2022-01

Case Studies in Construction Materials (Issue : 17) (Volume : 01281)

This research shows the results and conclusions of an experimental study that aims to shed light on the mechanical performance of Slurry Infiltrated Fiber Concrete (SIFCON) (i.e. compressive strength, splitting tensile strength, flexural strength, Poisson’s ratio, elastic modulus, and ultrasonic pulse velocity (UPV) and explore its efficiency at elevated temperature (i.e. 200, 400 and 600 ◦C) with different steel fiber ratios of 5 %, 7.5 %, and 10 % cured standard and in boiling water (accelerated curing). Hence, sets of cylinders and prisms are cast and tested under ASTM standard conditions. The results indicate that mechanical properties improve by increasing the steel fiber ratio up to 7.5 % in the case of a standard curing system, but more improvement is achieved with a steel fiber ratio up to 10 % in case of accelerated curing with boiling water. Also, the results indicate the superiority of the accelerated curing method for flexural and splitting tensile strength. Fly ash has a good contribution to the enhancement of mechanical performance of SIFCON with high steel fiber ratios. A decreasing and drastic reduction in compressive strength with increasing temperature above 200 and 400 ◦C for control specimens and SIFCON specimens with fiber ratios of 5 %, respectively are observed. While a dramatic gain in the strength of SIFCON samples with fiber ratios of 7.5 % and 10 % is concluded. High ratios of steel fiber can retard the spalling of concrete; hence it makes SIFCON the unique material for resisting explosive loads.

2021-01

Journal of Cleaner Production (Issue : 324) (Volume : 129251)

The disposal of waste rubber tires has become a main ecological issue around the world. Each year, millions of tires are disposed of, buried, or thrown away, which is a severe hazard for the environment due to its prolonged degrading period. Therefore, recycling waste rubber as aggregates as a supplemental construction material is beneficial. The usage of crumbs rubber (CR) would be led to sustainable utilization of waste material, which would preserve depleting natural aggregate sources and protecting the environment. This paper reviews the published research on the performance of concrete containing CR as eco-friendly aggregates. Moreover, it highlights the impact in terms of aggregate substitution content, form, size, and waste treatment on the fresh and mechanical properties of crumb rubber concrete (CRC). The paper also aims to update the database for further experimental and numerical research on rubberized concrete.

2017-01

Elsevier, Engineering Science and Technology, an International Journal (Issue : 20) (Volume : 20)

In this article, the efficiency of waste glass powder was investigated in enhancing the mechanical properties of concrete at high temperature. Chemical composition of this powder reveals that it plays good role as effective inert very fine material in concrete strength improvement. Conventional reactive pozzolanic powder of silica fume was used also in present work to show the degradation degree in concrete strength under firing in comparison to concrete made with waste glass powder. The experimental program was comprised of tests for examining fire resistance and mechanical properties of high strength concrete (HSC) after firing. Fifty-six concrete cylinders and prisms were manufactured for measuring their compressive and flexural strengths, modulus of elasticity and stress-strain behavior at high temperature. Failure modes were considered also for the specimens after fire exposure. Results demonstrate the great role of waste glass powder in conserving residual strength at high temperature. Accordingly, it is proved that the HSC made with waste glass powder has strength at high temperature more than that for concrete fabricated by silica fume.

2017-01

Journal of University of Duhok (JDU) (Issue : 1) (Volume : 20)

Present endeavor is devoted to investigate the flexural strength of beams fabricated by ordinary concrete (OC) and retrofitted with high strength concrete (HSC). Old part of beams is represented the deteriorated concrete; while the new part is referred to retrofitted portion of the deteriorated beam. Bond strength between two concrete parts of beam was enhanced via preparing rough interfacial surface in various ways, namely, sand blast, holes, grooves and steel brush. Experimental measurements are given in terms of flexural load – deflection relationship and cracking pattern of the beams. It is demonstrated that the beams with sand blast interfacial surface show reasonable performance with high flexural toughness and safer cracking at collapse.

2016-10

ZANCO Journal of Pure and Applied Sciences (Issue : 28) (Volume : 4)

The paper presents results of an experimental investigation carried out on reinforced, low strength concrete columns strengthened by Carbon Fiber Reinforced Polymers (CFRP). The columns were tested under concentric compression until failure. The shape and the slenderness of the column, the thickness and the configuration of confinement were the basic parameters considered in the experimental program. The main objective of the investigation was to study the effectiveness of using CFRP as an external strengthening method to increase the ultimate load of the low concrete strength columns. Using the CFRP enhanced the ultimate load of the columns for all specimens, the increase in ultimate load ranges between 15 % and 291 % compared to the control specimens. The partial confinement is not as effective in increasing the column ultimate load as compared with full confinement. The CFRP confinement is not as effective in increasing the ultimate load of square columns as for circular columns. The gain in ultimate load increases as the number of CFRP wraps. The strength behavior was affected by the cross-section shape and slenderness ratio.

2013-07

International Journal of Civil Engineering (IJCE) (Issue : 3) (Volume : 2)

Ultra-high performance fiber reinforced concrete (UHPC) is a new class of concrete that has been developed in recent decades, it has enhanced properties such as; very high compressive strength, improved tensile strength. In this study, three types of concrete were used based on the compressive strength of concrete, named; Normal Strength Concrete (NSC) of (𝑓′ 𝑐 = 42 MPa), High Strength Concrete (HSC) of (𝑓′ 𝑐 = 63.75 MPa) and Ultra High Performance Concrete (UHPC) of (𝑓′ 𝑐 = 134.5 MPa).The experimental program included casting and testing of fifteen reinforced concrete deep beams without web reinforcement (stirrups), nine specimens of (UHPC), three specimens of (HSC) and three specimens of (NSC), in order to study the shear strength and behavior of deep beams under two point loading. Considered variables were; the compressive strength of concrete (42, 63.75 and 134.5 MPa), the shear span to depth ratio (a/d) (1, 1.5 and 2) and over all depth of the beam (h) (180, 240 and 300 mm), while the width of all beams was (120 mm). The experimental results showed that the compressive strength of concrete also the shear span to depth ratio (a/d) has a significant effect on failure load, while the increase in overall depth of the beam from (180 to 240) mm reduces the nominal shear stress significantly, but beyond which no obvious size effect can be seen.