Measuring the Specific Gravity and Absorption of Steel Slag and Crushed Concrete Coarse Aggregates: A Preliminary Study

摘要

The research objective is to evaluate a new test procedure for determining the specific gravity and absorption of steel slag and crushed concrete, which are recycled and manufactured coarse aggregates, respectively. Steel slag and crushed concrete, unlike many coarse aggregates possess special physical characteristic such as many effective surface voids. It is hypothesized that the current AASHTO T 85 (24±4 hours) test method fails to adequately saturate these effective voids on the coarse aggregate surfaces. When the steel slag and crushed concrete were soaked for 36 and 48 hours, it underscored the fact that AASHTO T 85 underestimates the absorption capacity of special porous coarse aggregates. A new proposed vacuum saturation approach is thus utilized to suck the trapped air within the effective pores while replacing it with water. This method is expected to better determine the specific gravity and absorption of these special aggregates. The steel slag and crushed concrete were tested at 30 minutes of vacuum saturation under 30mm Hg pressure. Statistical analysis indicated that this proposed method was viable in determining the specific gravities and absorption of these aggregates. An extended research is ongoing to expand the scope of coarse aggregates in addition to testing at reduced saturation times to increase the efficiency of the proposed method.