Effects of Pressure on Resistance to Freezing and Thawing of Fiber-Reinforced Cement Board

摘要

Fiber-reinforced cement board (FRCB) is used in residential construction applications as an alternative to wood for siding, roofing, and backerboard products. To improve the resistance to freezing and thawing of FRCB, some manufacturers have started pressing the material after it is formed, expelling excess water and possibly improving the interlaminar bond. The objective of this project is to determine the effects of this pressure on the resistance to freezing and thawing of FRCB. Materials were subjected to as many as 300 freezing-and-thawing cycles based on a modified version of ASTM Standard C 1185. Mechanical properties, including flexural and interlaminar bond (ILB) strength, were measured. In addition, microstructural properties were evaluated using mercury intrusion porosimetry and scanning electron microscopy (SEM). The results indicate that, before freezing and thawing, pressure treatment improves the flexural and ILB strength and decreases the porosity. After freezing-and-thawing cycling, however, pressure treatment appears to improve the ILB strength but does not affect the flexural strength or porosity.