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This study evaluates the environmental impacts of a newly designed precast Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) cantilever retaining wall as a sustainable alternative approach compared with the conventional precast Reinforced Concrete (RC) cantilever retaining wall. Nowadays, according to the shocking reports of many researchers worldwide global warming is one of the most devastating problems of human being. To date, lots of research has been undertaken in the concrete industry to tackle this issue through reducing the environmental footprints of our structural designs. In this regard, UHPFRC technology offers substantial benefits through efficient use of materials as well as optimization of the structural designs resulting less CO_2 emissions, Embodied Energy (EE) and Global Warming Potential (GWP). UHPFRC as a sustainable construction material is mostly appropriate for the use in the fabrication of precast members such as precast concrete cantilever retaining walls. This study demonstrates the overview of the designed precast concrete cantilever retaining wall manufactured from UHPFRC and its Environmental Impact Calculations (EIC) versus the conventional precast RC cantilever retaining walls. Based on the EIC results, the precast UHPFRC cantilever retaining walls are generally more environmentally sustainable than those built of the conventional RC with respect to the reduction of CO_2 emissions, EE and GWP. In summary, the precast UHPFRC cantilever retaining wall proposed in this study is an alternative sustainable solution compared with the conventional precast RC cantilever retaining wall which can be used in many civil engineering projects.

One of the main breakthroughs in the concrete technology in the 20th century was the development of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) as a new generation of sustainable construction material. This paper is presented in two parts. The analysis and design procedures as well as the Environmental Impact Calculations (EIC) of the precast UHPFRC cantilever retaining walls as a sustainable alternative approach to conventional precast Reinforced Concrete (RC) cantilever retaining walls were presented in the first part (Part I) of this paper. In this part (Part II), the reliability of the precast UHPFRC cantilever retaining walls were evaluated through full scale experimental testing. In the experimental tests, four full-scale UHPFRC wall specimens with the dimensions of 2.5 m in height, 2 m in length, and 2 m in width were cast. The area of the steel bars used in the wall stem of the specimens, and the volumetric ratio of the steel fibers used in the UHPFRC mix design were the test parameters. The experimental results proved that the precast cantilever retaining walls manufactured from UHPFRC as a sustainable alternative solution has superior properties in all aspects compared to the conventional precast RC cantilever retaining wall.

Ultra-high Performance Fiber Reinforced Concrete (UHPFRC) is a new generation of cementitious based construction material developed in the mid 1990s that its unique characteristics such as high durability and impermeability, negligible shrinkage/creep and high impact resistance lead to almost maintenance free and direct enhancement of the life-span of a structure. UHPFRC is an ecofriendly and environmentally green construction material which has the capacity to compete not only with conventional Reinforced Concrete (RC) or prestressed concrete design, but it is also able to compete with conventional steel design. This paper is presented in two parts. The first part (Part I) of this paper presents the analysis and design procedures of the precast UHPFRC cantilever retaining walls as a sustainable alternative approach to conventional precast RC cantilever retaining walls. Further, the Environmental Impact Calculations (EIC) of the precast UHPFRC cantilever retaining walls were compared against the conventional precast RC cantilever retaining walls as the benchmark. The second part (Part II) of this paper evaluates the reliability of the precast UHPFRC cantilever retaining walls through experimental tests on full scale UHPFRC wall specimens. The EIC results proved that cantilever retaining walls fabricated from UHPFRC are generally more environmentally sustainable than those built of the conventional RC with respect to the reduction of CO2 emissions, Embodied Energy (EE) and Global Warming Potential (GWP). Finally, advantages of the precast UHPFRC cantilever retaining walls versus the conventional precast RC walls were presented.

While the database of tests on shear in reinforced concrete members without stirrups is extensive, the pool of test data for fiber-reinforced specimens is limited. Fewer still are tests undertaken on high-performance fiber-reinforced concrete members with the fiber concrete designed to carry the full shear capacity. This paper reports the results of a testing program on ultrahigh-performance steel fiber-reinforced concrete beams. Eight prestressed concrete beams were tested in shear with the test variables being the shear span-to-depth ratio and the quantity and type of steel fibers. The results of the tests, together with additional tests reported in the literature, are compared to the values derived from the plastic shear variable engagement predictive model for the determination of shear strength of steel fiber-reinforced concrete beams. A good correlation is observed with a mean model to experimental strength ratio of 0.92 and coefficient of variation of 0.12.

Experimental results from tests on seven 650 mm deep large-scale reactive powder concrete (RPC) I-section girders failing in shear are reported herein. The girders were cast using 150 170 MPa steel fiber RPC and were designed to assess the capacity to carry shear stresses in thin webbed prestressed beams without shear reinforcement. The tests showed that the quantity and types of fibers in the concrete mix did not significantly affect the initial shear cracking load but increasing the volume of fibers increased the failure load. A design model is developed to calculate the strength of the RPC beams tested in this study. The model is based on crack sliding and uses plasticity theory combined with observations from the variable engagement model for mode I failure of fiber reinforced concrete. The results of the model are compared with test data and show a good correlation.

One of the significant breakthroughs in concrete technology in the 20th century was the development of ultra high performance fiber reinforced concrete (UHP-FRC) or reactive powder concrete (RPC) more commonly known as ultra high performance ‘ductile’ concrete (UHPdC) with compressive strength over 150 MPa and flexural strength over 30 MPa; and enhanced durability compared to conventional concrete. In brief, UHPdC is a cementitious based composite material that consists of the distinctive characteristics of the ultra-high performance concrete and high tensile strength steel fibers. UHPdC is a sustainable construction material with considerable amount of durability, ductility and tensile capacity which is mostly appropriate for use in the fabrication of precast members in civil engineering, structural and architectural applications. This paper presents a review on the UHPdC technology including an overview of material characteristics of a Malaysian UHPdC blend (i.e. Dura®), the principles of UHPdC development, its mix design, its advantages, and its applications.

This paper presents an overview on the use of high performance cementitious products and in using cement replacement materials, such as geopolymers in the development of sustainable design and construction. The design approach not only accounts for the limit states design, it also takes into consideration the environmental impact and durability of the designed structure. Two examples of environmental impact calculations, a bridge structure and a retaining wall, are provided for conventional Portland cement concrete, geopolymer concrete and reactive powder concrete solutions. The comparison studies show that many structures constructed of reactive powder concrete and of geopolymer concrete can provide for environmentally sustainable alternatives to the use of conventional concrete construction with respect to the reduction of CO2 emissions, embodied energy and global warming potential. The enhanced durability of reactive powder concrete and geopolymer concrete also provides for significant improvements in the design life, further ­supporting the concept of sustainable development.

This paper describes how a finite element model (FEM) is developed for the analysis of fiber reinforced concrete plane stress members that failed by the mode I fracture. The constitutive law is built on the variable engagement model where the behavior of a fiber composite is obtained by integration of its parts (fibers and concrete matrix) over the cracked surface. In developing the model in this way the formulation is made generally applicable to any type of steel fiber-cement based matrix and to fiber cocktails with any combination of fibers in the mix in any ratios. The model is demonstrated for a reactive powder concrete girder failing in shear using local and non-local modeling. The paper describes how the finite element formulation is shown to be capable of modeling the girder, with good accuracy observed for the global load versus displacement history and is shown to correctly capture the localized shear failure mechanism.