Barzin Mobasher

Arizona State University | ASU · School of Sustainable Engineering and the Built Environment

Hybrid reinforced concrete (HRC) is referred to as a structural member that combines continuous reinforcement with randomly distributed chopped fibers in the matrix. An analytical model for predicting flexural behavior of HRC which is applicable to conventional and fiber reinforced concrete (FRC) is presented. Equations to determine the moment–curv...

Closed form equations for generating moment–curvature response of a rectangular beam of fiber reinforced concrete are presented. These equations can be used in conjunction with crack localization rules to predict flexural response of a beam under four point bending test. Parametric studies simulated the behavior of two classes of fiber reinforced c...

The utilization of Ultra-High-Performance Concrete (UHPC) for connecting bridge elements in accelerated bridge construction has become increasingly prevalent. Among their various applications, connecting bridge decks using UHPC stands out due to its ability to leverage key properties, including enhanced shear strength, tensile strength, compressive...

There is tremendous potential to enhance the tensile force capacity of concrete using alternative reinforcements. This approach may offer a remedy to one of the most inefficient and unsustainable approaches in the structural design of reinforced concrete. Analytical results of standard design procedures show that the load-bearing capacity of a conc...

Textile-reinforced concrete (TRC) has gained a lot of attraction in recent years. Adequate bond between the phases in this system allows to transfer high loadings, thus enabling high performance. The terminus textile reinforcement, however, comprises many different types of fabrics, which differ in their chemical composition, geometry, surface prop...

Statistical process control (SPC) procedures are proposed to improve the production efficiency of precast concrete tunnel segments. Quality control test results of more than 1000 ASTM C1609/C1609M beam specimens were analyzed. These specimens were collected over 18 months from the fiber-reinforced concrete (FRC) used for the production of precast t...

The widespread use of carpets in residential and commercial buildings and their relatively short life span result in large volumes of carpet being landfilled. A potential solution to this problem is the use of post-consumer carpet fibers in concrete. To this end, this paper systematically identifies the common fiber types in a typical post-consumer...

Present research brings a broad analysis on the influence of steel fibers on quasi-static and fatigue rebar pull out loading. The analysis covers the impact of fiber addition on diverse mechanical parameters, such as peak bond strength, stiffness and bond degradation under fatigue. A model previously developed for single fiber pull out in the liter...

Present research brings a novel methodology to estimate FRC mechanical degradation throughout closed-form solutions for FRC beams. The first step consisted on deriving the constitutive relations for tension and compression. While a quad-linear model was used for tension, an elastic perfectly plastic model was applied for compression aiming to reach...

Structural applications of hybrid reinforced concrete (HRC) involve a composite system with a fiber-reinforced concrete (FRC) matrix in conjunction with conventional reinforcement. The system offers economic benefits by reducing the number of rebars, minimizing labor costs, and shortening the construction schedule. This paper presents the generaliz...

A pultrusion system was developed for manufacturing micro polypropylene textile-reinforced concrete (PP-TRC) composites. Warp-knitted textiles with pillar and tricot knitted patterns were produced from micro multifilament PP yarns and fed into the mortar in a computer-controlled production setup. Instrumented uniaxial tension mechanical tests were...

Structural applications of hybrid reinforced concrete (HRC) involve a composite system with a fiber-reinforced concrete (FRC) matrix in conjunction with conventional reinforcement. The system offers economic benefits by reducing the number of rebars, minimizing labor costs, and shortening the construction schedule. This paper presents the generaliz...

Textile-reinforced concrete (TRC) is used widely in thin-walled structures due to its unique construction characteristics and superior mechanical properties. However, previous studies of the dynamic flexural properties of alkali resistant (AR)-glass TRC thin plates did not consider the influence of exposure to high temperature. In this study, the e...

Precast tunnel lining segments manufactured with synthetic macro-fibers and steel fibers as the primary reinforcement were tested under flexural and edge compression loading. Since steel fibers are usually prescribed as the primary reinforcement of tunnel sections, the dosage of synthetic fibers was determined by matching their residual flexural st...

