Conference Papers
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Item Assessment of blast performance based on energy distribution(2008) Sastry, V.R.; Ram Chandar, K.Effective utilization of explosive energy in and around the blasthole gives better fragmentation with reduced unwanted results. Ineffective utilization of energy leads to dissipation of energy in the form of ground vibrations, noise, fly rock, back break etc. An attempt is made in this paper to present the results of the study on blast performance based on the energy dissipated into ground vibrations by analyzing the wave forms and estimating the energy distribution around blastholes by simulating blast patterns using JkSimBlast software.Generally, ground vibrations generated due to blasting operations are monitored at a known distance from blast site with a geophone / ground vibration monitor, in three mutually orthogonal, i.e longitudinal, transverse and vertical directions. Using such wave forms, the work done (energy) was estimated for all the signals in three directions, based on the principle that the area within the curve is 'work done'. Summation of energy in all three directions was considered to estimate the total work done (energy) from each blast event. Fourteen blasts were conducted in a limestone mine in southern India in 7 pairs. In each pair, one blast was conducted with shocktube initiation and other one with detonating cord initiation, keeping initiation patterns and all other parameters constant. Ground vibrations monitoring distance was also kept constant in each pair of blasts. The events were analyzed and the work done was estimated for each event. It was found that the detonating cord initiated blasts dissipated higher energy in the form of ground vibrations compared to shocktube initiated blasts. The blast performance was assessed based on the energy distribution around the blastholes. A comparative analysis was done with both the initiation systems. Once the blasthole is initiated, the explosive energy dissipates into the rock mass in the form of strain waves. The energy will be high at the vicinity of the blastholes, and it dissipates gradually with distance. If the energy is higher than the breaking strength of the rock mass the rock mass gets fragmented. Based on this concept, the blast patterns were simulated using JkSimBlast software. Around the blastholes, the energy distribution was divided into four zones / ranges. It was found that the area of highest energy zone around the blastholes is larger for shock tube initiated blasts than the detonating cord initiated blasts, which indicates effective energy utilization with shocktube initiation system.Item A study on suitability of iron ore overburden waste rock for partial replacement of coarse aggregates in concrete pavements(Institute of Physics Publishing helen.craven@iop.org, 2018) Gayana, B.C.; Ram Chandar, K.Concrete is the most widely used construction material, several sustainable materials are under investigation to reduce the impact of its production processes, by considering partial replacement of natural constituents with the waste materials without compromising the durability and strength of concrete in view to reduce both the demand of raw material and effective waste disposal of millions of tons from different sources. There has been a constant research to substitute the natural aggregates with other waste materials to develop sustainable pavements. In the process, the waste produced from Mining industry is one of such source. The aim of this study is to evaluate the suitability of iron ore waste as partial replacement of coarse aggregates in concrete with reference to the conventional materials. Physico-chemical properties and aggregate tests such as crushing, abrasion, impact, shape test, the specific gravity and water absorption were determined as per Standards and the results were within the limits indicating their applicability as a pavement material. Partial replacement by 20%, 40%, 60%, 80% and 100% with waste rock was tested for its mechanical properties and it was found that, 40% replacement of waste rock yielded highest compressive strength compared to the control mix. Regression analysis was carried out to predict the performance analysis of the compressive strength of the samples with IOT.The performance prediction analysis shows that curing days influencing more compared to % replacement with IOT. © Published under licence by IOP Publishing Ltd.Item Physico-mechanical properties of concrete with industrial waste-A case study(Avestia Publishing info@avestia.com, 2019) Gayana, B.C.; Shashanka, M.; Rao, A.N.; Ram Chandar, K.A few waste materials, such as demolition waste, steel slag, quarry dust, fly ash are dumped in landfills. This causes environmental issues and pollution. The present study aims to examine the effect of replacing two types of waste materials i.e., quarry dust and steel slag as partial replacement of cement and sand respectively. Cement was replaced partially with quarry dust between 5 to 20% with 5% intervals and sand was replaced by 75% steel slag consistently for all the concrete mixes. The concrete cubes, beams and cylinders were tested for their strength characteristics by measuring compressive strength, flexural strength and splitting tensile strength. The maximum increase of 4%, 34% and 38% in compressive, flexural and splitting tensile strength respectively was observed with 15% quarry dust replaced with cement and 75% steel slag replaced with sand. Based on the present experimental study, partial replacement of these waste materials shall mitigate the issues occurring due to storage and also by utilizing these materials in concrete as replacement for cement and sand resulting in higher strength properties compared to the naturally available construction materials. © 2019, Avestia Publishing.Item An experiment investigation on physical and mechanical properties of high strength concrete with suitable admixture(Trans Tech Publications Ltd ttp@transtec.ch, 2019) Gayana, B.C.; Shashanka, M.; Rao, A.N.; Ram Chandar, K.Concrete is an essential construction material. Even-though conventional concrete performs and satisfy the structures under normal conditions, a few special situations require very high compressive strength of concrete. An experimental investigation is done to develop high strength concrete with suitable admixtures and steel fibers. The properties of fresh and hardened concrete with alccofine as partial replacement for binder and poly-carboxylate ether (Glenium 8233) and steel fibers is investigated for the workability and mechanical properties i.e., compressive, splitting tensile and flexural strength of concrete. Based on the results, the strength increased with the addition of alccofine compared to the control mix. Hence, by optimum percentage of alccofine, high strength of concrete of 112 MPa can be obtained. © 2019 Trans Tech Publications Ltd, Switzerland.