Sharif Digital Repository

Effects of pozzolans and fibers on mechanical properties of RCC are addressed. The mechanical properties were evaluated using optimum moisture with different amounts of pozzolans, steel and polypropylene fibers. Using pozzolans, maximum increase in compressive strength was observed to occur between 28 and 90 days of age, rupture modulus was found to decrease; but toughness indices did not change considerably. The influence of steel fibers on compressive strength was often more significant than that of PP fibers; but neither steel nor PP fibers did contribute to increase in the rupture modulus independently from pozzolans. Also, the toughness indices increased when steel fibers were used  

The current study revealed the effectiveness of polypropylene (PP) fibers and cement to enhance the strength of black cotton soil. PP fibers and cement with different concentrations were mixed with black cotton soil. The strength of PP fiber and cement-based soil samples was measured in terms of unconfined compressive strength (UCS) and California Bearing ratio (CBR). Specimens for UCS and CBR tests were prepared at 2%, 4%, 6% and 8% of cement (by dry weight of soil) and seven percentages of polypropylene fibers i.e. 0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 0.6% (by dry weight of soil). Fourier transform infrared (FTIR) analysis confirmed the presence of polypropylene and cement contents in... 

The current study revealed the effectiveness of polypropylene (PP) fibers and cement to enhance the strength of black cotton soil. PP fibers and cement with different concentrations were mixed with black cotton soil. The strength of PP fiber and cement-based soil samples was measured in terms of unconfined compressive strength (UCS) and California Bearing ratio (CBR). Specimens for UCS and CBR tests were prepared at 2%, 4%, 6% and 8% of cement (by dry weight of soil) and seven percentages of polypropylene fibers i.e. 0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 0.6% (by dry weight of soil). Fourier transform infrared (FTIR) analysis confirmed the presence of polypropylene and cement contents in... 

In this article, the self-compacting lightweight concretes (SCLC) with different fibers were prepared and exposed to elevated temperatures, and their mechanical properties were investigated. Three types of fibers were steel fibers (SF), polypropylene fibers (PPF), and metal springs with a volume fraction of 0.4%. One hundred and fifty cylindrical specimens were prepared, and the compression, tensile and flexural tests were carried out on them after exposure to high temperatures ranging from 25 to 700°C. The findings indicate that incorporation of steel fibers and springs enhanced the compressive strength of concrete by 20% compared to the control specimen. Meanwhile, the polypropylene fibers... 

In this article, the self-compacting lightweight concretes (SCLC) with different fibers were prepared and exposed to elevated temperatures, and their mechanical properties were investigated. Three types of fibers were steel fibers (SF), polypropylene fibers (PPF), and metal springs with a volume fraction of 0.4%. One hundred and fifty cylindrical specimens were prepared, and the compression, tensile and flexural tests were carried out on them after exposure to high temperatures ranging from 25 to 700°C. The findings indicate that incorporation of steel fibers and springs enhanced the compressive strength of concrete by 20% compared to the control specimen. Meanwhile, the polypropylene fibers... 

One effective method for preventing corrosion of steel reinforcement and improving the mechanical properties of concrete is changing the physical nature of concrete by adding different materials. In this study, we have used polypropylene fibers as an additional material. We have compared the corrosion rate of rebar using different volume ratios and sizes of polypropylene fibers. Reinforcement potential increased as the amount of fibers increased from 0 to 2 kg m -3. The polypropylene fibers delay the initial corrosion process by preventing cracking, thereby decreasing permeability of the concrete. In addition, the corrosion rate of concrete samples made with Kish Island coral aggregate was... 

This paper presents the results of an experimental study of structural lightweight concrete with glass fiber reinforcement (GFRP) bar for prefabricated single footing. In this study, seven full scale concrete single footings specimens, which were reinforced by GFRP bar located on a bed of soil, were tested. One of the specimens was made of normal weight concrete and the others were made of structural lightweight concrete. Four of the lightweight footing specimens contained polymer fibers. Also, two of the lightweight footing specimens contained shear reinforcement. Results indicated that the maximum GFRP strain on normal weight and lightweight concrete footing with polypropylene fibers are... 

