Developing Low-Cost Activators for Alkali-Activated Phosphorus Slag-Based Binders

Maghsoodloorad, Hojjatollah; Allahverdi, Ali

doi:10.1061/(asce)mt.1943-5533.0001806

Cited by 16 publications

(9 citation statements)

References 35 publications

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“…Analysis of crushed mortars by DTA (see Fig.6) shows that almost no C-S-H or Ca(OH) 2 was found in the extremely low SAI mortars, which confirms that the low strength was caused by inhibited cement hydration. For the EDTMP extracted ISSA, the large amounts of phosphorus (see Table 3) may be partly responsible for the significant decrease in SAI (Takahashi et al, 2001;Maghsoodloorad and Allahverdi, 2017). But the reason for the citric acid extracted ISSA needs to be further studied.…”

Section: Pozzolanic Activitymentioning

confidence: 98%

Change in re-use value of incinerated sewage sludge ash due to chemical extraction of phosphorus

Chen

Wang

et al. 2018

Waste Management

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The potential of six different extractants to recover phosphorus (P) from incinerated sewage sludge ash (ISSA) was evaluated. Secondary effects such as the co-dissolution of Zn and Cu were also considered. The residual ISSA from each study was assessed in particular detail, focusing on the leachability of remaining Zn and Cu, major element composition, crystalline phases and overall degree of crystallinity and particle size distribution. The residual ISSA was also evaluated as a pozzolanic material using a Strength Activity Index (SAI) test with mortars containing Portland cement with a 20% substitution by ISSA. All results were compared to tests with untreated ISSA. Overall, the use of 3 of the 6 extractants could be ruled out due to poor P recovery potential and/or a serious compromise of the potential reuse of residual ISSA in Portland cement-based materials. The results highlight the added value of considering the potential reuse of residual ISSA when trying to optimize P recovery from ISSA by wet methods.

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Section: Pozzolanic Activitymentioning

confidence: 98%

Change in re-use value of incinerated sewage sludge ash due to chemical extraction of phosphorus

Chen

Wang

et al. 2018

Waste Management

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“…These materials are also known for their high costs, caustic alkalis, high shrinkage and fast setting [12][13][14][15][16][17][18]. On the other hand, medium alkaline activators such as sodium carbonate (Na2CO3, SC) can provide AAS mixes with lower environmental impacts, while presenting a more economical and less caustic solution with a lower shrinkage [19,20]. However, despite its promising environmental and mechanical performance, the use of SC has not been widely implemented in AAS systems, partially due to the long setting time and low mechanical performance it results in [11,21].…”

Section: Introductionmentioning

confidence: 99%

Improving the carbonation resistance of Na2CO3-activated slag mixes via the use of reactive MgO and nucleation seeding

Dũng

Hooper²,

Unluer³

2021

Cement and Concrete Composites

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When exposed to carbonation, Na2CO3-activated slag (SCAS) concrete demonstrated 53% mass loss and 57% reduction in compressive strength due to the decalcification of C-(A)-S-H.Improvements in the carbonation resistance of SCAS mixes via the inclusion of hydromagnesite seeds (S) and reactive MgO (M) were reported in this study. The conversion of MgO into hydrated magnesium carbonates (HMCs) and the additional formation of hydrotalcite were observed in the presence of these additives. HMCs contributed to the binding network and limited the diffusion of CO2 into the sample. The decalcification of C-(A)-S-H was retarded via the absorption of CO2 in hydrotalcite, producing huntite. These changes in the reaction kinetics of samples involving M and S enabled the retention of hydration products and formation of additional carbonation products, leading to denser microstructures and ~40% increase in compressive strength after carbonation, which was ~10 times higher than the control sample (58 vs. 6 MPa).

