Related Experiment Video
Updated: Aug 30, 2025
06:34
Operation of a 25 KWth Calcium Looping Pilot-plant with High Oxygen Concentrations in the Calciner
Published on: October 25, 2017
8.0K
Feasibility Study of Grinding Circulating Fluidized Bed Ash as Cement Admixture
Xingquan Du1,2, Zhong Huang2, Yi Ding3
1School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.
Materials (Basel, Switzerland)
|August 26, 2022
Summary
Grinding circulating fluidized bed ash (CFBA) improves its properties for use as a cement admixture. This process enhances fineness and activity, enabling sustainable utilization of CFBA in concrete applications.
Area of Science:
- Materials Science
- Civil Engineering
- Environmental Science
Background:
- Circulating fluidized bed (CFB) combustion technology generates significant amounts of CFB ash (CFBA).
- CFBA presents challenges for direct use as a cement admixture due to its loose, porous structure, large particle size, high water demand, and low activity index.
- Utilizing CFBA as a cement admixture offers a sustainable solution for carbon neutrality goals by reducing cement industry emissions and mitigating ash disposal issues.
Purpose of the Study:
- To investigate the impact of grinding on the physical and chemical properties of CFBA (fly ash and bottom ash).
- To evaluate the effectiveness of grinding in improving CFBA's suitability as a cement admixture.
- To determine optimal grinding parameters for enhancing CFBA's performance in cement applications.
Main Methods:
- CFBA (fly ash and bottom ash) from a CFB boiler without limestone desulfurization was collected.
- The CFBA samples were subjected to grinding for varying durations.
- Key properties including fineness, water-demand ratio, and activity index were measured before and after grinding.
- Compressive strength of cement with CFBA admixture was assessed.
Main Results:
- Grinding significantly improved the fineness and activity index of CFBA, while reducing its water-demand ratio.
- The water-demand ratio of CFBA initially decreased with grinding time, then increased.
- Optimal grinding times were identified: 10 min for CFB bottom ash (CFBBA) and 4 min for CFB fly ash (CFBFA).
- Grinding CFBBA for 10 min and CFBFA for 4 min reduced water demand by up to 105% and increased 28-day compressive strength by 7.05%.
Conclusions:
- Grinding is an effective method to enhance the properties of CFBA for use as a cement admixture.
- Optimized grinding ensures CFBA meets Chinese standards for cement admixtures.
- This process facilitates the resource utilization of CFBA, contributing to sustainable construction practices and carbon emission reduction.
More Related Videos
Related Concept Videos
01:15Fineness of Cement
199
The fineness of cement directly influences the rate of hydration, as the hydration begins at the surface of the cement particles. In addition to hydration, the fineness of cement is vital for various properties of concrete including workability, gypsum requirement, and long-term behavior. The fineness of cement is represented in terms of the specific surface of cement which is typically measured in square meters per kilogram, with several methods available for this determination.
Direct...
Direct...
199
01:29Additives and Fillers in Concrete
125
Additives and fillers are integral to enhancing the properties of concrete. Pozzolans and blast-furnace slag are additives or admixtures due to their reactions with calcium hydroxide released during cement hydration. Fillers, which are finely ground and similar in fineness to Portland cement, improve concrete attributes such as workability density, and reduce capillary bleeding or cracking. Some fillers possess hydraulic properties or participate in benign reactions within the cement paste.
The...
The...
125
01:21Pozzolans
182
Pozzolans are siliceous or aluminous materials blended with Portland cement. They interact with the calcium hydroxide produced during the hydration of Portland cement and contribute to improved strength and durability of concrete. The pozzolanic activity, a measure of a pozzolan's effectiveness, is typically assessed using the strength activity index, as defined in ASTM C 618-93, which calculates the ratio of the compressive strength of cement mixtures with and without pozzolan.
Fly ash is...
Fly ash is...
182
01:22Types of Cement II
165
Portland blast-furnace cement is made by blending Portland cement clinker with granulated blast-furnace slag, which accounts for 25 to 65 percent of the cement's weight. Despite its similarities to ordinary Portland (Type I) cement in terms of fineness and setting times, its early strength is lower, though it achieves comparable strength later on. It's particularly suited for mass concrete structures and marine environments due to its lower heat of hydration and superior sulfate...
165
01:24Hydration of Cement
369
Hydration of cement is a chemical reaction between cement particles and water. This process occurs primarily through two mechanisms: through-solution and topochemical. In the through-solution process, anhydrous compounds dissolve into their constituents, hydrates form in the solution, and then precipitate from the supersaturated solution. The topochemical process involves solid-state reactions at the cement particle surface. The through-solution process dominates the topochemical process at the...
369
01:21Portland Cement
294
Portland cement is the essential binding ingredient in concrete, made from finely ground materials including lime, iron, silica, and alumina. Lime is derived primarily from limestone, marble, marl, seashells, and clays, which also supply iron and alumina, while silica is sourced from sand, chalk, and bauxite. Contemporary manufacturing of Portland cement is a significant source of carbon dioxide emissions, prompting research into reducing its content in concrete through alternative...
294