Applications of Steel Slag Powder and Steel Slag Aggregate in Ultra-High Performance Concrete

Jin Liu,Runhua Guo

doi:10.1155/2018/1426037

Abstract

The applications of steel slag powder and steel slag aggregate in ultra-high performance concrete (UHPC) were investigated by determining the fluidity, nonevaporable water content, and pore structure of paste and the compressive strength of concrete and by observing the morphologies of hardened paste and the concrete fracture surface. The results show that the fluidity of the paste containing steel slag is higher. The nonevaporable water content of the hardened paste containing steel slag powder is close to that of the control sample at late ages. Both steel slag powder and steel slag aggregate react and connect tightly to gels and hardened paste, respectively. When the cement replacement ratio is no more than 10%, the proportion of pores larger than 50 nm in the hardened paste containing steel slag powder is close to that of the control sample, and the UHPC containing steel slag powder can display satisfactory compressive strengths. The UHPC containing steel slag aggregate demonstrates higher compressive strengths.

Highlights

Steel slag is a by-product of steel manufacturing [1]
Energy-dispersive X-ray (EDX) was used to detect the elemental distributions of the hardened pastes and aggregates. e nonevaporable water content of hardened paste was obtained from the mass difference between the sample dried at 105°C and heated at 1000°C normalized by the mass after only being dried at 105°C and correcting for the loss from the ignition of the unhydrated sample
When the cement replacement ratio is 20%, the fluidity of paste containing steel slag powder is approximately 25 mm higher than that of paste without steel slag powder. ese results indicate that using steel slag powder as a mineral admixture could improve the fluidity of paste, which is beneficial for the workability of concrete. is may be because that the activity of steel slag powder is lower than that of cement, and the water requirement of composite binder containing steel slag powder is less than that of the equal mass cement in the same plastic state. ese results are consistent with a previous study [17]

Summary

Introduction

Steel slag is a by-product of steel manufacturing [1]. Approximately 160 kg of steel slag is generated per ton of steel produced [2]. e common chemical compounds in steel slag are SiO2, CaO, Fe2O3, Al2O3, and MnO [3, 4]. e major mineral components of steel slag are C3S, C2S, C4AF, RO phase, and free-CaO [5, 6]. E application of steel slag powder as a mineral admixture in concrete has been investigated in many studies [12,13,14]. Studies have shown that concrete that contains steel slag powder performs better in terms of workability than plain cement concrete does [17]. Due to the negative influence of steel slag powder on the compressive strength, the chloride-ion penetration resistance, carbonation resistance, and sulfateattack resistance of concrete, the cement replacement ratio should not be very high [21,22,23]. Concrete containing steel slag aggregate displays satisfactory compressive strengths and flexural strengths [28,29,30]. The applications of steel slag as mineral admixture and aggregate in UHPC were discussed

Raw Materials and Test Methods

Results and Discussion

Conclusions