**1. Introduction**

Since the dawn of time, the industry has been considered one of the most important pillars that depend on the consumption of materials, the production of all that humanity needs for the well-being of life, and also is assumed as one of the most crucial reasons for the existence of waste materials.

From the financial and ecological points of view, the recycling of manufacturing wastes is well thought-out to be a significant issue. The increase of industrial waste materials, due to the rapid increase in populations and growth in the prosperity of humanity, has become a major social and environmental problem. Management of all industrial waste has become the most significant environmental issue in numerous expanding countries. Primary sources of solid waste are human liveliness, such as building and technology innovation. These wastes cause many complex problems concerning storage space, transportation, and

**Citation:** Khater, G.A.; El-Kheshen, A.A.; Farag, M.M. Synthesise and Characterization of Cordierite and Wollastonite Glass—Ceramics Derived from Industrial Wastes and Natural Raw Materials. *Materials* **2022**, *15*, 3534. https://doi.org/ 10.3390/ma15103534

Received: 23 March 2022 Accepted: 12 May 2022 Published: 14 May 2022

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environmental or atmosphere contamination. Utilizing manufacturing waste to produce beneficial resources via green chemical methods will be an essential step to having a hygienic and safe environment [1,2].

Cement is one of the most remarkable binding materials. It is manufactured in massive amounts all over the world. The cement industry is considered one industry that generates an enormous amount of solid waste. These wastes should be managed to guarantee a clean and harmless environment [3].

In Egypt, several cement factories create significant amounts of cement kiln dust (CKD), the by-product formed in cement kilns and associated procedures. It has a destructive outcome on all living organisms [4]. The chemical composition of CKD mainly depends on the composition of raw materials, speed of the gas in the kiln, and type of procedure. Usually, CKD contains calcined materials, un-reacted raw feed, clinker dust, ash, alkali sulfates, halides, and other volatile materials [5–8].

Efforts have been made by several researchers to recycle that harmful CKD waste through different valuable applications such as removal of heavy metals [9], treating contaminated soil [10], ceramic production [11], glass–ceramic fabrication [12–14], and so on.

The chemical composition of by-pass cement dust qualifies it for the glass–ceramic and glass industries [15]. As the glass–ceramics industry has various applications, such as in the microelectronics industry and construction. Utilizing cement dust to produce glass–ceramic materials is highly considered a technological, scientific, and cost-effective concept.

Glass–ceramic is one of the majority multipurpose and valuable materials needed in diverse industrial applications. Glass-ceramic has varieties of properties according to its composition, such as hardness, insulation, thermal shock resistance, low thermal expansion coefficient, toughness, and optical properties [16]. It is usually prepared by scheming glass crystallization. It also has fine-grained microstructure, low or no porosity, and lots of different properties that may be synchronized by changes in sample composition and the regime of heat treatment.

Wollastonite (CaSiO3) has been conventionally applied as a raw material for tiles, paint, paper industries [17], insulators [18], ceramics [19], and so on. It has good mechanical, thermal, and optical properties such as slight shrinkage, high strength, whiteness in color, and bending properties. Nowadays, the increasing demands for wollastonite are followed by the proportional increases in its fabrication worldwide [20]. Natural wollastonite is limited by its deposits condition so that it can be synthesized artificially [17]. Synthesized wollastonite glass–ceramics [21] are used for various purposes and must be studied.

Cordierite (2MgO–2Al2O3–5SiO2) is one of the most motivating phases of glass– ceramics; and has a broad collection of applications in many industrial areas [22]. It possesses features such as low thermal expansion, high chemical durability, high thermal resistance, low dielectric constant, and good mechanical properties, which give scientists the facility to use this compound to produce traditional or advanced products [23,24]. Cordierites have lower production costs and superior electrical properties, they can be used as substrate more than alumina in electronic industries and manufacturing multilayer circuit boards and thermal insulators.

This research aims to take advantage of cement dust as one of the industrial wastes produced in huge quantities from cement factories with some raw materials available in the earth's crust to produce high-performance glass–ceramic materials that can be used for construction applications. The purpose of the research is to take advantage of by-pass cement dust, one of the solid industrial wastes which harm the environment, in obtaining high-performance glass–ceramic materials based on the wollastonite–cordierite system that can be used for various industrial and construction purposes by using many techniques such as differential thermal analysis (DTA), X-ray diffraction (XRD), scan electron microscope (SEM: JEOL, XL30, Philips, Amsterdam, The Netherlands)), and thermal expansion coefficient (CTE).

#### **2. Experimental Techniques**
