Physical, mechanical and petrographic properties of Lesser Himalayan rocks from Kavre area: An assessment of quality for concrete aggregate

Abstract

With rapidly growing population, development of human civilization and increasing construction of infrastructures, the demand of aggregate is increasing day by day. The quarries of naturally occurring sand and gravel are not sufficient to fulfill the demand, and are disturbing the river environments. Therefore, the crushed-rock aggregates should be used to meet the requirements. The accessible resources, quality and quantity for aggregates play an important role in the durability of roads, buildings, projects, many other infrastructures and sustainable development. Negligence of quality of aggregates would lead to rapid degradation of concrete structures. Therefore, being aware of these things, quality of aggregates should be prioritized. The exploration of outcrops from which suitable aggregates can be exploited is essential. This study aims to explore and evaluate the resources and quality of crushed-rock aggregates from the Lesser Himalayan rocks in the Kavre area.

Different kinds of rocks were identified from the outcrop in the study area: quartzite, psammitic schist, calc­quartzite, metasandstone and metasiltstone. Thirteen representative samples were taken from different lithological formations. The water absorption value (WAY) of samples ranges from 0.302 to 2.393%. Dry density varies from2.308 to 2.743gm/cm³ and the uniaxial compressive strength value ranges from 23.62 to 217.92 MPa. In general, these values indicate that the aggregates are compact and strong. The aggregate crushing value (ACY) ranges from 19.56 to 35.4% and the aggregate impact value (AIV) ranges from 11.02 to 23.84%showing that the aggregates are resistant against compressive load and strong against impact load. The sodium sulphate soundness value (SSSV) lies between 5.95 to 16.66% and methylene blue absorption values (MBAV) in all samples are <1% indicating that the samples are durable and chemically sound. The alkali silica reactive features, swelling and expanding clay minerals like chert, opal, high-quartz, extremely deformed fractured quartz, smectite, and kaolinite are absent. Though some quartz grains are undulosed and fractured, they are mega and low-quartz. Only the clay mineral illite, IM type is present in very small proportion. All these parameters show that the samples of the Lesser Himalayan rocks from the Kavre area are suitable and acceptable for concrete aggregates of general.