Properties of Concrete Incorporating Recycled Post-Consumer Environmental Wastes

Ahmed Eisa 한국콘크리트학회 2014 International Journal of Concrete Structures and M Vol.8 No.3

The use of sustainable technologies such as supplementary cementitious materials, and/or recycled post-consumer environmental wastes is widely used in concrete industry in the last decade. This paper presents the results of a laboratory investigation of normal concrete containing sustainable technologies. Twenty one mixtures (21) were prepared with different combinations of silica fume, fly ash, olive’s seed ash, and corncob ash (CCA). Fresh and hardened concrete properties were measured, as expected the inclusion of the sustainable technologies affected both fresh and hardened concrete properties. Based on the results obtained in this study and the analyses conducted, the following observations were drawn: replacing the cement by olive’s seed ash or CCA has a significant effect on fresh concrete workability. Olive’s seed ash increased the slump by more than 200 % compared to the control mixtures. The compressive strength of mixtures containing olive’s seed ash showed by 45 and 75 % decrease compared to the control mixtures. The 28 days compressive strength of mixtures produced by CCA of 10 % replacement decreased by 41 % compared to the control mixture.

Improving the flexural toughness behavior of R.C beams using micro/nano silica and steel fibers

Eisa, Ahmed S.,Shehab, Hamdy K.,El-Awady, Kareem A.,Nawar, Mahmoud T. Techno-Press 2021 Advances in concrete construction Vol.11 No.1

Experimental investigation has been conducted to study the effect of using Micro/Nano Silica in presence of steel fibers on improving the static response of reinforced concrete beams. Twenty-one mixtures were prepared with micro silica (MS), Nano silica (NS) and steel fibers (SFs) at different percentages. Cement was replaced by 10% and 15% of Micro silica and 1%, 2% and 3% of Nano silica in the presence of steel fibers at different volume fractions 0%, 1%, and 2%. 258 concrete samples, (126 cubes, 63 cylinders, 63 prisms, and six R.C beams), were investigated experimentally in two stages. The first stage was to investigate the mechanical properties of the prepared mixtures. The second stage was to study the static behavior of R.C beams, using the designed concrete mixtures, under a four-point flexural test. The results showed that replacing cement by (10% MS and 1% NS) produces the optimum mix with a significant improvement in the mechanical properties and the response of R.C beams under static loads. In addition, incorporating steel fibers at different volume fractions have a considerable effect on the flexural toughness of concrete mixes.

Infestation of the Longhorned Beetles Species (Cerambycidae) on Acacia seyal Del var. seyal in the Gum Arabic Belt of Sudan

Eisa, Maymoona Ahmed,Adam, Yahia Omar Institute of Forest Science 2010 Journal of Forest Science Vol.26 No.2

The Acacia seyal Del. var. seyal belongs to family Mimosaceae is known locally as gum Talha tree. It is a multipurpose tree species occurs throughout the African gum belt in Savannah mostly in pure forest. In Sudan it thrives on heavy clay soils that receive an annual rainfall between 400-800 mm. It is an important source of rural energy (fuelwood and charcoal) and forage. As mentioned by Nair (2007) the economic damage causes by insect in natural forest often difficult to judge due to no enough research attention The tree is frequently affected by biotic factors among them the insect pests. During a survey in the 1980's the tree was severely infested by the longhorned beetles (Cerambycidae) severely infesting other Acacia species, but the ecological data are overlooked. Therefore, the objective of the study was to assess infestation characteristics and to determine environmental factors triggering the attack of longhorned beetles. A temporary random sampling technique was applied to observe the damage characteristics of the longhorned beetles on tree species during May-July 2007. Five sample plots occupies by A. seyal were taken in Kordofan region directly observed for the presence of hole of emergence of the longhorned beetles, presence of dusts, presence of insect stages, girdling as well as other characteristics of damage. The study results indicate that the infestation rate of trees in the sampled sites ranged between zero and 23.08%. Further ecological researches are recommended.

Infestation of the Longhorned Beetles Species (Cerambycidae) on Acacia seyal Del var. seyal in the Gum Arabic Belt of Sudan

Maymoona Ahmed Eisa,Yahia Omar Adam 강원대학교 산림과학연구소 2010 Journal of Forest Science Vol.26 No.2

