Influence of burning temperature and cooling methods on strength of high carbon ferrochrome slag lightweight aggregate

Zhang, Shaohua; Liu, Laibao; Ke-feng, Tan; Zhang, Lihua; Tang, Kaibin

doi:10.1016/j.conbuildmat.2015.04.045

Cited by 25 publications

(12 citation statements)

References 26 publications

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“…Besides, CSH attached to the surface of MWCNTs could form a shielding layer to slow down the thermal decomposition of hydration products, 26,28 thus improving the crack resistance of MWCNTs concrete. Furthermore, excessive thermal stress is another factor leading to concrete cracking 18 . MWCNTs are a kind of high thermal conductivity material (~2800 W/mK were used in this study), 24 and the thermal conductivity of the specimen is proportional to its density 38 .…”

Section: Resultsmentioning

confidence: 99%

Study on spalling and cracking behavior of MWCNTs concrete exposed to high temperatures

Gao

Tian

Cheng

2023

Structural Concrete

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This study aims to investigate the effects of multiwalled carbon nanotubes (MWCNTs) on the spalling and cracking behavior of concrete exposed to high temperatures, and also consider the mechanism of different cooling methods (including natural air cooling, spray cooling, and quench cooling) on its performance after high temperature. Meanwhile, the change rules of mechanical properties and pore structure of MWCNTs reinforced concrete during high temperature and cooling were explored by x‐ray computed tomography. The results demonstrated that spalling and cracking behavior of the concrete specimens exposed to high temperatures was effectively controlled by adding MWCNTs. Consequently, the thermal resistance and residual mechanical properties of concrete exposed to high temperatures were significantly improved. Moreover, the mesoscopic and microscopic observation showed that the MWCNTs have a favorable impact on reducing the porosity of the concrete specimens below 600°C. However, when the temperature exceeded 600°C, MWCNTs reached the burning point and lost the bridging effect. No trace of MWCNTs was observed in the concrete specimen, but the cumulative mitigation decreased the possibility of cracking and spalling of concrete at 800°C. Additionally, considering the influence of cooling methods, it is found that the spalling and cracking of the concrete specimens after high temperature caused by quench cooling were the most serious, while that of caused by spray cooling were the least.

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Section: Resultsmentioning

confidence: 99%

Study on spalling and cracking behavior of MWCNTs concrete exposed to high temperatures

Gao

Tian

Cheng

2023

Structural Concrete

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“…It can reach 1.34 MPa and 3.64 MPa, respectively. It can also be found that 1 h water absorption rate of LWA reduced from 68% to 25% with the increase of sintering temperature, mainly due to the high-density component is gradually formed in LWA to prevent moisture from entering the LWA as the sintering temperature increases (Zhang et al 2015). In addition, the overall grain density of samples gradually increase with the increase of sintering temperature.…”

Section: Physical Performance Testsmentioning

confidence: 89%

Lightweight aggregate obtained from municipal solid waste incineration bottom ash sludge (MSWI-BAS) and its characteristics affected by single factor of sintering mechanism

Han

Cao

Wang

et al. 2020

Journal of the Air & Waste Management Association

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To solve the disposal problem of municipal solid waste incineration bottom ash sludge (MSWI-BAS), using it as the main raw material to prepare lightweight aggregates (LWA) for resource utilization.Sintering is an important process to achieve the desired microstructure and material properties. This paper investigates the characteristics of LWA affected by single factor of sintering mechanism (sintering temperature, heating rate and soaking time). Results show that sintering temperature increased from 1130°C to 1160°C caused high-density microstructure materials gradually formed in LWA, leading to particle strength increased from 0.1 MPa to 3.64 MPa, particle density showed an overall upward trend, reaching a maximum of 916 Kg/m 3 at 1160°C, and 1 h water absorption reduced from 68% to 25%. The heating rate of 15 K/min was beneficial to the formation of dense phase structure which could increase the particle strength, and the water absorption rate reached the lowest at this time, while the particle density was less affected by heating rate. When soaking time extended from 5 min to 20 min, particle strength and compressive density were gradually increased, and 1 h water absorption showed an overall downward trend, indicating that a longer soaking time was not conducive to the retention of pores. This study demonstrates that the utilization of MSWI-BAS to make high-performance LWA is feasible, along with the preferable environmental and economic benefits.Implications: MSWI-BAS were selected to produce lightweight aggregate (LWA), so that the sludge disposal problem is reduced. The effects of sintering temperature, heating rate and soaking time on the characteristics of LWA were investigated. Compact glass structures are formed at 1150°C and 1160°C which greatly improve the strength. The heating rate has little influence on the physical properties of LWA products. The particle density of LWA increases after the sintering soaking time reaches 15 minutes.

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“…It is reported that this effect can be avoided in LWAs manufactured from clay using slow cooling (0.7 °C/min) and this resulted in 114% increase in strength [37]. The influence of cooling on the strength of LWA manufactured from clay and ferrochrome sludge has been reported and a relationship found between the pore structure and cooling rate [38]. The total porosity and average pore size were found to be higher in rapidly cooled LWAs compared to the same composition subjected to slow cooling.…”

Section: Properties Of Lwa Manufactured Using Claymentioning

confidence: 99%

“…Research results have also linked the presence of certain minerals to the physical properties of LWAs and compressive strength, in particular. For example, in LWAs manufactured from high carbon ferrochrome slag, the forsterite phase that belongs to the olivine group of nesosilicates, influences strength [38]. Forsterite has a poor resistance to thermal shock and if this phase is neo-formed, the internal stresses during cooling can lead to micro-cracks that reduces compressive strength.…”

Section: Mineralogy Of Clay Lwamentioning

confidence: 99%

Use of clay in the manufacture of lightweight aggregate

Ayati

Ferrándiz-Mas

Newport

et al. 2018

Construction and Building Materials

124

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Clay is used as a raw material for the production of lightweight aggregates because it is readily processed into suitable granules and forms low-density but high strength aggregate particles when sintered at relatively low temperatures. The use of waste clay generated by major infrastructure development projects to make lightweight aggregate has a positive environmental impact and contributes towards a more circular economy. This paper reviews the manufacturing process used to produce lightweight aggregates from clay and the influence of processing conditions on properties. It also reviews secondary materials that have been incorporated into clays to produce lightweight aggregates. Additional research is required to improve understanding of the effects of composition and production parameters on the pore structure, density, water adsorption and strength of clay derived lightweight aggregates.

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Influence of burning temperature and cooling methods on strength of high carbon ferrochrome slag lightweight aggregate

Cited by 25 publications

References 26 publications

Study on spalling and cracking behavior of MWCNTs concrete exposed to high temperatures

Study on spalling and cracking behavior of MWCNTs concrete exposed to high temperatures

Lightweight aggregate obtained from municipal solid waste incineration bottom ash sludge (MSWI-BAS) and its characteristics affected by single factor of sintering mechanism

Use of clay in the manufacture of lightweight aggregate

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