The Potential of Ladle Slag and Electric Arc Furnace Slag use in Synthesizing Alkali Activated Materials; the Influence of Curing on Mechanical Properties

Abstract

Alkali activation is studied as a potential technology to produce a group of high performance building materials from industrial residues such as metallurgical slag. Namely, slags containing aluminate and silicate form a useful solid material when activated by an alkaline solution. The alkali-activated (AA) slag-based materials are promising alternative products for civil engineering sector and industrial purposes. In the present study the locally available electric arc furnace steel slag (Slag A) and the ladle furnace basic slag (Slag R) from different metallurgical industries in Slovenia were selected for alkali activation because of promising amorphous Al/Si rich content. Different mixtures of selected precursors were prepared in the Slag A/Slag R ratios 1/0, 3/1, 1/1, 1/3 and 0/1 and further activated with potassium silicate using an activator to slag ratio of 1:2 in order to select the optimal composition with respect to their mechanical properties. Bending strength of investigated samples ranged between 4 and 18 MPa, whereas compressive strength varied between 30 and 60 MPa. The optimal mixture (Slag A/Slag R = 1/1) was further used to study strength development under the influence of different curing temperatures at room temperature (R. T.), and in a heat-chamber at 50, 70 and 90 °C, and the effects of curing time for 1, 3, 7 and 28 days was furthermore studied. The influence of curing time at room temperature on the mechanical strength at an early age was found to be nearly linear. Further, it was shown that specimens cured at 70 °C for 3 days attained almost identical (bending/compressive) strength to those cured at room temperature for 28 days. Additionally, microstructure evaluation of input materials and samples cured under different conditions was performed by means of XRD, FTIR, SEM and mercury intrusion porosimetry (MIP).

Alkali Activation of Metallurgical Slags: Reactivity, Chemical Behavior, and Environmental Assessment

“…56% of amorphous phase, while Slag R contains only 35%. Besides calcite, dolomite, and amorphous phase, both slags contain also quartz (SiO 2 ), merwinite ((Ca 3 Mg(SiO 4 ) 2 ), periclase (MgO), ankerite (Ca(Fe,Mg,Mn)(CO 3 ) 2 ), corundum (Al 2 O 3 ), and wüstite (FeO) and low amount of other phases as reported in Table 2 [ 21 ]. The particle size distribution (CILAS 920 (Cilas, Orleans Cedex, France)) was obtained by milling and sieving (63 µm) slag powders and dispersing with microscan dispersant type C (Quantachrome Corporation, FL, USA).…”

Influence of Activators on Mechanical Properties of Modified Fly Ash Based Geopolymer Mortars

“…To obtain geopolymer composites with specific properties, it is important to select adequate raw material, mix it with alkaline solution of appropriate molar concentration and Si/Al ratio, and cure it either at an ambient temperature or an elevated temperature [16][17][18]. As a binder metakaolin [19,20], fly ashes [21][22][23] or slags [24,25] are the most commonly used pozzolanic materials.…”

Utilisation the Industrial Wastes in Perm Region

“…Именно направления так называемого «бесшлакового» производства стали с максимальной оптимизацией технологических процессов и организацией переработки шлаков непосредственно на сталелитейном производстве активно реализуются по многих странах мира (Češnovar et al, 2019;Dervis et al, 2019;Dippenaar, 2004;Jiao Ma et al, 2018).…”