{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T13:53:00Z","timestamp":1787925180643,"version":"build-2784847793"},"reference-count":40,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2023,7,18]],"date-time":"2023-07-18T00:00:00Z","timestamp":1689638400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000038","name":"Natural Sciences and Engineering Research Council","doi-asserted-by":"publisher","award":["RGPIN-5613-2019"],"award-info":[{"award-number":["RGPIN-5613-2019"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Alkali-activated engineered composites (AAECs) are cement-free composites developed using alkali activation technology, which exhibit strain hardening and multiple micro-cracking like conventional engineered cementitious composites (ECCs). Such AAECs are developed in this study by incorporating 2% v\/v polyvinyl alcohol (PVA) fibers into alkali-activated mortars (AAMs) produced using binary\/ternary combinations of fly ash class C (FA-C), fly ash class F (FA-F), and ground-granulated blast furnace slag (GGBFS) with powder-form alkaline reagents and silica sand through a one-part mixing method under ambient curing conditions. The mechanical and microstructural characteristics of eight AAECs are investigated to characterize their strain-hardening performance based on existing (stress and energy indices) and newly developed tensile\/flexural ductility indices. The binary (FA-C + GGBFS) AAECs obtained higher compressive strengths (between 48 MPa and 52 MPa) and ultrasonic pulse velocities (between 3358 m\/s and 3947 m\/s) than their ternary (FA-C + FA-F + GGBFS) counterparts. The ternary AAECs obtained a higher fracture energy than their binary counterparts. The AAECs incorporating reagent 2 (Ca(OH)2: Na2SO4 = 2.5:1) obtained a greater fracture energy and compressive strengths than their counterparts with reagent 1 (Ca(OH)2: Na2SiO3.5H2O = 1:2.5), due to additional C-S-H gel formation, which increased their energy absorption for crack propagation through superior multiple-cracking behavior. A lower fracture and crack-tip toughness facilitated the development of enhanced flexural strength characteristics with higher flexural strengths (ranging from 5.3 MPa to 11.3 MPa) and a higher energy ductility of the binary AAMs compared to their ternary counterparts. The tensile stress relaxation process was relatively gradual in the binary AAECs, owing to the formation of a more uniform combination of reaction products (C-S-H\/C-A-S-H) rather than a blend of amorphous (N-C-A-S-H\/N-A-S-H) and crystalline (C-A-S-H\/C-S-H) binding phases in the case of the ternary AAECs. All the AAECs demonstrated tensile strain-hardening characteristics at 28 days, with significant improvements from 28% to 100% in the maximum bridging stresses for mixes incorporating 40% to 45% GGBFS at 365 days. This study confirmed the viability of producing green cement-free strain-hardening alkali-activated composites with powder-form reagents, with satisfactory mechanical characteristics under ambient conditions.<\/jats:p>","DOI":"10.3390\/ma16145077","type":"journal-article","created":{"date-parts":[[2023,7,19]],"date-time":"2023-07-19T01:02:23Z","timestamp":1689728543000},"page":"5077","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["The Strength and Fracture Characteristics of One-Part Strain-Hardening Green Alkali-Activated Engineered Composites"],"prefix":"10.3390","volume":"16","author":[{"given":"Khandaker M. Anwar","family":"Hossain","sequence":"first","affiliation":[{"name":"Department of Civil Engineering, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dhruv","family":"Sood","sequence":"additional","affiliation":[{"name":"Department of Civil Engineering, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,7,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2917","DOI":"10.1007\/s10853-006-0637-z","article-title":"Geopolymer technology: The current state of the art","volume":"42","author":"Duxson","year":"2006","journal-title":"J. Mater. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Saeed, A., Najm, H.M., Hassan, A., Sabri, M.M.S., Qaidi, S., Mashaan, N.S., and Ansari, K. (2022). 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