ACI 207.5R-11 Report on Roller-Compacted Mass Concrete Reported by ACI Committee 207 First Printing July 2011 American Concrete Institute® Advancing concrete knowledge Report on Roller-Compacted Mass Concrete Copyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of ACI. The technical committees responsible for ACI committee reports and standards strive to avoid ambiguities, omissions, and errors in these documents. In spite of these efforts, the users of ACI documents occasionally find information or requirements that may be subject to more than one interpretation or may be incomplete or incorrect. Users who have suggestions for the improvement of ACI documents are requested to contact ACI via the errata website at www.concrete.org/committees/errata.asp. 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Phone: 248-848-3700 Fax: 248-848-3701 www.concrete.org ISBN 978-0-87031-277-9 ACI 207.5R-11 Report on Roller-Compacted Mass Concrete Reported by ACI Committee 207 TimothyP.Dolen Chair JeffreyC.Allen TeckL.Chua DavidE.Kiefer HenryB.Prenger TerrenceE.Arnold BarryD.Fehl GaryR.Mass ErnestK.Schrader RandallP.Bass JohnW.Gajda TiborJ.Pataky StephenB.Tatro AnthonyA.Bombich RodneyE.Holderbaum JonathanL.Poole MichaelA.Whisonant Note:ACICommittee207wouldliketoacknowledgeTimDolenandNateTarboxfortheirsignificantcontributionstothedocument. Consultingmembers EricJ.Ditchey WilliamF.Kepler BrianA.Forbes TomW.Read* RichardA.Kaden *Deceased Roller-compactedconcrete(RCC)isaconcreteofno-slumpconsistencyin Chapter1—Introduction,p.2 itsunhardenedstatethatistypicallytransported,placed,andcompacted 1.1—General usingearthandrockfillconstructionequipment.Thisreportincludesthe 1.2—Whatisroller-compactedconcrete? useofRCCinstructureswheremeasuresshouldbetakentocopewiththe 1.3—History generationofheatfromhydrationofthecementitiousmaterialsandattendant 1.4—Advantagesanddisadvantages volume change to minimize cracking. Material mixture proportioning, properties, design considerations, construction, and quality control are 1.5—PerformanceofRCCdams covered. The materials, processes, quality control measures, and inspections Chapter2—Notationanddefinitions,p.9 describedinthisdocumentshouldbetested,monitored,orperformedas 2.1—Notation applicableonlybyindividualsholdingtheappropriateACIcertifications 2.2—Definitions orequivalent. Chapter3—Materialsandmixtureproportioning Keywords: admixtures; aggregates; air entrainment; compacting; forroller-compactedconcrete,p.9 compressive strength; conveying; creep properties; curing; lift joints; 3.1—General mixtureproportioning;monolithjoints;placing;shearproperties;vibration; 3.2—Materials workability. 3.3—Mixtureproportioningconsiderations 3.4—Mixtureproportioningmethods 3.5—Laboratorytrialmixtures ACICommitteeReports,Guides,Manuals,andCommentaries 3.6—Fieldadjustments are intended for guidance in planning, designing, executing, andinspectingconstruction.Thisdocumentisintendedforthe Chapter4—Propertiesofhardenedroller- use of individuals who are competent to evaluate the significanceandlimitationsofitscontentandrecommendations compactedconcrete,p.19 and who will accept responsibility for the application of the 4.1—General materialitcontains.TheAmericanConcreteInstitutedisclaims 4.2—Strength anyandallresponsibilityforthestatedprinciples.TheInstitute shallnotbeliableforanylossordamagearisingtherefrom. Reference to this document shall not be made in contract ACI207.5R-11supersedesACI207.5R-99andwasadoptedandpublishedJuly2011. documents.Ifitemsfoundinthisdocumentaredesiredbythe Copyright©2011,AmericanConcreteInstitute. Architect/Engineertobeapartofthecontractdocuments,they Allrightsreservedincludingrightsofreproductionanduseinanyformorbyany shallberestatedinmandatorylanguageforincorporationby means,includingthemakingofcopiesbyanyphotoprocess,orbyelectronicor theArchitect/Engineer. mechanicaldevice,printed,written,ororal,orrecordingforsoundorvisualreproduc- tionorforuseinanyknowledgeorretrievalsystemordevice,unlesspermissionin writingisobtainedfromthecopyrightproprietors. 1 2 REPORT ON ROLLER-COMPACTED MASS CONCRETE (ACI 207.5R-11) 4.3—Elastic properties 4.4—Dynamic properties 4.5—Creep 4.6—Volume change 4.7—Thermal properties 4.8—Tensile strain capacity 4.9—Permeability 4.10—Durability 4.11—Density Chapter 5—Design of roller-compacted concrete dams, p. 27 5.1—General 5.2—Foundation Fig. 1.1—RCC compaction with dual-drum, vibrating roller 5.3—Dam section considerations (Serra do Facõo Dam, Brazil, 2008). 5.4—Stress and stability analyses 5.5—Temperature studies and control capacity by providing a means by which they can be safely 5.6—Contraction joints and cracks overtopped. RCC has allowed new embankment dams to 5.7—Galleries and drainage optimize spillway capacity in over-the-embankment-type 5.8—Facing design and seepage control emergency spillways (Hansen 1992). 