Conservation of disappearing traditional manufacturing process for Chinese grey brick: Field survey and laboratory study

摘要

Grey brick is among the oldest and most durable construction materials in Chinese traditional architecture. However, many conservationists have found that the quality of the antique-style brick produced today is poorer than that of ancient bricks. Further, the scarcity of clay resources and low production efficiency have endangered the manufacturing process for traditional Chinese grey brick. Herein, we considered Jiangsu, Zhejiang, and Anhui provinces as sample areas and traced the ancient production processes for traditional Chinese grey bricks. We also conducted a field survey to determine the cause for the visible difference in quality between modern antique-style bricks and ancient bricks. Results showed that the raw materials used for modern antique-style bricks contained abundant organic impurities and gravel particles, and the brick blanks had poor integrity due to mechanization, which significantly deteriorated the quality. The water sorption of all the samples reached 17% or more, and the saturation coefficient was approximately 85%. Tests on 12 samples revealed compressive strengths of 12-20 MPa. To avoid lime blowing, the Ca content in the samples should be very low; hence, the raw material was prepared using low-calcium clay. The sintering temperature of the samples was approximately 900-1000 degrees C; the porosity was within 30%-45%; and the sample was cycled up to 95 times in an anti-freeze-thaw test, and up to 172 times in the salt crystallization resistance test. (C) 2019 Elsevier Ltd. All rights reserved.