Evaluation of Limestone Filler in Gravel Mixtures "Asphaltic Concrete", R-228, 1968

(1968) Evaluation of Limestone Filler in Gravel Mixtures "Asphaltic Concrete", R-228, 1968. Transportation, Department of

Preview

PDF IADOT_r228_Evaluation_Limestone_Filler_Gravel_Mix_Asphalt_Concrete_1968.pdf File Size:577kB

Abstract

This study was designed to provide background information on asphaltic concrete mixtures peculiar to northwest Iowa. This background is necessary to provide the basis for future specifications. There were several projects let in 1967 involving l", 3/4" and 3/8" mixes of Type "B'' asphaltic concrete which specified in part, II Not less than 40% of the material passing the No. 200 sieve shall be pulverized limestone or mineral filler, but in no case shall the per cent of pulverized limestone or mineral filler passing the No. 200 sieve be less than 2%. No credit will be allowed for limestone in gravel - II Northwest Iowa has no suitable limestone or mineral filler locally available. As a result, this material has to be imported, raising the cost of the mix approximately twenty-five cents per ton. The purpose of this study, therefore, was designed to compare some original job mix samples with alternate mixes from the same local material, but without the addition of pulverized limestone or mineral filler. Since the filler from the crushed gravel does not have the same crushing characteristics or sieve analysis as the pulverized limestone or mineral filler, they could not be compared on an equal percentage basis. Therefore, the alternate mixes were made to conform to the following proposed specification, "No less than 40% of the material passing No. 200 sieve shall be pulverized limestone or mineral filler or a 100% crushed gravel, but in no case shall the per cent of pulverized limestone or mineral filler or a 100% crushed gravel passing the No. 200 sieve be less than 2%."