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“…To investigate the underground environmental impact of P, F, and heavy metals in CPB, the horizontal oscillating method (HJ 557-2010) (HVM) was used to investigate the dynamic leaching S10 6 3 0 66 S11 6 4 0 66 S12 6 5 0 66 S13 8 3 0 66 S14 10 3 0 66 S15 14 3 0 66 S16 4 3 0 69 S17 6 3 0 69 S18 8 3 0 69 S19 10 3 0 69 S20 14 3 0 69 S21 4 3 5 69 S22 6 3 5 69 S23 8 3 5 69 S24 10 3 5 69 * e quicklime and cement were added according to the HPG quality. 4 Advances in Materials Science and Engineering behavior of original HPG, PS, and specimens cured for 28 days with the recommended parameters [41]. en, the results were compared with Categories III and IV water quality standards of the Chinese Groundwater Quality Standard (DZ/T 0290-2015).…”

Section: Dynamic Leachability Testsmentioning

confidence: 99%

“…In contrast, HPG is mainly composed of CaSO 4 • 0.5H 2 O, which presents better self-gelling properties during CaSO 4 • 0.5H 2 O conversion to CaSO 4 • 2H 2 O [3]. Phosphorus slag (PS) is also a by-product of yellow phosphor production via the electric furnace method and is mainly composed of CaSiO 3 , which contains active SiO 2 and Al 2 O 3 and has weak gelling properties [4,5]. Besides, PG and PS contain a small amount of harmful impurities such as phosphorus, fluorine, and heavy metals, which limit its comprehensive utilization [1,6,7].…”

Section: Introductionmentioning

confidence: 98%

“…DPG, the main phase of which is CaSO 4 • 2H 2 O, cannot form a solidified body without heat treatment. In contrast, HPG is mainly composed of CaSO 4 • 0.5H 2 O, which presents better self-gelling properties during CaSO 4 • 0.5H 2 O conversion to CaSO 4 • 2H 2 O [3]. Phosphorus slag (PS) is also a by-product of yellow phosphor production via the electric furnace method and is mainly composed of CaSiO 3 , which contains active SiO 2 and Al 2 O 3 and has weak gelling properties [4,5].…”

Section: Introductionmentioning

confidence: 99%

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Cost-Effective Treatment of Hemihydrate Phosphogypsum and Phosphorous Slag as Cemented Paste Backfill Material for Underground Mine

Xue

Kang

et al. 2019

Advances in Materials Science and Engineering

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The environmental pollution caused by the discharge of phosphogypsum (PG) and phosphorous slag (PS) is a common issue for all countries. In order to fully utilize hemihydrate PG (HPG) and PS and treat goafs in mines, the HPG and PS were used as cementitious materials for cemented paste backfill (CPB). The physical and chemical properties of HPG and PS were first analyzed, and then, the characteristics of CPB were evaluated through fluidity tests, gas detection, uniaxial compressive strength (UCS) tests, bleeding tests, and scanning electron microscopy (SEM). After this, the underground environmental impact of CPB-based HPG and PS was investigated through a dynamic leachability experiment. The results show that (1) the UCS of CPB increases with the increase of the HPG content and mass fraction, and the addition of 3% quicklime can eliminate CO2, H2S, and SO2 generated from the slurry of CPB-based HPG-PS; (2) the addition of 3% quicklime and 5% cement to the HPG-PS mixtures can offset the strength loss of CPB in the late curing stage; (3) the UCS of the recommended specimen reaches 1.15–3.32 MPa after curing from 7 to 28 days, with their slump values varying from 15 mm to 26 mm, and the bleeding rates between 0.87% and 1.15%, which can meet the technical requirements of mining methods; (4) the UCS of CPB is the result of the cohydration reaction of hemihydrate gypsum (HG) in HPG and active Al2O3 and SiO2 in PS; and (5) the leaching indexes meet Category IV of the Chinese Groundwater Quality Standard (DZ/T 0290-2015). The results of this investigation provide a cost-efficient way for the efficient mining of phosphate resources and the comprehensive utilization of HPG and PS.

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Developing Low-Cost Activators for Alkali-Activated Phosphorus Slag-Based Binders

Cited by 16 publications

References 35 publications

Change in re-use value of incinerated sewage sludge ash due to chemical extraction of phosphorus

Change in re-use value of incinerated sewage sludge ash due to chemical extraction of phosphorus

Improving the carbonation resistance of Na2CO3-activated slag mixes via the use of reactive MgO and nucleation seeding

Cost-Effective Treatment of Hemihydrate Phosphogypsum and Phosphorous Slag as Cemented Paste Backfill Material for Underground Mine

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