A pultrusion system was developed for manufacturing micro polypropylene textile-reinforced concrete (PP-TRC) composites. Warp-knitted textiles with pillar and tricot knitted patterns were produced from micro multifilament PP yarns and fed into the mortar in a computer-controlled production setup. Instrumented uniaxial tension mechanical tests were...

A piecewise linear parametric constitutive model of elastic-plastic-hardening in tension and elastic-plastic in compression is used to develop closed-form solutions for flexural moment-curvature of generalized sections. Brittle matrix composite such as Textile Reinforced Concrete (TRC) is homogenized using three zones of elastic, distributed cracki...

The mechanical response of textile-reinforced aerated concrete sandwich panels was modeled for flexural loading. The core material used in the sandwich composite consisted of plain autoclaved aerated concrete (AAC) and fiber-reinforced aerated concrete (FRAC). The stress skins for the sandwich beams were made out of AR-glass (ARG) textiles embedded...

The interfacial shear bond strength (τ) between fibers and matrix is typically measured by fiber pullout test to determine the critical fiber length (Lc) in fiber reinforced composites. In fiber reinforced asphalt concrete (FRAC), the τ is a time-dependent property and it is affected by asphalt modulus. The main objective of this study was to estab...

Textile reinforced concrete (TRC) is becoming an emerging high-performance construction material due to its outstanding load-bearing capacity, corrosion resistance, and durability. However, the influences of textile type and design parameters on the mechanical performance of TRC have not been fully understood. Therefore, this study aims to enhance...

Synopsis: The influence of engineered hydrophilic polypropylene fibers in the formation of distributed cracking and the associated strengthening and toughening of cement-based composites under mechanical loading was studied by conducting, correlating, and modeling tensile and flexural tests. An automated filament winding system was used to manufact...

Textile reinforced concrete (TRC) has a higher sustainable potential than conventional reinforced concrete, with a significantly lower CO2 footprint. To study the dynamic flexural behavior of TRC composites, the Alkali Resistant (AR)-glass textile reinforced concrete (TRC) plate specimens was investigated with the three-point bending test under low...

The life cycle costs of structural systems are a function of raw materials, labor, energy, environmental impact, serviceability, and durability. Textile Reinforced Concrete (TRC) using alternative reinforcing systems are cost competitive and have gained popularity among new construction materials. TRC composites are uniquely lightweight with a very...

Fiber reinforcement in precast tunnel segments is quite attractive since it reduces the cost and labor associated with the fabrication process while it improves the post-cracking behavior considerably. Among the benefits, one can address improvements in handling, fatigue, impact resistance and durability while reducing the crack widths significantl...

A n article by Johan L. Silfwerbrand in the May 2021 issue of Concrete International discussed applications of steel fiber-reinforced concrete (SFRC) in industrial floors. 1 Several statements warrant further discussion, particularly concerning the so-called Belgian/Continental (Belgian) and Swedish approaches for the design of SFRC slabs. In the i...

Description As the field of additive construction continues to grow exponentially, new standards will be needed for this expanding technology to ensure the safety of the public. Sponsored by ASTM International Committee C09 on Concrete and Concrete Aggregates, this book provides the provides the latest qualification procedures being proposed by res...

Foamed concrete is an attractive material for structural use and insulation of buildings, which can replace flammable organic insulating materials on the market. This study investigated the compressive and thermal properties of the plain, fly ash and expanded polystyrene (EPS) foamed concrete ranging widely in density from 180 to 1800 kg/m³. Furthe...

The fiber-reinforced polymer (FRP) composites are currently widely used in infrastructure construction, and the study on the dynamic performance and temperature sensitivity is still under investigation. Understanding the effects of strain rate and temperature on the tensile behaviour of FRP composites is vital to design the composite structures und...

An overview of the modeling work on the structural performance of textile reinforced concrete materials is presented. Key components of the composite response, mechanisms, and modes that contribute to ductility are addressed in terms of crack distribution, strain hardening/softening and tension stiffening. Three different approaches are used for te...

The nature of cracking in flexural specimens made using ultra-high-performance concrete (UHPC) is studied in the context of mechanisms of enhanced strength and ductility. The effect of fibers on the suppression of cracking and the attendant toughening mechanisms are addressed at two different fiber contents to elucidate the strain-softening and str...

