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Natural and Man-Made Modes of Entry in Agronomic Areas
Published in Richard C. Honeycutt, Daniel J. Schabacker, Mechanisms of Pesticide Movement into Ground Water, 1994
James M. DeMartinis, Sandra C. Cooper
Natural modes of entry refer to natural fissures or cracks or channels that develop in the soil as a result of pedogenic processes or as the result of soil flora and/or fauna activities. These pathways include insect and animal burrows, deeply penetrating plant roots that can create channels, and specific soil properties such as the shrink/swell capacity of a clay. For example, soils containing appreciable quantities of montmorillonitic clay exhibit shrink/swell processes upon alternating wet/dry cycles and can be deeply fractured by cracks after long dry spells. Additionally in karst terranes, development of solution cavities or the dissolution of the underlying limestone can result in the development of sinkholes which can serve as direct conduits to ground water.1
Evaluating the impact of different types of stabilised bases on the overall performance of flexible pavements
Published in International Journal of Pavement Engineering, 2019
Andraé Francois, Ayman Ali, Yusuf Mehta
Five field sections located on Route 165 (between utility poles 304 and 521) in Rhode Island (RI) were evaluated in this study. These sections are part of a controlled study currently being conducted by RI Department of Transportation (RIDOT) to evaluate their long-term field performance. A summary of the five field sections is presented in Table 1. Four of the five sections were constructed using stabilised base layers and one was constructed as a control section using untreated reclaimed asphalt pavement (RAP) aggregates base. Four different stabilising agents (i.e. calcium chloride, emulsified asphalt, Portland cement and geogrids) were utilised to construct the four stabilised base layers. All these sections were constructed in 2013. All the test sections were constructed on glacial till and stratified kame that contained deposits of sand, gravel, silt, peat and organic silt. The natural soil beneath the test sections had a plasticity index of zero, a low shrink–swell capacity, and an AASHTO soil classification that ranged from A-1 to A-4. It is important to note that the natural soil had a high water table due to the presence of granite near its surface and a high susceptibility to frost action.