5.9—Spillways, aprons, and stilling basins This document summarizes the current state of the art for 5.10—Outlet works design and construction of RCC in mass concrete applications. It is intended to guide the reader through developments in Chapter 6—Construction of roller-compacted RCC technology, including materials, mixture proportioning, concrete dams, p. 39 6.1—General properties, design considerations, construction, and quality 6.2—Aggregate production and batching and mixing plant control and testing. Although this report deals primarily with location mass placements, RCC is also used for pavements (refer to ACI 325.10R) and for dam stability improvement and as 6.3—Batching and mixing embankment dam slope protection (United States Society on 6.4—Transporting and placing Dams 2003). 6.5—Compaction 6.6—Lift joints 1.2—What is roller-compacted concrete? 6.7—Contraction joints ACI Concrete Terminology (2010) defines roller- 6.8—Forms and facings compacted concrete (RCC) as “concrete compacted by roller 6.9—Curing and protection from weather compaction; concrete that, in its unhardened state, will 6.10—Galleries and drainage support a roller while being compacted.” RCC is usually mixed using high-capacity continuous mixing or batching Chapter 7—Quality control of roller-compacted equipment, delivered with trucks or conveyors, and spread concrete, p. 56 7.1—General with bulldozers in layers prior to compaction with vibratory 7.2—Activities before RCC placement rollers (Fig. 1.1). Because of RCC’s zero-slump consistency, 7.3—Activities during RCC placement subsequent lifts can be placed immediately after compaction of the previous lift. RCC can use a broader range of materials 7.4—Activities after RCC placement than conventional concrete, and derives its strength and durability from a mixture philosophy that relies on using just Chapter 8—References, p. 66 8.1—Referenced standards and reports enough paste volume to fill the aggregate voids and no more 8.2—Cited references water content than what is needed for proper workability. CHAPTER 1—INTRODUCTION 1.3—History 1.1—General The rapid worldwide acceptance of RCC is a result of Roller-compacted concrete (RCC) is probably the most economics and of RCC’s successful performance. A bibliog- important development in concrete dam technology in the raphy of dams constructed is available from the International past quarter century. The use of RCC has allowed many new Commission on Large Dams. Other listings of dams dams to become economically feasible due to the reduced constructed can be obtained from the United States Society cost realized from the rapid construction method. It also has on Dams (2003) and from the U.S. Army Corps of Engineers provided design engineers with an opportunity to economically (USACE), EM 1110-2-2006 (USACE 2000). During the rehabilitate existing concrete dams that have problems with 1960s and 1970s, applications of RCC materials led to the stability and need buttressing in addition to improving development of RCC in engineered concrete structures. In existing embankment dams with inadequate spillway the 1960s, a high-production no-slump mixture that could be REPORT ON ROLLER-COMPACTED MASS CONCRETE (ACI 207.5R-11) 3 spread with bulldozers was used at Alpe Gere Dam in Italy (Engineering News Record 1964; Gentile 1964) and at Manicougan I in Canada (Wallingford 1970). The mixtures were consolidated with groups of large internal vibrators mounted on backhoes or bulldozers. Fast construction of gravity dams using earthmoving equipment, including large rollers for compaction, was suggested in 1965 as a viable approach to more economical dam construction (Humphreys et al. 1965). The fast construction method did not receive much attention until it was presented for the “optimum gravity dam” (Raphael 1971). The concept considered a section similar, to but with less volume than, the section of an embankment dam. During Fig. 1.2—Willow Creek Dam, OR. (USACE 1984). the 1970s, a number of projects including laboratory and design studies, test fills, field demonstrations, nonstructural uses, and emergency mass uses were accomplished and evaluated using RCC. These efforts formed a basis for the first RCC dams, which were constructed in the 1980s. Notable contributions were made in 1972 and 1974 by the Tennessee Valley Authority (Cannon 1972, 1974). The U.S. Army Corps of Engineers conducted studies of RCC construction at the Waterways Experiment Station in 1973 (Tynes 1973) and at Lost Creek Dam in 1974 (Hall and Houghton 1974). The early work by the U.S. Army Corps of Engineers was in anticipation of construction of an optimum gravity dam for Zintel Canyon Dam (Sivley 1976). Zintel Canyon Dam construction was not funded at the time, but many of its concepts were carried over to Willow Creek Dam, which was completed in 1982 and became the first Fig. 1.3—Shimajigawa Dam (Ministry of Construction 1984). RCC dam in the U.S. Developed initially for the core of Shihmen Dam in 1960, “rollcrete” was used for massive rehabilitation efforts at and drains. Also typical of RCD are thick lifts with delays Tarbela Dam in Pakistan beginning in 1974 (Hansen and after the placement of each lift to allow the RCC to cure and, Reinhardt 1991). Workers placed 460,000 yd3 (350,000 m3) subsequently, be thoroughly cleaned before placing the next of RCC at Tarbela Dam in 42 working days to replace rock lift. The RCD process results in a dam with conventional and embankment materials for outlet tunnel repairs. Additional concrete appearance and behavior, but it requires additional large volumes of RCC were used later in the 1970s to cost and time compared with dams that have a higher rehabilitate the auxiliary and service spillways at Tarbela percentage of RCC to total volume of concrete. Dam (Johnson and Chao 1979). Willow Creek Dam (Schrader and Thayer 1982) (Fig. 1.2) Dunstan (1978; 1981a,b) conducted extensive laboratory and Shimajigawa Dam (Ministry of Construction 1984) studies and field trials in the 1970s using high-paste RCC in (Fig. 1.3) are the principal structures that initiated the rapid the UK. Further studies were conducted in the UK and led to acceptance of RCC dams. They are similar from the stand- more refined developments in laboratory testing of RCC and point that they both used RCC, but they are dissimilar with construction methods, including horizontal slipformed regard to design, purpose, construction details, size, and cost facing for RCC dams (Dunstan 1981a,b). (Schrader 1982). Willow Creek Dam was completed in 1982 Beginning in the late 1970s in Japan, the design and and became operational in 1983. The 433,000 yd3 (331,000 m3) construction philosophy referred to as roller-compacted dam flood control structure was the first major dam designed and (RCD) was developed for construction of Shimajigawa Dam constructed entirely of RCC. Willow Creek Dam also (Hirose and Yanagida 1981; Chugoku Regional Construction incorporated the use of precast concrete panels to form the Bureau 1981). In the context of this report, both RCC and the upstream facing of the dam without transverse contraction material for RCD are considered the same. Shimajigawa joints (Schrader and McKinnon 1984). Dam was completed in 1981, with approximately half of its Winchester Dam was the second RCC dam in the U.S. and total concrete (216,000 yd3 [165,000 m3]) being RCC. The was completed in 1983. The major contribution of the RCD method uses RCC for the interior of the dam with Winchester Dam was its use of a polyvinyl chloride (PVC) relatively thick (approximately 3 ft [1 m]) conventional membrane at the upstream face as the primary method of mass-concrete zones at the upstream and downstream faces, providing watertightness for the dam (Hansen and Reinhardt the foundation, and the crest of the dam. Frequent joints 1991). The membrane was attached to the inside (RCC side) (sometimes formed) are used with conventional waterstops of the precast concrete panels. Once the panels were set, the 4 REPORT ON ROLLER-COMPACTED MASS CONCRETE (ACI 207.5R-11) concrete facing of 12 in. (300 mm) was placed at the same time as the RCC to create a monolithic spillway facing. The dam experienced high velocity (100 ft/s [30 m/s]) spillway flows and was also constructed in a region with heavy rain seasons. Other countries quickly started developing their own RCC projects that incorporated lessons learned from early applications. They also started developing new design details and construction methods. The Saco De Nova Olinder Dam was Brazil’s first RCC dam, and was completed in 1986. This 184 ft (56 m) high dam used 180,000 yd3 (138,000 m3) of RCC and was placed in 110 days. Brazil has constructed 36 RCC dams higher than 50 ft (15 m) (Andriolo 1998), including the 220 ft (67 m) high Salto Caxias Dam that has the largest hydroelectric generating capacity (6500 MW) of any RCC dam constructed to date. The design Fig. 1.4—Upper Stillwater Dam, UT. (Photo courtesy of the philosophy in Brazil is centered around using conventional U.S. Bureau of Reclamation, 1988.) concrete for the upstream facing, using little fly ash (only 2% of Brazil power comes from coal), using stone dust or membrane joints between abutting panels were sealed with a crushed powder as a filter material (some cases have shown strip of membrane by heat welding. This facing system is pozzolanic properties), and incorporating 8 to 