The rate-sensitive properties of ultra-high performance concrete (UHPC) subjected to flexural and direct tensile loads were investigated. Dynamic flexural tests were performed by means of a drop hammer impact machine, whereas a servo-hydraulic system was utilized to conduct direct tension tests. The absorbed energy of the UHPC specimens under flexu...

Mechanical response of textile-reinforced aerated concrete sandwich panels was investigated using instrumented three-point bending tests under quasi-static and low-velocity impact loads. Two types of core material were compared in the sandwich composite consisting of plain autoclaved aerated concrete (AAC) and fiber-reinforced aerated concrete (FRA...

Statistical process control procedures are widely applied to improve the production efficiency of industrial products. Application of quality control procedures in monitoring the production, delivery, and construction process are essential, especially when the historical data collected on various projects can be used to gain better insight to the o...

This study examines the merits of using biochar to delay aging in construction while promoting the economic viability of biofuel production and enhancing the biomass value chain. Biochar residue from pyrolysis of biomass to biofuel was introduced to neat asphalt and rubberized asphalt binders. The study results showed biochar can delay oxidation an...

Ultra-high performance (UHP) cement pastes with 30–50% of cement (by mass) replaced by multiple cement replacement materials are evaluated in this study through concise nanomechanical investigations and qualitative chemical intensity mapping. Nanomechanical clustering identifies high density (HD) C-S-H and an ultra-high stiffness (UHS) phase as the...

This guide addresses the use of externally bonded (EB) fabricreinforced cementitious matrix (FRCM) and steel-reinforced grout (SRG) systems for repair and strengthening of masonry structures. FRCM and SRG are composite materials composed of a reinforcement in the form of open fabric bonded on the masonry surface through an inorganic matrix. In part...

Textile reinforced ultra high performance concrete (TR-UHPC) is developed to further improve the tensile strength and ductility with reduced steel fiber contents. Alkali resistant glass textiles are used to partially replace steel fibers in a hybrid manner. The effects of different steel fiber content on the tensile and bending properties is invest...

Precast concrete segments are the predominant support method used in tunnels dug by Tunnel Boring Machines (TBM) in soft ground and weak fractured rock, providing the initial and final ground support. Conventionally, steel bars are used in concrete segments to resist tensile stresses developed due to all loading cases from the time of casting throu...

This paper presents a novel strategy to design the binder phase of ultra-high performance concrete (UHPC) from commonly available cement replacement (fly ash, slag, microsilica, metakaolin) and fine filler (limestone) materials. A packing algorithm is used to extract the number density, mean centroidal distance, and coordination number of the micro...

The increasing demands of sustainable design and construction with economical sections, reduced cover, and more efficient time schedule require more flexibility in the design methodologies. The development of ultra‐high performance concrete (UHPC) have gained increasing interests as an attractive option for structural members with lightweight and s...

The nanomechanical signature of highly heterogeneous ultra-high performance (UHP) cement pastes are explored in this paper. The UHP pastes are proportioned using 30% or 50% (by mass) of commonly available cement replacement materials including fly ash, microsilica, and fine limestone. Nanoindentation experiments coupled with a Bayesian information...

This report addresses the development of non-proprietary mix designs for manufacturing ultra-high–performance concrete (UHPC) mixtures using materials commercially available in Arizona. The comprehensive work carried out addresses the development of paste, mortar, and concrete mixtures based on theoretical, analytical, and experimental optimization...

Coupling of separate optimizations of binder and aggregate phases to produce sustainable and economical ultra high-performance concrete (UHPC) mixtures is reported. Binders containing commonly available cement replacement materials with a (mass-based) cement replacement level between 30% and 50% are selected using microstructural packing-and rheolo...

The effect of the microstructure of hydrophilic polypropylene (PP) fibers in the distribution of cracking associated with the strengthening and toughening mechanism of cement-based composites under tensile loading was studied. Using a filament winding system, continuous cement-based PP fiber composites were manufactured. The automated manufacturing...

