Abstract
In a corrosive environment similar to that of the Arabian Gulf, use of high-performance concrete is one of the options to ensure a target service life of concrete structures. However, in absence of good quality coarse aggregates, it is a challenging task to produce high-performance concrete. Recently, the possibility of producing ultra-high-performance concrete (UHPC) has been widely reported in the literature. UHPC is produced without coarse aggregates at very low water to cementitious materials ratio, high amounts of cement, mineral admixtures, and superplasticizer along with fine quartz sand as aggregate, quartz powder as micro-filler, a nd steel fibres for fracture toughness. In the present work, an effort was made to utilize local waste materials as alternative mineral admixtures and local dune sand as aggregate in producing different UHPC mixtures without addition of quartz powder. The mechanical properties, shrinkage, and durability characteristics of the UHPC mixtures were studied. Test results indicate that it is possible to produce UHPC mixtures using alternative waste materials, which would have targeted flow, strength, toughness, and resistance against reinforcement corrosion. The information presented in the paper would help in optimum selection of a mixture of UHPC considering the availability of local materials, exposure conditions and structural requirements.
Highlights
In recent years, the possibility of producing ultra-high-performance concrete (UHPC) has been widely reported in the literature
UHPC is produced without coarse aggregates at very low water to cementitious materials ratio, high cementitious materials content, and quartz fine sand, quartz powder as micro-filler, silica fume or any other suitable mineral admixture, steel or polymer fibres, and high dosage of superplasticizer
The particle size ranges of cement, supplementary cementitious materials, fine quartz sand and quartz powder should be selected in such a way that the grading curve for the mixture of granular materials would match with the optimum grading curves, reported in literature, for example optimum grading curve given by Schmidt and Fehling [17] and particle size distribution model for optimization of the composition of mixture of granular materials used for UHPC [18,19]
Summary
The possibility of producing ultra-high-performance concrete (UHPC) has been widely reported in the literature. UHPC is produced without coarse aggregates at very low water to cementitious materials ratio, high cementitious materials content, and quartz fine sand, quartz powder as micro-filler, silica fume or any other suitable mineral admixture, steel or polymer fibres, and high dosage of superplasticizer. UHPC is reported to possess very high strength, elastic modulus, ductility (i.e., fracture toughness), and excellent durability characteristics. The mixtures of UHPC are developed based on four principles: (i) reduction in porosity through close packing of raw materials and reduction in water/cementitious materials ratio with the help of superplasticizer; (ii) improvement in microstructure through close packing of solid materials, facilitating hydration and pozzolanic reactions, and improving the interfacial transition zone between aggregates and cementitious products; (iii) enhancement in homogeneity by eliminating coarse aggregate and using fine raw materials; (iv) increase in toughness by using fibres. Besides selection of suitable raw materials and mixture design, the mixing methods and curing regimes significantly affect the quality of UHPC [5]
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