12% fines in referred to as the Winchester method (Sexton et al. 2010) the RCC mixture. The success of this facing system has contributed to Growth and acceptance of the RCC process increased in designers specifying a membrane system (with or without the late 1980s (Hansen and Reinhardt 1991). In 1983, there precast panels) for 6% of all RCC dams worldwide. An were only two RCC dams in the world. By the end of 2001, alternative to attaching the membrane to precast panels is to there were 264 large (greater than 50 ft [15 m] high) RCC place the membrane on the exposed face of the dam after dams in 37 countries. Thirty-three of these dams were RCC placement is concluded. As of 2009, the 318 ft (97 m) greater than 300 ft (90 m) high, and were mainly located in high Olivenhain Dam near San Diego was the only RCC dam China and Japan. The highest completed RCC gravity dam is in the U.S. that has the exposed membrane facing system. the Longtan Dam in southern China, which is 715 ft (218 m) Wenquanpu Dam in China is the only RCC arch dam that has high. Dams are increasingly using larger volumes of RCC. a membrane (exposed) facing system. Several dams that have a The 1.6 mi (2.6 km) long Tha Dan Dam in Thailand has membrane facing system also have a geotextile/geocomposite 6.45 million yd3 (4.9 million m3) of RCC whereas the layer between the RCC and the membrane to collect any Longtan Dam in China has 6.5 million yd3 (4.9 million m3). leakage. By adding this drainage medium, designers can At the end of 2007, there were 74 completed RCC gravity consider taking a reduction in uplift pressures at lift joints dams in the U.S., ranging in height from 10 to 318 ft (3 to because the drainage medium collects any water that might 97 m); 83 overtopping spillways of existing embankment bypass the membrane. dams; 12 uses of RCC for added support of existing concrete In the 1980s, the U.S. Bureau of Reclamation used and masonry dams; and another 72 miscellaneous uses of concepts of high-paste RCC for the construction of Upper RCC in water resources applications. Based on these statistics Stillwater Dam (Fig. 1.4) (Oliverson and Richardson 1984). and the potential for using RCC to rehabilitate numerous Laboratory investigations and field trials were performed to existing dams that lack sufficient spillway capacity and/or demonstrate that an RCC placed with sufficient paste could suffer from structural deficiencies, the largest market for provide bonding between successive layers without bedding RCC in the U.S. may be in the rehabilitation of existing concrete or mortar. Notable innovations at this structure dams. In 2003, the United States Society on Dams published included using a steep compound downstream slope (0.6 a comprehensive document emphasizing the practical horizontal to 1.0 vertical (0.6H:1.0V) for the lower 215 ft aspects of RCC uses for dam rehabilitation. In addition to (65 m) of the dam and 0.32 horizontal to 1.0 vertical for the RCC mixture design and specifications, the document covers upper 75 ft (23 m) and using 3 ft (0.9 m) high, horizontally- RCC for overtopping protection of embankment dams, dam slipformed upstream and downstream facing elements as an stability improvement, spillways, dam raising, and seepage outer skin of conventional low-slump, air-entrained concrete. control. McDonald and Curtis (1997) summarized a wide The RCC mixture consisted of 70% Class F pozzolan by mass variety of RCC applications in rehabilitation and replacement of cement plus pozzolan (Dolen et al. 1988). of hydraulic structures. The Taum Sauk replacement dam In Australia, the Copperfield Dam was constructed in (Fig. 1.5) has 2.96 million yd3 (2.25 million m3) of RCC. 1984, containing 183,000 yd3 (140,000 m3) of RCC that was A summary of RCC references is given in the 1994 U.S. placed in 16 weeks. (Forbes 1985). It was designed with Committee on Large Dams Annotated Bibliography (1994). vertical monolith joints, RCC was placed directly against References are also given by CHINCOLD and SPANCOLD, vertical forms for the upstream face, and a thin conventional “Proceedings of the International Symposium on Roller REPORT ON ROLLER-COMPACTED MASS CONCRETE (ACI 207.5R-11) 5 Fig. 1.6—Olivenhain Dam, CA. (Photo courtesy of San Diego County Water Authority, 2002.) Fig. 1.5—Taum Sauk Dam, MO. (Photo Courtesy of ASI Constructors, Inc., 2007). Compacted Concrete Dams,” Beijing, China, 1991; Santander, Spain, 1995; Chengdu, China, 1999; Madrid, Spain, 2003; and Gulyang, China, 2007. 