Investigations on mechanical performance of cementitious composites micro-engineered with poly vinyl alcohol fibers Saptarshi Sasmal ⇑ , G. Avinash CSIR-Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai 600113, India highlights  Engineering of cementitious composites using Polyvinyl alcohol (PVA) fibers.  Influence of matrix constituents and fiber geometry on response of composite.  Flexural strength shifts from the first crack to post crack with higher w/c.  Higher flexural strength doesn’t guarantee better ductility.  Both the fracture energy and complementary play great role for ductility.  Deformability could be increased by 10 times through PVA fibers incorporation. article info Article history: Received 19 April 2016 Received in revised form 16 September 2016 Accepted 6 October 2016 Keywords: Polyvinyl alcohol fiber (PVA) Mircomechanics Strain hardening Complementary energy Ductility abstract Polyvinyl alcohol fiber (PVA), being hydrophilic, has the capability to strongly bond with the cement matrix in the presence of water. Water which helps in developing the hydration product is also essential for the development of chemical bonding between the PVA fiber and the matrix. PVA fiber has two impor- tant characteristics when embedded in a cement matrix, viz. chemical bond and interface friction. The present study employs a micro-mechanics based approach and brings out a clear understanding on the behaviour of PVA fibers inside cement matrix. Flexure and fracture studies are carried out on the cemen- titious composites engineered with PVAs where the volume fraction and length of PVA fibers, the water- cement ratios (w/c) and sand to cement ratios (s/c) are the parameters. Results from flexural strength show that when water-cement ratio is varied from 0.3 to 0.4, gain of absolute strength shifts from the first crack to post crack. Lesser w/c ratio provides high strength but, the ductility could not be achieved whereas higher w/c ratio helps to activate chemical fibers, hence strain hardening phenomenon in PVA incorporated cement composite is achieved. The fracture studies depict that with clear understanding of mechanical behaviour and feasible tailoring thereafter, it is possible to develop the constituents to achieve the high fracture energy. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction Cement is a binding material mainly used for the construction purposes. The property of cement gets activated after addition of water, the process known as hydration. Many composites have been developed with cement as the primary binder. Cement mor- tar, plain and reinforced concrete, fiber reinforced concrete are some of the examples. The annual global consumption of concrete is about 12 billion metric tons [1]. With the usage of concrete being increased, its limitations are also more noticeable. The hardened cement composite is strong in compression, but it is ineffective when subjected to tensile load. This has made cement composites prone to brittle and catastrophic failure [2,3]. The brittleness of the composite is due to lack of energy dissipation mechanisms. Unlike metals, energy dissipation is not an inherent property in cement composites. Compressive strength being the most important mate- rial parameter of concrete, the focus of several research works is more inclined towards improving the compressive strength as a measure to improve the concrete performance. The improvement in compressive strength doesn’t guarantee good structural perfor- mance as any failure occurs due to tension only. This is because even under compressive loading, concrete undergoes tensile frac- ture failure and compressive strength doesn’t govern the failure http://dx.doi.org/10.1016/j.conbuildmat.2016.10.025 0950-0618/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Nano-Infra Engineering and Bridge Engineering Group, CSIR-Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai 600113, India. E-mail addresses: saptarshi@serc.res.in, sasmalsap@gmail.com (S. Sasmal). Construction and Building Materials 128 (2016) 136–147 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat