# Cleaner Design and Production of Lightweight Aggregates (LWAs) to Use in Agronomic Application
## 2 Materials and Methods  
### Raw Materials Characterization  
White (WC) and black (BC) clays were provided from a clay pit in Bailen, Jaea Province, Spain, and red clay (RC) came from a clay pit in Roncobotto, Modena province, Italy. The sludge from wastewater treatment plant (BS) was supplied by a brewery industry, Jaen province, Spain, and identified as non-hazardous waste (EWC 02-07-05). The cattle bone flour ash (CBA) and Glassy Sand (GS) were provided from local industries from Modena province, Italy. Calcined bone meal ash (CBA) was specially prepared for the experimental work by calcination of the flour (900 \({}^{\circ}\)C, 2h) and supplied by an Italian company that converts a wide range of meat industry by-products into protein floors for pet food. GS is a claimed glass derived from the secondary treatment, not classified as waste; it is a commercial product. Specific procedures are performed on the starting glass cullet to obtain shallow impurities (<0.068%), hence the fraction non-suitable for glassworks is submitted to a successive treatment to obtain two ends of waste: Glassy Sand (GS), with characteristics for glassworks, and ceramics sand, usually used in ceramic industry.  
Raw materials were tested to determine their physical and chemical characteristics, as follows: total content of C, H, N, and S was determined by combustion in O\({}_{2}\) atmosphere using the CHNS-O Thermo Finnigan Elementary Analyzer Flash EA 1112. The chemical composition was determined by X-ray fluorescence (XRF) using ARL-ADVANT 'XP+ (THERMO equipment), Uniquant software. SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\) percentages, and the flux elements (flux = K\({}_{2}\)O + Na\({}_{2}\)O + CaO + MgO + FeO + Fe\({}_{2}\)O\({}_{3}\)) were recalculated from the original chemical composition and the loss on ignition (LOI) results, and these oxides were plotted on the Riley Diagram [34] on the theoretical suitability for bloating. The SiO\({}_{2}\)/flux was also calculated for the same purpose, considering that a ratio \(>\)2 is typical for samples where suitable viscosity conditions are achieved [35; 36].  
X-ray diffractometry (XRD) was carried out using an automatic diffractometer PANalytical EMPYREAN, with radiation \(\alpha\)1,2 (1.5406 A) and slits (Soller) fixed at 1/4\({}^{\circ}\) and 0.04 rad. The measurements were performed from 5\({}^{\circ}\) to 80\({}^{\circ}\) 2 \(\theta\) for approximately 1 h with a step size of 0.0167\({}^{\circ}\). The tube operated at 45 kV and 40 mA. The identification of crystalline phases was made by High Score Plus PANalytical software comparing with data on the JCPDS files. The samples were dried for 24 h at 105 \({}^{\circ}\)C and then pulverized in an agate mortar until the consistency of talc (\(<\)38.00 \(\mu\)m) was achieved.  
A simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC-TG) was performed with a Mettler Toledo TGA/DSC 1 Thermal Analyzer equipment coupled with a Pfeiffer Vacuum ThermoStar TM GSD 320 mass spectrometer--approximately 10 mg of sample was tested in an Al\({}_{2}\)O\({}_{3}\) crucible, O\({}_{2}\) atmosphere (80 mL/min), and a heating rate of 10 \({}^{\circ}\)C/min up to 1000-1200 \({}^{\circ}\)C.