1.3.1 Production and delivery—Many of the early-1980s dams successfully demonstrated the high production rates possible with RCC construction. Nearly 1.5 million yd3 (1.1 million m3) of RCC were placed at Upper Stillwater Dam in 11 months of construction between 1985 and 1987 (McTavish 1988). The 150 ft (46 m) high Stagecoach Dam was constructed in only 37 calendar days of essentially continuous placing; it had an average rate of height advance of 4.1 ft/day (1.2 m/day) (Arnold and Johnson 1992). At Elk Creek Dam, RCC placing rates exceeded 12,000 yd3/day (9200 m3/day) (Hopman 1992). For a short time, Olivenhain Dam (Fig. 1.6) held the world Fig. 1.7—Continuous all-conveyor placing, Miel Dam, record for 1-day placement: 16,000 yd3 (12,250 m3) was Colombia. (Photo courtesy of INGETEC S.A., 2002). placed in a 19.5-hour day. It also had a maximum monthly placement of 287,790 yd3 (220,025 m3) (Pauletto et al. 2003), Beginning in 1989, the benefit of conveyors was extended and is only one of three RCC dams that had an average of over by using systems that could deliver RCC to essentially every 130,000 yd3 (100,000 m3) per month placement rate. location on the lift surface. At Marmot Dam near Sandy, OR, Placement rates have continued to increase for several in 1989, conveyors were used to transport RCC from the reasons. Engineers understand that fast, uninterrupted mixing plant to a tower embedded in the dam (this dam was placement of RCC generally leads to better overall quality, removed in 2007 to improve fish migration). A pivoting particularly at lift joints, and that minimizing obstructions to conveyor on top of the tower could deposit RCC at nearly RCC placement leads to faster productions rates. Contractors any location on the dam lift surface. In 1992 at Siegrist Dam have improved on their means and methods of delivering the near Pine Grove, PA, the first crawler-placer was used to RCC to the placement area. At Willow Creek Dam, scrapers place RCC. This system included a mainline conveyor from were used to bring the RCC from the mixing plant to the dam the mixing plant to the upstream face of the dam, a conveyor surface. On smaller lift areas, traffic on the lift surface mounted on the upstream face of the dam that was raised becomes increasingly confined, and efficiency suffers. with the dam, a tripper conveyor that delivered RCC to the Beginning in 1984, conveyors began to deliver RCC from crawler placer, and the crawler placer that traveled across the mixing plants to the lift surface. At Middle Fork Dam in lift surface. This system was subsequently used on several Colorado, a series of stacker conveyors was used with a rock dams, including Spring Hollow Dam in Virginia in 1993 and ladder to drop the RCC from the conveyor to the lift surface at Meil I Dam in Colombia (Fig. 1.7). to minimize segregation (Parent et al. 1985). Similar setups Several dams have used a vacuum chute to transport the using a variety of conveyors and drop chutes were subsequently RCC down very steep abutments without segregation into used at Elk Creek, Upper Stillwater, Grindstone Canyon, trucks on the lift surface. At Shapai Dam in China, a high Stagecoach, and Quail Creek Dams in the U.S. In all of these negative-pressure chute was used with a height of 238 ft cases, haul vehicles were used to deliver RCC from the (72.5 m). A variation of this type of system was used at the conveyor discharge above the lift surface to the active Platanovryssi Dam in Greece, and at the 508 ft (155 m) high placement locations throughout the lift surface. Ralco Dam in Chile. At Ralco, RCC was conveyed down a 6 REPORT ON ROLLER-COMPACTED MASS CONCRETE (ACI 207.5R-11) of the uncompacted lift. In both cases, the RCC section with grout is vibrated using large immersion vibrators. The typical process consists of altering the composition of RCC by adding cementitious grout to the RCC mixture. The intent is to distribute the grout through the RCC by internal pneumatic vibrators, producing a mixture similar to conven- tional concrete. Other facing systems commonly used in RCC construction include stay-in-place precast panels with or without geomembranes, conventional and roller-compacted concrete with geomembranes, and slip-formed concrete. Shapai Dam in China and Ghatghar Dam in India used GEVR for both upstream and downstream facing. Bolivia’s first RCC dam, La Canada Dam at 170 ft (52 m) high, used GEVR. GERCC was used at Ralco Dam for facing and abutment treatment and for the gallery walls. The first significant uses of GERCC in the U.S. were at Olivenhain Fig. 1.8—Overview of conveyor transporting RCC to Dam, where it was used at the upstream face and the abutment waiting trucks on dam surface, Olivenhain Dam, CA. (Photo contacts, and at Hickory Log Creek Dam, where it was used courtesy of San Diego County Water Authority, 2002). in the non-overflow steps. The U.S. Army Corps of Engineers has a research program 45-degree right abutment slope using an additional conveyor to study