Improvement effect of a double-level phase change material on compressive strengths of Portland cementitious materials after elevated temperatures

Abstract

In this investigation, a specially prepared double-level phase change material (DL-PCM) was introduced to ordinary Portland cement(OPC) to improve compressive strengths after elevated temperatures. Solid-liquid phase transition characteristics of DL-PCM and changes in compressive strength, water absorption, mass, as well as meso structures and mineral compositions of OPC after elevated temperatures were determined to clarify improvement mechanisms of DL-PCM on compressive strengths of OPC after elevated temperatures. Results show after 500 °C and 600 °C exposures, compressive strengths of OPC added with DL-PCM were basically equal to or a little higher than those at room temperatures. Cracks in DL-PCM introduced OPC matrix and water absorptions were significantly reduced. During the heating and cooling process, DL-PCM experienced solid-liquid-solid phase transitions, forming hard densifed solids to fill cracks and pores, significantly improving integrity of OPC matrix. Consequently, compressive strengths of DL-PCM introduced OPC were significantly increased compared to those without DL-PCM after elevated temperatures.

Keywords:

• ordinary Portland cement
• double-level phase changes
• compressive strength
• elevated temperatures

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors gratefully acknowledge the financial supports provided by State key R & D Program of China (2019YFC1904304) and the National Natural Science Foundation of China (51972337). The authors also appreciate the financial support provided by Young Doctor Fund of Jiangsu Collaborative Innovation Center for Building Energy Saving and Construct Technology (SJXTBZ2102).