21 resultados para holocene beach sand
Resumo:
The specifications for concrete sand in Iowa have been used for many years with very good results. In several locations of the state, it is becoming more difficult to produce concrete sand consistently at a reasonable cost. Both ASTM and AASHTO have specifications for concrete sands that allow a finer, poorer graded sand than the Iowa specification. The ASTM and AASHTO specifications are based on the use of trial mix testing prior to construction. Iowa does not currently use the trial mix procedure.
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In response to the mandate on Load and Resistance Factor Design (LRFD) implementations by the Federal Highway Administration (FHWA) on all new bridge projects initiated after October 1, 2007, the Iowa Highway Research Board (IHRB) sponsored these research projects to develop regional LRFD recommendations. The LRFD development was performed using the Iowa Department of Transportation (DOT) Pile Load Test database (PILOT). To increase the data points for LRFD development, develop LRFD recommendations for dynamic methods, and validate the results of LRFD calibration, 10 full-scale field tests on the most commonly used steel H-piles (e.g., HP 10 x 42) were conducted throughout Iowa. Detailed in situ soil investigations were carried out, push-in pressure cells were installed, and laboratory soil tests were performed. Pile responses during driving, at the end of driving (EOD), and at re-strikes were monitored using the Pile Driving Analyzer (PDA), following with the CAse Pile Wave Analysis Program (CAPWAP) analysis. The hammer blow counts were recorded for Wave Equation Analysis Program (WEAP) and dynamic formulas. Static load tests (SLTs) were performed and the pile capacities were determined based on the Davisson’s criteria. The extensive experimental research studies generated important data for analytical and computational investigations. The SLT measured load-displacements were compared with the simulated results obtained using a model of the TZPILE program and using the modified borehole shear test method. Two analytical pile setup quantification methods, in terms of soil properties, were developed and validated. A new calibration procedure was developed to incorporate pile setup into LRFD.
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Summary of bacteria monitoring of Iowa's beaches.
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Summary of bacteria monitoring of Iowa's beaches.
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Sand Creek is the most significant recreational fishery in Delaware County because of its location to Manchester and Lake Delhi. It is a feeder stream for game fish to the main stem of the Maquoketa River which is limited by the dams at Manchester and Lake Delhi. Sand Creek encompasses 16,045 acres and is dominated by row crop agriculture. It is being impacted by sediment, nutrients and E coli bacteria. Sand Creek will be a good example for habitat impaired watershed. The purpose of this project is to decrease the amount of sediment and nutrients reaching Sand Creek and to increase the habitat in Sand Creek to make it a better spawning and growing area for the fish and the food chain for the fish. The objectives of this project are to reduce sediment delivery by 40%, to improve in-stream habitat on 40% of identified critical areas and implement an information/education program. The project will install 3,800 acres of new no-till planting, 6 water and sediment control basins, 4,000 feet of terraces, 20,000 feet of improved or new waterways, 3,200 feet of streambank/ habitat enhancement, 4,500 feet of livestock exclusion fencing and 6 acres of wetlands.
Resumo:
Fly ash, a by-product of coal-fired electricity generating plants, has for years been promoted as a material suitable for highway construction. Disposal of the large quantities of fly ash produced is expensive and creates environmental concerns. The pozzolanic properties make it promotable as a partial Portland cement replacement in pc concrete, a stabilizer for soil and aggregate in embankments and road bases, and a filler material in grout. Stabilizing soils and aggregates for road construction has the potential of using large quantities of fly ash. Iowa Highway Research Board Project HR-194, "Mission-Oriented Dust Control and Surface Improvement Processes for Unpaved Roads", included short test sections of cement, fly ash, and salvaged granular road material mixed for a base in western Iowa. The research showed that cement fly ash aggregate (CFA) has promise as a stabilizing agent in Iowa. There are several sources of sand that when mixed with fly ash may attain strengths much greater than fly ash mixed with salvaged granular road material at little additional cost