Study on Deterioration of Gray Brick with Different Moisture Contents under Freeze–Thaw Environment

Abstract

Generally, brick buildings are in the open-air environment year round, and damage to them is aggravated by the effect of repeated freezing and thawing cycles. In order to determine freeze–thaw damage and deterioration mechanism, the initial moisture content of gray brick specimens was set as 20%, 40%, 60%, 80%, 100%. The effects of moisture content and the number of freeze–thaw cycles on the quality, mechanical properties and microstructure of gray brick were investigated by uniaxial compression tests and scanning electron microscopy (SEM) tests. Numerical simulations were applied to model the freezing and thawing process. The results showed that: as the number of freeze–thaw cycles increased, the mass loss rate and peak strength reduction rate of gray brick both increased. The initial moisture content had a greater impact on damage to gray brick due to freeze–thaw; ω = 80% was defined as the limit moisture content of gray brick. Under the repeated action of freeze–thaw cycles, the areas affected by thermal stress were mainly concentrated in the center of the outer surface and the center of the side of gray bricks. The maximum thermal stress after 55 freeze–thaw cycles was 1.522 × 10−2 MPa. This research results provide a theoretical basis for the prevention and protection of frost damage of brick buildings in a freeze–thaw environment.

Prediction Model for the Evolution of the Deterioration of Bricks in Heritage Buildings in Venice Caused by Climate Change

“…Several studies are available in the literature that connect climatic parameters and material deterioration. In particular, for bricks [14,15], some deterioration processes, such as freeze-thaw action for different levels of relative humidity and salt-crystallization, have been studied. Figure 3, taken from Yue et al [15] shows an example of mass loss rate as a function of the number of freeze-thaw cycles and relative humidity.…”

Common Faults Prevention of Autoclaved Aerated Concrete Block Masonry

“…Freeze injury will appear in AACB masonry at low-temperature areas. There are many modes of water seepage in AACB and its masonry [10]:…”

“…The formation process of the gel is shown in Figure 3. It can be seen that the gel has the characteristics of large specific surface area, amorphous and possessing large dry shrinkage value [10]. The block will dry shrinkage as it is used, resulting in shrinkage stress.…”

“…The strength design of masonry mortar and plastering mortar shall match the strength grade of AACB, and the grade difference shall not be too far. For masonry with special performance requirements, special masonry mortar and plastering mortar shall be used [10]. Ⅲ.…”

Microstructure and Shear Mechanical Properties of Fractured Rock Mass Reinforced by Aeolian-Sand (AS) Cement Mortar after Freeze-Thaw (F-T) Cycles

“…The geotechnical engineering industry is also seeking a low-carbon, environmentally friendly and sustainable development path. As China's infrastructure construction continues to develop in cold regions with extreme weather and harsh conditions [1][2][3][4]. Geotechnical engineering in high-altitude and cold regions is met with major obstacles due to the specific conditions of low temperature, low pressure, F-T cycle, and fragile ecology [5][6][7][8].…”