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1 – 4 of 4Abdulla A. Sharo, Ahmed Mohammed Ashteyat, Ahmed S. Alawneh and Bashar Ali Bany Khaled
The purpose of this paper is to evaluate the possible use of oil shale as a soil stabilizing agent for expansive soils.
Abstract
Purpose
The purpose of this paper is to evaluate the possible use of oil shale as a soil stabilizing agent for expansive soils.
Design/methodology/approach
An experimental work has been fulfilled to investigate the influence of oil shale ash (OSA) on the geotechnical behavior of the expansive soil of Irbid, Jordan. Three swelling-shrinkage soils were considered in this study along with various percentages of OSA varying at 2, 4, 6, 8, 10 and 12 per cent by dry weight of the soil. A series of laboratory tests were conducted on the soil samples before and after mixing it with OSA. These tests were soil classification, Atterberg limits, compaction test, falling head permeability test, unconfined compression test, free swelling, swelling pressure and California bearing ratio (CBR) test.
Findings
Laboratory tests results indicated that OSA is effective in improving the texture and strength of the treated soil by reducing plasticity index, swelling potential and swelling pressure and moderately enhancing soil strength properties including the unconfined compressive strength (qu), maximum dry unit weight (γd-max.) and CBR test.
Originality/value
OSA showed potential as a low-cost soil stabilizing agent for swell-shrink soils.
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Yousef Al Rjoub, Ala Obaidat, Ahmed Ashteyat and Khalid Alshboul
This study aims to conduct an experimental study and finite element model (FEM) to investigate the flexural behavior of heat-damaged beams strengthened/repaired by hybrid…
Abstract
Purpose
This study aims to conduct an experimental study and finite element model (FEM) to investigate the flexural behavior of heat-damaged beams strengthened/repaired by hybrid fiber-reinforced polymers (HFRP).
Design/methodology/approach
Two groups of beams of (150 × 250 × 1,200) mm were cast, strengthened and repaired using different configurations of HFRP and tested under four-point loadings. The first group was kept at room temperature, while the second group was exposed to a temperature of 400°C.
Findings
It was found that using multiple layers of carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) enhanced the strength more than a single layer. Also, the order of two layers of FRP showed no effect on flexural behavior of beams. Using a three-layer scheme (attaching the GFRP first and followed by two layers of CFRP) exhibited increase in ultimate load more than the scheme attached by CFRP first. Furthermore, the scheme HGC (heated beam repaired with glass and carbon, in sequence) allowed to achieve residual flexural capacity of specimen exposed to 400°C. Typical flexural failure was observed in control and heat-damaged beams, whereas the strengthened/repaired beams failed by cover separation and FRP debonding, however, specimen repaired with two layers of GFRP failed by FRP rupture. The FEM results showed good agreement with experimental results.
Originality/value
Few researchers have studied the effects of HFRP on strengthening and repair of heated, damaged reinforced concrete (RC) beams. This paper investigates, both experimentally and analytically, the performance of externally strengthened and repaired RC beams, in flexure, with different FRP configurations of CFRP and GFRP.
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Ahmed Ashteyat, Ala Taleb Obaidat, Yasmeen Taleb Obeidat and Ahmad Bani Awwad
The paper aims to introduces an experimental work to investigate the torsional behavior of reinforced concrete (RC) beams strengthened by near-surface mounted (NSM) carbon…
Abstract
Purpose
The paper aims to introduces an experimental work to investigate the torsional behavior of reinforced concrete (RC) beams strengthened by near-surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) ropes.
Design/methodology/approach
In this research, nine rectangular RC beams of 250 mm × 300 mm cross-section and 1,600 mm in length were constructed and tested considering the studied parameters. These parameters include the length of the CFRP rope, the orientation of the CFRP rope, the arrangement of longitudinal and the scheme of NSM-CFRP ropes.
Findings
In comparison to control specimens, the results demonstrate a considerable improvement in the torsional response of RC beams strengthened with the CFRP rope. Additionally, specimens strengthened with 90° vertical ropes increase torsional moment capacity more efficiently than specimens strengthened with 45° inclined ropes since the stress concentration leads to premature debonding of the CFRP rope. Whereas RC beams' ability to withstand torsional moments is reduced as the distance between reinforcing CFRP ropes is increased. According to test results, adding CFRP ropes to RC beams' bottoms had a slightly positive impact on torsional response.
Originality/value
This paper fulfills an identified need to study how the using of the CFRP rope is effective in strengthening RC beam subjected to torsion moment.
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Yasmin Murad, Rana Imam, Husam Abu Hajar, Dua’a Habeh, Abdullah Hammad and Zaid Shawash
The purpose of this paper is to develop new predictive models using gene expression programming in order to estimate the compressive strength of green concrete, as accurate models…
Abstract
Purpose
The purpose of this paper is to develop new predictive models using gene expression programming in order to estimate the compressive strength of green concrete, as accurate models that can predict the compressive strength of green concrete are still lacking.
Design/methodology/approach
To estimate the compressive strength of plain concrete, fly ash concrete, silica fume concrete and concrete with silica fume and fly ash, four predictive GEP models are developed. The GEP models are developed using a large and reliable database that is collected from the literature. The GEP models are validated using the collected experimental database.
Findings
The R2 is used to statistically evaluate the performance of the GEP models wherein the R2 values for the GEP models including all data are 85, 95, 80 and 95.3 percent for the models that predict the compressive strength of plain concrete, fly ash concrete, silica fume concrete and concrete with silica fume and fly ash, respectively.
Originality/value
The GEP models have high R2 values and low RMSE and MAE, which indicates that they are capable of predicting the compressive strength of green concrete with a reasonable accuracy.
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