air-entrained RCC and GERCC for potential belt on top of the RCC to keep it from running down or application in lock and guide walls where the RCC would be spilling off the belt (Croquevielle et al. 2003). This system critically saturated and in a freezing-and-thawing environment. has supported a 10-day moving average production rate of Early results have demonstrated that an air-entrained RCC 6860 yd3 (5244 m3) per day with a monthly peak of face is resistant to freezing-and-thawing cycles, but 186,676 yd3 (142,714 m3). producing a stable air-entrained grout and ensuring that the Since the early 1990s, a variety of portable conveyor grout is uniformly distributed throughout the GERCC in the systems have been used throughout the U.S. A popular setup, field is difficult and still undergoing further study especially for smaller dams and spillways, uses conveyors (McDonald 2002). on moving crawler-tractors or telescoping conveyors from 1.3.3 Lift configurations—Most RCC dams have horizontal trucks. These setups are situated off of the structure, level RCC lift surfaces. Several dams have a cross-fall slope minimizing lift surface traffic and facilitating construction in the upstream direction to increase the resistance to sliding. of high-quality lift joints. Their portability makes them Miel II Dam used a 1 on 100 cross-fall slope (Marulanda et economical for small-volume projects where access by al. 1992), and Saluda Dam in Columbia, SC, completed in vehicles is impossible or less practical. 2004, used a 1 on 30 cross-fall slope. Due to high rainfall at Many of the large production projects used off-road dump Ralco Dam, Chile, RCC lifts were placed at 1% downstream trucks as a major component of the delivery system. At cross fall to improve drainage (Croquevielle et al. 2003). Olivenhain Dam (Fig. 1.8) and Yeywa Dam, Myanmar, For the taller RCC dams being built in particularly high conveyors were used to transport RCC from the mixing plant seismic regions, lift joint strength and impermeability are to a fixed transfer point on the dam. Trucks were then used crucial design parameters. To maximize lift joint strength to transport RCC to various locations on the lift. This method properties, successive RCC lifts should be placed before the is a popular method for large dams because of the relatively initial set of the previous lift has occurred. If no retarder is large work area available for equipment on the dam. used in the RCC mixture, most mixtures will have an initial 1.3.2 Facing systems—There are more than a dozen set time of 1 to 3 hours; for large dams, it may take between different facing systems for RCC gravity dams (Hansen 15 and 30 hours to cover one lift. The Ta Sang Dam in 2001). The two most common systems are the conventional Myanmar will have 32.3 million yd2 (2700 hectars) of total concrete facing that is placed concurrently with each RCC lift joint surface area, an average of over 70,000 yd2 (5.8 hectars) lift and RCC placed against conventional formwork using per lift. With the normal horizontal lift construction method, the grout-enriched RCC (GERCC) method. Another name it would take many hours to place one lift. The sloping layer associated with GERCC is grout-enriched vibratable RCC placement method was developed in China as a method to (GEVR) (Forbes 1999). GERCC is used for upstream and improve lift quality, maximize strength properties, and downstream facing of RCC dams. The first dam to use minimize the use of bedding mortars. It was first used at the GERCC was Jiangya Dam in China. While the grout- 430 ft (131 m) high Jiangya Dam, followed by the Fenghe enriched zone is generally limited to the facing or abutment No. 2 Dam, Mianhuatan Dam, and Dachaoshan Dam, which contact zones, the location or sequence of grout placement is are all located in China (Forbes 1999). Tannur Dam in one of the biggest variations between users. Sometimes the Jordan and portions of Lajeado Dam in Brazil have also used grout is placed on top of the compacted RCC lift just before the sloping layer method. At Jiangya Dam, the RCC was the next lift is placed. Other times, the grout is placed on top initially placed on a 1:10 slope in the cross canyon direction REPORT ON ROLLER-COMPACTED MASS CONCRETE (ACI 207.5R-11) 7 to an eventual height of 10 ft (3 m). This process proceeded across the entire length of the dam until the dam was brought up by 10 ft (3 m). The process was again repeated for another 10 ft (3 m). The contractor eventually changed to a 1:20 slope. The first application for the sloping layer method in the U.S. was at Table Rock Dam in Missouri, where RCC was placed to support a large gated conventional concrete spillway. 