The effect of metakaolin on the properties of MSWI fly ash-slag binder: Compressive strength and chloride ions immobilization.

Effects of municipal solid waste incineration fly ash on the characterization of cement-stabilized macadam

Utilisation of municipal solid waste incinerator (MSWI) fly ash with metakaolin for preparation of alkali-activated cementitious material

Utilization of municipal solid waste incinerator fly ash under high temperature sintering and alkali excitation for use in cementitious material

Effect of microbially induced calcium carbonate precipitation treatment on the solidification and stabilization of municipal solid waste incineration fly ash (MSWI FA) - Based materials incorporated with metakaolin

The research was conducted to investigate the physical properties, chemical and mineralogical compositions of municipal solid waste incineration (MSWI) fly ash collected from mass-bum incinerator in Phuket, Thailand. MSWI fly ash was used to replace cement for making fly ash-cement mortars. Mechanical properties of MSWI fly ash mortar under investigation included water requirement, setting time, and compressive strength. The development of hydration and pozzolanic reactions of fly ash-cement pastes was also conducted using X-ray diffraction (XRD) analysis. Solidified fly ash products were evaluated for their environmental safety by performing the leachate extraction procedure described in the Notification of Ministry of Industry No. 6 (1997). The experimental results indicated that MSWI fly ash could not be classified as a pozzolanic material according to ASTM C618 requirements. MSWI fly ash mortars showed slightly lower compressive strengths and longer setting times as well as required more water to obtain normal consistency than the control. MSWI fly ash can be used to directly replace Portland cement up to 15 percent by weight with a 1 : 2.75 ratio of binder to sand and a water to binder ratio of 0.485. The 28-day unconfined compressive strength of this optimum mortar mix possessed satisfactory strength of about 90% of the control. Finally, the amounts of all heavy metals in leachates of both MSWI fly ash and solidified MSWI fly ash products met the regulatory limits.

This paper presents a method to solidify/stabilize the municipal solid waste incineration (MSWI) fly ash by originally employing the microbial induced carbonate precipitation (MICP) technique. In this method, the rich endogenous calcium in the MSWI fly ash was utilized to induce calcite precipitation, which is different from the operation of adding extra calcium source in previous researches. The fly ash sample had a CaO content of 44.5%, and its leaching concentrations of Zn, Cr and Pb exceed the limits of the identification standard for hazardous wastes in China. The optical density at 600 nm (OD600) of the bacterial solution was about 1.0 after the processes of bacterial activation and reproduction. The prepared fly ash sample was well mixed with bacterial solution at an ash-liquid ratio of 1 kg: 0.3 L and cured at a temperature of 20 °C and a humidity of ≥95% for 7 days. After treatment, the heavy metal leachability significantly reduced to meet the standard for pollution control of landfill site, and the unconfined compressive strength increased approximately 40%. The precipitated carbonates were verified by SEM-EDS analysis and quantified by measurement of carbonate content via acid-dissolving method. The results shone a light on the possibility of using MICP technique as a useful and efficient tool to stabilize the MSWI fly ash before being reused or properly stored in landfills.•The MICP method is efficient to reduce the heavy metal leachability and increase the compressive strength of MSWI fly ash.•The endogenous calcium in MSWI fly ash was utilized to induce calcite precipitation.•The heavy metals in MSWI fly ash were well immobilized by the formation of carbonates.

This study investigates effects of sintering temperatures on the hydration activity of the municipal solid waste incineration(MSWI) fly ash. MSWI fly ashes are rich in heavy metals, salts and toxic organic compounds. Therefore, in order to materialize it as cement materials, we should research the behavior of toxic materials at high temperature and the hydration activity of the MSWI fly ash sintered at high temperature. So, first of all, MSWI fly ashes were sintered at 800°C, 1000°C, 1100°C, 1200°C, 1300°C, and 1400°C for an hour respectively. As a result of the first stage, MSWI fly ashes sintered at 1200°C and 1300°C contain cement components, C2S(2CaO-SiO2) and C3S(3CaO-SiO2) respectively. Moreover, the amount of heavy metals in MSWI fly ashes decreases as sintering temperature is raised. Secondly, the hydration activity of the MSWI fly ash sintered at various temperatures was measured. As a result of the second stage, MSWI fly ashes sintered at 1200°C and 1300°C have the great hydration activity. Finally, MSWI fly ashes sintered at 1300°C are the most suitable choice that could be recycled as cement materials.

Solidification/stabilization and optimization of municipal solid waste incineration fly ash with aluminosilicate solid wastes

Manufacture of alkali-activated cementitious materials using municipal solid waste incineration fly ash (MSWIFA): The effect of the Si/Al molar ratio on fresh and hardened properties

Effect of silica fume on the mechanical property and hydration characteristic of alkali-activated municipal solid waste incinerator (MSWI) fly ash

Synthesis of metakaolin-based geopolymer foamed materials using municipal solid waste incineration fly ash as a foaming agent

Simultaneous wastewater decoloration and fly ash dechlorination during the dye wastewater treatment by municipal solid waste incineration fly ash

In order to realize the large-scale resource utilization of solid waste in building materials, geopolymer mortar was prepared by alkali excitation technology with municipal solid waste incineration fly ash (MSWIFA), waste glass powder (WGP) and metakaolin (MK) as raw materials. After 28 days of curing, compressive strength and heavy metal leaching concentration of MSWIFA-WGP-MK geopolymer mortar were measured. The microstructure and phase composition of geopolymer samples were examined using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis. The results demonstrated that the compressive strength of mortar increased as the MSWIFA content decreased and the alkali activator (AA) content increased. The mortar containing 30% MSWIFA and 35% AA achieved the highest 28-day compressive strength of 70.9 MPa. The high compressive strength was strongly associated with the compact microstructure, as revealed through scanning electron microscopy. The heavy metals in MSWIFA were solidified well in geopolymer matrix, and the leaching concentrations of heavy metals were below the regulatory thresholds. Based on the test results of mortars, concrete pavement bricks were produced. The performance of the optimized concrete paving brick satisfied requirements of the specification. The results indicated that the MSWIFA and WGP can be utilized in building materials.

The effects of a washing pre-treatment of municipal solid waste incineration (MSWI) fly ash with deionised water on both the physico-chemical characteristics of this material and the hydration behaviour and physical properties of ash—Portland cement mixtures rich in MSWI fly ash (55 wt% of total solids) were investigated in view of a possible reuse of such solidified products as concrete aggregates in the building industry. A four-stage washing pre-treatment was found to be able to convert the raw MSWI fly ash into a material with improved chemical characteristics for its incorporation into cementitious matrices (reduced concentrations of alkali chlorides and sulphates, transformation of metallic species in less reactive forms). As a result, the cementitious mixtures incorporating washed fly ash in place of raw fly ash were found to exhibit better performance characteristics in terms of setting, dimensional stability, compressive strength and environmental quality.

Preparing high-strength ceramsite from ferronickel slag and municipal solid waste incineration fly ash