A Critical Bound Meeting the Physical and Engineering Requirements for Best Cement Stabilization Effect on Clay–Sand Mixtures   Evangelos I. Stavridakis B.Sc., M.Sc., Ph.D., F.G.S., Lecturer, Laboratory of Soil Mechanics and Foundation Engineering, Geotechnical Engineering Division, Department of Civil Engineering, Aristotle University of Thessaloniki, Greece
			ABSTRACT

The use of cement for treating originally unsuitable soils, used in the construction of infrastructural soil works, is a technique which presents a remarkable contribution to the safeguard of environmental wealth.

Conventional cement – stabilization methods are used mainly for surface treatment. However the use of cement has recently been extended to a greater depth in which cement columns were installed to act as a type of soil reinforcement (deep cement – soil mixing). The object is to bind the soil particles together so that a rigid mass will be obtained with high load – bearing strength and resistance to the effects of weathering (durability). Therefore mineralogy of bonding [type of clay (active – inactive) – cement] of cementing material (cement or other cementing additive) is an important property that controls strength and durability.

A great deal of this work, in literature and practice, has proceeded without much consideration of the variations in the mineral compositions of the soils investigated. However, sufficient information is now available for an attempt at a correlation of engineering (strength – durability) behavior of cement treated soil mass with its clay mineral composition. From this point of view a research was carried out in order to define critical areas of strength and durability meeting the physical and engineering requirements for efficient cement stabilization. For these reasons both slaking and unconfined compressive strength tests were carried out on bentonite – kaolin – sand mixtures stabilized with cement.

Finally triangular diagrams were prepared to study and classify the development of strength, slaking (durability) and liquid limit of cement – stabilized clayey – sand mixtures due to their compaction and mineral composition.

A derived final conclusion was that a critical value, of strength, slaking and liquid limit as well as bentonite and sand content was determinative for the development of an efficient cement stabilization area, in triangular diagrams, for each degree of compaction.

Keywords: efficient cement stabilization, critical value, clays, strength, durability.

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