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Analysis and Modeling of Electromechanical Properties of Cement-Based Nanocomposites
Published in Antonella D’Alessandro, Annibale Luigi Materazzi, Filippo Ubertini, Nanotechnology in Cement-Based Construction, 2020
Siqi Ding, Liqing Zhang, Xun Yu, Yiqing Ni, Baoguo Han
Saafi et al. (2013) observed that impedance can be used as a sensing signal to describe the sensing behavior of geopolymer cement concrete with carbon nanotubes under bending (as shown in Fig. 6.2) [39].
Plants and Biodeterioration
Published in Thomas Dyer, Biodeterioration of Concrete, 2017
Two types of cement were evaluated—Portland cement and a geopolymer cement made using fly ash. In the case of the Portland cement concrete, the corrosion potential of the steel maintained a very slightly negative value (indicative of a low potential for corrosion) throughout the 14 day experimental period. Evaluation of cell numbers showed that the algae were completely eradicated by 7 days, presumably as a result of the high pH of the culture medium (around 10) originating from the Portland cement. Where the geopolymer concrete was exposed to the culture medium in the absence of algae, the corrosion potential rapidly dropped to a more negative value, indicating a greater potential for corrosion. This was presumably either due to the lower pH of the cement limiting passivation of the steel surface or the higher porosity of the cement matrix, or a combination of both. However, when algae were present the corrosion potential remained at a level comparable to the Portland cement concrete until the end of the 14-day experiment, at which point there was an abrupt drop to a more negative value. This drop approximately coincided with the extinction of the algae population, leading the researchers to propose that the algae might, in fact, be protecting the steel by maintaining a higher pH through oxygen production.
Actions during service
Published in Geert De Schutter, Damage to Concrete Structures, 2017
Besides HSR cement, other special cements can significantly improve the resistance against sulfate attack such as calcium aluminate cement, phosphate cement, alkali silicate cement, and geopolymer cement (Skalny et al. 2002). A discussion of these special cement types, however, is beyond the scope of this textbook.
Challenge of adopting relatively low strength and self-cured geopolymer for road construction application: a review and primary laboratory study
Published in International Journal of Pavement Engineering, 2021
Peerapong Jitsangiam, Teewara Suwan, Kedsarin Pimraksa, Piti Sukontasukkul, Prinya Chindaprasirt
To partially or totally replace the consumption of Portland cement, alternative cementitious materials have been developed, including ‘geopolymer cement’. Most of the geopolymer properties compare to OPC standards, although its formation is entirely different. This paper summarises the research findings related to geopolymer synthesis and the factors affecting its properties and characteristics when cured at ambient temperatures. The fineness of raw materials directly affected the dissolution rate and ion transportation, forming aluminosilicate species, which thereby controlled the initial setting time and geopolymeric gel phase. The mixing order of alkaline activators was one of the potential factors influencing performance of hardened geopolymer cement, as it enhanced the degree of reaction. Sodium hydroxide and sodium silicate solutions were the most widely used for the dissolution of aluminosilicate minerals and initiating geopolymeric formation, respectively. Higher concentration alkaline liquids gave rise to a stronger ion-pair formation, which provided a complete and fast poly-condensation process at the particle interface. However, too high concentrations could lead to an increase in the formation of a coagulated structure.
Stabilisation of black cotton soil for subgrade application using fly ash geopolymer
Published in Road Materials and Pavement Design, 2020
Anant Lal Murmu, Nupur Dhole, Anjan Patel
The fly ash (FA)-based Geopolymer has been used by many researchers (Mohammadinia et al., 2015; Phummiphan et al., 2016). This is due to the reason that fly ash is considered as a waste material unlike cement and lime and the global FA production from thermal power plants accounts for about 1 billion tons per annum (Kumar, 2002; Pandian, 2004). On the other hand, the worldwide utilisation of produced FA is only about 50% (Mahvash, López-Querol, & Bahadori-Jahromi, 2017). This makes FA, a frequent choice as precursor for the synthesis of geopolymer. As per different sources (i.e. Ecoinvent the world’s most consistent and transparent life cycle inventory database, 2018; Chen, Habert, Bouzidi, Jullien, & Ventura, 2010; Flower & Sanjayan, 2007; Habert et al., 2011; PE International’s Gabi database, 2018), the global warming potential (GWP) of fly ash, cement and lime ranges between 0.00526 and 0.027 kg CO2eq/kg, 0.82–0.948 kg CO2eq/kg and about 0.416 kg CO2eq/kg, respectively. The replacement of about 40% ordinary Portland cement with fly ash is found to reduce the carbon footprint by 36–43% (Nath, Sarker, & Biswas, 2018). In another study by Chan, Thorpe, and Islam (2015), fly ash-based geopolymer cement is reported to reduce carbon footprint by 25% as compared to ordinary Portland cement. Although, many literatures can be found on its application to produce building materials, application of FA-based geopolymer for subgrade and sub-base stabilisation is still rare. Sargent, Hughes, and Rouainia (2016) used a GGBS geopolymer (a low carbon binder) to improve the strength weak soil through deep dry soil mixing method. Phummiphan et al. (2016) used FA-based geopolymer to stabilise marginal laterite soil. Similarly, Mohammadinia et al. (2015) investigated stabilisation of construction and demolition waste for application in sub-base and base, using FA-based geopolymer. In recent years, geopolymerisation has been used in the construction of concrete roads for highways (NETRA-CSIR, 2017) and airfield (Davidovits, 2015). Hence, geopolymerisation could be also a better option for preparation of stabilised sub-base and subgrade soil as it is already being projected as next generation stabiliser by the researchers (Zhang, Guo, El-korchi, Zhang, & Tao, 2013).