یک مطالعه تجربی جامع درباره بتن با استحکام بالا از ضایعات سرامیک بازیافتی (RWCA)
Abstract
1- Introduction
2- Experimental program
3- Experimental procedures
4- Results and discussion
5- Conclusions
References
Abstract
This study investigated the effects of combined utilization of wollastonite particles and recycled waste ceramic aggregate (RWCA) on high strength concrete (HSC) properties. Two groups of mixtures were manufactured: 1) concrete mixtures in which cement was partially replaced with wollastonite at values ranging from 10% to 50%, and 2) mixtures in which wollastonite was used at the aforementioned dosages and 50% of natural coarse aggregate was replaced with RWCA. In addition, 10% of cement weight micro-silica was added to all mixtures. The concrete behavior in terms of strength, durability, resistance against acidic environment, and performance under elevated temperatures ranging from 20 °C to 800 °C was assessed. Furthermore, the effect of wollastonite and RWCA inclusions on the microstructure of samples was studies using scanning electron microscopy (SEM). It was shown that wollastonite has an adverse impact on concrete workability and compressive strength. For example, 34% and 6% reduction in slump and 28-day compressive strength at wollastonite dosage of 50% was observed, respectively. On the other hand, the 28-day splitting tensile strength and flexural strength were respectively increased by 4.25% and 10% at 50% wollastonite content with respect to the control concrete. Furthermore, inclusions of RWCA improved the performance of concrete. For example, the 28-day compressive strength was increased by 24% in mixture with 50% wollastonite content with reference to the control concrete. In addition, the strength retention at 800 °C for mixture with RWCA was 16% higher than that of mixture without RWCA. Thus, it was concluded replacing coarse aggregate with RWCA improves the strength and durability properties of concrete and replacing 30% of cement with wollastonite particles strikes a balance between workability and strength of concrete.
Introduction
Concrete is one the most widely used structural material in construction industries due to the ease of access of its ingredients, high durability, and low maintenance cost. Large volumes of concrete are being manufactured all around the world, which has raised some concerns regarding depletion of natural raw aggregate [1] and greenhouse effects generated by ordinary Portland cement production [2–5]. In this regard, green concrete construction, which is concerned with effective management of different forms of industrial or agricultural wastes through introducing them into concrete has drawn the attention of many researchers. In this regard, a great part of the studies has been dedicated to the utilization of industrial by-products such as ground blast furnace slag [6–9], steel slag [10,11], cement kiln dust [12] and also agricultural by-products including rice husk ash [13], sugarcane bagasse ash [14,15], fly ash [16,17], palm oil fuel ash [18] as replacement of cement or aggregate to manufacture sustainable, green and eco-friendly concrete. Also, other types of materials such as pozzolanic materials [13] and fiber-type materials including metallic fibers [19], polymeric fibers (e.g. nylon and polypropylene) [20], glass fibers [21,22], and natural fibers [23] have been successfully incorporated in concrete production. With the growth in population and subsequent urban developments, ceramic waste is being disposed in large volumes, causing environmental issues in terms of landfilling and waste treatment. The large amount of this waste material has encouraged many researchers to incorporate it in concrete manufacturing [24,25]. Anderson et al. [26] studied the mechanical behavior of concrete containing 20%, 25%, 35%, 50%, 65%, 75%, 80% and 100% ceramic waste used as replacement of coarse aggregate. Rashid et al. [27] conducted an experimental and numerical study on the performance of concrete with ceramic waste aggregate. It was shown that replacing natural aggregate with 30% ceramic waste leads to the highest compressive strength and minimal environmental impact. Martins et al. [28] evaluated the residual strength of concrete containing 20, 50, and 100% recycled ceramic waste subjected to temperatures of 200, 400, and 600 C for 60 min. Significant reduction in strength and also spalling were observed at the highest temperature. In a similar study, Vieira et al.