Utilization of Calcium Carbide Residue as Solid Alkali for Preparing Fly Ash-Based Geopolymers: Dependence of Compressive Strength and Microstructure on Calcium Carbide Residue, Water Content and Curing Temperature

Wang, Qiang; Guo, Haozhe; Yu, Ting; Yuan, Peng; Deng, Liangliang; Zhang, Baifa

doi:10.3390/ma15030973

Cited by 32 publications

(10 citation statements)

References 72 publications

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“…This is due to insufficient alkaline activator to activate the aluminosilicate source materials, causing less reaction product to form and reducing compressive strength. Moreover, the presence of a high amount of unreacted fly ash increases the roughness of the matrix and reduces the compressive strength of the material [ 39 , 40 ].…”

Section: Resultsmentioning

confidence: 99%

Mechanical and Durability Analysis of Fly Ash Based Geopolymer with Various Compositions for Rigid Pavement Applications

et al. 2022

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Ordinary Portland cement (OPC) is a conventional material used to construct rigid pavement that emits large amounts of carbon dioxide (CO2) during its manufacturing process, which is bad for the environment. It is also claimed that OPC is susceptible to acid attack, which increases the maintenance cost of rigid pavement. Therefore, a fly ash based geopolymer is proposed as a material for rigid pavement application as it releases lesser amounts of CO2 during the synthesis process and has higher acid resistance compared to OPC. This current study optimizes the formulation to produce fly ash based geopolymer with the highest compressive strength. In addition, the durability of fly ash based geopolymer concrete and OPC concrete in an acidic environment is also determined and compared. The results show that the optimum value of sodium hydroxide concentration, the ratio of sodium silicate to sodium hydroxide, and the ratio of solid-to-liquid for fly ash based geopolymer are 10 M, 2.0, and 2.5, respectively, with a maximum compressive strength of 47 MPa. The results also highlight that the durability of fly ash based geopolymer is higher than that of OPC concrete, indicating that fly ash based geopolymer is a better material for rigid pavement applications, with a percentage of compressive strength loss of 7.38% to 21.94% for OPC concrete. This current study contributes to the field of knowledge by providing a reference for future development of fly ash based geopolymer for rigid pavement applications.

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Section: Resultsmentioning

confidence: 99%

Mechanical and Durability Analysis of Fly Ash Based Geopolymer with Various Compositions for Rigid Pavement Applications

et al. 2022

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“…The UCS curves at the different curing ages of 7 d and 28 d show that the advantage of CSS in improving the strength of cement stabilized aggregates gradually emerged with the increase in curing age. The UCS of CFC-2 was higher than CFC-7 by 0.6 MPa at a curing age of 7 d. The UCS of CFC-1 was significantly lower than that of CFC-2 due to the decrease in the proportion of fly ash in the inorganic binder, which led to the insufficient participation of [SiO 4 ] and [AlO 4 ] in the precursors of the hydration reaction, resulting in the generation of fewer hydration products [ 21 ]. The mechanical properties of CSS cement stabilized aggregates were significantly better than those of cement stabilized aggregates without CSS, when the amount of CSS was mixed into the range of 3~13% of the total binding material at 28 d.…”

Section: Resultsmentioning

confidence: 99%

Experimental Study on Subgrade Material of Calcium Silicate Slag

et al. 2022

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Calcium silicate slag (CSS) is used as a secondary solid waste produced by aluminum extraction technology from high alumina fly ash, and its resource utilization has always been a key issue to be solved. In this study, CSS was used to replace a portion of fly ash (FA) to prepare a new inorganic binder stabilized material for road base. The unconfined compressive strength (UCS), phase composition, microstructure, durability and performance index of the base of the test section of the CSS pavement base material were studied. The results showed that with the increase in CSS content, the UCS of pavement base materials gradually increased. Under standard curing conditions, the UCS increased 6.90~17.24% after 7 days, and 7.90~28.95% after 28 days. The main reason was that as the hydration time increased from 7 d to 28 d, the hydration products C-A-S-H gel and C-S-H gel increased, the [SiO4] polymerization degree increased, the crystal type changed, and the structure denser, which supported the good development of mechanical strength of CSS pavement base material. In addition, the research has been successfully applied to a pilot test in Hohhot, China. The freeze–thaw resistance, water stability and UCS of the CSS pavement base material were tested to meet the requirements of Chinese road construction standards, indicating that the application of CSS in pavement base is feasible.

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“…where ∆UCS represents the strength difference, kPa; UCS (3) , UCS (7) and UCS (28) are the UCS of CPDS cured for 3 days, 7 days and 28 days, respectively, kPa; and UCS gr represents the strength growth rate, %. Moreover, the ∆UCS and UCS gr were also used to assess the impact of maintenance time on the CPDS strength gain of all samples.…”

Section: Effect Of Curing Agementioning

confidence: 99%

“…Among them, China is the largest manufacturer and consumer of calcium carbide around the world, accounting for 90-95% of global supply and demand, and the annual output of dry CCR in China is 900,000-1,140,000 t [26]. In recent years, CCR has been widely utilized for cement manufacturing [26][27][28], but its total utilization rate remains still low (no more than 10%) [29]. Moreover, most of them are landfilled in waste dumps, which not only results in valuable land occupation but also causes huge contamination to the surrounding environment including the pollution of ground water and soil due to its high alkalinity [30].…”

Section: Introductionmentioning

confidence: 99%

Effect of Calcium Carbide Residue on Strength Development along with Mechanisms of Cement-Stabilized Dredged Sludge

et al. 2022

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The purpose of this research is to explore the feasibility of using calcium carbide residue (CCR), a by-product from acetylene gas production, as a solid alkaline activator on the strength development in CCR–Portland cement-stabilized dredged sludge (CPDS). The effects of cement content, CCR content and curing time on the strength development of CPDS were investigated using a series of unconfined compressive strength (UCS), pH and electric conductivity (EC) tests. Scanning electron microscopy and X-ray diffraction analyses were performed to gain additional insight into the mechanism of strength development. Meanwhile, the carbon footprints of CPDS were calculated. Following the results, it was found that CCR can significantly improve the strength of cemented dredged sludge. On the basis of the strength difference (ΔUCS) and strength growth rate (UCSgr), it was recommended that utilizing 20% cement with the addition of 20% CCR is the most effective way to develop the long-term strength of CPDS. In addition, the microstructural analysis verified that the optimum proportion of CCR benefits the formation of hydration products in CPDS, particularly needle-like gel ettringite, resulting in a less-porous and dense inter-locked structure. Furthermore, the solidification mechanism of CPDS was discussed and revealed. Finally, it was confirmed that CCR can be a sustainable alternative and effective green alkaline activator for the aim of improving cemented dredged sludge.

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Utilization of Calcium Carbide Residue as Solid Alkali for Preparing Fly Ash-Based Geopolymers: Dependence of Compressive Strength and Microstructure on Calcium Carbide Residue, Water Content and Curing Temperature

Cited by 32 publications

References 72 publications

Mechanical and Durability Analysis of Fly Ash Based Geopolymer with Various Compositions for Rigid Pavement Applications

Mechanical and Durability Analysis of Fly Ash Based Geopolymer with Various Compositions for Rigid Pavement Applications

Experimental Study on Subgrade Material of Calcium Silicate Slag

Effect of Calcium Carbide Residue on Strength Development along with Mechanisms of Cement-Stabilized Dredged Sludge

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