An innovative material using the thermal insulation concrete (TIC) mixed with a sufficient volume of glazed hollow beads (GHBs) is described and discussed. The effects of glazed hollow beads on the mechanical properties, thermal conductivity and, microstructure of the TIC were first investigated. The study results show that with the increase of the replacement ratio of GHBs, the density, compressive strength, elasticity modulus, and thermal conductivity coefficient of concrete decrease. The optimal mixing amount of glazed hollow beads in the concrete is 15-20%. Then, the properties related to the bonding between the TIC and rebars in freeze-thaw environment were investigated. A total of 132 pullout specimens and 216 cubic specimens made of the TIC were tested, which cover three concrete strength grades, three rebar diameters, and six anchorage lengths. The compressive strength, splitting tensile strength, bond strength, slip, and relative dynamic modulus of elasticity were studied. The research results indicate that the bond performance of the TIC is mainly affected by the rebar diameter and anchorage length, rather than the concrete strength. The TIC is found to be satisfactory in terms of frost resistance and may be utilized in engineered structures in cold regions. Lastly, the effects of recycled coarse aggregate (RCA) on the compressive strength, thermal conductivity, and microstructure of recycled aggregate thermal insulation concrete (RATIC) are presented. The pore fractal dimension was established by using the mercury-injection test data. The average fractal dimension was used to characterize the thermal conductivity of RATIC.

• Wenjing Wang(School of Architecture & Civil Engineering, Taiyuan university of technology)
• Zhu Li(School of Architecture & Civil Engineering, Taiyuan university of technology)
• Y. Frank Chen(School of Architecture & Civil Engineering, Taiyuan university of technology,Department of Civil Engineering, The Pennsylvania State University)
• Yuanzhen Liu(School of Architecture & Civil Engineering, Taiyuan university of technology)
• Zeping Zhang(School of Architecture & Civil Engineering, Taiyuan university of technology)
• Lin Zhao(School of Architecture & Civil Engineering, Taiyuan university of technology)