Mechanical Properties and Constitutive Modelling of UHPC with Ultra Fine Waste Glass Powder (UFWGP), Micro Silica, Fly Ash and Steel and Polypropylene Fibres


== Abstract ==

<p>Ultra-high-performance concrete (UHPC) offers superior mechanical
performance but remains limited by high cement content, sustainability
concerns, and the lack of reliable constitutive models capable of capturing its full stress–strain response including pre-peak and post-peak
behaviour. This study presents an integrated experimental and constitutive modelling investigation of UHPC incorporating ultra-fine waste
glass powder, micro silica, fly ash, and different fibre reinforcement.
Two UHPC mix designs with a water-to-cementitious material ratio of
0.20 were developed, yielding 24 independent mixtures. Cement was
partially replaced with 20% ultra-fine waste glass powder and combined with either micro silica or fly ash. Fibre reinforcement was introduced independently using 2% straight steel fibres and 1.5% crimped
polypropylene fibres to evaluate flowability, viscosity, uniaxial compressive strength, modulus of elasticity, splitting tensile strength, flexural
strength and drying shrinkage behaviour. Experimental results demonstrate that UHPC with micro silica, UFWGP and steel fibres, prepared
following the ACI 239 R-18 mix design, achieved the highest 28 days
compressive, splitting tensile and flexural strength of 144.8, 12.8 and
36.1 MPa, respectively. Steel fibre-reinforced mixes exhibited up to a 42%
increase in compressive strength and significantly enhanced post-peak
ductility compared to the control mix (without fibre). Crimped Polypropylene fibre-reinforced UHPC attained compressive strength up to
129.7 MPa, provided improved strain capacity, and effectively reduced
drying shrinkage, highlighting their suitability for crack control and deformation mitigation. The incorporation of UFWGP consistently improved
flowability, reduced viscosity, and enhanced mechanical performance,
while fly ash improved rheological behaviour but resulted in lower earlyage strength compared to micro silica-based mixes. To capture the compressive response of UHPC, an elasto-damage model previously proposed
by Khan and Zahra was reformulated by recalibrating the compression
damage parameter (β) using experimentally derived and literature based
compressive strength and elastic modulus. The proposed model reproduces both pre-peak and post-peak stress–strain behaviour, with prediction errors generally within ±7% of experimental results ranging from 72.4
to 148.5 MPa. The findings provide robust experimental evidence and a
validated constitutive framework for the sustainable design and structural
application of UHPC</p>

== Document ==
<pdf>Media:Review_627330519584_4041_TSP_RIMNI_77623.pdf</pdf>