Ultra-High Performance 'Ductile' Concrete Technology Toward Sustainable Construction

This paper briefly presents an overview of the material characteristics of a Malaysia blend of ultra-high performance ductile concrete (UHPdC) know as DURA®. Examples of the environmental impact calculations of UHPdC structures compared to that of conventional reinforced concrete design are presented. The comparison studies show that many structures constructed from UHPdC are generally more environmentally sustainable than built of the conventional reinforced concrete with respect to the reduction of CO2 emissions and embodied energy. The enhanced durability of UHPdC also provides for significant improvements in the design life, which further supporting the concept of sustainable construction

Variable Engagement Model for the Design of Fibre Reinforced Concrete Structures

In this paper a model is developed to describe the behaviour of randomly orientated discontinuous fibres in reinforced composites subject to uniaxial tension. The model is built by integrating the behaviour of single, randomly oriented, fibres over 3D space and is capable of describing the peak and post-peak response of fibre-cement-based composites in tension. The model is used to form a constitutive law for use in finite element analysis of reactive powder concrete members with a prestressed reactive powder beam failing in shear analysed. A good correlation between the theoretical and experimental results attained

Structural Insulated Panels: Past, Present, and Future.

Since the emergence of construction technology, construction of affordable and environmentally-sensible home at fast pace has brought dream home within the reach. Structural Insulated Panel (SIP) has become a topic of interest among researchers in the recent years. SIP has the advantages of minimal material wastage and labour-savingness whilst having potential to save house builders' time and money as well as retaining the controlled quality. Nonetheless, it suffers from few drawbacks which should be further explored by researchers in its future design. This study present a brief overview of SIP history and common methods and materials utilised for SIP production. It reviews the recent research in the field of SIP by evaluating its application and drawbacks which enable SIP designers improve on SIP. The review of evaluating SIP application and its drawbacks clearly point to the need for further studies to progress beyond the current SIP to an improved one. It might be achieved by replacement of new material with common material used as skin and core of SIP. Considerably more research will need to be done to obtain SIP universal design standard

Design and Construction of a 50m Single Span Ultra High Performance Ductile Concrete Composite Road Bridge

A single span 50m long prestressed road bridge was constructed under Public Works Department in the State of Negeri Sembilan, Malaysia contract recently. The bridge was constructed at a small village, Kampung Linsum, crossing a river, Sungai Linggi. To date, this bridge is the Malaysia first and may also be the world longest composite road bridge which made from ultra-high performance ductile concrete (UHPdC). This paper presents the feature of the UHPdC precast girder; brief in-sight of the manufacturing of the girder; the construction sequence of the bridge; the design method and lastly the environmental impact calculation. The midspan deflections of the bridge at different construction history were compared against the collected field data and it showed that the calculated values generally agree well with the field data

Utilizing Ultra-High Performance Concrete Overlay for Road Pavement Repair and Strengthening Applications

This study aims to develop a new thixotropic ultra-high-performance concrete (UHPC) overlay for the repair and strengthening of damaged hot mix asphalt (HMA) pavements. The overlay is purposely designed to accommodate the roadway slope of up to 10% due to presence of viscosifying agent materials. The original UHPC materials are comprised of granite aggregate, ultra-fine calcium carbonate, shrinkage-reducing admixture, viscosifying agent, and expansive agent. The study is conducted with three sets of samples provided and considers thixotropic and mitigated shrinkage properties through comparing control (non-thixotropic) overlay 1 (thixotropic), and overlay 2 (thixotropic) mixtures. Based on the obtained results, only overlay 1 corresponds to the minimum requirement for pavement rehabilitation, with 160-200 mm flowability and -545.3 µm/m free shrinkage. As a result, an average 50 mm thick overlay 1 is selected to repair a damaged HMA pavement (1800 m2), while the field implementation procedures and drawing details are also presented in this paper

