Greener engineered cementitious composite (ECC) – The use of pozzolanic fillers and unoiled PVA fibers

Engineered cementitious composites (ECC) with ductile strain-hardening and fine multiple cracking behaviors have been commonly accepted as an advanced and resilient alternative to conventional mortar and concrete. However, the conventional ECC has three issues: (1) uneconomical due to the high cement content and expensive polyvinyl alcohol (PVA) fibers; (2) environmentally unfriendly due to high cement content; (3) low workability due to very fine PVA fibers, all of which limit the practical application of ECC. Nevertheless, these problems of ECC can be resolved effectively by replacing cement partially with finer pozzolanic industrial solid wastes (ISWs) such as fly ash, silica fume and ground granulated blast furnace slag. These multi-sized substitutes of cement can improve the wet packing density and hence strength and workability of ECC, while the lower cement content can decrease the embodied carbon and contribute a greener ECC. Furthermore, an inexpensive type of unoiled PVA fiber is advocated herein for producing ECC. For verification, a test program was designed to investigate the compressive, tensile and flexural strength, as well as tensile strain and average crack width of ECC with two types of PVA fibers. It is evident that the use of unoiled fiber can preserve most of the technical performance indicators of ECC with conventional oiled fiber, which contributes to a more cost-effective and greener solution of cement composite.