Engineering

Publication Search Results

Now showing 1 - 8 of 8
  • (2007) Wong, Allan; Childs, Paul; Terry, William; Gowripalan, Nadarajah; Peng, Gang-Ding
    Journal Article
    Drying shrinkage and creep are two of the most important time-dependent properties of concrete, and the health monitoring of any large-scale concrete structure is practically the monitoring of the combined effects of these two physical properties. We present a fibre-optic sensing technique using fibre Bragg grating (FBG) sensors for the experimental investigation of drying shrinkage and creep of structural grade (40 MPa) concrete. It offers many advantages over the conventional electrical and mechanical methods for both structural health monitoring and standard tests of the mechanical properties. The FBG sensors are directly embedded into concrete specimens and the data are obtained by an optical measurement system. Standard mechanical method, as specified by the Australian Standards, is also used for comparison. Good agreements between the two methods are achieved for both drying shrinkage and creep. The long-term behaviours are predicted from the experimental data, and the accuracies of prediction are discussed. This optical technique can yield a strain resolution of better than 3 ìå.

  • (2002) Li, Xiao; Ge, Linlin; Ishikawa, Y; Peng, Gang-Ding
    Conference Paper

  • (2007) Wong, Allan; Childs, Paul; Berndt, Richard; Macken, Anthony; Peng, Gang-Ding; Gowripalan, Nadarajah
    Journal Article
    The physical properties of reactive powder concrete (RPC) at early-age, i.e., the first 24 h from casting, and up to an age of 7 days is investigated experimentally using fibre Bragg gratings (FBGs), a type of fibre-optic sensors. A number of FBG sensors are multiplexed together and embedded directly into the RPC specimens, and the shrinkage and temperature change are measured directly and simultaneously. The final setting time and specimen size effect were also investigated. Results showed that there is an interplay between the shrinkage and temperature. The overall shrinkage for 7 days is 488 ìå, with the early-age shrinkage contributing about 77% of this. The temperature curve exhibits a double peak behaviour, with the first peak appears at about 7 h, which is the final setting time. There is a size effect in that smaller prisms have a higher overall shrinkage and lower temperature change than larger prisms. © 2007 Elsevier Ltd. All rights reserved.

  • (2007) Childs, Paul; Wong, Allan; Gowripalan, Nadarajah; Peng, Gang-Ding
    Journal Article
    Fibre Bragg Grating (FBG) sensors were embedded into cement mortar and ultra-high strength reactive powder concrete (RPC) prisms. Thermal tests are performed to accurately characterise the coefficient of thermal expansion (CTE) of these prisms using the measured signals from the embedded sensors. With the use of the fibre optic sensors, the difficulties inherent in using conventional techniques, such as strain gauges or vibrating wire gauges, to measure the thermal properties of cementitious materials are overcome. The error values associated with the measurements, typically measured to be as low as ± 0.04 ìå/K, are a full order of magnitude less than what is expected for standard conventional testing using a length comparator. © 2007 Elsevier Ltd. All rights reserved.

  • (2008) Childs, Paul; Wong, Allan; Terry, William; Peng, Gang-Ding
    Journal Article
    Fibre Bragg grating sensors are embedded into concrete cylinders to monitor cracking deep within the specimens. Loading cycles and loading till failure tests are performed, with measurements from the sensors collected up to, and during, failure. Calibration of the off-axis angle of the optical fibre sensors is performed and the spread of this angle noted. The use of the bandwidth of the gratings to indirectly measure the differential strain across the grating, and thus the amount of internal cracking within the specimens, is proposed and tested. The results accord well with the theoretically predicted behaviour of bulk concrete. © 2008 IOP Publishing Ltd.

  • (2002) Ge, Linlin; Peng, Gang-Ding; Rizos, Christopher; Ishikawa, Y; Li, Xiao
    Conference Paper

  • (2003) Li, Xiao; Peng, Gang-Ding; Rizos, Christopher; Ge, Linlin; Tamura, Yukio; Yoshida, Akihito
    Conference Paper