In this paper, the effects of both pozzolans and (steel and poly-propylene) fibers on the mechanical properties of roller compacted concrete are studied. Specimens for the experiments were made using a soil-based approach; thus, the Kango's vibration hammer was used for compaction. The tests in the first stage were carried out to determine the optimal moisture requirements for mix designs using cubic 150 × 150 × 150 mm specimens. In the tests of the second stage, the mechanical behaviors of the main specimens made using the optimal moisture obtained in the previous stage were evaluated using 28, 90, and 210 day cubic specimens. The mechanical properties of RCC pavements were evaluated using... 

The aim of the present study was to investigate the effect of pyrogenic nanosilica with different specific surfaces areas (200 and 380 m2/g) on mechanical properties of fiber-reinforced high-performance concrete (FRHPC) produced with two different types of fibers including steel and polypropylene fibers. Accordingly, different mechanical tests (compressive, splitting tensile and flexural strengths) as well as electrical resistivity were performed at 7, 28, and 91 curing days. In addition, the modulus of rupture and flexural toughness of FRHPC prisms were calculated based on the flexural testing results. Also, scanning electron microscopy test (SEM) was conducted to evaluate the... 

In the present paper, the effect of Nano silica on mechanical properties and durability of concrete containing polypropylene fibers has been investigated. Here, the length and length to diameter ratio of used polypropylene fibers were considered to be fixed and equal to 18 mm and 600 respectively and the cement content was 479 kg/m3. The effect of fibers and Nano silica in four different percentages for each one at 0.1, 0.2, 0.3 and 0.4 percent by volume for fibers and 3 percent for Nano silica in concrete with water to cement ratio of 0.33, 0.36, 0.4, 0.44 and 0.5 have been compared and evaluated. In total, more than 425 cubic and cylindrical specimens were made according to ASTM standards.... 

Alkali-activated slag (AAS) binder has been recognized as a suitable material for construction applications owing to its low carbon footprint and good mechanical and durability performance. As a promising alternative to the conventional Portland cement binder, it is important to maximize the performance of AAS composites under normal and harsh environmental conditions such as exposure to fire. The use of fibers in a brittle matrix is a well-known approach to enhance the mechanical strength and cracking behavior under thermal loading. In this study, polypropylene fiber (PPF), glass fiber (GF), and basalt fiber (BF) are used at volume fractions of 0.5%, 1%, and 1.5% in AAS mortar mixes. First,... 

Fracture process of fiber-reinforced concrete notched beams is investigated here. Polypropylene macrosynthetic fibers are utilized for reinforcing concrete specimens, and a high-strength mix design is used to produce strong bonds between the embossed polypropylene fibers and the cementitious matrix of beams. Considering different locations for the notch, this study focuses on bridging mechanism under different conditions using both experimental and numerical approaches. First mode of fracture occurs due to opening of crack faces. This mode of failure is simulated by imposing symmetric boundary conditions on middle-notched beams. Inducing the notch with an offset from the middle, mixed-mode... 

This paper aims to study the behavior of UPVC-confined columns reinforced with polypropylene fibers under axial compression. A sum of 42 column specimens has been tested, including 18 Unconfined Concrete Cylinders (UCC) and 24 confined Concrete-Filled UPVC Tube (CFUT) specimens. To investigate the sensitivity of these columns to various parameters, different levels of material volumes have been used, which include two concrete strengths of 40 and 50 MPa, two tube grades of PN6 and PN10, and three polypropylene fiber content of 0, 1 and 3 kg/m3 of the concrete mixture. The influence of each variable on the ultimate strength, ductility and confinement effectiveness of the specimens have been... 

In composite beams, shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface. This paper presents an experimental study on the behavior of channel shear connectors embedded in a solid concrete material slab under monotonic and low-cycle fatigue loading. The latter would be applicable to composite structures subjected to seismic events. Of specific interest are the behavior and effects of different concrete materials. A series of push-out specimens made of plain concrete, reinforced concrete (RC), fiber reinforced concrete (FRC) and engineered cementitious composite (ECC) were tested for this evaluation. The results show that the reversed...