1.3.4 Design sections—The vast majority of RCC gravity dams have vertical upstream faces and sloping downstream faces. The downstream slopes have ranged from 1H:1V to 0.8H:1V, with a few exceptions. Upper Stillwater Dam has a compound downstream slope. The lower two-thirds of the Fig. 1.9—Wolwedans Dam, South Africa (Hollingworth et face was at a 0.6H:1V, and the upper section was at 0.32H:1V. al. 1988). At Olivenhain Dam, the slope was placed at a 0.8H:1V, but transitioned on a 232 ft (70 m) radius to near vertical on the upper quarter of the slope. The radius concept was used to reduce any stress concentrations at an abrupt change in section slope. Spain has more than 24 RCC dams, and all are straight gravity dams with the exception of one arch-gravity dam. Several of these dams have a sloping or battered upstream face to provide the necessary stability. Santa Eugenia Dam has a 0.05H to 1V upstream face, and Val Dam has a 0.2H to 1V upstream slope transitioning to a vertical upstream approximately halfway up the dam. The first RCC arch gravity dams were constructed in South Africa by the Department of Water Affairs and Forestry for the Knellport and Wolwedans Dams (Fig. 1.9) (Hollingworth et al. 1988). China has built several thin RCC arch dams, starting with Wenquanpu Dam at 208 ft (63.5 m) high, and followed by the 358 ft (109 m) high Shi Menzi Dam. The Shapai Dam is the highest arch dam to date at 423 ft (129 m) high with a crest length of 820 ft (250 m). It is a three-centered single curvature arch dam containing 477,000 yd3 (365,000 m3) of RCC. 1.3.5 Extreme climates—RCC dams are commonly located in regions where extreme weather conditions are Fig. 1.10—Le Presa Ralco Dam, Chile. (Photo courtesy of prevalent. At La Presa Ralco Dam (Fig. 1.10), the annual B. Forbes and E. Warren, 2003). rainfall averages 120 in. (3000 mm), with temperatures ranging between 50 to 100°F (12 to 39°C) (Moreno 2003). RCC production was limited to the time of the year between During normal RCC placement, the mixture had a consistency November to May. Maximum allowable ambient placing time of 15 to 18 seconds, but during wet periods, it was temperature was restricted to 73°F (23°C) (Azari et al. increased to 20 to 25 seconds, and the bedding mortar, which 2003). The first RCC dam in India, Ghatghar Dam, had air was used on every lift, had some water removed. The temperatures as hot as 104°F (40°C) and a monsoon period bedding mixture placement was limited to no more than that lasted 4 to 5 months (Shelke et al. 2006). 20 ft (6 m) in advance of the RCC placement. With these 1.3.6 Mixture proportions—The mixture proportions used mixture modifications, rainfall rates of up to approximately throughout the world have varied widely (Portland Cement 0.1 in. (3 mm) per hour could be accommodated. During the Association 2002). Many of the first-generation dams used cold periods, the mixing water was heated to 140°F (60°C), lean dry mixtures, such as Middle Fork Dam in the U.S., and extra thick insulation blankets were used. The Bio Bio which used a cement content of 112 lb/yd3 (66 kg/m3) and River Dam had a minimum flow rate of 3000 ft3/s (90 m3/s) no ash, and Galesville Dam (also in the U.S.), which used and a recorded maximum flow rate of 120,000 ft3/s (3390 m3/s). 89 lb/yd3 (53 kg/m3) of cement and 86 lb/yd3 (51 kg/m3) of The original cofferdam failed, and the RCC-modified fly ash. The Upper Stillwater Dam is an exception, with replacement overtopped on several occasions. The main dam 134 lb/yd3 (79 kg/m3) of cement and 292 lb/yd3 (172 kg/m3) overtopped when the cofferdam was overtopped or its of fly ash. Most dams constructed in the U.S. today average spillway operated. more than 200 lb/yd3 (118 kg/m3) of cementitious materials. The first RCC dam in Iran was Jahgin Dam, which was Urugua Dam in Argentina has a cement content of only 256 ft (78 m) high. During the summer, the ambient air 102 lb/yd3 (60 kg/m3) with no pozzolans. Rock fines from a temperature would reach 122°F (50°C). Because of this, basalt quarry were used to provide adequate paste in the dry 8 REPORT ON ROLLER-COMPACTED MASS CONCRETE (ACI 207.5R-11) Worth, TX, replaced an earth dam that overtopped twice and failed each time during construction before a concrete shell could be completed. Following the second failure, an RCC gravity dam was constructed. During the 16 days of RCC placement, the project was overtopped during a flash flood, but sustained no damage or construction delay. Other projects that overtopped during construction include Big Haynes Dam and Tie Hack Dam in the U.S. and Le Presa Ralco Dam in Chile (Fig. 1.11). Although it is almost routine for efficiently designed RCC dams to be the least costly alternative when compared with other types of dams, there are conditions that may make RCC