Browsing by Author "Rahbar, Nima"

Now showing 1 - 3 of 3

Effect of waste water bottle and treated sisal fibers on the durability and mechanical properties of concrete
(Nature Publishing Group UK, 2025-03-07) Fode, Tsion; Jande, Yusufu; Kivevele, Thomas; Rahbar, Nima
Globally, the disposal of waste plastic bottles is challenging. However, many researchers reported the importance of incorporating waste polyethylene-based waste water bottles (WWB) as a fiber and treated sisal fiber separately in the concrete mixture. However, it is novel to reinforce concrete by WWB fiber and treated sisal fiber together for more production of sustainable concrete. So the present study investigated the effect of using different doses of WWB fiber with and without treated sisal fiber on the physical and mechanical properties of concrete. Also, it is detail discussed its effect on concrete durability like in different elevated temperatures and acidic environments. As the result indicates, the reinforcement of concrete by WWB and treated sisal fibers lessens the fresh density and in 5% of HCl solution, it give higher strength and lower mass loss compared to the control concrete. Also, concrete WF25 increased compressive strength by 34.6%, 7.42%, and 3.6% respectively at 28, 56, and 180 days of concrete age, while concrete sample WF100 highly increased the splitting tensile strength of concrete by 26.67% compared to the control concrete mixture. Concrete having only WWB without treated sisal fiber reduced water absorption, increased mass loss, and lessened strength at 200, 300, and 400 °C elevated temperatures. So, this study is significant for implementing improved construction material performance by WWB and treated sisal fibers, as well as supporting the reduction of plastic bottles from the environment.
Effects of different lengths and doses of raw and treated sisal fibers in the cement composite material
(nature, 2025-01-10) Fode, Tsion; Chande Jande, Yusufu; Kim, Young-Deuk; Ham, Min-Gyu; Lee, Jieun; Kivevele, Thomas; Rahbar, Nima
Sisal fiber moisture sensitivity and degradation are treated by alkaline and pozzolanic methods, such as silica fume and kaolin surface coating. However, it is novel that the treatment of sisal fiber by calcined bentonite slurry can coat sisal fiber from moisture and protect it from cement hydration by consuming free lime and reducing cement matrix alkalinity. Therefore, the present study treated sisal fibers with calcined bentonite slurry and investigated the effect of using different lengths and doses of treated and raw sisal fibers in a mortar. The results indicate that the treatment of sisal fiber with bentonite slurry improved the roughness of the fiber, reduced fresh bulk density, improved resistance in acid, salt, and alkaline conditions, and increased compressive and flexural strength at 28 and 56 days compared to the control mixture and raw sisal fiber-employed mortar. Therefore, TS1L10 improved compressive strength by 30.62% and 1.8% at 28 and 56 days, respectively. Also, TS1L10 enhanced strength and residual strength in 5% HCl by 54.54% and 72.25%, respectively, compared to the control mixture at 56 days. Generally, the present study revealed the importance of calcined bentonite-treated sisal fibers in a mortar mixture for improved durability, physical and mechanical properties.
Modeling and optimization of calcined bentonite replacement in the mechanical and durability properties of mortar
(Elsevier, 2024-11) Fode, Tsion; Chande Jande, Yusufu; Kivevele, Thomas; Rahbar, Nima
Currently, pozzolanic materials are mostly recommended to improve the properties of cement composite materials and reduce environmental pollution, challenging the world owing to ordinary Portland cement (OPC) production. Bentonite is mostly available natural pozzolana, however, extensive studies conducted on other clays like kaolin and some studies reported that bentonite exists in a consolidated form which requires heating activation methods. Therefore, it is essential to investigate the properties of bentonite in detail for its sustainable use, and it is novel to model and optimize the optimum bentonite calcination temperature and time for the best performance replacement in mortar. Hence, the present study investigates the optimum bentonite calcination temperature, calcination time, and replacement dose for mortar strength and free lime using the central composite design-response surface method (CCD-RSM). The mortar was prepared by replacing the calcined bentonite with cement weight with different values of the factor variables, bentonite dose, calcination temperature, and calcination time. Durability tests were conducted after 56 days. Thus, the results indicate that the selected model of response variables for compressive strength and free lime were significant, accurate, reliable, and had excellent fitness to the experimental work. Hence, CCD-RSM predicted the optimum for independent factors of bentonite dose 19.99 %, calcination temperature 799.99 °C, and calcination time 135.04 min and experimentally validated, which improved the strength by 24.94% and reduced free lime by 3.08% compared to the control mortar, besides reducing CO2 emissions compared to OPC production, which requires 1450 °C. Furthermore, the optimized bentonite replacement parameters have highly enhanced durability in different environments such as water, acids, salt, and elevated temperature compared to the control mixture at the age of 56 days.