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Modification of recycled cement with phosphogypsum and ground granulated blast furnace slag.
- Source :
-
Construction & Building Materials . May2024, Vol. 426, pN.PAG-N.PAG. 1p. - Publication Year :
- 2024
-
Abstract
- Unmodified thermal-activated recycled cement (RC) paste has unfavorable properties like fast setting. This paper intends to modify RC by adding phosphogypsum (PG) and ground-granulated-blast-furnace-slag (GGBS). A comprehensive experimental program combining isothermal calorimetry, mechanical tests, TG, XRD, MIP, 29Si NMR and SEM of modified RC (PG-GGBS-modified-recycled-cement) pastes was conducted. The results show that GGBS and PG not only effectively modified the setting time but also contributed to a more compact skeleton. The final setting time was extended from 12 mins to 84 mins. The 28d and 90d compressive strength reached 29.8 and 36.9 MPa, increaseing by 21.1 % and 39.9 %, respectively. It is shown that PG acted as a sulfate excitation to the active Al 2 O 3 in the GGBS and RC to generate AFt. Rehydrated C-S-H gel could both wrap and protect the CaSO 4 ·2 H 2 O crystals and crystalline contact points, and effectively filled the pores of the hardened paste, thus promoting the generation of C(-A)-S-H and Ca 5 (SiO 4) 2 (OH) 2. The rehydration of modified RC was associated with a remarkable amount of AFt and AFm intergrowing with the reformed C-S-H gel and generating a compact network skeleton. • Modification of recycled cement with phosphogypsum and GGBS was investigated. • GGBS and PG not only effectively modified the setting time but also contributed to a more compact skeleton. • Rehydrated C-S-H gel could effectively fill the pores, thus promoting the generation of C(-A)-S-H and Ca 5 (SiO 4) 2 (OH) 2. • The final setting time of recycled cement was extended from 12 mins to 84 mins. • The 28d and 90d compressive strength reached 29.8 and 36.9 MPa, increased by 21.1 % and 39.9 %. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09500618
- Volume :
- 426
- Database :
- Academic Search Index
- Journal :
- Construction & Building Materials
- Publication Type :
- Academic Journal
- Accession number :
- 176686230
- Full Text :
- https://doi.org/10.1016/j.conbuildmat.2024.136241