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A platform for research: civil engineering, architecture and urbanism
Modification of recycled cement with phosphogypsum and ground granulated blast furnace slag
https://orcid.org/0000-0001-9674-9689
https://orcid.org/0000-0002-1148-777X
https://orcid.org/0000-0002-8133-3055
https://orcid.org/0009-0000-5058-9931
https://orcid.org/0000-0001-9625-4520
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 Al2O3 in the GGBS and RC to generate AFt. Rehydrated C-S-H gel could both wrap and protect the CaSO4·2 H2O crystals and crystalline contact points, and effectively filled the pores of the hardened paste, thus promoting the generation of C(-A)-S-H and Ca5(SiO4)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.
Highlights 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 Ca5(SiO4)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 %.
Modification of recycled cement with phosphogypsum and ground granulated blast furnace slag
https://orcid.org/0000-0001-9674-9689
https://orcid.org/0000-0002-1148-777X
https://orcid.org/0000-0002-8133-3055
https://orcid.org/0009-0000-5058-9931
https://orcid.org/0000-0001-9625-4520
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 Al2O3 in the GGBS and RC to generate AFt. Rehydrated C-S-H gel could both wrap and protect the CaSO4·2 H2O crystals and crystalline contact points, and effectively filled the pores of the hardened paste, thus promoting the generation of C(-A)-S-H and Ca5(SiO4)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.
Highlights 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 Ca5(SiO4)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 %.
Modification of recycled cement with phosphogypsum and ground granulated blast furnace slag
https://orcid.org/0000-0001-9674-9689
https://orcid.org/0000-0002-1148-777X
https://orcid.org/0000-0002-8133-3055
https://orcid.org/0009-0000-5058-9931
https://orcid.org/0000-0001-9625-4520
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 Al2O3 in the GGBS and RC to generate AFt. Rehydrated C-S-H gel could both wrap and protect the CaSO4·2 H2O crystals and crystalline contact points, and effectively filled the pores of the hardened paste, thus promoting the generation of C(-A)-S-H and Ca5(SiO4)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.
Highlights 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 Ca5(SiO4)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 %.
Modification of recycled cement with phosphogypsum and ground granulated blast furnace slag
Xu, Lei (author) / Wang, Junjie (author) / Hu, Xiaochuan (author) / Ran, Bo (author) / Huang, Rong (author) / Tang, Huiyu (author) / Li, Zhe (author) / Li, Bowei (author) / Wu, Shenghua (author)
2024-04-11
Article (Journal)
Electronic Resource
English
<sup>29</sup>Si NMR , <sup>29</sup>Si nuclear magnetic resonance spectroscopy , α'<inf>H</inf>-C<inf>2</inf>S, β-C<inf>2</inf>S , alpha′<inf>H</inf> dicalcium silicate, beta dicalcium silicate [2CaO·SiO<inf>2</inf>] , AFm , monosulfoaluminate, hemicarboaluminate, monocarboaluminate et al. , AFt , ettringite [Ca<inf>4</inf>Al<inf>2</inf>(SO<inf>4</inf>)<inf>3</inf>(OH)<inf>12</inf>(H<inf>2</inf>O)<inf>26</inf>] , CH , portlandite, calcium hydroxide [Ca(OH)<inf>2</inf>] , C-S-H , calcium silicate hydrate , C-A-S-H , calcium silicoaluminate hydrate , GGBS , ground-granulated blast-furnace slag , Hc , hemicarboaluminate [Ca<inf>4</inf>Al<inf>2</inf>(OH)<inf>12</inf>(OH)(CO<inf>3</inf>)<inf>0.5</inf>(H<inf>2</inf>O)<inf>5</inf>] , HT , hydrotalcite , IC , isothermal calorimetry , LOI , loss on ignition , Mc , monocarboaluminate [Ca<inf>4</inf>A<inf>l2</inf>(OH)<inf>12</inf>(CO<inf>3</inf>)(H<inf>2</inf>O)<inf>5</inf>] , MIP , mercury intrusion porosimetry , OPC , ordinary Portland cement , RC , recycled cement , RH , relative humidity , SCMs , supplementary cementitious materials , SEM , scanning electron microscopy , TAT , thermal activation temperature , TG , thermogravimetry , w/b , water to binder ratio , XRD , X-ray diffraction , Recycled cement , Modification , Phosphogypsum (PG) , Ground-granulated blast-furnace slag (GGBS) , Microstructure
Investigation on phosphogypsum-steel slag-granulated blast-furnace slag-limestone cement
| British Library Online Contents | 2010