Ceramic waste powder an alternative cement replacement – Characterization and evaluation

In a rapidly growing world population and toward meeting consumers' needs, solid waste landfills will continue receiving extensive volumes of waste. Transforming large amount of solid wastes into an alternative resource will preserve the reducing nonrenewable resources of materials; maintain the required energy and in addition will help solve environmental and exhausted landfill problems. The utilization of solid waste materials in concrete, which is a predominant construction material, has attracted numerous studies especially those that can replace cement which is a major contributor to global green-house gas emissions. Ceramic tiles industry generates ceramic waste powder during the final polishing process. Ceramic waste powder (CWP) can cause soil, water and air pollution. Using ceramic waste powder (CWP) as an alternative ingredient in concrete will have a positive environmental impact. The aim of this study was to characterize the CWP with respect to its composition, morphology and activity. Also, the study evaluated the use of CWP as an alternative ingredient partially replacing cement on the performance of fresh and hardened concrete. In this investigation, concrete mixtures incorporating CWP as cement replacement with different replacement levels (i.e., 10%, 20%, 30% and 40% by mass) were examined. Three concrete grades with different cement contents were used (i.e., 25 MPa, 50 MPa and 75 MPa). The fresh concrete workability retention of the mixtures was evaluated by measuring time to reach zero slump. Compressive strength development with age (i.e., 7, 28 and 90 days) and drying shrinkage strain at 120 days were measured. The chloride ion penetration (i.e., rapid chloride ion penetration test - RCPT) and bulk electrical resistivity were conducted to evaluate durability performance of the mixtures. The permeable pores were measured to assess the development in the concrete microstructure. Test results showed that CWP has potential to be used as an ingredient in concrete mixtures to partially replace cement. The study showed that concrete mixtures with ceramic waste powder (CWP) had variable performance of the measured properties depending on the replacement level used. In general, CWP can be used in concrete mixtures to partially replace cement and improve specific performance criteria. A performance index (PI) approach was developed in order to be able to select the suitable CWP replacement level to optimize the mixture's specific properties to achieve a desired performance criteria. In this study, the PI considered workability retention, compressive strength and durability as performance measures for selecting the most suitable CWP replacement level. The PI could be extended to include additional criteria. The use of 10% CWP replacement level was adequate for strength improvement, replacement levels between 10% and 20% could be used to improve workability retention while a level of 40% replacement was needed for durability enhancement. For more than one performance criteria the CWP replacement level varied; a 10% to 20% CWP was suitable for optimizing the workability retention and strength of the mixture. However, the use of 30% to 40% CWP would optimize the combination of all studied criteria.