3 resultados para 271

em Iowa Publications Online (IPO) - State Library, State of Iowa (Iowa), United States


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A study was made of the detrimental effects of trace amounts of calcium sulfate (occurring naturally in halite deposits used for deicing) on portland cement concrete pavements. It was found that sulfate introduced as gypsum with sodium chloride in deicing brines can have detrimental effects on portland cement mortar. Concentrations of sulfate as low as 0.5% of the solute rendered the brine destructive. Conditions of brine application were critical to specimen durability. The mechanisms of deterioration were found to be due to pore filling resulting from compound formation and deposition. A field evaluation of deteriorating joints suggests that the sulfate phenomena demonstrated in the laboratory also operates in the field. A preliminary evaluation was made of remedies: limits on sulfates, fly ash admixtures, treatment of existing pavement, and salt treatments. This report gives details of the research objectives, experimental design, field testing, and possible solutions. Recommendations for further study are presented.

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Newsletter for State of Iowa Alcoholic Beverages Disvision

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The planning, construction and maintenance of its highways is the state's second highest business, next only to education. Of the nearly 113,090 miles of roads and streets in Iowa, the 10,271 miles in the Interstate and primary system are the direct responsibility of the Highway Commission.From its central headquarters in Ames, the Commission coordinates its statewide activities through facilities located in each of the 99 counties. These include six district offices, 47 resident offices and 165 maintenance garages.