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Applicability of Electric Resistivity Method For Quality Evaluation of Soil-Cement Column
Fujii, Mamoru (Tokai University) | Watabnabe, Ken (Tokai University) | Kubo, Yutaka (System Measure Co., Ltd) | Keizo, Minagawa (System Measure Co., Ltd) | Arai, Mauricio Jun (System Measure Co., Ltd) | Kitamura, Keisuke (Kensho Co., Ltd) | Yamashita, Tatsunori (Yamashita Industry Co., Ltd)
ABSTRACT While the deep-mixing soil stabilization method creates improved soilcement column by mixing cement binders and ground soil, the quality of the improved ground must be evaluated constantly. The conventional methods such as rotary sounding test, integrity test and unconfined compression test of core samples, can be directly evaluate the soundness of the improved columns. These methods are normally applied considerably long time after the completion and depend on the results of tests, are necessary to reworks. We have developed and studied the applicability of resistivity method capable of evaluating the quality variations of improved ground immediately after the construction. This method is done by the axial resistivity changes of a cone sensor pressed in the hardening body and proven to be very effective in the evaluation of soil-cement column. INTRODUCTION The deep-mixing soil stabilization method creates improved soil columns by mixing cement binders and the soil ground. Such a column which is made by the deep-mixing soil stabilization method is generally called as a soil-cement column. The strength of the soil-cement column is affected by a property of the soil, rotary speed, pH and the shape of the blade wing. We used electric resistivity in this quality evaluation. It is known that the resistivity of soil is affected by the size of the soil particles (Fujii M, 1981). The study on the resistivity of the soil-cement until now related to finding the faults in the soil-cement body (Chiaki H, 1996; Mizoguchi E, 1998; Tamura M, 1988, 2000a, 2000b). The purpose of this study is to clarify the variation of the strength and the variation of resistivity of the soil- cement. In laboratory test, a commercially available electric current meter was used, while the Schlumberger type 4-electrode resistivity meter was used in field test.
- Energy > Oil & Gas > Upstream (0.54)
- Health & Medicine (0.36)
Ductile-Fiber-Reinforced Cementitious Composite Using Shirasu Fine Aggregate
Watanabe, Ken (Dept. of Architecture and Building Engineering, School of Engineering, Tokai University) | Sato, Fumiyasu (Dept. of Architecture and Building Engineering, School of Engineering, Tokai University) | Fujii, Mamoru (Dept. of Architecture and Building Engineering, School of Engineering, Tokai University) | Arai, Jun Mauricio (Dept. of Architecture and Building Engineering, School of Engineering, Tokai University)
ABSTRACT Recently, ductile-fiber-reinforced cementitious composites (DFRCCs) have been developed, which show performance largely superior to those of fiber-reinforced concretes so far known. DFRCCs are composites of cementitious material reinforced with fibers, which have multiple cracking characteristics and much improved toughness during bending, tension, and compression fractures. In the present study, we have used white cement and shirasu, which is a pyroclastic flow deposit obtainable in a large quantity from South Kyushu, as fine aggregate. We examined material properties of white cement-shirasu mortar reinforced with PVA fibers, targeting interior and exterior panels as secondary products of concrete. INTRODUCTION Nowadays it is very important to deal with global environmental issues in the concrete industry. Therefore, extensive research on concretes with recycled aggregates has been carried out in order to solve the problem of environmental destruction due to natural aggregate extraction, as well as the problem of exhaustion of natural aggregate resources. Because of this, Takewaka et al. (Takewaka et al., 1987) and Kawamata et al. (Kawamata et al., 1988) have made a series of investigations on the applicability of shirasu, which is a pyroclastic flow deposit obtainable in large quantities from South Kyushu, as an alternative to fine aggregate for concretes. They revealed the mix proportions and material properties such as the strength of shirasu concrete. Examples of the application of shirasu concrete to pier foundations have also been reported (Takewaka, 2004). Kaku et al. have proposed a formula for the estimation of concrete strength based upon their study on concretes with shirasu as fine aggregate and lapilli as coarse aggregate (Kaku et al., 1989). From these results, the alternative use of shirasu to fine aggregate for concretes appears promising, and shirasu concrete can be used not only for structural members, but also for a variety of other applications.