Research Paper: Study on Durability, Impact Resistance, and

Flexural Behaviour of Fibre Hybridized Engineered

Abstract

Engineered Cementitious Composites (ECC) have gained significant attention due to their superior
mechanical and durability properties compared to conventional concrete. This research focuses on
the durability, impact resistance, and flexural behaviour of fibre hybridized ECC, specifically
Polyvinyl Alcohol (PVA) and glass fibre hybridized composites. The study evaluates the influence
of fibre hybridization on the mechanical properties, durability under aggressive environments, and
the ability to absorb impact energy. Various tests, including impact, flexural, and durability tests
under acidic and sulfate-rich environments, were conducted. The findings suggest that the addition
of fibres improves the performance of ECC significantly, particularly in flexural toughness,
ductility, and resistance to environmental deterioration.

1. Introduction

Concrete, a widely used construction material, exhibits strength in compression but is weak in
tension and is inherently brittle. Engineered Cementitious Composites (ECC), a high-performance
class of fibre-reinforced Cementitious composites, offer a solution to this problem. Developed by
Victor Li, ECCs exhibit strain-hardening behaviour and improved ductility, primarily due to the
inclusion of short, random fibres like Polyvinyl Alcohol (PVA) fibres. This study investigates the
performance of fibre hybridized ECC, where a combination of PVA and glass fibres is used to
enhance the composites durability, impact resistance, and flexural behaviour. The study aims to
address the brittleness of conventional high-strength concrete and propose ECC as a viable material
for structural applications, particularly in seismic zones.

2.1 General
A review on previous research studies conducted on properties of Engineered Cementitious
Composites (ECC) has been presented in this chapter. It provides a brief review on special
characteristics of ECC with addition of various mineral admixtures and fibres in it.

