Contribution of Zeolite to Deterioration of Pelitic Rocks from Asu-River Group and Variation of the Deterioration with Water Sorption

Abstract

The contributions of water-absorbent minerals to the deterioration of some pelitic rocks have been assessed. The assessment followed subjecting nine pelitic rock samples collected from five Albian pelitic quarry units to aggregate impact value (AIV) test, x-ray diffraction (XRD) and degradability test. The AIV was to ensure that the rocks have the acceptable mechanical competencies of rock aggregates; the XRD was to determine the water-absorbent mineralogy of the rocks while the degradability test was to determine the susceptibility of the rocks to deterioration caused by inter-seasonal wetting and drying and also to determine their water absorption potentials. Results of the degradability and XRD tests were further subjected to regression analysis to infer the water-absorbent mineral species that contribute most to deterioration of the rocks. The AIV test revealed that all the nine samples are mechanically competent. Results of the XRD revealed that eight samples contain appreciable amount (35%) of water-absorbent minerals notably: clay-minerals, zeolite, oxides and hydroxides. Results of the degradability test revealed that five samples showed significant (>1%) deterioration. It also revealed that pelitic rocks susceptible to deterioration do not absorb the same amount of water in every wetting process. The regression analysis revealed that amongst the identified water-absorbent minerals, zeolite contributes most to deterioration of the studied pelitic rocks. This work has shown that individual water-absorbent mineral species contribute more to pelitic rock deterioration, caused by inter-seasonal wetting and drying, than summed water-absorbent minerals and that deterioration of pelitic rock is followed by an increased water-absorption.