A Study on the Soundness of Parent Rocks in Sri Lanka

Abstract

Studies on the engineering properties of different rock types provide a prior knowledge on the quality of such rock types as well as potential locations of suitable sources for the industry. The property "soundness" of a material measures the tendency to split into pieces similar to physical weathering during expansion and contraction processes within it. This soundness varies according to the type of minerals in a rock and its' origin. If rocks are using for aggregates for concrete or other applications the estimation of their soundness is necessary. With the aim of that, fresh rock samples of different rock types were collected from quarries and exposed rocks in different locali-ties in Sri Lanka to study the variation of soundness property in different rock aggregates. Samples were tested in the geotechnical engineering laboratory using sodium sulfate solution according to the Standard Method ASTM C88-99a. The rock types were Chranockite/charnockitic gneiss, garnet/hornblende/biotite gneiss, Microcline/Granitic gneiss, Garnet/biotite gneiss, Marble, Hornblende biotite gneiss, Quartzite, pegmatite, pink granite and Miocene limestone. Accordingly charnockite/ charnockitic gneiss shows the lowest loss of weight percentage as the highly sound rock for aggregates. Miocene limestone is the highly unfavorable rock.

Influence of Type of Sleeper–Ballast Interface on the Shear Behaviour of Railway Ballast: An Experimental and Numerical Study

“…where τ p , σ n , and σ c denote the peak shear stress, normal stress, and uniaxial compressive strength of the parent rock, respectively, while a and b are dimensionless constants. In this study, the uniaxial compressive strength of the parent rock of fresh ballast was considered as 120 MPa [40]. Based on that, the non-linear Mohr-Coulomb failure envelopes were developed for each interface, as presented in Figure 14.…”