Screen-Out Stones Activated with Mineral Binders and Used as Material for Earth Construction

The article presents the e valuation o f h ow suitable waste from the production of aggregates in quarries could be in earthwork using the example of screen-outs from Krosno sandstone. The waste, called screen-out, is characterised by an uncontrolled content of dust and clay fractions. Screen-outs have a relatively low bearing ratio (CBR not exceeding 20%) and a tendency to heave due to frost (SE <35). To check whether the geotechnical properties can be improved, mixtures with 2%, 5%, and 8% binders, such as lime, fly ash, and two road binders with lime, fly ash, and cement were prepared. The analysis was based on the results of the CBR and compressive strength tests. The use of mineral binders caused the value of the immediate CBR to increase compared to the screen-out itself from a dozen to as much as 50%. For a binder containing 20% Portland clinker, the CBR was about 60% after 4 days of saturation, while for a binder containing up to 50% Portland clinker, it was over 200%. The value of compressive strength after 28 days of maturing ranged from about 100 kPa to 1 MPa for all mixes tested. The lowest values were obtained for screen-outs activated with fly ash, and the highest for road binder with cement content of up to 50%.