Physicomechanical and gamma-ray shielding properties of high-strength heavyweight concrete containing steel furnace slag aggregate

Abstract

An extensive review of literature on heavyweight concrete (HWC) reveals that this material is not economical to produce due to the required use of expensive special heavyweight aggregates and high water-to-cement (W/C) ratios. This study aimed to develop the utilization of steel furnace slag (SFS), as an aggregate to produce high-strength HWC with optimized water content for gamma (γ) ray shielding. A method was established for the optimization of the volumetric ratio of fine and coarse SFS aggregates and their influence on the cement content. Meanwhile, the optimum W/C ratio was determined to improve the performance of concrete. Thirteen concrete mixes were prepared by utilizing SFS as fine and coarse aggregates with the addition of a superplasticizer very-high-range water reducer admixture [VHRWRA] as a modern chemical admixture to achieve high strength after extensive mix design development. An investigation program was implemented in two parts. Firstly, compressive strength and density were determined after 7, 28, 56 and 90 days for the first six mixes with various W/C ratios between 0.2 and 0.45. Secondly, the properties of concrete mixes with different binder and aggregate ratios (C1S2G4, C1S1.5G3, C1S2G3, C1S2.5G3, C1S2.5G2.5, C1S2.5G2, and C1S3G2) were examined in terms of fresh density and workability in fresh concrete. The mechanical strength, durability and γ-ray shielding properties of the hardened concrete were also evaluated. Results showed that the use of third-generation VHRWRA reduced the W/C ratio to 0.23 whilst maintaining desirable workability. The concrete's compressive strength reached 106 MPa at 28 days, and all of the concretes' mechanical, durability and the γ-ray attenuation properties were improved. These observations show SFS is suitable to be used as aggregates (fine and coarse) in HWC to provide protection from radioactive rays.