CBM-CI International Workshop, Karachi, Pakistan
Engr. F. Silva and Dr. R. D. T. Filho
SISAL FIBER REINFORCEMENT OF DURABLE THIN WALLED STRUCTURES – A NEW PERSPECTIVE
Engr. Flavio de Andrade Silva Department of Civil Engineering, COPPE/UFRJ P.O. Box 68506, CEP 21941-972, Rio de Janeiro – RJ Brazil Dr. Romildo Dias Toledo Filho Department of Civil Engineering, COPPE/UFRJ P.O. Box 68506, CEP 21941-972, Rio de Janeiro – RJ Brazil
ABSTRACT: The durability and low performance of natural fiber reinforced concrete has always been a major drawback. To overcome this problem, a new approach was used: long fibers combined with the development of a matrix compatible with natural fibers. Durable cement-based laminates reinforced with five layers of long, unidirectionally aligned sisal fibers were developed. Flat sheets were cast by a manual hand lay-up technique in a selfcompacted cement matrix and then compressed with a pressure of 3 MPa. To ensure the durability of the composites, the portland cement (PC) matrix was modified by the replacement of PC by metakaolin and calcined waste crushed clay brick to consume the calcium hydroxide generated during the hydration of the portland cement. To evaluate the durability, accelerated aging tests was performed. Wetting and drying cycles were conducted, and their results showed that the use of free calcium hydroxide matrices resulted in a composite with improved durability. Scanning electron microscopy was used to investigate the composite’s microstructure.
The use of fibers as reinforcement is as old as human civilization. Traces of natural fibers such as flax, cotton, silk, wool and plant fibers have been located in ancient civilizations all over the globe. For example, the recorded usage of flax can be dated back to 5000 BC; it is considered the oldest natural textile fiber. More recently, the use of natural fibers in construction has been limited to thin elements for roofing, cladding, and...