Author
Dimitra Zaharaki
Bio: Dimitra Zaharaki is an academic researcher from Technical University of Crete. The author has contributed to research in topics: Geopolymer & Compressive strength. The author has an hindex of 17, co-authored 27 publications receiving 1774 citations.
Topics: Geopolymer, Compressive strength, Biochar, Pyrolysis, Evaporation pond
Papers
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TL;DR: A review of the most important research findings over the last 25 years is presented in this paper, which elucidates chemistry and reaction mechanisms for most important categories of materials involved, identifies the gaps in the existing body of knowledge and underlines the reasons why this promising technology has not become widely accepted by the industry.
754 citations
TL;DR: In this article, the compressive strength of concrete, bricks and tiles collected from various demolished buildings were mixed with the activating solution (NaOH and Na 2 SiO 3 ), and various synthesis conditions (curing at 60-90°C, 8-14 m NaOH molarity, particle size) were considered.
194 citations
TL;DR: In this article, the feasibility of geopolymer synthesis from low Ca electric arc ferronickel slags was investigated through a 23 factorial design and the experimental results and the variance analysis have shown that only aging period has a statistically very significant and positive effect on the final compressive strength while the effect of other factors as well as of their interactions were either less significant or negligible.
Abstract: The present experimental study investigates the feasibility of geopolymer synthesis from low Ca electric arc ferronickel slags. Additives used include kaolinite, sodium silicate, sodium hydroxide and water. The effect of the main factors considered (heating temperature, heating time and aging period) as well as of their interactions on the final compressive strength of the geopolymers produced was studied through a 23 factorial design. The experimental results and the variance analysis have shown that only aging period has a statistically very significant and positive effect on the final compressive strength while the effect of the other factors as well as of their interactions were either less significant or negligible. Identification of new phases formed in order to elucidate geopolymerisation mechanisms was carried out by XRD and FTIR. Sodalite, maghemite, thermonatrite, trona and calcite are the major phases identified. The structural integrity of the produced geopolymers was studied by subjecting them to accelerated freeze–thaw cycles. Finally, the durability of the produced geopolymers when immersed in various aquatic and acidic solutions was investigated.
176 citations
TL;DR: The potential of inorganic polymer technology as a feasible option for the utilisation of certain potentially hazardous mining and metallurgical wastes towards an increased sustainability of the wider minerals sector is discussed.
172 citations
TL;DR: In this article, a number of analytical techniques were used to identify the composition of gel and thus elucidate to a certain extent the mechanisms involved during synthesis of inorganic polymers, and the effect of the presence in the starting mixture of heavy metals such as Pb or Cu and anions such as NO3 − or SO4 − 2− on the quality of the gel formed and subsequently on the compressive strength of polymers are studied and discussed.
Abstract: In the present experimental study, a number of analytical techniques were used to identify the composition of gel and thus elucidate to a certain extent the mechanisms involved during synthesis of inorganic polymers. The raw materials used, low calcium slag from a ferronickel plant and commercial glass, were alkali activated by Na2SiO3 and KOH solutions. X-ray diffraction (XRD) is used to identify new formed phases; deconvolution of the amorphous peaks in X-ray powder diffraction patterns enables the quantitative estimation of the amorphous phases present. The morphology and composition of the inorganic polymer gel may be defined by optical reflection microscopy (ORM) and scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) is a useful tool for the identification of specific molecular structures including Si–O–Si and Al–O bonds, which define the degree of polysialation. Thermogravimetric analysis (TG) determines water evaporation rates in inorganic polymer structures by recording the weight loss under controlled heating. Finally, the effect of the presence in the starting mixture of heavy metals such as Pb or Cu and anions such as NO3
− or SO4
2− on the quality of the gel formed and subsequently on the compressive strength of inorganic polymers are studied and discussed.
121 citations
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TL;DR: In this paper, the potential position of and drivers for inorganic polymers (“geopolymers”) as an element of the push for a sustainable concrete industry are discussed.
1,444 citations
TL;DR: In this paper, a brief discussion of the class of cementing materials known as "alkali-activated binders" is provided, which are identified to have potential for utilization as a key component of a sustainable future global construction materials industry.
1,052 citations
TL;DR: In this article, the authors carried out a detailed environmental evaluation of geopolymer concrete production using the Life Cycle Assessment methodology and found that the production of most standard types of OPC concrete has a slightly lower impact on global warming than standard Ordinary Portland Cement.
868 citations
TL;DR: A review of the most important research findings over the last 25 years is presented in this paper, which elucidates chemistry and reaction mechanisms for most important categories of materials involved, identifies the gaps in the existing body of knowledge and underlines the reasons why this promising technology has not become widely accepted by the industry.
754 citations