Enhancing the Performance of Recycled Aggregate Concrete Using Micro-Carbon Fiber and Secondary Binding Material

Abstract

In this study, the effect of micro-carbon fiber on the properties of concrete incorporating recycled coarse aggregate at three different levels, i.e., 0%, 50%, and 100% by volume replacement of natural coarse aggregate, was studied. Carbon fiber was incorporated at a dosage of 0.5% by volume fraction. The effect of silica fume or micro-silica on the efficacy of fiber reinforcement was also investigated. Studied parameters include important mechanical properties, such as compressive strength, splitting tensile strength, and flexural strength, and physical/quality parameters such as water absorption capacity and ultrasonic pulse velocity. The results showed that the mechanical and durability performance deteriorates with the increasing percentage of recycled coarse aggregate. Carbon fiber can significantly improve the tensile properties of recycled aggregate concrete. The combination of carbon fiber and silica fume proved to be highly useful in addressing both mechanical and durability concerns simultaneously. Concrete made with 50% recycled coarse aggregate, 8% silica fume, and 0.5% carbon fiber yielded 20% greater tensile and flexural strength compared to the control mix. Likewise, concrete containing 100% recycled coarse aggregate with silica fume and carbon fiber yielded higher tensile strength compared to the control mix. Silica fume ameliorated the bonding between fibers and matrix and improved the overall efficacy of fiber reinforcement.

Enhanced Compatibility of Secondary Waste Carbon Fibers through Surface Activation via Nanoceramic Coating in Fiber-Reinforced Cement Mortars

“…Percentages of increase in flexural strength of FRCCs with vCFs and rCFs reported in 6 articles (Refs. [16][17][18][42][43][44]) and comparison with the results achieved in the present work using sCFs.…”

“…Fractography observations (Figure 15) confirmed the near total disappearance of fibrous agglomerates and a significant reduction in porosity in the sCF-ANC samples compared to the counterparts incorporating unconditioned fibers. Another valuable result found in the present work is that the strength improvement achieved by using this type of waste fibrous filler after nanoceramic conditioning is superior to the mechanical properties achieved by other researchers [16][17][18][42][43][44] who have employed vCFs or rCFs as concrete reinforcements (Figure 16). Notably, only the configurations with the best strength performances were considered in this survey, i.e., the carbon fiber contents that promoted the greatest increases in relation to the plain reference Another valuable result found in the present work is that the strength improvement achieved by using this type of waste fibrous filler after nanoceramic conditioning is superior to the mechanical properties achieved by other researchers [16][17][18][42][43][44] who have employed vCFs or rCFs as concrete reinforcements (Figure 16).…”

“…Another valuable result found in the present work is that the strength improvement achieved by using this type of waste fibrous filler after nanoceramic conditioning is superior to the mechanical properties achieved by other researchers [16][17][18][42][43][44] who have employed vCFs or rCFs as concrete reinforcements (Figure 16). Notably, only the configurations with the best strength performances were considered in this survey, i.e., the carbon fiber contents that promoted the greatest increases in relation to the plain reference Another valuable result found in the present work is that the strength improvement achieved by using this type of waste fibrous filler after nanoceramic conditioning is superior to the mechanical properties achieved by other researchers [16][17][18][42][43][44] who have employed vCFs or rCFs as concrete reinforcements (Figure 16). Notably, only the configurations with the best strength performances were considered in this survey, i.e., the carbon fiber contents that promoted the greatest increases in relation to the plain reference matrix.…”

Predicting the Compressive Strength of Concrete Containing Crumb Rubber and Recycled Aggregate Using Response Surface Methodology

“…The strength of recycled aggregates (RCA) is less than that of natural aggregate because it has hardened cement paste on its surface, a higher porosity, and a water absorption of three to five times that of natural aggregate [14,15]. Adding RCA to concrete reduces its mechanical properties and shortens its lifespan [16][17][18][19][20]. One possible alternative to the traditional method of disposing of scrap rubber and the massive volumes of demolition waste is to recycle crumb rubber and RCA in concrete production as partial substitutes for fine and coarse aggregates, respectively.…”

Property Improvement of Recycled Coarse Aggregate by Accelerated Carbonation Treatment under Different Curing Conditions

“…For the disposal of waste concrete, China still mainly utilizes the pile and bury methods, which seriously affects the surrounding ecological environment and results in a waste of social resources. China is aiming for carbon peaking by 2030 and carbon neutrality by 2060, and thus, reducing carbon dioxide emissions and capturing and using carbon dioxide has become a popular research focus [5][6][7][8][9]. Promoting the use of waste concrete to produce RA and recycled aggregate concrete (RAC) can effectively aid in waste resource conservation and intensification and promote sustainable development [10][11][12][13].…”