Predicting the long-term durability of limestones subjected to freeze–thaw cycles (case study: Guilan province, north of Iran)

Document Type : Research Paper

Authors

Department of Geology,Faculty of Science , Bu-Ali Sina University, Hamedan,Iran

Abstract

Mesozoic limestones with Cretaceous and Jurassic age are widely seen in the Guilan province, north of
Iran. Regarding the climate of this area, the development of limestone with a high percent of CaCO3
(rather than 80%) and karst morphology development was investigated to evaluate the effect of freezingthawing (F-T) cycles concerning the karst development. In this way, the physical and mechanical
properties of the four lithology units (Kl1, Kl2, Km2, and Jkl) were assessed before and after F-T cycles
to study the weathering effects. The survey of the petrography of rocks shows that the samples were
grainstone and packstone type, according to Donham classification. The highest deterioration occurred
in sample Kl2 after 60 F-T cycles. The physical and mechanical properties of rock samples such as ɣ
(unit weight), wa (water absorption), Pv (P-wave velocity), and UCS (uniaxial compressive strength) for
both dry and saturated conditions, and after 60 cycles of freezing-thawing (F-T) were attained. The
softening coefficient (K1) and freezing coefficient (K2) of samples were calculated using the UCS
values. The F-T cycles caused significant losses in the UCS values. The measured Vp during the F-T
cycles provided a suitable tool for calculating the damage value and decayed constant (λ). This study
showed that the F-T test is capable of creating microcrack and fractures within the rock as the initial
factors for increasing the contact surface in the dissolution process. The increase in Dn (damage
variable), porosity, water absorption, and decrease of Vp after 60 F-T cycles confirm this result. Also,
the increase in tangent Young’s modulus and decrease in strain show that the samples were brittle after
60 F-T periods. Therefore, it is concluded that the freezing and softening coefficient and Vp are effective
tools for assessing the rock damage during F-T periods. 

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Article Title [فارسی]

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Articles in Press, Accepted Manuscript
Available Online from 18 April 2021
  • Receive Date: 25 January 2021
  • Revise Date: 27 March 2021
  • Accept Date: 18 April 2021