## 2 Experimental Program, Materials, Mix Designs, Mix Preparation, and Test Methods
### Test Methods  
The physical workability properties in terms of the slump flow, flow time (T50), and fresh density of AAECs with MgO and MWCNTs/rGO and MgO-MWCNTs/rGO were evaluated immediately after mixing. The slump flow and fresh density of AAECs were measured as per the ASTM C1611 [71] and ASTM C138 [72] standards, respectively. The hardened density of the AAECs was evaluated following the conventional weight and volume measurement methods. The slump flow spread characteristics of the mixes, of which a typical one is presented in Figure 4a, were assessed through a slump cone test in compliance with ASTM C1437 [73]. Additionally, the slump flow time (T50) to reach 500 mm slump flow was recorded to calculate the slump flow velocity. A compressive strength test using cube specimens (Figure 4b) at 7, 14, 28, 56, and 180 days was conducted according to ASTM C109/C109M [74] by applying a loading rate of 1 kN/s. An ultrasonic pulse velocity (UPV) test was conducted on the same cube specimens using a Portable Ultrasonic Non-Destructive Digital Indicating Tester as per ASTM C597 [75]. At least three specimens were tested at each age for the compressive and UPV tests.  
SEM and EDS analyses were performed on the AAECs to determine the reaction products by taking chip specimens (approximately 10 mm \(\times\) 5 mm \(\times\) 5 mm) from the core of the failed compression test cubes at 180 days followed by coating them gold to make the surface conductive. The fracture surface was studied using secondary electrons (SEs)  
Figure 4: (**a**) Slump flow test, (**b**) compressive strength test.  
Figure 3: MWCNT at three stages: (**a**) before sonication (dry), (**b**) during sonication, and (**c**) after sonication.  
and backscattered electron (BSE) microscopy at 20 kV. The specimens' morphologies were studied at 100\(\times\) (100 \(\upmu\)m), and the assessment of the reaction products was performed at 2000\(\times\) (10 \(\upmu\)m).  
The specimen preparation for the XRD analysis consisted of grinding the specimen taken from the core of the 180-day failed compression cubes. The ground specimen was passed through a 200-mesh sieve. A Bruker D8 Endeavor diffractometer equipped with a Cu X-ray source and operating at 40 kV and 40 mA; a range of 5-70 deg \(\theta\); a step size of 0.02 deg 2\({}^{\circ}\); a time per step of 0.5 s; a fixed divergence slit, an angle of 0.30; a sample rotation of one rev/s was used to identify the mineral phases using the PDF4/Minerals ICDD database.  
Like the XRD analysis, the powder from the AAEC specimens was subjected to Fourier transform infrared spectroscopy (FTIR) analysis. The FTIR spectra were recorded with the Perkin Elmer Spectrum 400 spectrometer in mid-IR mode. Before beginning the analysis, rubbing alcohol was used to clean the sample platform. Approximately 5 mg of the powder specimen was decanted onto the platform for further analysis. The spectrum was obtained over a range from 4000 to 400 cm\({}^{-1}\). FTIR measurements were performed on a Fourier transform infrared spectrophotometer (Jasco 4200 Type A, Jasco, Easton, MD, USA). The FTIR spectra were obtained within a wavenumber range from 400 to 4000 cm\({}^{-1}\) at a resolution of 4 cm\({}^{-1}\). The KBr pellet was used to carry out the FTIR measurements and the pellets were prepared by pressing a mixture of the sample in a die set. In FTIR analysis, the sample was irradiated with infrared light over a range of frequencies. The interaction between the infrared light and the material caused the absorption or transmission of specific wavelengths, which was detected and analyzed to identify the functional groups and chemical bonds within the material.