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<br />compressive strength results for moist cured samples are approximately 50 to 60 percent of <br />the seven day strength (moist cured for six days and soaked in water for 24 hours). Once <br />the design strength mix is determined, a 24-hour test will be run using the mix to obtain a <br />24-hour compressive strength which will be used to monitor the daily output of the central <br />plant. Seven (7) day samples will also be taken for final acceptance. The amount of <br />stabilizer thus determined by laboratory testing shall continue to be monitored throughout <br />the life of the project with modifications as required for existing field conditions. <br /> <br />NOTE: The stabilizer is defined as the cementitious portion of the mix which may be <br />composed of portland cement only or a mixture of portland cement and fly ash or other <br />supplement. <br /> <br />The cementitious portion of the soil-cement mix shall consist of one of the following <br />alternatives: <br /> <br />(1) One hundred percent (100%) portland cement <br /> <br />(2) Eighty five percent (85%) portland cement and fifteen percent (15%) fly ash by wei~lht of <br />stabilizer. <br /> <br />The ratio of replacement shall be one kilogram of fly ash to one kilogram of portland cement <br />removed meaning one to one replacement by weight. <br /> <br />Mixino Method <br /> <br />Soil Cement shall be mixed in an approved central plant having a twin shaft continuous-flow <br />or batch-type pugmill. The plant shall be equipped with screening, feeding and metering <br />devices that will add the soil, cement, fly ash (if utilized), and water into the mixer in the <br />specified quantities. Figure 2.7 illustrates a typical continuous flow mixing plant operation. <br />In the production of the soil cement, the percent of cement content and the percent of tl1e <br />cement plus fly ash shall not vary by more than +/- 0.3 percent from the contents specified <br />by the Engineer. <br /> <br />NOTE: Soil cement can also be mixed in place, although for most bank protection projects <br />the central plant method is preferred. <br /> <br />Blendino of Cement and Flv Ash <br /> <br />The blending procedure shall provide a uniform, thorough, and consistent blend of cement <br />and fly ash. The blending method and operation shall be approved before soil cement <br />production begins. In blending of the stabilizer, the percent of fly ash content shall not vary <br />by more than +/- 0.50 percent of the specified content. <br /> <br />Scales are required at both the cement and fly ash feeds. An additional scale may also be <br />required at the stabilizer feed. <br /> <br />Reauired Moisture <br /> <br />The moisture content of the mix shall be adjusted as needed to achieve the compressive <br />strength and compaction requirements specified herein. <br /> <br />2.8 <br />