2.2 Review of literature

 Hakan Nuri Atahan et al. (2013) conducted various studies on the performance of ECC with
different types of fibres and explored the effects of fibre volume fractions on the mechanical
properties of PVA fibre-reinforced composites.
 Hezhi Liu et al. (2017) focused on the durability of ECC in sulfate and chloride
environments, demonstrating that ECC retains its mechanical properties even after
prolonged exposure. Additionally, hybridization of fibres has been shown to significantly
improve the mechanical performance of composites.
 Pakravan et al. (2017) investigated the impact of hybridizing PVA fibres with polypropylene
fibres, noting enhanced ductility at reduced costs. However, limited research exists on the
combined use of PVA and glass fibres in ECC, particularly in structural applications
subjected to impact and harsh environmental conditions. This study fills that gap by
analyzing the hybridization effects on ECC’s performance under various loading conditions
and environmental exposures.
 Jun Zhang et al. (2017) studied the impact of adding steel fibres to a composite with a
constant 2% polyvinyl alcohol (PVA) fibre content, focusing on compressive, bending, and
tensile properties. They used two types of cement—ordinary portland cement (OPC) and
calcium sulfoaluminate cement (SAC)—and varied the steel fibre content (0, 0.3, 0.6, 1.0,
2.0%). The water-to-binder ratio was 0.2, and the sand-to-binder ratio was 0.833. Results
showed increased cracking and tensile strength with higher steel fibre content.
 Wuman Zhang et al. (2017) studied the impact of hammer weight and drop height on steel
and polypropylene fibre reinforced concrete. They found that increasing drop height reduced
impact strength, while increasing weight enhanced it. Steel fibres improved ductility and
impact resistance, while polypropylene fibre concrete remained brittle.
 Ali N. Al-Gemeel et al. (2018) examined the mechanical properties of ECC with hollow
glass microspheres (HGM) and a PVA-steel hybrid fibre mix. Mono-fibre ECC (2.0% PVA,
0% steel) showed higher compressive and flexural strengths than hybrid mixtures. Using
HGM reduced strength but provided lightweight composites. Reducing the water-to-binder
ratio from 0.56 to 0.45 improved strength and reduced unit weight further.
 Ali N. Al-Gemeel et al. (2018) studied ECC with hollow glass microspheres (HGM) and
PVA-steel hybrid fibres. Mono-fibre ECC (2% PVA) had higher strength than hybrid
mixtures. HGM reduced strength but lightened the composite, while lowering the water-to-
binder ratio improved strength and reduced unit weight.
 Yanhua Guan et al. (2018) studied the flexural behavior of ECC-concrete composite beams,
focusing on bonding and fibre mesh reinforcement. Using an ECC mix with 2% PVA fibre
and concrete with 40 MPa strength, tests showed that bonded beams had higher load
capacity, while unbonded ECC was better at controlling cracking and preventing corrosion
damage.
 F.B.P. da Costa et al. (2019) evaluated the durability of ECC with PP fibres and 30% rice
husk ash (RHA) replacing cement. Tests on pore structure and shrinkage showed that adding
RHA improved durability by increasing capillary resistance and enhancing pore tortuosity.
 Maninder Singh et al. (2019) reviewed studies on ECC with various mineral admixtures and
fibres, focusing on the effects of water-cement ratio, fibre shape and length, mixing
techniques, temperature, and high-volume fly ash. ECC-M45 mix proportions were
provided, and a 2% fibre volume showed excellent strain-hardening and tensile strain
capacity with multiple cracks.
 Srinivasa Rao Naraganti et al. (2019) studied the impact resistance of structural concrete
with sisal fibres, comparing it to polypropylene (PP) and steel fibres. Drop-weight tests
showed that increasing fibre content improved impact resistance and delayed initial
cracking.
 M.K.I. Khan et al. (2020) studied concrete encased steel composite (ECC-CES) columns
using finite element modeling. The model incorporates material and geometric
nonlinearities, addressing the inelastic behavior of ECC, concrete, and steel with suitable
constitutive laws. It also accounts for initial geometric imperfections, contact interactions,
 and the effects of steel and ECC confinement on the concrete core. A concrete damaged
plasticity model was used to describe failure, and the FE model was validated against
experimental results, showing good predictions of the compressive behavior of ECC-CES
columns.
 Yu-Zhou Zheng et al. (2020) studied five Reinforced Concrete (RC) beams strengthened
with Basalt Fibre Reinforced Polymer (BFRP) grid and Engineered Cementitious Composite
(ECC), along with one conventional RC beam for comparison. They conducted finite
element analyses using ABAQUS/Standard to estimate the shear capacity of the
strengthened beams. The results showed strong agreement with the test data, effectively
predicting the shear capacity of the BFRP-ECC composite strengthened RC beams.
 Raad A. Al-Ameri, Sallal Rashid Abid and Mustafa Özakça (2021) This study investigates
the repeated impact performance of Engineered Cementitious Composites (ECCs) rein-
forced with polypropylene fibers after exposure to high temperatures. Compressive and
flexural strengths were tested along with repeated impact resistance using the ACI 544-2R
procedure. ECC specimens were heated to 200°C, 400°C, and 600°C, then cooled to room
temperature for testing. Results showed that ECCs at room temperature and after 200°C ex-
posure exhibited high impact resistance with ductile failure and fine surface cracking. How-
ever, exposure to 400°C and 600°C significantly reduced the impact resistance and ductility.
Despite the degradation, ECC specimens maintained impact resistance at least four times
higher than normal concrete, even after high-temperature exposure.
 Radhika Sridhar (2022) This research investigates the mechanical and durability properties
of Engineered Cementitious Composites (ECC) enhanced with polyvinyl alcohol (PVA) and
steel fibers. The study aims to assess the long-term durability of ECC under chloride,
sulfate, and combined sulfate-chloride conditions. Six different ECC mixtures with a fiber
volume fraction (Vf) of 2% were prepared and tested for compressive, flexural, and uni-
axial tensile strengths. The results show that ECC specimens with 1.5% PVA and 0.5% steel
fibers exhibited improved flexural and tensile strength compared to conventional ECC. The
optimized fiber dosage demonstrated strong durability in aggressive environments,
maintaining performance when exposed to chloride and sulfate-chloride solutions.
 Maninder Singh, Babita Saini and H.D. Chalak (2023) This study explores sustainable
Engineered Cementitious Composites (ECC) using hybrid fibers (PVA, PET, and MSE) and
alternative materials like silica sand (SS), river sand (RS), and stone processing waste
(SPW). SPW, considered hazardous due to fine particles and inorganic substances, was used
to create a cost-effective and eco-friendly ECC. Various properties such as slump flow,
compressive strength, tensile strength, flexural strength, air permeability, and ecological
behavior were evaluated. The results showed that hybrid fibers improved ECC performance,
while SPW increased flowability, strength, and durability. The use of SPW also helped
reduce carbon emissions and matrix costs, making it a viable alternative to traditional ECC
materials.
 Naser Shabakhty, Hamid Reza Karimi, Abbas Yeganeh Bakhtiary (2024) This study
investigates the performance of cementitious composites reinforced with a hybrid of elastic
and hyperelastic fibers (glass and polypropylene, PP) in various proportions and fiber
lengths (12, 25, 50, and 100 mm). Tensile strength tests under unidirectional direct tension
show that PP fibers significantly enhance strain-hardening behavior compared to glass
fibers, especially as fiber length increases. Glass fiber shows a tensile strength increase from
4.7 to 6.5 MPa as length increases, while PP fibers improve from 3.7 to 11.3 MPa. Strain
values vary, with 12 mm glass fibers achieving 2.5% strain, while 100 mm PP fibers enable
 up to 24% strain with notable strain hardening. The study concludes that PP fibers perform
better in the plastic phase of ECCs, and a predictive model was developed with statistical
analysis to estimate results accurately.

