Experimental Study on the Roundness of Silica Sand from Sidrap: Improvement by Means of Abrasion and Measurement Using a Practical New Method

Abstract

Improving roundness of a local silica sand was conducted by abrasion using a laboratory ball mill having a diameter of about 156 mm with steel milling balls of 2800 g. Abrasion was conducted at a fixed speed of 30 rpm; with various sand loadings of 150, 200, and 250 g; and milling time of 60, 105, and 120 min. Roundness was evaluated based on Wadell equation and topography of particle surface was measured by using a new practical method consisting of a build-in camera in mobile phone and common image processing application. Results of measurement using this new proposed method had been confirmed with roundness reported from two service laboratories. The abrasion could increase the roundness of Sidrap sand from 0.20 to an average of 0.31, while the measured roundness of Ottawa standard sand was about 0.46. Three types of mortar were prepared from Sidrap sands before and after abrasion, as well as Ottawa sand. Compressive strengths of mortar after aging of 28 days were 345, 375, and 333 MPa respectively.