more costly. RCC may not be appropriate when aggregate material is not reasonably available, the foundation rock is of poor quality or not close to the surface, or where foundation Fig. 1.11—Le Presa Ralco Dam, Chile, overtopping during conditions can lead to excessive differential settlement. construction. (Photo courtesy of B. Forbes and E. Warren, 2003). Sometimes it is difficult for an RCC dam to compete with an earthfill dam unless the dam is on a large drainage basin. For consistency mixture. The trend in Spain is the use of high large inflows, many earthfill dams require a separate large paste mixtures of 250 lb/yd3 (150 kg/m3) cementitious reinforced conventional concrete spillway that can cost more materials, with fly ash making up to 70% of the cementitious than the dam itself. In these situations, RCC dams can be materials. In Brazil, fly ash is not readily available, so stone competitive because flows can then be passed over the dam dust or crushed powder is used as a filler. Some of these in a spillway section. fillers have shown pozzolanic properties. In Jordan, three RCC dams were designed during the same period, with 1.5—Performance of RCC dams Tannur Dam having a high paste, Wala Dam having a Because RCC technology is relatively new and documentation medium paste, and Mujib Dam having a lean consistency. of structural performance is not readily available, the performance record for RCC dams is somewhat limited. The 1.4—Advantages and disadvantages rapid acceptance of this approach to dam construction, The advantages in RCC dam construction are extensive, however, has resulted in many completed projects with a but there are also some disadvantages that should be vast range of details, sizes, and locations. This allows both recognized. Some of the advantages are primarily realized generalized and detailed comments to be made about with certain types of mixtures, structural designs, production performance to date. methods, weather, or other conditions. Likewise, some Performance involves design and construction in addition to disadvantages apply only to particular site conditions and strength and operation of the completed structure. Completed designs. Each RCC project should be thoroughly evaluated RCC dams are performing their intended purpose quite well. based on technical merit and cost. Each type of RCC material and design tends to have advantages The main advantages are reduced cost, time of construction, and disadvantages, and performs better in some areas than in and lower spillway costs. Another advantage of RCC dams others. This includes seepage, in-place strength, and properties is that the technology can be implemented rapidly. For including lift joints, cracking, and durability. emergency projects such as the Kerrville Ponding Dam, In 1988, there were eight RCC dams in the U.S., one in RCC was used to rapidly build a new dam downstream of an Brazil, and one in Australia; other RCC dams were being embankment dam that was in imminent danger of failure due completed or put into operation. At that time, any RCC dam to overtopping (Engineering News Record 1986). RCC was had been in operation a maximum of only 5 years, with most also used to quickly construct Concepcion Dam in Honduras of the dams having been just recently completed. The major after declaration of a national water supply emergency performance aspects of each project, including cost, (Giovagnoli et al. 1991). Following the devastating fires at schedule, strength, thermal stress and cracking, and seepage Los Alamos, NM, Pajarito Dam was built as a design/build were reported (ASCE 1988). project. This 130 ft (40 m) high dam was designed and Only 15 years later, there were more than 250 completed constructed in less than 6 months. When compared with RCC dams in approximately 39 countries. There are many embankment-type dams, RCC usually gains an advantage types of RCC, many approaches to design, and many ways when spillway and river diversion requirements are large, to detail various aspects of the work. No single approach is where suitable foundation rock is close to the surface, and best for all situations. Each project should be evaluated to when suitable aggregates are available near the site. Another determine the best options and overall approach. Data are advantage is reduced cofferdam requirements because, once needed to evaluate the overall performance of RCC dams in started, an RCC dam can be overtopped with minimal different environments. Important data need to include lift impact, and the height of the RCC dam can quickly exceed line bonding properties, seepage and the performance of the height of the cofferdam. The 4th Street RCC dam in Fort various facing methods, long-term strength performance,