A Zolfaghari, A Sohrabi Bidar, Mr Malekijavan, M Haftani,
Volume 8, Issue 2 (11-2014)
Abstract
Today the effects of grouting are usually confirmed by the results of permeability tests but this method is not enough to show the changes in mechanical properties of rock masses. Although many investigators use the in situ tests for evaluation of rock mass mechanical property improvement. But this tests are time consuming and expensive. Grouting reduces the permeability and improves the condition of joints and ultimately increases the rate of rock mass classification in rock engineering. So with measurement of rock mass quality index values (Q-value) in cores obtained from grouted boreholes, the efficiency and success in improving the mechanical properties of rock mass can be showed. This paper for first time introduces Q-logging as a simple method to assess the impact of grouting in improvement of the rock mass quality. Here in, the results of Q-Logging in trial injection panels in the Bakhtiary, Bazoft and Khersan II dams have been examined. The deformation modulus were calculated from the Q-Logging for before and after of grouting. Results show that there is a good agreement between calculated rock mass parameters based on the Q-Logging method and the measured from in-situ test in the studied site. This agreement confirms the efficiency and applicability of the Q- Logging method for assessment of grouting success as well as the estimation of the rock mass parameters in grouted areas. Also it has been shown that the deformation modulus in weak rock mass with low quality has been more improved than rock mass with beater quality.
Alimohammad Ajorloo, A. Yadolahi, A.r. Zolfaghari,
Volume 9, Issue 4 (3-2016)
Abstract
The use of heavy concrete as a protective shield against high-energy gamma rays is very common. It is also an effective, versatile and economical material. The heavy concrete production can use lead slag as raw materials. The use of lead slag in the production of concrete blocks saves natural resources and reduces the environmental problems caused by the accumulation of industrial waste. However, concrete production, due to the presence of heavy metals with high atomic number can be used as an effective shield against gamma radiation. This study examines the use of lead slag produced in the battery recycling process as concrete aggregates. For this purpose, strength and gamma-ray attenuation coefficient for concrete samples prepared by replacing 40 to 60 percent lead slag instead of natural aggregate. The effect of 1 to 5 percent lead powder in setting time of concrete was measured. The results showed that by increasing the amount of lead slag, density, mechanical strength and gamma-ray attenuation coefficient for concrete samples increased significantly, but lead powder delays setting time of cement paste. In general, appropriate lead slag concrete construction with minimal thickness, reduce the cost of protection and provides the highest level of attenuation
