Flow and Strength Characteristics of Ultra-high Performance Fiber Reinforced Concrete: Influence of Fiber Type and Volume-fraction

Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) has emerged all of the concrete in the construction industry because of its high strength, durability, serviceability and excellent ductility recently. Due to its high production cost, UHPFRC restricts its large-scale structural application. The conventional UHPFRC preparation consists of expensive materials such as specially graded sands which require complex mixing and curing process. The aim of this paper is to determine flow and strength properties of UHPFRC with the variation of fiber type and fiber volume-fraction. The UHPFRC composition was selected with four different fiber volume fractions (Vf = 0%, 1%, 2%, and 3%) of three different steel fibers at varying curing ages of 7, 28, 56 and 90 days within an identical mortar matrix. The paper provides an overview on the workability properties of UHPFRC followed by the presentation of compressive strength test results with different fibers and its volume-fraction with varying curing ages. The higher fiber volume-fraction resulted in a lower flow, and consequently an improvement of compressive strength observed up to 3% volume-fraction of fibers at 56 days curing. Finally, test results are compared and discussed with regard to the main variables: fiber volume-fraction, types of fiber; and curing ages of the specimens

Performance of self-compacting concrete incorporating waste glass as coarse aggregate

The purpose of this paper is to develop gather data on the rheological and mechanical properties of self-compacting concrete (SCC) containing varying percentages of waste glass aggregate (WGA). In this current experiment, the coarse aggregate was substituted by adding WGA, with replacement percentages of 0%, 10%, 20%, and 30% by weight being investigated. The rheological properties of SCC were performed to explore the consequence of WGA using various methods, including the J-ring, slump flow, L-box, and V-funnel. In contrast, the compressive, flexural, modulus of elasticity, and stress-strain responses of hardened concrete were assessed in this study. The results of the fresh concrete tests revealed that the substitution of an optimal level of waste glass in SCC provides adequate implementation in flowability, passing ability, and viscosity behaviors. Besides, hardened characteristics were shown to have a steady decrease in strength with increasing WGA content in the concrete mixtures

Critical project management success factors analysis for the construction industry of Bangladesh

Purpose – This paper aims to identify the critical project management success factors and analyze those factors to achieve a sustainable construction industry in Bangladesh. Design/methodology/approach – This study identified 41 major problematic factors from the related literature. In this research, a detailed questionnaire survey was conducted among the experts and stakeholders of the construction industry of Bangladesh. The survey was carried out on a Likert scale and ranked the critical factors using the relative importance index (RII). The 41 problematic factors were divided into five group factors and ranked by the RII index to prioritize the factors. Finally, stakeholders’ opinions were analyzed with the critical assessed factors, which was a very effective technique to eliminate the risks and uncertain occurrences in the construction industry of Bangladesh. Findings – The factors analysis revealed that cost overrun, traffic jam, low wedges, slow payment for completed works and financial issues of the owner were leading critical factors in construction projects. Moreover, the critical factors are divided into five-factor groups, namely, financial management, monitoring and feedback, competency management, communication and coordination management, and risk management, which exhibit 0.767, 0.720, 0.711, 0.710 and 0.658 RII values. After all, the stakeholders’ opinion suggested that implementing modern tools and techniques can help to avoid the critical situation in the construction industry of Bangladesh. Practical implications – The construction industry of Bangladesh is moving away from stable construction work day by day. Previously, the potential CSFs were discussed unstructured way. Hence, detecting early warning signals in a structured way has become necessary for the building firm’s survival. Originality/value – Though some scattered critical issues are discussed in different literature, the critical issues of the Bangladeshi construction industry were not investigated extensively. Therefore, this study finds out the potential critical issues of the construction industry of Bangladesh to accumulate such harmful construction issues in a single platform so that the construction industry can have an overview of them with the help of innovative technologies

Eco-friendly self-consolidating concrete production with reinforcing jute fiber.

