ویژگی های شکستگی کامپوزیت های مبتنی بر سیمان تقویت شده با فیبر بروسیت
Abstract
1- Introduction
2- Materials and methods
3- Results and discussion
4- Conclusion
References
Abstract
In this work, the mechanical properties, stress-strain behaviors, and microstructure of brucite fiber reinforced cement-based composites are determined. The results reveal that the incorporation of brucite fiber limits the compressive strength reinforcement of cement-based composite but leads to a significant increase of tensile strength by 136% and flexural strength by 73%. The employment of brucite fiber increases the fracture toughness S Kc and Q Kc of the cement-based composite by 450% and 98%. The incorporation of brucite fiber increases the linear elastic fracture toughness energy GF by 455% and elastic-plastic fracture toughness energy JC by 279%. The constitutive model of brucite fiber reinforced cement paste is also established. The diameter of the brucite fiber bundle is 1.5-16.3μm, and the diameter of the single dispersed fiber is around 45-110nm. There are about 15-363 single fibers in a bundle. Due to the brucite fiber possesses an intrinsic fibrous anisotropy, and network topology, the brucite fiber reinforced cement composites exhibit advantages of greater bending strength and crack bridging, as well as better crack resistance properties.
Introduction
Development of construction project applications causes an urgent need to explore higher performance construction materials possessing high strength, toughness, cracking resistance, durability, etc. Fiber reinforced cement composite (FRCC) is one of the engineering materials, which are extensively used to enhance the structural resistance and performance under various loading combinations. However, ordinary FRCC is costly, and the production of FRCC increases the energy consumption and carbon footprint, one possible solution is to employ eco-friendly and economic fibers in FRCC to address the question. Brucite fiber is a kind of naturally existing fibrous mineral which is formed in an alkaline medium [1]. The main chemical composition of brucite is Mg(OH)2, and the crystal structure of brucite fiber belongs to the trigonal crystal system and octahedron structure. The length of brucite fiber used as an additive to reinforce cement or asphalt is generally 10-80 mm [3]. Compared with other fibers such as polyester fiber, basalt fiber, and glass fiber, brucite fiber possesses excellent properties including fiber bundle-splitting, dispersing properties and compatible with the silicate cement [6, 7, 10]. Brucite fiber is also quite different from asbestos in chemical compositions, crystal structures, and chemical properties, and it has been proved that brucite fiber is a harmless mineral to the human body [3-5]. With excellent anti-alkaline property (brucite fiber exists stably in strongly alkaline medium with an alkaline loss of 2%), good mechanical performance (tensile strength is around 900 MPa) [6], reasonable price and abundant resources [5], the employment of brucite fiber is dependable and environmental in the industrial applications.