• Explosives and Blasting
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• v.21 no.1
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• pp.41-47
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• 2003

A large scale blasting is necessary for the construction or road, harbor or ground foundation of building and it is common that the blasting work is performed by a specialist subcontracted from the construction company who is originally responsible for the project. Sometimes the latter do not agree with the former in total amount of blasted rock. They try to find out real work amount as precisely as possible. The estimation is sometimes carried out by an entrusted person when it is impossible to come to an agreement with each other. There are several methods in estimating the blasted rock volume; a calculation by prescribed equivalents of explosive before construction, a calculation by specific charge per unit volume of rock, and a calculation by rock volume per detonator. In this study, the last method is reviewed and recommended as most reliable one.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.299-306
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• 2016

In this research, influence of low quality aggregate on engineering properties of concrete was evaluated experimentally. From the experiment, the fresh properties of slump and air content were controlled with unit water and AE dosage and all mixture were designed to have similar fresh properties of slump and air content with various quality of aggregate. Under this conditions, comparing with the mixture with high quality aggregate, the mixture with low quality aggregate showed the unit water and AE dosage were increased about 18 and 98%, respectively, because of poor grading and quantity of fines. For compressive strength, the low quality aggregate, specifically, exploded debris, clay sand, and sea sand contributed on decreasing compressive strength about 20~35%. Additionally, the concrete mixture including low quality fine and coarse aggregate showed adverse quality in not only compressive strength but also durability of freeze-thawing resistance, drying shrinkage, carbonation, and chloride ingression. Therefore, it is considered that for low quality aggregate, extra treatment processes such as washing or controlling gradation, and regulation to limit the use of low quality aggregate are needed.