A proper quantity of dust particles of various sizes has long been recognized as important in the construction of stone bases and pavements. Screenings for water bound macadam bases are required to contain not less than a specified amount of dust sizes, and dense-graded limestone bases have controlling limits for the dust fraction. It is generally assumed that these particles serve a dual purpose: (1) in filling void spaces created by larger particles, thus enhancing the gross structure of the aggregate, and (2) in acting as a binder material in the presence of water. Furthermore, it has been demonstrated that the addition of small amounts of certain chemicals may improve the strength characteristics of lime stone dusts.

Former studies have been concerned primarily with the overall strength properties of aggregate mixtures containing dust, rather than with the properties of the dust itself. However, in cases where binding properties are of primary concern, a more fundamental approach would be to investigate the dust and fine aggregate fractions before studying the mixture as a whole.

The purpose of this project was to study the binding properties of several different limestone dusts. The stones selected showed considerable differences in composition, and undoubtedly the scope of these differences encompassed the majority of limestones in Kentucky. In addition, an attempt was made to detect variations (if any) in the response of these stones to the effects induced by admixtures of calcium chloride - directly or indirectly.

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Report Number

No. 104

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