FUNDAMENTAL EXPERIMENTS OF CONCRETE USING LIMESTONE AGGREGATE WITH HIGH VOLUME OF POWDER

Abstract

Limestone aggregate has much powder because of weak resistant to abrasion. In case of using limestone with rich powder, the powder may affect several properties of concrete, such as fresh properties and strength development. The objective of this study is to investigate fundamental properties of concrete using limestone aggregate with rich powder, and to obtain the upper limit of powder volume for structural concrete. Some fundamental tests were conducted using limestone coarse aggregate with rich powder up to 30％. This paper reports adiabatic temperature rises of the concretes as well as fresh properties. In addition, the paper presents coefficients of thermal expansion of hardened concrete; and reports compressive and tensile strength developments. The test results indicate that concrete including the powder of 30％ has notable fresh properties, lower slump and air content. According to the simplified test using Styrofoam, the volume of limestone powder slightly affects the temperature rise at early age, but it hardly influences on the ultimate temperature rise of concrete. Furthermore, all limestone concretes used herein indicate lower coefficient of linear expansion than the coefficient of typical concrete. Strength of the concrete at early age tends to be improved by powder volume, especially splitting tensile strength develops significantly. The strength development, however, becomes negligible in over 20％ of the powder volume. Based on these test results, the upper limit of powder should be considered as 20％ of the aggregate.