The pullout behavior of single filament jute fibers and yarns from a low calcium hydroxide cement matrix were studied. Pullout tests were performed in the micro and meso scales. In the micro scale, the tests were conducted inside an environmental SEM. The fibers were treated with styrene butadiene polymer to improve the fiber-matrix bond and a doub...

First Principles-Based Design of Economical Ultra-High Performance Concrete

The prospect of TRC as a legitimate alternative to common construction materials shows promise of many advantages including cost reduction, sustainability, and structural longevity. An automated TRC manufacturing process based on the standard industrial techniques was developed and used to produce and test full scale TRC composite structural sectio...

This paper presents design procedures for 1-D and 2-D strain hardening cement composites (SHCC) members based on analytical models. Closed-form solutions of moment-curvature responses of SHCC are derived based on elastic perfectly plastic compressive model and trilinear strain hardening tension model. Tension stiffening behavior of SHCC due to fibe...

The fracture response of cementitious composites containing compliant microencapsulated inclusions and its influence on the fracture process zone (FPZ) are reported. The incorporation of small amounts of phase change material (PCM) microcapsules (replacing up to 10% by volume of sand) is found to slightly improve the strength, fracture toughness, c...

The new rapid chloride permeability test, in which chloride ions are driven into concrete samples electrically over a 6-hour period, is becoming widely used and has been accepted as an American Association of State and HighwayTransportation Officials (AASHTO) standard, T277. This paper summarizes the results of an extensive series of laboratory tes...

This paper reports synthesis routes and microstructural and performance characterization of a family of economical, multifunctional porous ceramics developed through geopolymerization of an abundant volcanic tuff (aluminosilicate mineral) as the primary source material. Metakaolin, silica fume, alumina powder, and pure silicon powder are also used...

Materials and mechanical design procedures for ultra-high performance cement composites (UHPC) members based on analytical models are addressed. A procedure for the design of blended components of UHPC is proposed using quaternary cementitious materials. The blending procedures are used using a packing and rheology optimization approach to blend hi...

A constitutive model consisting of a tri-linear tensile stress-strain with residual strength was applied in characterization and prediction of long term flexural behavior of several cement-based composite materials. Flexural test results were back-calculated to obtain material parameters and establish their relationship with aging. The material beh...

A standard approach is presented to obtain analytical solutions for deflection field of determinate beams subjected to conventional loading patterns. The solutions are based on a trilinear moment–curvature response using a deflection hardening behavior characterized by flexural crack initiation, inelastic response due to crack extension, and full p...

Fiber reinforcement has emerged as an alternative to traditional reinforcing bars and welded wire mesh reinforcement for precast concrete tunnel segments. This is mainly due to improved postcracking behavior and crack control characteristics of fiber-reinforced concrete (FRC) segments. A hybrid solution of fibers and reinforcing bars is adopted whe...

Mechanical properties of strain-hardening cement-based composites (SHCC) subjected to impact and high-speed tensile loading were studied. The impact test setup was based on a free-fall drop weight on a three-point bending specimen. A servohydraulic high-speed tensile machine was used for tension tests. As the input impact energy increased from 6.7...

This paper reports strategies to design the binder phase of ultra-high performance concretes (UHPC) from commonly available cement replacement (fly ash, slag, microsilica, metakaolin) and fine filler (limestone) materials. A packing algorithm is used to extract the number density, mean centroidal distance, and coordination number of the microstruct...

Textile reinforced concrete (TRC) has emerged in recent years as an attractive new high performance cement-based composite. Textiles can significantly improve the mechanical behavior of cement matrices under static and dynamic conditions, and give superior tensile strength, toughness, ductility, energy absorption and protection against environmenta...

This study proposes a comprehensive analysis on the structural performance of reinforced Recycled Aggregate Concrete members. Particularly it summarizes the results of an experimental investigation aimed at analyzing the tension stiffening behavior of normal and high strength class concretes produced with Recycled Concrete Aggregates (RCAs). The mi...

This study proposes a comprehensive analysis on the structural performance of reinforced Self Compacting High Strength Fiber Reinforced Concrete members. Particularly, it summarizes the results of an experimental investigation aimed at analyzing the tension stiffening behavior of concrete mixtures produced with different kinds of natural aggregates...