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Lack of vibrations on fresh concrete negatively in uences the compaction and thus the quality of concrete. This is particularly concerning with geopolymer concrete (GPC) containing sodium silicate (Na 2 SiO 3 ), which is viscous in nature. In this study, self-compacting geopolymer concrete (SCGC) containing y ash (FA) and ultra ne slag (UFS) with copper slag aggregates (CSA) was proposed and investigated. CSA were used as a substitute to sand (by weight) in SCGC at different percentages up to 60%. In the fresh state, slump, T500 slump ow, V-funnel, L-box, U-box, and sieve aggregation ratio tests were performed to investigate owability, passing ability, and viscosity. At the hardened state, the compressive strength, water absorption, chloride ion resistance and sorptivity tests were examined. The owability of SCGC improved when CSA were added, and the highest slump of 735 mm was achieved for the mix with 60% CSA. Substitution of up to 20% of CSA enhanced the properties of SCGC at all ages. Mix having 20% CSA (20CSA-SCGC) was superior to other mixes, exhibiting the highest compressive strength (47 MPa) at 365 days while possessing the lowest water absorption, sorptivity, and the highest chloride ion resistance. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses also con rmed the improved microstructure of Mix 20CSA-SCGC. Meanwhile, X-ray diffraction (XRD) analysis con rmed the presence of quartz and calcium silicate hydrate (CSH) products, which were the main contributors to properties enhancement. HighlightsUtilization of copper slag aggregates as partial substitution to sand. SCGC with improved mechanical and durability properties.Microstructure of SCGC studied using SEM, XRD and EDS analyses.Correlations between different properties were established.

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 (Na 2 SiO 3 ) 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 [H 2 SO 4 ]), 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.

Despite their low impact on the environment and excellent mechanical strength, alkali‐activated concretes (AAC) can potentially replace ordinary Portland cement based concrete (OPC). However, AAC can be eco‐friendly and more sustainable by incorporating agricultural waste such as rice husk ash (RHA). Therefore, this study investigated the impact of RHA on the strength and durability performance of ground granulated blast furnace slag (GGBS) based AAC. For this purpose, seven mixes were made, in which RHA partially substituted GGBS with an increment of 5% up to 30%. The results of the experiments show that the workability and unit weight of AAC mixes decreased as the amount of RHA in the mix increased. The compressive strength of AAC mixes lies between 39.78 and 64.80 MPa, which is adequate for structural application. The AAC showed similar trends for all the mixes in terms of water absorption, permeable voids, apparent porosity and sorptivity. Compared to other mixes, the 5% GGBS substituted with RHA yields the highest resistance against carbonation. Compared to the sulfuric acid (H2SO4) cured sample, the specimen treated with hydrochloric acid (HCl) performed better in loss in mass, strength and ultrasonic pulse velocity. From scanning electron microscope test, the dense microstructure with pore refinement was observed in GGBS based AAC mix with 10% RHA content. According to the findings, RHA content up to 10% substitution can be used as a substitute for the binder to produce sustainable AAC with greater durability and could eventually replace conventional concrete in structural applications.

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