Effects of crumb rubber inclusion on strength, permeability, and acid attack resistance of alkali-activated concrete incorporating different industrial wastes

This study examines the suitability of alternate binders and crumb rubber (CR) to produce light weight alkali-activated concrete (AAC). For this, strength, and durability performance of AAC incorporating CR by partially replacing fine aggregate was studied. To produce AAC, four different binders, including fly ash, rice husk ash (RHA), metakaolin, and bottom ash were used. Fine aggregates were substituted with CR at 0%, 10%, 20%, and 30% for each AAC mix (with different binders). Furthermore, the mixes were prepared using 12 M sodium hydroxide (NaOH) solution, and the ratio of sodium silicate (Na2SiO3) to NaOH was taken as 2.5. The samples were cured at ambient temperature. Strength and durability properties, including permeability through water absorption and acid attack (hydrochloric acid [HCl] and sulfuric acid [H2SO4]), were also checked. Results of this study revealed that the strength decreased with the increase in CR content. Further, this decrease was high at 30% replacement but strength was satisfactory. AAC showed good relationships among compressive, flexural, and split tensile strengths. Similar footprints were observed for permeability results. However, highest water absorption was observed for bottom ash binder (with 30% substitution of CR). Mixes with fly ash and metakaolin binders outperformed the other mixes while comparing the compressive strength of acid exposed samples. Overall, a sustainable and durable light weight AAC can be prepared using 20% CR.