Mechanical properties and micro-mechanisms of marine soft soil stabilized by different calcium content precursors based geopolymers

Zhou, Hengyu; Wang, Xiushan; Wu, Yuepeng; Zhang, Xiaoyuan

doi:10.1016/j.conbuildmat.2021.124722

Cited by 31 publications

(7 citation statements)

References 53 publications

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“…In addition, metakaolin contains a small amount of CaO, which is involved in the reaction after dissolution, and diffraction peaks of hydrated calcium silicoaluminate gels (C-A-S-H) were also detected in the geopolymer [32]. Due to the amorphous and semi-amorphous properties of hydrated silicoaluminate gels and C-A-S-H gels, which are often described as "featureless peaks" and difficult to index, these phases in the geopolymer form broad diffraction peaks at 2θ of 28-30 • and 34-35 • [33]. Comparing the XRD patterns of N 1 , N 2 , and N 14 , and those of K 2 , K 7 , and K 9 , it can be seen that the diffraction peak intensity of the silicoaluminate gels produced by the alkali excitation reaction gradually increased and the diffraction peak shifted to the right as the concentration of the alkaline solution increased and the mass ratio of Na 2 SiO 3 /MOH increased.…”

Section: Xrd Analysismentioning

confidence: 99%

Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests

Dai

Wang

et al. 2022

Materials

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Metakaolin was used as a raw material for the preparation of geopolymers, where two types of alkali activators (Na2SiO3 + NaOH and Na2SiO3 + NaOH) were used to prepare metakaolin geopolymers at room temperature. The mechanical properties and microstructures of the metakaolin geopolymers were analyzed. A three-factor, four-level orthogonal test was designed to investigate the mechanical properties of the metakaolin geopolymer with different ratios. The compressive and flexural strength of different specimens were tested for 7 and 28 days. Both the Na-based and K-based geopolymers exhibited excellent mechanical properties, but the K-based geopolymer had better mechanical properties. The optimal compressive strength and flexural strength of the K-based geopolymer were 73.93 MPa and 9.37 MPa, respectively. The 28-day optimal compressive strength of the Na-based polymer was 65.79 MPa, and the flexural strength was 8.71 MPa. SEM, XRD, and FTIR analyses showed that the mechanical properties of the geopolymers could be greatly improved by using a higher alkaline solution concentration, proper Na2SiO3/MOH mass ratio, and proper mass ratio of alkali exciter to metakaolin. Amorphous silicoaluminate was more favorable for the dissolution of silicon–alumina raw materials, promoted the formation of an amorphous silicoaluminate gel, and caused the internal structure of the geopolymer to be more compact.

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Section: Xrd Analysismentioning

confidence: 99%

Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests

Dai

Wang

et al. 2022

Materials

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“…The OPCbased binder is capable of undergoing a series of physico-chemical interactions with SC to optimize the properties of solidified soils [8][9][10]. However, the production process of OPC is energy-intensive and emits large amounts of pollutants as well as greenhouse gases, which poses a huge environmental burden [11,12]. There is an urgent need to develop an environmentally friendly binder with excellent performance to replace OPC.…”

Section: Introductionmentioning

confidence: 99%

The Design of a Novel Alkali-Activated Binder for Solidifying Silty Soft Clay and the Study of Its Solidification Mechanism

Jing,

Zhang,

Zhang

et al. 2024

Materials

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In order to overcome the problems of the high economic and environmental costs of a traditional ordinary portland cement-based binder, this study used self-combusted coal gangue (SCCG), granulated blast furnace slag (GBFS) and phosphorous slag (PS) to prepare a novel SCCG-GBFS-PS (SGP) ternary alkali-activated binder for solidifying silty soft clay (SC). Firstly, the parameters of the SGP ternary binder were optimized using orthogonal experiments. Then the effects of the SGP ternary binder content (mass ratio of the SGP ternary binder and the SGP-solidified soil), initial water content of SC (mass ratio of SC’ water and SC) and types of additives on the unconfined compressive strength (UCS) of the SGP-solidified soil were analyzed. Finally, the hydration products and microstructure of the SGP-solidified soil were analyzed to investigate the solidification mechanism of the SGP ternary binder. The results showed that the optimal mass ratio of GBFS and PS is 2:1, and the optimal alkali activator content (mass ratio of Na2O and the SGP ternary binder) and modulus of alkali activator (molar ratio of SiO2 and Na2O of alkali activator) were 13% and 1.3, respectively. When the SGP ternary binder content was 16% and the initial water content of SC was 35%, the SGP-solidified soil met the requirement of UCS for tertiary cured soil. The incorporation of triethanolamine and polyvinyl alcohol improved the UCS, while the incorporation of Na2SO4 significantly deteriorated the UCS of the SGP-solidified soil. The C-S-H gels and C(N)-A-S-H gels generated by hydration of the SGP-solidified soil were interspersed, interwoven and adhered to each other to form a network-like space structure that played the roles of skeleton, bonding soil particles and filling pores, which improved the macroscopic properties of the SGP-solidified soil. The results of this study provide a reference for the design and development of a solid waste-based binder for solidifying SC.

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“…Soft or extremely compressible soils are present in many civil engineering project sites. These soils cannot support the loading during construction or the duration of the service life [1,2]. Soft soil (SS) is frequently linked to a fluctuation in water content that reduces shear strength and causes swelling, shrinkage, settlement, and consolidation, which can seriously harm a civil engineering project [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…They revealed that the unconfined compressive strength (UCS) increases with metakaolin dosage and curing time. Zhou et al [2] studied marine SS's mechanical characteristics and micromechanisms stabilized by various calcium-based precursors. Researchers discovered that the stabilizing effects of low-calcium content geopolymers, high-calcium content geopolymers, and OPC on soft marine soil were due to the formation of an amorphous gel network structure.…”

Section: Introductionmentioning

confidence: 99%

Influence of Curing Time and Initial Moisture Content on Metakaolin-Based Geopolymer-Stabilized Soft Soil

Wassie,

Demir,

Köktan

2023

Advances in Civil Engineering

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This study thoroughly investigated the impact of initial moisture content and curing time on metakaolin (MK)-based geopolymer stabilized soft soil. The stabilized soft soil was characterized with an unconfined compressive strength test, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), and compaction test. The geopolymer was used at different concentrations (5%, 10%, and 15% of the dry weight of the soil), and the soft soil was prepared at its initial moisture content, which ranges from 0.75 LL to 1.25 LL. The results of the test indicate that there was an increase in yield stress at low initial moisture content. Conversely, the yield stress experienced a decrease at high initial moisture content. Furthermore, the strength of geopolymer-stabilized soil increased as the curing time increased, regardless of the binder and initial moisture contents. The microstructure analysis confirmed that the stabilized soil had a denser microstructure, the formation of homogeneous gel, and fewer microcracks and pores. As the automatic compaction test revealed, the maximum dry density increased at higher binder contents while the optimum moisture content decreased. This research demonstrates that stabilizers made with metakaolin can efficiently stabilize soft soils. It is worthwhile to conduct further studies on the durability, shear tests, and cost of using geopolymer for soil stabilization under varying environmental conditions.

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Mechanical properties and micro-mechanisms of marine soft soil stabilized by different calcium content precursors based geopolymers

Cited by 31 publications

References 53 publications

Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests

Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests

The Design of a Novel Alkali-Activated Binder for Solidifying Silty Soft Clay and the Study of Its Solidification Mechanism

Influence of Curing Time and Initial Moisture Content on Metakaolin-Based Geopolymer-Stabilized Soft Soil

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