3. Materials and Methods

3.1 Materials

Cement : Ordinary Portland Cement (OPC) 53 grade as per IS 269:2015.

3.2 ECC Mix Proportions

The mix design for ECC was developed using micromechanical principles. The hybrid fibre ECC
contained 1.5% PVA and 0.5% glass fibre for Mix M1, 1.0% PVA and 1.0% glass fibre for Mix M2,
and 0.5% PVA and 1.5% glass fibre for Mix M3. The control mix (MC) contained no fibres. The
water-to-binder ratio was maintained at 0.28, and the admixture dosage was 1.2% by weight of the
binder.

3.3 Test Methods

Impact Resistance Test: A drop-weight impact test was performed as per ACI 544 to assess the
energy absorption capacity of ECC panels (300mm x 300mm x 50mm).

Flexural Test: A two-point loading test as per IS 516:2018 was used to determine the flexural
strength of ECC slabs (700mm x 300mm x 25mm).

Durability Test: The durability of ECC was evaluated by exposing cube specimens (100mm x
100mm x 100mm) to hydrochloric acid, sulphuric acid, magnesium sulfate, and sodium chloride
solutions for 120 days. Water absorption tests were also conducted to assess porosity and
permeability

4. Results and Discussion

4.1 Impact Resistance

The energy absorption capacity of fibre hybridized ECC was significantly higher than the control
mix. Mix M3 (0.5% PVA + 1.5% glass fibre) demonstrated the highest energy absorption capacity,
with an ultimate value of 1277.26 J, compared to 68.7 J for the control mix. The ductility index,
calculated as the ratio of ultimate to initial energy absorption, also increased with fibre content. M3
exhibited the highest ductility index of 2.59, reflecting its enhanced ability to undergo deformation
without failure (Figure 1).
4.2 Flexural Behaviour

Flexural strength increased with the hybridization of fibres. Mix M3 showed the highest flexural
strength of 12.16 N/mm², a 46% increase compared to the control mix (MC). The numerical
simulations using ABAQUS/CAE confirmed these experimental results, with a close agreement
between predicted and actual load-deflection responses. Flexural toughness, measured by the area
under the load-deflection curve, was also highest for M3 (98.39 N-m), indicating improved
resistance to bending loads (Figure 2).

4.3 Durability
The durability tests showed that hybridized ECC exhibited better resistance to chemical attacks.
Mix M3 displayed the least weight loss and compressive strength loss under acid and sulfate
exposure. After 120 days of immersion in hydrochloric acid, M3 recorded a 1.26% weight loss and
a 3.32% strength loss, compared to 4.15% and 12.35% for the control mix. Similarly, M3
demonstrated excellent performance in magnesium sulfate and chloride environments, with minimal
weight and strength losses. The water absorption test confirmed the low permeability of ECC, with
M3 showing only 0.97% absorption after 28 days (Figure 3).

5. Conclusion

Fibre hybridization significantly enhances the mechanical and durability properties of ECC. The
inclusion of glass and PVA fibres improves the energy absorption capacity, flexural toughness, and
resistance to environmental degradation. Among the tested mixes, Mix M3 (0.5% PVA + 1.5% glass
fibre) exhibited the best overall performance, making it a suitable candidate for applications
requiring high impact resistance and durability. These findings suggest that hybrid fibre ECC is a
promising material for seismic and marine structures, where both mechanical strength and
environmental resistance are critical.

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