-Shasta Dam_____--------_-_---------- 26 18 Reservoir temperatures-Owyhee Dam- - _ _ _ _ _ - _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ 27 19 Reservoir temperatures-Hungry Horse Dam _ _ - - _ - - _ _ - - - _ - - - _ _ 28 20 Reservoir temperatures-Hiwassee Dam-_---_----____-_-------- 29 21 Reservoir temperatures-Fontana Darrl----------_-_---__-_--___ 30 22 Reservoir temperatures-Elephant Butte Dam - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 31 23 Reservoir temperatures-Grand Lake, Colorado _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 32 24 River water temperatures-Sacramento River- - - - _ _ - - _ - - _ - _ - _ - _ - 33 25 Increase in temperature due to solar radiation-Latitudes 30°-35’- 34 26 Increase in temperature due to solar radiation-Latitudes 35’-40’- 35 27 Increase in temperature due to solar radiation-Latitudes 40’-45’- 36 28 Increase in temperature due to solar radiation-Latitudes 45’-50°- 37 CONTENTS vii NW7lbU Page 29 Variation of solar radiation during year------- _____ --_-___-----_ 38 30 Temperat$ure history of artificially cooled concrete- _ _ . - - - _ _ __ _ _ _ - - 40 3 1 Temperature rise in mass concrete-type of cement - _ - _ - _ _ - _ - - _ _ - 42 32 Effect of initial temperature on heat of hydration-- - - _ _ _ _ _ _ _ _ _ - _ - 43 33 Ross Dam-Schmidt’s Method of temperature computation- - - - _ - - 46 34 Ross Dam-Temperature distribution by Schmidt’s Method-- _ - _ - _ 47 35 Temperature variations with depth in semi-infinite solid _ _ - - - - - _ _ _ 50 36 Pipe cooling of concrete-values of “X”- _ - - _ - - _ _ _ _ _ _ - - _ _ _ _ _ _ _ _ _ 51 37 Pipe cooling of concrete-values of “Y”- _ _ - - _ _ - _ - _ - _ _ _ _ - _ _ _ - - - _ 52 38 Pipe cooling of concrete-values of “Z” _____ _ _ _ - _ - - - - _ _ _ _ - - _ - - - - 53 39 Foundation restraint factors ____------___-_-- _____ - __________ -- 59 40 Typical temperaturerisecurves----- .______ ---_-___-- _________ 62 41 Tensions versus concrete strength-early age- _ _ _ _ _ - _ _ - - _ _ - _ _ _ _ _ _ 64 TABLES I Thermal Properties of Concrete for Various Dams- - - - - _ _ _ _ _ _ - _ 18 II Amplitudesof Air Temperatures-----------------..-- ________ 19 III Related Values of Ax and At for Schmidt’s Method- - - _ - _ - _ _ - - _ 44 IV Computation of Temperatures in 5-foot.-thick Concrete Wall- _ - _ 49 V ValuesofD,02,andh2,forPipeCooling-----_---- _____ ----___ 54 VI Effect of ArtificialCooling Pipe _____---_- ____ ---- _____ -_- ____ 55 VII Temperature Treatment Versus Block Length- _ _ _ _ _ _ - - _ _ _ - _ _ _ _ 60 VIII Computation for Temperature of Concrete Mix- - - - - - _ _ _ _ _ - - _ _ _ 63 IX Computationof TemperatureStress_-- _______ -----_-__-_--___ 69 Introduction CRACKING in mass concrete structures is undesir- regular structural cracks of varying width which able as it affects the water-tightness, durability, completely cross construction blocks, to the regular appearance, and internal stresses of t,he structures.