## 2 Materials and Methods
### Experimental Programme
#### 2.2.2 Test Procedures  
(1) Compressive strength: The compressive strength of AASR samples were determined at the age of 3, 7, 14 and 28 days according to the Chinese National Standard GB/T17671-1999 [16]. All of the results of compressive strength reported the average value of three samples. (2) Porosity: The connected porosity was assessed by measuring accessible porosity according to ASTMC642 [17]. The paste specimens of the specified age were immersed in a water tank at 20 \({}^{\circ}\)C for 72 h. The moisture was then removed from the surface with a towel, and the mass of the surface-dried specimen was determined (\(m_{\text{imm}}\), g); The samples were then suspended by a wire to determine their apparent mass in water (\(m_{\text{suss}}\), g), and after this, the samples were dried in an oven at a temperature of 40 (\(\pm\)5) \({}^{\circ}\)C to a constant weight, and the mass was recorded as \(m_{\text{40}^{\circ}\text{C-dry}}\) (g). The connected porosity was calculated according to the following equation:  
\[\phi_{\text{C}}=\frac{\left(m_{\text{imm}}-m_{\text{40}^{\circ}\text{C-dry}} \right)}{\rho_{\text{w}}V}\]  
where \(\phi_{\text{C}}\) is the sample connected porosity (%); \(m_{\text{imm}}\) is the mass of saturated sample (g); \(m_{\text{40}^{\circ}\text{C-dry}}\) is the constant mass of sample dried at 40 \({}^{\circ}\)C (g); \(\rho_{\text{w}}\) is the density of water (g/cm\({}^{3}\)); and \(V\) is the bulk volume of cement paste (cm\({}^{3}\)). Micro-porosity: In addition to the connected porosity, the AASR specimens also contain micro-pores (most of which are gel pores), which reflect the changes in the microstructure properties of specimens. In this study, referring to the existing studies [18; 19; 20], the mass loss of the samples dried between 40 \({}^{\circ}\)C and 105 \({}^{\circ}\)C are used to determine the micro-porosity via the following equation:  
\[\phi_{M}=\frac{\left(m_{\text{40}^{\circ}\text{C-dry}}-m_{\text{10}^{\circ} \text{C-dry}}\right)}{\rho_{\text{w}}V}\]  
where \(\phi_{M}\) is the paste micro-porosity (%); \(m_{\text{40}^{\circ}\text{C-dry}}\) is the constant mass of samples dried at 40 \({}^{\circ}\)C (g); \(m_{\text{10}^{\circ}\text{C-dry}}\) is the constant mass of samples dried at 105 \({}^{\circ}\)C (g); \(\rho_{\text{w}}\) is the density of water (g/cm\({}^{3}\)); and \(V\) is the bulk volume of cement paste (cm\({}^{3}\)). (3) Isothermal calorimetry: The hydration process of all the pastes was monitored by hydration heat analysis with an isothermal calorimeter (TAM Air Thermometric, I-CAL4000/8000 Made by Calmetrix Corporation, Boston, MA, USA set at 25 \({}^{\circ}\)C). In order to \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Binder** & **GGBFS/g** & **RM/g** & **WG/g** & **NaOH/g** & **Water/g** \\ \hline AAS-Control & 500 & / & 157.15 & 15.39 & 136.16 \\ AAS-30\%RM & 350 & 150 & 157.15 & 15.39 & 136.16 \\ AAS-50\%RM & 250 & 250 & 157.15 & 15.39 & 136.16 \\ AAS-70\%RM & 150 & 350 & 157.15 & 15.39 & 136.16 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: AASR pastes mixture proportions (per group). ensure a precise binder content and a temperature close to the measurement temperature when the sample was charged, all raw materials were stored in the calorimeter at 25 \({}^{\circ}\)C for 24 h prior to mixing, and 30.00 g paste was prepared directly in the calorimeter sample cup. Manual mixing with a disposable spoon was applied for the desirable homogeneity, and the hand mixing lasted for 90 s. In order to minimize any loss of binder, the spoon was left in the sample cup after mixing. Measurements were taken every minute for 168 h.  
(4) XRD analyses: The 28-day paste samples were crushed and ground into powders followed by drying in a vacuum oven at 40 \({}^{\circ}\)C, and then the powders are sieved through a 200-mesh sieve. After this, the powders were sandwiched flat between low absorbing films of a PANalytical's XPert Pro X-ray diffractometer with a configuration of convergent beam with a focalizing mirror.