Author(s):
W.M. Moore, R. Van Pelt, F.H. Scrivner, G.W. Kunze
Publication Date
February 1968
Abstract
The 1966-67 plan of research for Phase 2 of Research Study 2-8-65-81 outlined an investigation to determine the limiting ranges of natural soils which can be fired to produce aggregates suitable for use in flexible base materials. This is a progress report of that investigation. Its purpose is to report the more significant findings to date, so that early utilization of the research may be possible. The findings are listed briefly below. They are based on limited study and should be considered preliminary and subject to change with future research.|1. The clay minerals, montmorillonite, illite, and kaolinite, will not rehydrate under atmospheric conditions once they have been completely dehydrated (dehydroxylated); therefore, once they have been completely dehydrated, they become chemically stabilized for use as highway construction materials. Complete dehydration is accomplished by heating the clay and holding it at the elevated temperature for sufficient time to allow the dehydration to occur. A period of 15 minutes at 1400°F. was sufficient to completely dehydrate the clay present in the small, oven dry laboratory specimens made from the Texas soils investigated.|2. Incomplete dehydration of aggregates made by dehydrating clay-type soils can be detected by a relatively simple laboratory test. The test procedure is given in Appendix 8.1.1.|3. Most (if not all) clay-type soils having a relatively high strength when air dried can be fired to produce hard, durable aggregates suitable for use in flexible base and asphaltic concrete.|The authors feel that synthetic aggregates produced from soils that are suitable for flexible base and asphaltic concrete will also, in many cases, be suitable for use as Portland cement concrete aggregates. However, it should be noted that there are many chemical compounds present in synthetic aggregates produced from naturally occurring soils. Some of these compounds, though not detrimental in flexible base or asphaltic concrete applications, may adversely affect the hydration of Portland cement concrete. Application of synthetic aggregates to Portland cement concrete is the subject of Phase 1 of this research study and is not considered in this report.
Report Number:
81-5
Link(s):
Document/Product
http://tti.tamu.edu/documents/81-5.pdf
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