Roller-compacted concrete ( RCC ) or rolled concrete ( rollcrete ) is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for portland cement . The partial substitution of fly ash for Portland Cement is an important aspect of RCC dam construction because the heat generated by fly ash hydration is significantly less than the heat generated by portland cement hydration. This in turn reduces the thermal loads on the concrete and reduces the potential for thermal cracking to occur. RCC is a mix of cement/fly ash, water, sand, aggregate and common additives, but contains much less water. The produced mix is drier and essentially has no slump . RCC is placed in a manner similar to road paving ; the material is delivered by dump trucks or conveyors , spread by small bulldozers or specially modified asphalt pavers , and then compacted by vibratory rollers .
20-620: The Portugués Dam (Spanish: Represa Portugués ) is a roller-compacted concrete thick arch dam on the Portugués River , three miles (5 km) northwest of the city Ponce , in Barrio Tibes , Ponce, Puerto Rico . Construction on the dam began in April 2008, soon after the U.S. Army Corps of Engineers , Jacksonville District awarded the Spanish firm Dragados USA , a division of Grupo ACS , with
40-572: A $ 180 million contract in March 2008 to build the dam. The primary purpose of the dam is flood control ; it provides flood protection for 40,000 people and over 13,000 residential structures. The dam is the final component of the Portugués and Bucana Flood Protection Project and the first dam of its type constructed by the U.S. Army Corps of Engineers in the United States or Caribbean . The final cost of
60-481: A 130 ft × 160 ft (40 m × 49 m) Pre-Columbian era ceremonial plaza (" batey " or ball court) used by the ancient Tainos was discovered at a construction site used for disposing of the Portugués Dam's construction rubbish. A 60 ft (18 m) long row of intricately carved stones bearing petroglyphs that appeared to date to the 11th or 12th century was also discovered. Additionally,
80-488: A burial ground containing 40 well-preserved sets of human remains was discovered. Fifteen percent of the site was believed to have been uncovered up to that point and it was reported that as many as 400 bodies may be buried there. The site had been initially marked during a cultural resource survey in 1979 but excavation work in 2007 prompted the major discovery. The Army Corps of Engineers found an alternate rubbish disposal site and performed mitigation work in order to preserve
100-640: A downstream slope that resembles a concrete staircase. Once a layer is placed, it can immediately support the earth-moving equipment to place the next layer. After RCC is deposited on the lift surface, small dozers typically spread it in one-foot-thick (about 30 cm) layers. The first RCC dam built in the United States was the Willow Creek Dam on Willow Creek, a tributary in Oregon of the Columbia River . It
120-587: A further cost of US$ 2 million, which initially reduced the leakage by nearly 75%; over the years, seepage has since decreased to less than 10% of its initial flow. Concern over the dam's long-term safety has continued however, although only indirectly related to its RCC construction. Within a few years of construction, problems were noted with stratification of the reservoir water, caused by upstream pollution and anoxic decomposition, which produced hydrogen sulfide gas. Concerns were expressed that this could in turn give rise to sulfuric acid , and thus accelerate damage to
140-422: Is 110 feet (34 m) thick at its base and 35 feet (11 m) thick at its crest. The dam has an uncontrolled spillway center-left side, over the river bed; 21 ft (6.4 m) below the dams crest of 534.6 ft (162.9 m) above sea level. The center of the dam straddles an intake and outlet structure which will draw water from behind the dam and discharge it into the river valley. During excavation,
160-478: The 1970s, the U.S. Army Corps of Engineers had been investigating a site to build the Portugués Dam. Despite the many different geographic challenges, the Army Corps was able to choose a suitable dam location and double-curvature thin arch dam design in the 1980s. In the 1990s, foundation test grouting and foundation curtain grouting along with the excavation of 350,000 cubic yards (270,000 m) of material for
180-550: The Financial Means to Satisfy Them). It was a report to the Mayor of Ponce, Luis Porrata-Doria . Up to that point, the recommended solution to control the river had generally been to change its course, but Gandia Cordoba opposed it recommending instead that a dam be created. While other measures were undergone, such as widening the path of the river within the city of Ponce, no dam-building would take place for over seven decades. Since
200-594: The aggregate production, and ½ dam RCC placement tasks; Phase 4, at $ 41.1 million, involved the final dam RCC placement, the spillway, and the intake structure jobs; and Phase 5, at a cost of $ 29.7 million included the remaining items, such as the valve house, the access road, and mechanical and electrical structures. As of March 2011, Phase 3 work was underway and the project was 48% complete. The rolled-compacted concrete production facilities had been completed, 700,500 tons of aggregate (for use in concrete) had been produced while foundation preparation continued. RCC placement
