Research on Thermal Insulation Properties of Plant Fiber Composite Building Material: A Review

The annual output of crops in China is about 900 million tons. Improper handling of large amounts of straw waste increases the negative impact on the environment. Recently, many scholars have studied the rational use of crop straw, and found that straw was rich in plant fiber, which combined with some kinds of building materials could be used to produce new green composite building materials. The composite building materials are more environment friendly and economical than the traditional materials, which can greatly improve the wall insulation performance. However, there are numerous factors affecting the thermal insulation performance of composite building materials. Conducting an in-depth analysis of the main factors and trends influencing the thermal insulation performance of composite building materials is necessary. This paper firstly introduced the current situation and existing problems of crop straw waste utilization, then discussed the influence of main factors on the thermal insulation properties of composite building materials. According to the analysis, the straw content is the most principal factor affecting the thermal insulation performance of composites. In a certain value range, the thermal conductivity of the composites decreases with the increase of straw content and the decrease of moisture content. Composites produced with pretreated plant fiber have better thermal insulation performance than composites without pretreatment. The thermal conductivity value of the composites decreases with increase in fiber length. Based on the research of functional rule of various influencing factors on the thermal insulation performance of composites, composite building materials with better thermal insulation performance could be obtained.