Self-consolidating concrete (SCC) has many advantages compared to traditional concrete. However, it often suffers from high brittleness that limits its various applications. Reinforcing the SCC by fiber inclusion can be a fruitful way to enhance its performance. This study aims to investigate how the rheological and mechanical characteristics of SCC are affected by the addition of jute fibers for a specific length of 20 mm at various volumetric fractions of 0.1%, 0.25%, 0.50%, 0.75%, and 1%. Slump flow, J-ring flow, V-funnel, L-box, and Sieve stability tests were performed to investigate the rheological properties of jute fiber reinforced self-consolidating concrete (JFRSCC); while, compressive, splitting tensile, and flexural strength tests were conducted to determine mechanical properties at 7 and 28 days. Scanning electron microscopy (SEM) testing was also used to examine the microstructures of JFR-SCC. These rheological and hardened states were then compared with the control SCC. JFR-SCC performed satisfactorily in terms of flowability, viscosity, and segregation resistance. However, adding more than 0.25% jute fiber in SCC mixes significantly affected the passing ability. The maximum improvements in compressive, splitting tensile, and flexural strength were 2%, 21%, and 18%, respectively, over the reference mix at 28 days. The jute fibers can fill the microcracks in concrete and prolong the ultimate failure. Hence, SCC with jute fiber can be adopted as an eco-friendly alternative to SCC with artificial fibers

Development of Self-Compacting Concrete Incorporating Rice Husk Ash with Waste Galvanized Copper Wire Fiber

This research work is devoted to the experimental investigation of both rheological and mechanical properties of self-compacting concrete (SCC) produced with waste galvanized copper wire fiber and rice husk ash (RHA). In the study, three different volume fractions of 0.5 p to 0.75 percent, 1 percent of scrap copper wire fiber as reinforcing material, and 2 percent RHA as cement replacement were used. To evaluate the fresh characteristics of SCC, the slump flow, J-ring, and V-funnel experiments were conducted for this investigation. Compressive strength, splitting tensile strength, and flexural strength of the concrete were conducted to assess the hardened properties. The test was carried out to compare each characteristic of plain SCC with this modified SCC mixture, containing RHA as pozzolanic materials and copper fiber as reinforcing material. Incorporating copper fiber in the SCC leads to a drop in fresh properties compared to plain SCC but remains within an acceptable range. On the other hand, the inclusion of 2% RHA makes the SCC more viscous. Although adding 2% RHA and 1% copper wire in SCC provide the highest strength, this mix has an unacceptable passing ability. The SCC mix prepared with 2% RHA and 0.75% copper fiber is suggested to be optimum in terms of the overall performance. According to this study, adding metallic fiber reinforcement like copper wire and mineral admixture like RHA can improve the mechanical properties of SCC up to a certain level

Performance of self-compacting concrete incorporating waste glass as coarse aggregate

The purpose of this paper is to develop gather data on the rheological and mechanical properties of self-compacting concrete (SCC) containing varying percentages of waste glass aggregate (WGA). In this current experiment, the coarse aggregate was substituted by adding WGA, with replacement percentages of 0%, 10%, 20%, and 30% by weight being investigated. The rheological properties of SCC were performed to explore the consequence of WGA using various methods, including the J-ring, slump flow, L-box, and V-funnel. In contrast, the compressive, flexural, modulus of elasticity, and stress-strain responses of hardened concrete were assessed in this study. The results of the fresh concrete tests revealed that the substitution of an optimal level of waste glass in SCC provides adequate implementation in flowability, passing ability, and viscosity behaviors. Besides, hardened characteristics were shown to have a steady decrease in strength with increasing WGA content in the concrete mixtures

Assessing the influence of fly ash and polypropylene fiber on fresh, mechanical and durability properties of concrete

This paper focuses on the investigation of fresh, mechanical, and durability properties of concrete with the influence of fly ash and polypropylene fiber. In this study, cement was partially replaced by 15 % and 30 % fly ash content in weight, whereas polypropylene fiber was incorporated in concrete mixes at 0.06 %, 0.12 %, and 0.18 % by volume. Twelve concrete mix proportions were developed, and slump, density, ball penetration, and compacting factor tests were conducted to examine the fresh concrete properties. Besides, mechanical characteristics, including the uniaxial compressive and splitting tensile strength of concrete, were evaluated at 7, 28, and 90 days. Further tests of concrete durability, including rapid chloride permeability test, sorptivity, and water penetration, were performed at 90 days. The results exhibited that the incorporation of fly ash developed fresh concrete properties, while polypropylene fiber decreased the fresh characteristics of concrete. Furthermore, the combination of fly ash and polypropylene fiber in concrete was substantially attained to improve the mechanical and durability characteristics compared to the control mix. Mix proportion of 15 % fly ash and 0.12 % polypropylene fiber exhibited a pronounced influence on compressive strength, chloride permeability, sorptivity, and water penetration compared to other concrete mixtures

