## 2 Materials and Methods
### Method
The specimen was dried for at least 60 min in an electrothermal drying oven maintained at 100-110 \({}^{\circ}\)C. The specimen was subsequently pre-sintered at 950 \({}^{\circ}\)C for 30 min in a high-temperature chamber electric furnace (XD-1700M, Tianzong Electrical equipment Co., Ltd. Zhengzhou, China) with a heating rate of 10 \({}^{\circ}\)C/min, followed by calcination at target temperatures of 1350 \({}^{\circ}\)C, 1400 \({}^{\circ}\)C, and 1450 \({}^{\circ}\)C, each for 30 min. After calcination, the specimen was rapidly removed and cooled to room temperature (25 \({}^{\circ}\)C) using a fan, in preparation for subsequent experiments. Clinker was calcined using the raw material proportions specified in Table 4  
\[\text{G}_{\text{a}}=\frac{\text{q}\times\text{w}(\text{A}_{\text{ad}})\times \text{S}}{100\times\text{Q}_{\text{net}}} \tag{1}\]  
\(\text{G}_{\text{a}}\)--mixing amount of fuel ash in clinker, %;  
\(\text{Q}_{\text{net}}\)--calorific value of fuel, kJ/kg;  
\(\text{w}(\text{A}_{\text{ad}})\)--air dry basis ash content of fuel, %;  
q--heat consumption per unit clinker, kJ/kg;  
S--fuel ash deposition rate, %, choose100%. \(\text{K}_{2}\text{CO}_{3}\) and \(\text{Na}_{2}\text{CO}_{3}\) were ground using an agate mortar and subsequently sieved through 80 um and 200 um square hole sieves for further processing. The particle size distribution is presented in Figure 3.  
Figure 2: Particle size distribution of raw materials. The free calcium oxide content in two parallel groups of clinker samples at 1350 \({}^{\circ}\)C, 1400 \({}^{\circ}\)C, and 1450 \({}^{\circ}\)C was analyzed using the glycerol-ethanol method as specified in Chinese National Standard GB/T 176-2017 [43], and the optimum clinker calcination temperature was identified. The Cl\({}^{-}\) content in the clinker at the determined calcination temperature was evaluated, and the corresponding cement was synthesized for subsequent experiments [44]. Cement of grade 52.5 was prepared using 95 wt% clinker and 5 wt% dihydrate gypsum as raw materials, following the specifications outlined in the Chinese National Standard GB/T 175-2023 [45]. Cement mortar was prepared with a water-to-cement ratio of 0.5 and a cement-to-sand ratio of 1:3. 225 \(\pm\) 1 g of water and 450 \(\pm\) 2 g of cement were added in sequence and mixed for 30 s. Subsequently, the mechanical strength was measured using a strength tester (CDT1305-2, Mesiste Industrial Co., Ltd. Shenzhen, China) with loading rates set at 50 \(\pm\) 10 N/s and 2400 \(\pm\) 200 N/s. The strength values for each sample were determined based on the average of three sets of cement mortar measurements. Additionally, cement paste samples with a curing age of 28 days were crushed and immersed in anhydrous ethanol for 72 h to terminate hydration [46; 47], then dried in a vacuum drying oven at 50 \({}^{\circ}\)C in preparation for subsequent XRD and TG analyses [48; 49]. The crystalline phases of the clinker and hydration products were analyzed using XRD, operated at 30 kV and 60 mA, with a scanning speed of 10\({}^{\circ}\)/min and a step size of 0.02\({}^{\circ}\). TG under N\({}_{2}\) atmosphere was performed on the hydration products from 30 \({}^{\circ}\)C to 950 \({}^{\circ}\)C at a constant heating rate of 10 \({}^{\circ}\)C/min. For microstructural observation, a representative sample was coated with a thin layer of gold and examined using a scanning