Concrete made with steel slag and waste glass and its application in concrete-filled steel tubular columns

Abstract

In recent years, there has been a growing emphasis on the utilisation of waste materials and by-products in construction materials, which is a partial solution to environmental and ecological problems. The utilisation not only helps in reducing the cost of cement and concrete manufacturing, but also has numerous indirect benefits such as reducing landfill cost, saving energy, and protecting the environment from possible pollution. This thesis presents a study on the behaviour of concrete made with steel slag and waste glass at both ambient and elevated temperatures and its application in concrete-filled steel tubular (CFST) columns. A literature review highlights that no research has been devoted to investigate the combined use of steel slag and waste glass in concrete. Previous studies only focused on the post-fire properties of concrete with steel slag or waste glass, indicating further research is needed on the "hot" behaviour of concrete made with steel slag and waste glass. Also, only a few experimental studies have been conducted to investigate the feasibility of using steel slag or waste glass in reinforced concrete members. No similar research using steel slag or waste glass in CFSTs has been reported in open literature. Thus, this research aims to address the above research gaps. In this thesis, material properties such as slump, density, modulus of elasticity, compressive strength and flexural strength of concrete made with steel slag and waste glass are compared with those of reference limestone concrete and lightweight concrete. The effects of steel slag and waste glass on the full-range stress-strain curve of concrete are evaluated. Several existing models were used to predict the stress-strain curves of concrete made with steel slag and waste glass. Suitable modifications were made to two of the models to improve the prediction accuracy. Furthermore, tests were conducted on CFST stub columns, demonstrating the feasibility of using steel slag and/or waste glass to replace partial or all concrete aggregates for CFST columns. The test results were compared with predictions of Eurocode 4 and finite element analysis and the agreement between them is reasonable. The hot compressive strength and thermal properties of concrete made with steel slag and waste glass were measured and compared with those of limestone concrete and lightweight concrete. A series of fire resistance tests was also carried out on plain concrete columns made with steel slag and/or waste glass aggregates. Additionally, the effects of aggregate type (limestone, lightweight, steel slag and waste glass aggregates), together with other parameters including the section type and load eccentricity, were studied by fire tests on CFST columns. Results indicate that steel slag and waste glass have the potential to improve the fire resistance of concrete and CFST columns. The study in this thesis confirms the benefits of the combined use of steel slag and waste glass in concrete. Due to the confinement from the steel tube, the possible volumetric instability of concrete can be eliminated and steel slag and waste glass can be safely used as concrete aggregate in CFST columns. In addition, steel slag and waste glass may be used to improve the thermal insulation or fire performance of concrete.

Date of Award	2017
Original language	English