## 3 Research Methodology
### Laboratory Testing Procedure and Case Studies  
#### 3.2.1 Experimental Methodology  
Concrete testing followed the methods outlined in AS/NZS 1012.8.2 [52], with both compressive and tensile tests conducted on cylindrical specimens measuring 100 mm diameter and 200 mm height. The compressive load rate was set to 20 MPa/min, in accordance with AS 1012.9 [53]. Indirect tensile testing was performed at a load rate of 1.5 MPa/min, as specified by AS 1012.10 [54]. Testing was conducted at 28 days, with three samples measured. Average values and standard deviation measurements were recorded. Figure 2: System boundaries considered for the current study assessment models. Mechanical tests were conducted using the Matest C088-11 N Servo-Plus Evolution testing machine, along with the Cyber-Plus Evolution data acquisition system. Textile materials were sourced from pre-used high-visibility construction vests, from which polyester fibres were extracted. These vests were shredded and converted into a fibrous material for further laboratory analysis. The primary materials used to reduce the ordinary Portland cement (OPC) content in the mix designs include waste corrugated cardboard and metakaolin (MK). Waste cardboard was processed into a fibrous material through the addition of silica fume (SF), which served as a fibre modification technique. The process begins by immersing the waste cardboard in water and using rotating mixing methods to reduce it into a pulp. SF slurry is then applied to the cardboard fibres, resulting in silica fume kraft fibres (SFKFs). These SFKFs undergo a moisture removal process and are mixed further in a rotating mixer to form a fibrous material. The SF applied to the cardboard fibres (KFs) meets the Australian Standard AS/NZS 3582.3 [55] for silica fume in cementitious materials. MK, used as a partial cement substitute, adheres to the ASTM C-618 [56] Class N specification for natural and calcined pozzolans. OPC, conforming to AS/NZS 3972 [57], serves as the primary component for pozzolanic reactivity in the mix. Locally sourced aggregates (20 mm coarse and 0.6 mm fine) from Melbourne, Australia, were used in accordance with AS/NZS 1141.6.2 [58] and AS/NZS 1141.5 [59], respectively. Regular potable water was used for preparing the specimen designs. Sample preparation followed the guidelines of AS/NZS 1012.2 [60], using a mortar mixer. The materials were dry mixed for five minutes, after which water was added, and mixing continued for another five minutes. Once the mix was ready, the concrete materials were placed into moulds in three layers. Each layer was compressed twenty times with a steel rod before the next layer was added. The moulds were kept at a room temperature of approximately 20 \({}^{\circ}\)C for 24 h before being transferred to curing baths. Slump tests were performed according to the procedures outlined in AS/NZS 1012.3.1 [61]. The mechanical and microstructure investigations for the mix designs including the % waste material addition as virgin material replacement was determined based on rigorous experimental investigations and these findings were published previously [2; 7; 8]. The experimental program included testing of at least 10 cylindrical specimens for each test. The target compressive strength for all concrete specimens was 40 MPa. The experimental mechanical analysis included five different mix designs. The first design served as the control, with no fibre integration. The second design incorporated 2.5% textile (T2.5) materials for reinforcement. The third design used 5% SFKFs (SFKF5), replacing 5% of the cement. The fourth mix design (MKT) combined 5% MK and 5% SFKFs, partially replacing cement with 2.5% textile reinforcement. The fifth design (KFT) combined 2.5% textiles for reinforcement with 5% SFKFs to partially replace cement. Detailed formulations of the mix designs can be found in Table 1. The optimum mix designs are obtained from several simulations and trail experimentation. The density of the fibre materials was adjusted based on their intended purpose.