Title:
Properties of Tunnel Fireproof Mortar: Effect of Alkali Equivalent
Author(s):
Shuanghui Wen, Wei Zhao, Xiaowen Zhao, Yongning Liang, and Tao Ji
Publication:
Materials Journal
Volume:
123
Issue:
1
Appears on pages(s):
63-74
Keywords:
alkali-activated slag; desulfurization gypsum; Na2O equivalent; tunnel fireproof mortar; wind and vibration resistance
DOI:
10.14359/51749269
Date:
1/1/2026
Abstract:
Desulfurization gypsum—alkali-activated slag-based tunnel fireproof mortar (GAM)—is a lightweight, cement-based fireproof material. A series of tests were conducted to investigate the effect of varying Na2O equivalents (2, 4, 6, and 8%) on the wind and vibration resistance of GAM, along with its bond strength, and so on. Through X-ray diffraction (XRD), thermogravimetric-
derivative thermogravimetric analysis (TG-DTG), scanning electronic microscope (SEM), and mercury intrusion porosimetry (MIP) analyses, the underlying mechanisms were elucidated. The study indicates that as the Na2O equivalent increases, the weight loss of C-(A)-S-H gel and AFt phase exhibits an initial increase followed by a decrease. The weight loss of CaSO4·2H2O crystals, the crystal-to-gel ratio, and total porosity first decrease and then increase. Therefore, the fire resistance of GAM first decreases and then increases, while the dry density, compressive strength, bond strength, and wind and vibration resistance of GAM initially increase and subsequently decrease with increasing Na2O equivalent. GAM with an Na2O equivalent of 4% demonstrates optimal wind and vibration resistance.
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