Evaluating the effects of recycled concrete aggregate size and concentration on properties of high-strength sustainable concrete

This paper studies the fresh and mechanical properties of high-strength concrete (HSC) by incorporating recycled concrete aggregates (RCA) of varying sizes and concentrations. The recycled aggregate concrete (RAC) was prepared by partially replacing RCA with natural coarse aggregate (NCA) at 0%, 15%, 30%, and 45%, with aggregate sizes ranging from 5 to 12 and 12–20-mm. Fresh concrete properties, such as slump, Kelly ball, compacting factor, K-slump, and fresh density, were tested to determine the influence of RCA size and concentration. In addition, the mechanical properties were studied through the execution of compressive, split-tensile, and stress-strain tests. The test results revealed that increasing the RCA concentration declines the fresh and hardened properties of HSC. In the fresh concrete experimentation, the 12–20 mm aggregate size RAC mixes exhibited greater workability than the 5–12 mm aggregate mixes. On the contrary, 5–12 mm aggregate mixes RAC had higher compressive and split-tensile strength and a higher modulus of elasticity than 12–20 mm aggregate mixes concrete. When it comes to sustainability, the study found that the smaller size range of RAC produces inferior embodied CO2 (eCO2) and provides a cost-effective and sustainable solution for the construction industry

Mechanical Properties and Flexural Response of Palm Shell Aggregate Lightweight Reinforced Concrete Beam

This work focuses on examining the mechanical characteristics and flexural response of reinforced concrete (RC) beams by incorporating oil palm shell (OPS) lightweight aggregate from oil palm shell waste. The OPS aggregates are replaced in various percentages, such as 0 to 50% of natural coarse aggregate (NCA). Mechanical properties of OPS concrete were conducted, and these properties were used to quantify the flexural performance of RC beams. Five RC beams with several gradations of OPS aggregates were cast and tested for this investigation. The first cracking, ultimate strength, load-deflection behavior, ductility index, and failure patterns of OPS aggregate beams were investigated as the corresponding behaviors to the NCA concrete beam. The fresh properties analysis demonstrated lessening the slump test by varied concentrations of OPS concrete. Furthermore, compressive strength was reduced by 44.73%, 50.83%, 53.33%, and 57.22% compared to 10%, 15%, 20%, and 50% OPC substitution at 28 days. Increasing OPS content in concrete mixes decreased splitting tensile strength, comparable to the compressive strength test. Modulus of rupture and modulus of elasticity experiments exhibited a similar trend toward reduction over the whole range of OPS concentrations (0–50%) in concrete. It was revealed that the flexural capacity of beams tends to decrease the strength with the increased proportion of OPS aggregate. Moreover, crack patterns and failure modes of beams are also emphasized in this paper for the variation of OPS replacement in the NCA. The OPS aggregate RC beam’s test results have great potential to be implemented in low-cost civil infrastructures

Integration of Rice Husk Ash as Supplementary Cementitious Material in the Production of Sustainable High-Strength Concrete

The incorporation of waste materials generated in many industries has been actively advocated for in the construction industry, since they have the capacity to lessen the pollution on dumpsites, mitigate environmental resource consumption, and establish a sustainable environment. This research has been conducted to determine the influence of different rice husk ash (RHA) concentrations on the fresh and mechanical properties of high-strength concrete. RHA was employed to partially replace the cement at 5%, 10%, 15%, and 20% by weight. Fresh properties, such as slump, compacting factor, density, and surface absorption, were determined. In contrast, its mechanical properties, such as compressive strength, splitting tensile strength and flexural strength, were assessed after 7, 28, and 60 days. In addition, the microstructural evaluation, initial surface absorption test, = environmental impact, and cost–benefit analysis were evaluated. The results show that the incorporation of RHA reduces the workability of fresh mixes, while enhancing their compressive, splitting, and flexural strength up to 7.16%, 7.03%, and 3.82%, respectively. Moreover, incorporating 10% of RHA provides the highest compressive strength, splitting tensile, and flexural strength, with an improved initial surface absorption and microstructural evaluation and greater eco-strength efficiencies. Finally, a relatively lower CO2-eq (equivalent to kg CO2) per MPa for RHA concrete indicates the significant positive impact due to the reduced Global Warming Potential (GWP). Thus, the current findings demonstrated that RHA can be used in the concrete industry as a possible revenue source for developing sustainable concretes with high performance