The Pleistocene of Iowa: An Engineering Appraisal

Pleistocene deposits from wind, water and ice dominate the soil engineering in Iowa. For foundation engineering the in situ properties of soils must be evaluated, the most pertinent properties being shear strength and compressibility. Alternately if the soil is to be used as a construction material, for example in embankment or earth dam construction, disturbed properties such as grain size and plasticity are utilized and are reflected in engineering classification. The shear strength, compressibility, and engineering classification of the various types of Pleistocene and Recent deposits in Iowa are presented and discussed, and examples of the use of shear strength data in slope stability and bearing capacity problems are presented

Unit Cell Parameters of a Pozzolanic Reaction Product

Powder X-ray analysis of a slurry of the dolomitic lime Ca(OH)2 + MgO plus Otay bentonite, after being sealed and stored at room temperature for one year, showed complete loss of Ca(OH)2 and partial loss of the MgO, some or all of which went to Mg(OH)2. New X-ray lines indicate formation of pozzolanic reaction products. Crystals of one of these products were isolated and studied by means of a diffractometer and single crystal orienter, and the unit cell was calculated. Individual crystals were then rushed to give Debye-Scherrer powder diffraction data. The chemical composition of the crystals is not yet known. Differential thermal and X-ray analysis of the reacted limebentonite mixture shows considerable alteration of the bentonite

On the Curious Resemblance Between Fly Ash and Meteoritic Dust

This paper is a discussion of W. J. Thomsen\u27s prize-winning paper presented to the Geology Section of the Iowa Academy of Science in 1952 and entitled The Annual Contribution of Meteoritic Dust to the Mass of the Earth (1). The present paper presents evidence that Thomsen\u27s unusually high estimate for the annual deposition of meteoritic dust may be due to the presence of fly-ash in the magnetic dust samples he collected

Comparison of Various Commercial Hydrated Lime for Reducing Soil Plasticity

Atterberg limits tests were performed on mixtures of gumbotil soil and the various chief chemical compounds found in hydrated limes. The results were then checked with commercial hydrated limes of varying chemical compositions. Results indicate that among the major constituents of hydrated limes Ca(OH)2 is most effective in reducing soil plasticity. MgO shows a moderate effect, but Mg(OH)2 and CaCO3 show practically no effect. There is, however, practically no difference between different types or between the same type of commercial hydrated limes for the reduction of soil plasticity. The choice of lime for soil-lime stabilization should, therefore, be dictated by the relative price and pozzolanic strength characteristics of the lime

Variation of Loess Thickness and Clay Content in Southern Iowa

This report summarizes two aspects of the Wisconsin loess in southern Iowa and presents some information on the sandy-silt immediately underlying the loess and overlying the till in southcentral Iowa. The data has originated from project work done over the last five year on the loess and glacial till of Iowa (Project 283-S) in .an attempt to solve the problem of stabilization of loess and till for roads. This paper incorporates data procured to date on the loess of southwest, southern and east-central Iowa and present studies in progress in south-central Iowa. (See references 1, 2, 3 and 4.

Exchangeable Potassium and Clay Minerals in Selected Iowa Soil Profiles

Exchangeable K values and X-ray diffraction patterns were obtained for soil samples from several modal profiles of nine different soil series in Iowa. Exchangeable K in moist subsoils was consistently low and almost always lower than in the moist surface soil. Drying increased exchangeable K in all the soils, but the increase due to drying varied between soil series and with depth in the profile of each series. Reversion of exchangeable K to a non-exchangeable form on rewetting the oven-dry samples generally increased with depth in the profile but the exchangeable K never decreased to the original moist level. X-ray diffraction analyses showed the presence of montmorillonite, chorlite, illite and/ or mica, and kaolinite in all the profiles, with mortmorillonite predominating. Vermiculite was present in some of the soil series. No relationship between the clay mineral content and the amount of exchangeable K could be established

Depth Studies of the Wisconsin Loess in Southwestern Iowa: I. Particle-Size and In-Place Density

The Soil Research Laboratory of the Iowa Engineering Experiment Station has been studying areal and stratigraphic variations in properties of the Wisconsin (Peorian) loess in southwestern Iowa since September, 1950. The information on loess properties is being utilized in soil stabilization studies now in progress. A paper presented before the Geology Section of the Iowa Academy of Science in 1952 (1) discussed the distribution of and some property variations in the Wisconsin loess in the southwestern Iowa area shown by Figure 1. While last year\u27s paper presented some depth data, the main emphasis was on areal property variations. More detailed studies of selected Wisconsin loess sections are now in progress to determine the variations in properties with depth. The present paper, Part I of two parts, presents particle-size, field moisture, and in-place density data. Part II will cover chemical, mineralogical, and additional physical property data

Chemical composition profiles during alkaline flooding at different temperatures and extended residence times

The objective of this work was to investigate whether or not caustic sweeps the major portion of the reservoir efficiently during an alkaline flood process. It was also the objective of this work to study the state of final equilibrium during a caustic flood through determination of the pH and chemical composition profiles along the porous medium. For this purpose, a long porous medium which provided extended residence times was required. It was necessary to set up the porous medium such that the changes in the pH and chemical composition of the solution could be monitored. Four Berea sandstone cores (8 in. length and1 in. diameter) placed in series provided the desired length and the opportunity for sampling in-between cores. This enabled establishment of pH and chemical composition profiles. The experiments were run at, temperatures up.to 180[degrees]C, and the flow rates varied from 4.8 to 0.2 ft/day. The samples were analyzed for pH and for Si and Al concentrations.The results show that caustic consumption is insignificant for temperatures up to 100[degrees]C. Above 100[degrees]C consumption increases and is accompanied by a significant decrease in pH. The sharp decline in pH also coincides with a sharp decline in concentration of silica in solution. The results also show that alumina is removed from the solution and solubility of alumina ultimately reaches zero. Sharp silica and pH declines take place even in the absence of any alumina in solution. As a result, removal of silica from solution is attributed to the irreversible caustic/rock interaction. This interaction is in the form of chemisorption reactions in which silica is adsorbed onto the rock surface consuming hydroxyl ion. Once these reactions were satisfied, caustic breakthrough occurs at a high pH. However, significant pore volumes of caustic must be injected for completion of the chemisorption

Evidence of Multiple Loess Deposition in Western Iowa

Several Wisconsin Loess sections were described before the Iowa Academy of Science in 1953 (1), and data for in-place density and particle size were presented. The thickest of these sections was exposed in a newly opened quarry near Crescent City, Iowa (Fig. 1). This section was of particular interest because it showed several zones of clay concentration at different depths, and at that time it was suggested that the clayey zones might be related to lulls in deposition of the Wisconsin loess. The clayey zones divide the loess into four units which could supposedly correlate with the four advances of Wisconsin glaciation (Appendix A)