Artificial alkali-activated aggregates developed from wastes and by-products: A state-of-the-art review

Qian, Lan-Ping; Xu, Ling-Yu; Alrefaei, Yazan; Wang, Tiao; Ishida, Tetsuya; Dai, Jianhua

doi:10.1016/j.resconrec.2021.105971

Cited by 72 publications

(11 citation statements)

References 139 publications

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“…In order to produce artificial aggregates, after mixing of both solid and liquid precursors with the respective mix designs, shaping of the aggregates is required. There are various methods for shaping the aggregates, including pelletization, mold casting, crushing, and hand shaping [ 80 ].…”

Section: Processing and Producing Geopolymer-based Artificial Aggregatesmentioning

confidence: 99%

“…In addition, in terms of method processing, as reported in Table 4 , it was found that sintered artificial aggregates had lower specific gravity (less than 2.0) of aggregates produced compared to cold-bonded artificial aggregates, suggesting the potential of artificial aggregates derived from geopolymers for lightweight application, as according to BS EN 13055-1, the specific gravity of lightweight aggregates should be less than 2.0. This is due to the reduction of weight loss by the firing of unburnt coal and the formation of internal gases during the sintering process, thus creating voids and pores [ 80 ]. For cold-bonded aggregates, the addition of foaming agent is crucial for utilization in lightweight applications.…”

Section: Properties Of Geopolymer-based Artificial Aggregatesmentioning

confidence: 99%

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Geopolymer-Based Artificial Aggregates: A Review on Methods of Producing, Properties, and Improving Techniques

et al. 2022

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The depletion of aggregate-related natural resources is the primary concern of all researchers globally. Recent studies emphasize the significance of recycling and reusing various types of natural or by-product material waste from industry as a result of the building industry’s rising demand for aggregate as the primary component in concrete production. It has been demonstrated that the geopolymer system has exceptional features, such as high strength, superior durability, and greater resistance to fire exposure, making it a viable alternative to ordinary Portland Cement (OPC) concrete. This study will examine the present method utilized to generate artificial aggregate-based geopolymers, including their physical and mechanical properties, as well as their characterization. The production process of geopolymer derived from synthetic aggregates will be highlighted. In conjunction with the bonding of aggregates and the cement matrix, the interfacial transition zone (ITZ) is highlighted in this work as an additional important property to be researched in the future. It will be discussed how to improve the properties of geopolymers based on artificial aggregates. It has been demonstrated that cold bonding provides superior qualities for artificial aggregate while conserving energy during production. The creation of ITZ has a significant impact on the bonding strength between artificial aggregates and the cement matrix. Additionally, improvement strategies demonstrate viable methods for enhancing the quality of manufactured aggregates. In addition, other recommendations are discussed in this study for future work.

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Section: Processing and Producing Geopolymer-based Artificial Aggregatesmentioning

confidence: 99%

Section: Properties Of Geopolymer-based Artificial Aggregatesmentioning

confidence: 99%

Geopolymer-Based Artificial Aggregates: A Review on Methods of Producing, Properties, and Improving Techniques

et al. 2022

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“…In recent years, scholars from various countries have devoted themselves to the use of low-cost industrial and agricultural solid wastes in the preparation of geopolymers, which can effectively reduce cement consumption [11][12][13][14][15][16]. Moreover, its energy consumption and CO 2 emissions are approximately 60% and 10-20% of Portland cement [17][18][19][20][21][22][23]. Previous studies have shown that the mechanical properties of slag geopolymers depend on the concentration and modulus of the alkaline activator solution [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Unconfined Compression Strength and Microstructure Characteristics of Slag and Fly Ash-Based Geopolymer Stabilized Riverside Soft Soil

Luo

Zhao

et al. 2022

Polymers

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To solve the issues of insufficient early strength of cement stabilized soil and high resource cost, high reduction cost, and high environmental cost induced by the application of cement, the slag and fly ash-based geopolymer was adopted as the stabilizer to treat riverside soft soil. This study mainly investigated the effects of stabilizer content, slag-to-fly ash ratio, and alkaline activator content on the strength of geopolymer stabilized soils with different curing ages. Unconfined compressive strength (UCS), scanning electron microscope (SEM), and X-ray energy spectrum analysis (EDS) tests were carried out. The results show that the stabilizer content, slag–fly ash ratio, and alkaline activator content have a decisive influence on the UCS of geopolymer-stabilized soil. The mix-proportions scheme of geopolymer stabilized riverside soft soil, with a geopolymer content of 15%, a slag–fly ash ratio of 80:20, and an alkaline activator content of 30%, is considered optimum. It is proven by SEM that the uniformly distributed gelatinous products formed in the geopolymer-stabilized soil bind the soil particles tightly. Moreover, the EDS analysis confirms that the gelatinous products are mainly composed of C-S-H gel and sodium-based aluminosilicate (N-A-S-H).

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“…At present, raw materials for geopolymers are generally obtained from industrial solid wastes, such as fly ash and blast furnace slag [ 13 , 14 , 15 , 16 ]. Compared to cement, the production of geopolymer can reduce energy consumption by about 60% and reduce carbon emissions by 80–90% [ 17 , 18 , 19 , 20 , 21 ]. In addition, the secondary utilization of industrial solid waste is realized, which has a positive impact on environmental protection [ 22 , 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Multiple Factors on the Workability and Early Strength Development of Alkali-Activated Fly Ash and Slag-Based Geopolymer-Stabilized Soil

Zhao

Hu³

et al. 2022

Materials

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The complexity of composite geopolymer materials results in instability in the setting and hardening of geopolymer-stabilized soil. In order to determine the appropriate mix proportion scheme for composite geopolymer-stabilized soil, this study investigated the effects of two preparation methods, fly ash/slag ratio and alkali activator modulus, on workability and strength development trends in alkali-excited fly ash and slag-based geopolymer-stabilized soil. The results showed that the high ambient temperatures created by the one-step method were more conducive to the setting and hardening of the geopolymer-stabilized soil; its 3 d/28 d UCS (unconfined compression strength) ratio was 62.43–78.60%, and its 7 d/28 d UCS ratio was 70.37–83.63%. With increases of the alkali activator modulus or the proportion of fly ash, the setting time of stabilized soil was gradually prolonged, and its fluidity increased. Meanwhile, the strength development of stabilized soil was significantly affected by the proportion of fly ash and the alkali activator modulus; the maximum UCS value was obtained at II-2-O, prepared by the one-step method, with an alkali activator modulus of 1.2 and a fly ash/slag ratio of 20/80. Specifically, the 3, 7, and 28 d UCS values of II-2-O were 1.65, 1.89, and 2.26 MPa, respectively, and its 3 d/28 d UCS ratio and 7 d/28 d UCS ratio were 73.01% and 83.63%, respectively. These results will be of great importance in further research on (and construction guidance of) composite geopolymer-stabilized soil.

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Artificial alkali-activated aggregates developed from wastes and by-products: A state-of-the-art review

Cited by 72 publications

References 139 publications

Geopolymer-Based Artificial Aggregates: A Review on Methods of Producing, Properties, and Improving Techniques

Geopolymer-Based Artificial Aggregates: A Review on Methods of Producing, Properties, and Improving Techniques

Experimental Investigation of Unconfined Compression Strength and Microstructure Characteristics of Slag and Fly Ash-Based Geopolymer Stabilized Riverside Soft Soil

Influence of Multiple Factors on the Workability and Early Strength Development of Alkali-Activated Fly Ash and Slag-Based Geopolymer-Stabilized Soil

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