Utilization of ultra-high performance fibre concrete (UHPFC) for rehabilitation–a review

Under normal circumstances, reinforced concrete structures (RCS) show excellent performance in terms of durability and structural behaviour except for the zones that are subjected to severe mechanical or cyclic loading and aggressive environmental conditions. Therefore the methods of rehabilitation or strengthening of these zones should be reliable, effective and economical. Today, many scientists, academics and engineers understood the extremely low porosity and low permeability characteristics of ultra high performance fibre concrete (UHPFC) giving its enhanced durability over high performance concrete (HPC), thus making it potentially suitable for rehabilitation and retrofitting problematic RCS. The advantages of utilising the technology of UHPFC in repairing works includes (i) decrease the working time needed for the rehabilitation works; and (ii) increase the serviceability and durability to an extent where

Structural behavior of precast Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) cantilever retaining walls: part II — full scale experimental testing

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

Radiation shielding of ultra-high-performance concrete with silica sand, amang and lead glass

Barite in Malaysia is limited; therefore, a locally available alternative source must be identified to meet the requirements of high-density concrete for radiation shielding. We selected steel fibre-reinforced ultra-high-performance concrete (UHPC) samples with different inert materials, namely, silica sand, amang and lead glass, as the study object and tested them experimentally for their mechanical properties and radiation absorption capabilities. The UHPC samples showed compressive strength values exceeding 155 MPa at 28 days. Meanwhile, UHPC with lead glass underwent decreased of compression strength in a long period, and UHPC with amang caused an issue related to radiological safety despite that it was effective as a γ-ray shield. Thus, the use of UHPC with silica sand is practical for constructing nuclear facilities because of the abundance and cost-effectiveness of the involved materials

Refinement of Strut-and-Tie Model for Reinforced Concrete Deep Beams.

Deep beams are commonly used in tall buildings, offshore structures, and foundations. According to many codes and standards, strut-and-tie model (STM) is recommended as a rational approach for deep beam analyses. This research focuses on the STM recommended by ACI 318-11 and AASHTO LRFD and uses experimental results to modify the strut effectiveness factor in STM for reinforced concrete (RC) deep beams. This study aims to refine STM through the strut effectiveness factor and increase result accuracy. Six RC deep beams with different shear span to effective-depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were experimentally tested under a four-point bending set-up. The ultimate shear strength of deep beams obtained from non-linear finite element modeling and STM recommended by ACI 318-11 as well as AASHTO LRFD (2012) were compared with the experimental results. An empirical equation was proposed to modify the principal tensile strain value in the bottle-shaped strut of deep beams. The equation of the strut effectiveness factor from AASHTTO LRFD was then modified through the aforementioned empirical equation. An investigation on the failure mode and crack propagation in RC deep beams subjected to load was also conducted

Strut Deformation in CFRP-Strengthened Reinforced Concrete Deep Beams

Strut-and-tie model (STM) method evolved as one of the most useful designs for shear critical structures and discontinuity regions (D-regions). It provides widespread applications in the design of deep beams as recommended by many codes. The estimation of bottle-shaped strut dimensions, as a main constituent of STM, is essential in design calculations. The application of carbon fibre reinforced polymer (CFRP) as lightweight material with high tensile strength for strengthening D-regions is currently on the increase. However, the CFRP-strengthening of deep beam complicates the dimensions estimation of bottle-shaped strut. Therefore, this research aimed to investigate the effect of CFRP-strengthening on the deformation of RC strut in the design of deep beams. Two groups of specimens comprising six unstrengthened and six CFRP-strengthened RC deep beams with the shear span to the effective depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were constructed in this research. These beams were tested under four-point bending configuration. The deformation of struts was experimentally evaluated using the values of strain along and perpendicular to the strut centreline. The evaluation was made by the comparisons between unstrengthened and CFRP-strengthened struts regarding the widening and shortening. The key variables were a/d ratio and applied load level