The Acacia seyal Del. var. seyal belongs to family Mimosaceae is known locally as gum Talha tree. It is a multipurpose tree species occurs throughout the African gum belt in Savannah mostly in pure forest. In Sudan it thrives on heavy clay soils that receive an annual rainfall between 400-800 mm. It is an important source of rural energy (fuelwood and charcoal) and forage. As mentioned by Nair (2007) the economic damage causes by insect in natural forest often difficult to judge due to no enough research attention The tree is frequently affected by biotic factors among them the insect pests. During a survey in the 1980´s the tree was severely infested by the longhorned beetles (Cerambycidae) severely infesting other Acacia species, but the ecological data are overlooked. Therefore, the objective of the study was to assess infestation characteristics and to determine environmental factors triggering the attack of longhorned beetles. A temporary random sampling technique was applied to observe the damage characteristics of the longhorned beetles on tree species during May-July 2007. Five sample plots occupies by A. seyal were taken in Kordofan region directly observed for the presence of hole of emergence of the longhorned beetles, presence of dusts, presence of insect stages, girdling as well as other characteristics of damage . The study results indicate that the infestation rate of trees in the sampled sites ranged between zero and 23.08%. Further ecological researches are recommended.

Green gold@chitosan nanocomposite via solid-state synthesis; a separable catalyst for reduction of Cr(IV)

Ahmed Atia,Yasser K. Abdel-Monem,A.H. Salama,Salah M. El-kousy,Wael H. Eisa 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-

A clean and high-throughput synthesis of gold@chitosan nanocomposite using nontoxic oxalic acid as areducing agent was developed. The synthetic route was carried out in completely dry conditions, i.e. solid-state reaction. The gold nanoparticles were bound with chitosan through the hydroxyl and aminogroups, as confirmed by Fourier transform infrared spectroscopic analysis. Scanning and transmissionelectron microscopy imaging confirmed the formation of semi-spherical gold particles with an averagesize of 8–15 nm. The catalytic performance of the synthesized gold nanoparticles for the reduction ofchromium(IV) in the presence of formic acid was evaluated. The film-forming ability of chitosan enabledthe design of separable/reusable heterogeneous catalyst which is convenient for real industrial applications. The proposed solid-state synthetic route could be adapted to produce a wide variety of nanostructuredmaterials that are characterized by high-yield, greenness, and low cost in very simple steps.

Alternatives to Enhance Flat Slab Ductility

Mohamed Husain,Ahmed S. Eisa,Ramy Roshdy 한국콘크리트학회 2017 International Journal of Concrete Structures and M Vol.11 No.1

Flat slab systems are vastly used in multi-story buildings because of their savings in story height and construction time, as well as for their flexibility in architectural remodeling. However, they frequently suffer brittle punching-shear failure around columns, especially when subjected to lateral loads. Therefore, seismic codes labeled flat slabs as non-ductile systems. This research goal is investigating some construction alternatives to enhance flat slab ductility and deformability. The alternatives are: adding different types of punching-shear reinforcement, using discreet fibers in concrete mixes, and increasing thickness of slab around columns. The experimental study included preparation and testing of seven half-scale interior slab-column connections up to failure. The first specimen is considered a reference, the second two specimens made of concrete mixes with different volumetric ratios of polymer fibers. Another three specimens reinforced with different types of punching-shear reinforcement, and the last specimen constructed with drop panel of inverted pyramidal shape. It is found that using the inverted pyramid-shape drop panel of specimen, increases the punching-shear capacity, and the initial and the post-cracking stiffnesses. The initial elastic stiffnesses are different for all specimens especially for the slab with closed stirrups where it is experienced the highest initial stiffness compared to the reference slab.

Alternatives to Enhance Flat Slab Ductility

Husain, Mohamed,Eisa, Ahmed S.,Roshdy, Ramy Korea Concrete Institute 2017 International Journal of Concrete Structures and M Vol.11 No.1

Flat slab systems are vastly used in multi-story buildings because of their savings in story height and construction time, as well as for their flexibility in architectural remodeling. However, they frequently suffer brittle punching-shear failure around columns, especially when subjected to lateral loads. Therefore, seismic codes labeled flat slabs as non-ductile systems. This research goal is investigating some construction alternatives to enhance flat slab ductility and deformability. The alternatives are: adding different types of punching-shear reinforcement, using discreet fibers in concrete mixes, and increasing thickness of slab around columns. The experimental study included preparation and testing of seven half-scale interior slab-column connections up to failure. The first specimen is considered a reference, the second two specimens made of concrete mixes with different volumetric ratios of polymer fibers. Another three specimens reinforced with different types of punching-shear reinforcement, and the last specimen constructed with drop panel of inverted pyramidal shape. It is found that using the inverted pyramid-shape drop panel of specimen, increases the punching-shear capacity, and the initial and the post-cracking stiffnesses. The initial elastic stiffnesses are different for all specimens especially for the slab with closed stirrups where it is experienced the highest initial stiffness compared to the reference slab.

