As allophane has a high moisture content of 100-250%, it is necessary to decrease the moisture content by some means so that plasticity index (PI) of the stabililized allophane decreases and that the trafficability is improved in early stage of earthwork. The treatment of such clay soil with quick lime is quite effective for this purpose. On the other hand, new minerals produced by the reaction of allophane with hydrated lime were appreciated by the forwer reports, but the strength of allophane could not be satisfactorily improved by hydrated lime.
Studies were made on the characteristics of strength of allophane stabililized with quick lime as compared with hydrated halloysite and a typical clay soil of Kanto loam which consists of 75% hydrated halloysite and 25% allophane.
From test results the following was obtained.
(1) In allophane stabililized with quick lime, the increase in plastic limit (PL) is accomparied by a decrease in liquid limit (LL). Consequently the plasticity index (PI=LL-PL) is greatly reduced.
(2) The unconfined compressive strength of hydrated halloysite and that of Kanto loam increase by means of treatment with quick lime of under 20% content by weight of dried soil, but that of allophane does not increase with the same content of quick lime.
(3) The stabilization with quick lime of above 30% content can make it possible to develop the strength of allophane.
(4) The unconfined conpressive strength of dried allophane treated with quick lime increases as compared with that of undried allophane with the same content of quick lime.
(5) The generating rate of reaction products of allophane with quick lime can be accelerated by drying the clay soil.
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