The control of harmful fines in concrete sands-a case study

摘要

A programme of work was undertaken to determine the impact of a European test for the presence of harmful clay fines on sand and gravel operations. A survey was undertaken in which silt contents and MBV's were determined on stands from over 70 quarries using draft European procedures. For quarries with sands containing large quantities of harmful fines the effects of varying quantities on the water demand and strength of concrete were determined. Limiting vlaues, below which the effects on concrete properties were acceptable, were established. These values were consistent with those proposed for inclusion in the European Standard.