Strengthening of Cutouts in Existing One-Way Spanning R. C. Flat Slabs Using CFRP Sheets

Hamdy K. Shehab,Ahmed S. Eisa,Kareem A. El-Awady 한국콘크리트학회 2017 International Journal of Concrete Structures and M Vol.11 No.2

Openings in slabs are usually required for many different applications such as aeriation ducts and air conditioning. Opening in concrete slabs due to cutouts significantly decrease the member stiffness. There are different techniques to strengthen slabs with opening cutouts. This study presents experimental and numerical investigations on the use of Carbon Fiber Reinforced Polymers (CFRP) as strengthening material to strengthen and restore the load carrying capacity of R.C. slabs after having cutout in the hogging moment region. The experimental program consisted of testing five (oneway spanning R.C. flat slabs) with overhang. All slabs were prismatic, rectangular in cross-section and nominally 2000 mm long, 1000 mm width, and 100 mm thickness with a clear span (distance between supports) of 1200 mm and the overhang length is 700 mm. All slabs were loaded up to 30 kN (45% of ultimate load for reference slab, before yielding of the longitudinal reinforcement), then the load was kept constant during cutting concrete and steel bars (producing cut out). After that operation, slabs were loaded till failure. An analytical study using finite element analysis (FEA) is performed using the commercial software ANSYS. The FEA has been validated and calibrated using the experimental results. The FE model was found to be in a good agreement with the experimental results. The investigated key parameters were slab aspect ratio for the opening ratios of [1:1, 2:1], CFRP layers and the laminates widths, positions for cutouts and the CFRP configurations around cutouts.

Strengthening of Cutouts in Existing One-Way Spanning R. C. Flat Slabs Using CFRP Sheets

Shehab, Hamdy K.,Eisa, Ahmed S.,El-Awady, Kareem A. Korea Concrete Institute 2017 International Journal of Concrete Structures and M Vol.11 No.2

Openings in slabs are usually required for many different applications such as aeriation ducts and air conditioning. Opening in concrete slabs due to cutouts significantly decrease the member stiffness. There are different techniques to strengthen slabs with opening cutouts. This study presents experimental and numerical investigations on the use of Carbon Fiber Reinforced Polymers (CFRP) as strengthening material to strengthen and restore the load carrying capacity of R.C. slabs after having cutout in the hogging moment region. The experimental program consisted of testing five (oneway spanning R.C. flat slabs) with overhang. All slabs were prismatic, rectangular in cross-section and nominally 2000 mm long, 1000 mm width, and 100 mm thickness with a clear span (distance between supports) of 1200 mm and the overhang length is 700 mm. All slabs were loaded up to 30 kN (45% of ultimate load for reference slab, before yielding of the longitudinal reinforcement), then the load was kept constant during cutting concrete and steel bars (producing cut out). After that operation, slabs were loaded till failure. An analytical study using finite element analysis (FEA) is performed using the commercial software ANSYS. The FEA has been validated and calibrated using the experimental results. The FE model was found to be in a good agreement with the experimental results. The investigated key parameters were slab aspect ratio for the opening ratios of [1:1, 2:1], CFRP layers and the laminates widths, positions for cutouts and the CFRP configurations around cutouts.

Synergistic Effects of Jerusalem Artichoke in Combination with Pegylated Interferon Alfa-2a and Ribavirin Against Hepatic Fibrosis in Rats

Abdel-Hamid, Nabil Mohie,Wahid, Ahmed,Nazmy, Maiiada Hassan,Eisa, Marwa Abdel-Moniem Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.4

Background: Complementary and alternative medicine has been highly appreciated as a supportive regimen for classical treatment strategies. Here we offer a nutrition-based adjuvant therapy for liver fibrosis, a major risk factor for cirrhosis and hepatocellular carcinoma. Aim of the study: To evaluate the possible hepatoprotective effects of Jerusalem artichoke tubers (JAT) in combination with interferon and ribavirin. Materials and Methods: Twelve groups of rats were administered JAT, interferon and ribavirin either separately or in combination from day one of $CCL_4$ administration until the end of the study. Animals were killed after 8 weeks of $CCL_4$-induced hepatotoxicity. Results: Hepatocytes from rats treated with triple combination of interferon, ribavirin, and JAT showed more less normal architecture compared to $CCL_4$-treated rats. We also detected significantly higher hepatic protein expression levels of p53, BAX and transforming growth factor-${\beta}$ (TGF-${\beta}$) in the $CCL_4$-intoxicated group compared to normal controls, as evidenced by immunohistochemical staining and western blotting analyses. Addition of JAT as a supportive regimen improved response to ribavirin and interferon and effectively participated in retaining normal histopathological and biochemical criteria and significantly lowered protein expression of p53, BAX, and TGF-${\beta}$. Conclusions: We suggest that addition of JAT as a supportive r egimen to interferon and ribavirin effectively potentiates their anti-fibrotic effects.