Thermodilatometric Study of the Decay of Zeolite-Bearing Building Materials.

Michele Pansini,Enrico Di Clemente,Angelo Cappi,Bruno De Gennaro,Rosa Buccino,Vincenzo Monetti,Maurizio De Gennaro,Marco D’Amore,Pierpaolo Santimone Nuzzi

doi:10.3390/ma14133551

Abstract

Six zeolite-bearing rocks, often used as building materials, were analyzed by thermodilatometry, together with a rock not bearing zeolites and a plaster covering a containing wall made of zeolite-bearing dimension stones, up to 250 °C. The main results obtained were the following: (i) the zeolite-bearing rocks exhibited very small, if any, positive variation of ΔL/Lo (%) up to about 100 °C, whereas they more or less shrank in the temperature range 100–250 °C (final values ranging from −0.21 to −0.92%); (ii) the rock not bearing zeolites regularly expanded through the whole temperature range, attaining a final value of 0.19%; (iii) the plaster showed a thermodilatometric behavior strongly affected by its water content. Obtained results were interpreted based on plain thermal expansion, shrinkage by dehydration, cation migration and thermal collapse of the zeolitic structure. The decay of the zeolite-bearing building materials was essentially related to: (i) the large differences recorded in the thermodilatometric behavior of the various rocks and the plaster; (ii) the different minerogenetic processes that resulted in the deposition of the various zeolite-bearing rocks.

Highlights

Natural zeolite-bearing rocks are widespread in many countries of the world in deposits of large dimensions that exhibit potential for practical applications [1]
Natural zeolite-bearing rocks have already been tested in environmental protection studies [2,3,4,5,6] for ceramization purposes aiming at tiles production [7,8,9], for producing lightweight aggregates to be used for concrete manufacture [10,11,12], in oenological refining processes [13], in the immobilization of radionuclides [14], as an additive in animal diets [15], as drug carriers [16], and in solar energy storage applications [17]
A careful comparison of the thermodilatometric curves performed on the cylindrical specimens directly cut from the various rocks with the thermodilatometric curve of the cylindrical compacts obtained by pressing the sands that resulted from grinding the original rocks shows that both curves exhibit the same shape

Summary

Introduction

Natural zeolite-bearing rocks are widespread in many countries of the world in deposits of large dimensions that exhibit potential for practical applications [1]. The use of natural zeolite-bearing rocks as building stones or building materials became a practice decidedly earlier than all the previous interesting applications, as the large number of ancient artistic and monumental building, located in many countries of the world, testify [18]. Such a widespread use is partly related to a group of technological peculiarities of natural zeolite-bearing rocks, which make them very valid building materials [19], and partly to their undoubtable beauty.

Methods

Results

Discussion

Conclusion