Field Evaluation of Quality Management Concrete, MLR-97-3, 1998

Quality management concrete allows the contractor to develop the mix design for the portland cement concrete. This research was initiated to gain knowledge about contractor mix designs. An experiment was done to determine the variation in cylinders, beams, and cores that could be used to test the strength of the contractor's mix. In addition, the contractor's cylinder strengths and gradations were analyzed for statistical stability and process capability. This research supports the following conclusions: (1) The mold type used to cast the concrete cylinders had an effect on the compressive strength of the concrete. The 4.5-in. by 9-in. (11.43-cm by 22.86-cm) cylinders had lower strength at a 95% confidence interval than the 4-in. by 8-in. (10.16-cm by 20.32-cm) and 6-in. by 12-in. (15.24-cm by 30.48-cm) cylinders. (2) The low vibration consolidation effort had the lowest strength of the three consolidation efforts. In particular, an interaction occurred between the low vibration effort and the 4.5-in. by 9-in. (11.43-cm by 22.86-cm) mold. This interaction produced very low compressive strengths when compared with the other consolidation efforts. (3) A correlation of 0.64 R-squared was found between the 28 day cylinder and 28 day compressive strengths. (4) The compressive strength results of the process control testing were not in statistical control. The aggregate gradations were mostly in statistical control. The gradation process was capable of meeting specification requirements. However, many of the sieves were off target. (5) The fineness modulus of the aggregate gradations did not correlate well with the strength of the concrete. However, this is not surprising considering that the gradation tests and the strength tests did not represent the same material. In addition, the concrete still has many other variables that will affect its strength that were not controlled.

Discharge water quality from old ditch networks in Finnish peatland forests

Tiivistelmä: Vanhoilta metsäojitusalueilta valuvan veden ominaisuudet

Sinkholes, hydrogeology, and ground-water quality in northeast Iowa, 1982

This report contains the results of geological studies in 22 counties in northeast Iowa. Pertinent geologic, hydrologic and water quality data were compiled and analyzed.

Water scarcity management and agricultural production (What we can do to produce more with less water)

Crop seasonal sensitivity to water stress is concerned with how to control water stress levels to optimise yield or profitability. It deals with when we can reduce irrigation and impose moderate water deficits without affecting our target, and when we can apply water to avoid too much stress.

Water Quality Summary 2000-2004

Summary of water quality data collected from Iowa streams from 2000 through 2004.

Water Quality Summary 2008

Summary of water quality data collected from streams in 2008

Water Quality Summary 2000-2008

Water quality summary of stream data collected from 2000 through 2008.

Water Quality Impairments in Iowa

Description of the impaired water listing process for Iowa.

Water Quality Summary, 2009

Summary of stream water quality data collected in 2009.

Water Quality Summary, 2000-2009

Summary of stream water quality data collected from 2000 through 2009.

Water Quality Summary, 2000-2010

Summary of water quality data from stream in Iowa from 2000 through 2010.

Water Quality Summary, 2010

Summary of water quality data collected from stream in 2010.

Water Quality Summary, 2000-2011

Summary of stream water quality data collected from 2000 through 2011.

Water Quality Summary, 2011

Summary of stream water quality data for 2011.

Lake Water Quality Summary, 2000-2011

Summary of lake water quality data collected from 2000 through 2011.