Use of steel slag and LAS-based modifying admixture in obtaining highly eco-efficient precast concrete products.

Abstract

This paper presents a study on improving the eco-efficiency of no-slump concrete for precast elements using Basic Oxygen Furnace Slag (BOFS). Recycled BOFS powders and aggregates have been produced to obtain mixtures with better particle size distribution and improved packing density based on a particle packing method. A comprehensive experimental investigation was carried out on mixtures with different cement contents (5%, 10%, and 15% vol.) and compaction energy levels (6, 10, and 20 blows in a sand rammer). A modifying admixture based on Linear Alkyl Benzene Sodium Sulfonate (LAS) has also been evaluated as a workability and cohesiveness enhancer for steel slag concretes. In addition, concrete eco-efficiency was evaluated by measuring the binder intensity (bi) and waste consumption. The highest compaction energy provided packing densities ranging from 0.78 to 0.80, and BOFS aggregates led to better mechanical performances. The BOFS concrete containing 15% cement obtained the best strength (52.1 MPa) and bi value (7.0 kg/m3 /MPa), with a waste consumption of 2356.57 kg/m3 . The mixture with the lowest cement consumption (5% - 121.56 kg/m3 ) and the highest consumption of waste (2637.82 kg/m3 ) reached 16 MPa, delivering a bi of 7.6 kg/m3 /MPa.