Study on the relationship between direction of joints and rock strength on blasting fragmentation at lafarge aggregate, Simpang Pulai, Perak
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Date
2019-07
Authors
Izral Arash Bin Ismail @ Zanudin
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Abstract
This research was done at Lafarge Aggregate quarry which located at Simpang Pulai, Perak. The objective of this research is to study on the relationship between direction of joints and rock strength on fragmentation. Directions of joints were chosen because the fragmentation of rock is affected by the structural geology features. The interception of bedding plane and set of joints that have aperture will make the rock shape and size followed the length of the discontinuities. The weathering will change the strength of the rock mass and affect the fragmentation during the blast activity. Geological mapping was done before the blasting carried out. The results were presented in stereonet. Next, rock strength was analysed by Uniaxial Compressive Strength (UCS) test and Point Load Test (PLT). Wipfrag software was used to analyse the size distribution of the muckpile after blasting. Direction of joints is important for the size of blasted rock. If the joints are near perpendicular to slope face, the size of blasted rock increase. The sample after UCS and PLT gives strength less than 250 MPa. Cracks present in the sample before UCS and PLT test will give lower strength. Main factor for the blasting fragmentation is the direction of joints. The spacing and aperture of the joints also resulting open fracture. The rock strength is less because the quarry is in contact zone limestone – granite. Limestone rock strength is in range 50 – 250 MPa. This could be the reason why the rock strengths are low. Recommendations for future work are use new and modern mapping method for geological mapping. Add more parameter which are spacing, persistence, roughness of discontinuity surface, infilling and weathering discontinuity surface.