Mineralogical and Technological Characterization of Zeolites from Basin and Range as Pozzolanic Addition of Cement

Our plain-English summary of Mineralogical and Technological Characterization of Zeolites from Basin and Range as Pozzolanic Addition of Cement, by G. Montesano, P. Cappelletti, D. Caputo, et al (Materials, 2022).

The study

• Authors: G. Montesano, P. Cappelletti, D. Caputo, B. Liguori, A. Campanile, C. Rispoli
• Journal: Materials
• Published: 2022;15(7)
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The present paper assesses petrographic, mineralogical, chemical, and technological features of different zeolitic tuff samples from various western USA districts of the Basin and Range Province containing mainly erionite, mordenite, clinoptilolite/heulandite and phillipsite. The aim of this characterization is to evaluate the pozzolanic activity of these samples according to European normative UNI-EN 196/5 (Fratini test) to program a possible use as addition for blended cements. Petrographic and mineralogical results show that the two phillipsite-bearing tuffs have a higher theoretical Cation Exchange Capacity (CEC) than the other samples; technological characterization shows a pozzolanic behavior for all the samples but higher for the tuff samples containing phillipsite, which shows a higher reactivity with CaO. All the samples could be thus advantageously employed for the preparation of blended cements, potentially reducing CO2 emissions by 70-90%.

In plain English

This laboratory study examined four zeolite-bearing volcanic rock (tuff) samples from the Rome Beds (Oregon), Fish Creek Mountains (Nevada), Shoshone (California) and Pine Valley (Nevada), in the Basin and Range Province of the western United States. The authors described each rock's minerals and chemistry. They then used the European Fratini test to check whether the rocks could serve as a pozzolanic (lime-reacting) addition to cement. The Rome Beds sample was mainly erionite (79 wt.%). Under the electron microscope this erionite formed bundles, occasionally individual fibers. Fibrous mordenite was occasionally seen in the Fish Creek sample. All four samples behaved as pozzolans: the calcium measured in solution was at least 69% lower than the theoretical solubility of calcium hydroxide at the measured alkalinity. For the phillipsite-rich Pine Valley sample, the measured value was about 90% below that theoretical figure. The authors concluded that all the samples could be used to make pozzolanic cements. They also wrote that using the erionite- and mordenite-bearing rocks is controversial because, like asbestos, these minerals are fibrous and pose a risk to human health. The study did not examine human exposure or disease.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory mineralogical, chemical and technological characterization of rock samples, with pozzolanic activity tested by the Fratini test (UNI EN 196-5); no human or animal subjects
• Who was studied: Four zeolitic tuff samples from the Basin and Range Province, western USA: Rome Beds, Oregon (25411); Fish Creek Mountains, Nevada (25521); Shoshone, California (25705); Pine Valley, Nevada (25706). Analyzed at the University of Naples Federico II.
• Exposure: No human exposure was studied. The materials tested were tuffs containing mainly erionite, mordenite, clinoptilolite/heulandite and phillipsite. Each tuff was blended with cement and tested for its reaction with lime.
• Main results:
  • The Rome Beds sample (25411) consisted mainly of erionite, 79 wt.%.
  • In sample 25411, erionite crystals were spread throughout the sample and appeared as bundles. Individual hexagonal erionite fibers were occasionally observed.
  • In the Fish Creek Mountains sample (25521), aggregates of acicular/fibrous mordenite crystals were occasionally seen.
  • All four samples showed pozzolanic activity: in the Fratini test their results fell below the calcium hydroxide solubility curve.
  • The effectiveness figure (E) compares the CaO concentration measured in the Fratini test with a theoretical concentration (CaOT). CaOT was calculated from an empirical formula for calcium hydroxide solubility at the measured alkalinity.
  • All samples showed a calcium reduction of at least 69%, measured relative to that theoretical concentration.
  • The phillipsite-bearing Pine Valley sample (25706) was the most effective, with a calcium reduction of about 90% relative to the theoretical concentration (E = 89.8% in Table 4). The authors attributed this to its less siliceous zeolite (phillipsite).
• The authors' conclusion: The authors concluded that all the investigated samples behaved as good pozzolanic materials and could be used to prepare pozzolanic cements. They added that using the mordenite- and erionite-bearing rocks is controversial because these minerals are fibrous like asbestos and represent a health risk.
• Limitations the authors state:
  • The authors stated that using the mordenite- and erionite-bearing rocks is controversial because, like asbestos, these minerals are fibrous and represent a risk to human health. This statement rests on cited literature, not on this study's data.
  • The authors stated that future work should evaluate the mechanical resistance of hardened blended cements containing these zeolites. This was not tested here.

Topics

Medical terms in this study, explained in our Lexicon: Zeolite, erionite, Cation.

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