Abstract
In order to comprehensively evaluate the properties of rock-filled concrete (RFC) with the strength of C15, lab experimental test and in-situ test are applied to explore the mechanical, hydraulic, ultrasonic characteristics of RFC in Hantang reservoir dam. Four types of defects within RFC are shown from the appearance of borehole cores specimens: (1) large sized voids existing in interfacial transition zone (ITZ) between self-compacting concrete (SCC) and rock block (RB); (2) bad cohesion in ITZ; (3) joints within rock block; (4) voids within SCC. For hydraulic aspects, the average porosity of RFC is 14.10%; the permeability rate of RFC ranges from 2.41 Lu to 10.41 Lu, with the average of 11.32 Lu, occasionally more than 25.52 Lu due to interconnected defects. For ultrasonic aspects, the ultrasonic velocity of RFC conforms to lognormal distribution, with the average of 2993.3 m/s and standard deviation of 650.5 m/s. For mechanical aspects, the average cubic compressive strength of RFC is 22.55 Mpa, with the standard deviation of 4.09 Mp. Thus the data shows a relatively great dispersion due to uneven distribution of some defects in RFC, which deteriorate the quality of RFC. Through the experimental investigation, it is shown that the quality of massive RFC in the Hantang dam is obviously non-homogeneous, mainly influenced by construction technology.
Highlights
Rock-filled concrete (RFC) is a new form of massive concrete with enough integrity, density, lower heat of hydration
The distribution law of porosity in interfacial transition zone (ITZ) [18,19], the thickness of ITZ [12], the effects of ITZ on permeability and compressive strength [20], as well as elastic modulus of concrete [13], have been intensively studied, which has greatly boosted the development of RFC technology; but there remain some questions to be solved in this field
Because these studies are based on lab experiments, where the size, shape of rock block and the thickness of casting layer are quite different to actual projects, the decrease of rock block size will certainly influence the properties of RFC
Summary
Rock-filled concrete (RFC) is a new form of massive concrete with enough integrity, density, lower heat of hydration. The distribution law of porosity in ITZ [18,19], the thickness of ITZ [12], the effects of ITZ on permeability and compressive strength [20], as well as elastic modulus of concrete [13], have been intensively studied, which has greatly boosted the development of RFC technology; but there remain some questions to be solved in this field Because these studies are based on lab experiments, where the size, shape of rock block and the thickness of casting layer are quite different to actual projects, the decrease of rock block size will certainly influence the properties of RFC. In-situ tests employed in this study include drilling on a dam body, water pressure tests and ultrasonic tests in boreholes, which were strictly conducted based on the “Test code for hydraulic concrete (SL352-2006)” issued by the Ministry of Water Resources of the P.R.C
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