Search

The shear strength and stiffness characteristics of steel slag indicate that it can potentially be utilized as a competent base/subbase material of bound and unbound pavement layers. However, concerns with respect to the utilization of steel slag remain due to its long-term swelling, corrosivity, and leaching characteristics. In this study, long-term swelling and corrosivity tests were performed on basic-oxygen-furnace steel slag (BOFSS) and electric-arc-furnace ladle steel slag [EAF(L)SS] generated in Indiana, USA. In order to reduce the 1D swelling strains of these slags, 5%, 10%, and 20% Class C fly ash (CCFA) and 10% ground rubber replacement ratios were used to prepare steel slag mixtures for testing. The improvement due to CCFA replacement was evaluated by performing unconfined compression and long-term swelling tests on selected steel slag–CCFA mixtures. The seven-day unconfined compression strengths of 90% EAF(L)SS + 10% CCFA and 90% BOFSS + 10% CCFA mixtures were 2,387 and 3,768 kPa, respectively. After nine months of monitoring, the maximum 1D swelling strains of soaked samples of BOFSS and EAF(L)SS mixtures prepared with 10% CCFA replacement were 0.1% or less. The unconfined compression and swelling test results for the steel slag–CCFA mixtures indicated superior strength gain characteristics and negligible swelling strains with time than for steel slags. [ABSTRACT FROM AUTHOR]

This study investigates the viability of using electric-arc-furnace steel slag (EAF SS)-blast furnace slag (BFS) and EAF SS-Class C fly ash (FA) mixtures as a replacement for lime or cement in subgrade stabilisation applications and describes the implementation and performance of the selected mixture in the field. In order to decide on the proportions of EAF SS, BFS and Class C FA to be used in the field, tests were performed to obtain the Proctor compaction curves and the Atterberg limits (AL) of mixtures of soil-7% EAF SS-3% BFS and soil-7% EAF SS-3% Class C FA; in addition, the one dimensional swelling behaviour of samples prepared with these mixtures was monitored for over two months. The strength of the stabilised mixtures was determined through unconfined compressive (UC) strength tests. Based on the laboratory test results, the soil-7% EAF SS-3% Class C FA mixture was selected and implemented as a subgrade material in a pavement project in Indiana. Field subgrade compaction quality control was done by performing Dynamic Cone Penetration Tests (DCPT) and Nuclear Gauge (NG) density tests. No cracks or signs of distress were observed on the surface of the subgrade before and after placement of the base course and concrete. [ABSTRACT FROM AUTHOR]

The volumetric instability of steel slag hinders its use in pavement layers and embankments. Accordingly, evaluating the swelling potential of steel slag and designing volumetrically stable steel slag mixtures is required to promote its sustainable utilization. This paper focuses on the comparison of the swelling response of basic-oxygen-furnace steel slag (BOFS), electric-arc-furnace steel slag (EAFS), BOFS-fly ash and BOFS-glass powder mixtures based on the results of three different types of tests: (i) long-term California bearing ratio (CBR) swelling, (ii) heated water bath swelling and (iii) autoclave tests. BOFS mixtures were prepared using glass powder or class F fly ash with 5%, 10%, and 20% replacement ratios. The compaction characteristics, permeability, and California bearing ratio (CBR) of steel slag and steel slag mixtures were also assessed within the framework of a detailed discussion of their swelling response. At the end of swelling tests, the measured maximum 1D strains of EAFS were all at negligible levels. Based on the test results, BOFS and BOFS-glass powder mixtures had ∼5.0–5.5% swelling strains after 20.5 months without signs of stabilization. 20% class F fly ash replacement stabilized the swelling strains of the mixture at about 0.75% after ∼3 months of monitoring in long-term tests. 1D swelling rates measured for all BOFS-class F fly ash mixtures decreased with increasing fly ash content. CBR and swelling response of BOFS-class F fly ash mixtures were more favorable compared to those of BOFS. The heated water bath tests provided higher estimates of the swelling strains compared to those obtained from autoclave tests for the steel slag mixtures that contain 15% or more fines. The results of this study showed that glass powder replacement is not effective in alleviating the swelling of BOFS. The volumetrically stable BOFS-class F fly ash mixtures indicated favorable mechanical properties for their use in pavement layers. [Display omitted] • Glass powder replacement is not effective in alleviating the swelling of BOF slag. • 20% class F fly ash replacement can suppress the 1D strains of BOF slag. • Autoclave may provide relatively low estimates of strain for steel slag with 15% or more fines. • Separate handling of EAF and ladle steel slag in the plants can help their utilization. • BOF steel slag-class F fly ash mixtures show potential to be used in bound pavement layers. [ABSTRACT FROM AUTHOR]

Fly ash and bottom ash are coal combustion by-products (CCBPs) that are generated in large quantities throughout the world. It is often economical to dispose ash as mixtures rather than separately; that notwithstanding, only a few studies have been performed to investigate the behavior of fly and bottom ash mixtures, particularly those with high contents of fly ash. Also, there is very limited data available in the literature on the field performance of structures constructed using ash mixtures. This paper describes the construction and the instrumentation of a demonstration embankment built with an ash mixture (60:40 by weight of fly ash:bottom ash) on State Road 641, Terre Haute, Ind. Monitoring of the demonstration embankment was conducted for a period of 1 year from the start of construction of the embankment. The settlement of the embankment stabilized approximately 5 months after the end of its construction. According to horizontal inclinometer readings, the differential settlement at the top of the embankment is about 5 mm. Results from field quality control tests performed during construction of the demonstration embankment and monitoring data from vertical and horizontal inclinometers and settlement plates indicate that the ash mixture investigated can be considered an acceptable embankment construction material. [ABSTRACT FROM AUTHOR]