220-576: The concrete. The controversy itself, as well as its handling, continued for some years. In 2004 an aeration plant was installed to address the root cause in the reservoir, as had been suggested 18 years earlier. In the quarter century following the construction of the Willow Creek Dam, considerable research and experimentation yielded many improvements in concrete mix designs, dam designs and construction methods for roller-compacted concrete dams. By 2008, about 350 RCC dams existed worldwide. As of 2018,
SECTION 10
#1732858501669240-579: The construction of the Alpe Gera Dam near Sondrio in North Italy between 1961 and 1964. Concrete was laid in a similar form and method but not rolled. RCC had been touted in engineering journals during the 1970s as a revolutionary material suitable for, among other things, dam construction. Initially and generally, RCC was used for backfill, sub-base and concrete pavement construction, but increasingly it has been used to build concrete gravity dams because
260-473: The dam was estimated at $ 375 million; 75% is funded by the U.S. Government and 25% by the Government of Puerto Rico . It is the first dam ever built in the United States that uses the single-centered roller-compacted concrete thick arch technique. An estimated inauguration date of October 2013 was announced in 2011 but was not met. Subsequently, an inauguration date of 28 January 2014 was also announced. The dam
280-501: The dam were requested in 2007 and Dragados USA was awarded an $ 180 million contract in March 2008 to finish the dam project. Construction on the dam began in April 2008 and consisted of five phases. Phase 1, at a cost of $ 24.5 million, included the mobilization, clearing, quarry overburden excavation, power-line relocation activities; Phase 2, costing $ 47.6 million involved the foundation excavation, aggregate production, dental concrete chores; Phase 3, budgeted at $ 37.3 million, comprised
300-462: The left and right abutments took place. When the dam was advertised for construction in 2000, only one proposal was received, and its cost was over the government's budget. To reduce costs, a five-year technical review program was started to research new, lower-cost designs for the dam. The investigation resulted in a lower cost design, switching from the double-curvature thin arch to a single-centered roller-compacted concrete thick arch. Proposals for
320-469: The low cement content and use of fly ash cause less heat to be generated while curing than do conventional mass concrete placements. Roller-compacted concrete has many time and cost benefits over conventional mass concrete dams; these include higher rates of concrete placement, lower material costs and lower costs associated with post-cooling and formwork . For dam applications, RCC sections are built lift-by-lift in successive horizontal layers resulting in
340-559: The site, adding $ 3 million in additional project costs. Despite objections of locals, the Army Corps was bound by federal law and had to transport artifacts and human remains to a federally-approved laboratory in Georgia . The artifacts and human remains would, reportedly, be returned to Puerto Rico when the investigation is complete. The site was covered, awaiting future excavation. Roller-compacted concrete In dam construction, roller-compacted concrete began its initial development with
360-461: Was constructed by the US Army Corps of Engineers between November 1981 and February 1983. Construction proceeded well, within a fast schedule and under budget (estimated US$ 50 million, actual US$ 35 million). On initial filling though, it was found that the leakage between the compacted layers within the dam body was unusually high. This condition was treated by traditional remedial grouting at
380-540: Was placed in 47 ft (14 m) of dam. Construction was initially expected to be completed by 2012, but was later postponed. In December 2013 the dam was completed and its inauguration occurred on 5 February 2014. Pending reservoir-filling and testing of the dam, making it operational was announced for early 2015. The Portugués Dam is a 220 feet (67 m) high and 1,230 feet (370 m) long single-centered roller-compacted concrete thick arch. Containing 367,000 cubic yards (281,000 m) of roller-compacted concrete, it
400-749: Was structurally completed in December 2013 and inaugurated on 5 February 2014. The dam is operated by the Puerto Rico Department of Natural and Environmental Resources . The first government official known to have proposed building a dam to tame Rio Portugues from its devastating effects on the lives and properties of Ponceños was Ponce's 1899 Municipal Engineer-Architect Ramon Gandia Cordoba in his 16 March 1899 report titled Estado Actual de Ponce: Sus Necesidades y Medios Economicos para Satisfacerlas (Current State of [the Municipality of] Ponce, its Needs, and
#668331