Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : flexural strength

Experimental Study on The Effect of Aspect Ratio on Flexural Behavior of Aluminum Sandwich Composite

Ganesh Radhakrishnan; Al Haitham Al Hattali; Al Muntasser Al Yahyai; Al Muntasser Al Riyami; Al Muatasim Al Hadhrami

Engineering and Technology Journal, 2022, Volume 40, Issue 7, Pages 1-6
DOI: 10.30684/etj.2022.134317.1234

Sandwich composites are one such kind of light-weight composites developed for structural and vehicle body buildings etc. Due to their remarkable features such as high specific strength, high toughness and resistance to inter laminar shear strength. In this study, commercially available aluminium sandwich composite (ASC) laminate was considered for investigating its flexural behavior and buckling behavior as it was mostly used for various structural applications. Flexural analysis was done for different aspect ratios in order to analyze the influence of cross section of the specimen and support span on the flexural capability of the sandwich beam. The composite specimens prepared for flexural test consist of length 150 mm and widths 15, 12 and 10 mm. The flexural test was done for support span of 90, 110 and 130 mm respectively. The performance measures of flexural test are maximum bending load, deflection, flexural stiffness and inter-laminar shear stress. The flexural analysis revealed the fact that the aspect ratio appreciably affected the flexural capacity of the sandwich composite laminates. Maximum flexural capacity with bending load around 3.5 to 4 kN and flexural stiffness around 2.5 to 4.7 kN/mm respectively was observed for the sandwich specuimen for the aspect ratios L/t = 30 and b/t = 5. Being a anisotropic structure, the flexural behavior of this sandwich composite exposed as a combination of bending and shear failure. The soft core material and ductile skin face sheets resulted in a combined failure against flexural load in static condition.

Mechanical Performance of Blended Fly Ash-based Geopolymer Concrete with GGBS and Metakaolin

Ali A. Ali; Tareq S. Al-Attar; Waleed A. Abbas

Engineering and Technology Journal, 2022, Volume 40, Issue 5, Pages 1-13
DOI: 10.30684/etj.2022.132647.1135

One of the most user-friendly alternatives to ordinary concrete is geopolymer concrete(GPC), which achieves the same result. GPC is a unique substance made by activating source materials with a high concentration of silica and alumina. As a result, geopolymer binders use less raw resources and emit less carbon dioxide. For these reasons, most academics are focusing on these sorts of resins to develop eco-friendly housing. This article reports on an experimental investigation that examined the Mechanical Performance of Blended Fly Ash based Geopolymer concrete at 7,28 and 360 days made with two different activator solution molarities and varying R (SiO2/Al2O3) ratios. Positive findings were seen at a larger percentage of GGBS (36%) with a concentration of a sodium hydroxide solution of 10 M and an R ratio of 2.75, compared with other proportions. The test findings indicate that increasing the concentration of sodium hydroxide (NaOH) solution and R enhances the compressive strength and decreases water absorption of geopolymer concrete.

Mechanical Properties Prediction of Normal and High Strength Geopolymer Concrete

Sameh B. Tobeia; Nada S. Assi; Narjis S. Abbas

Engineering and Technology Journal, 2021, Volume 39, Issue 12, Pages 1781-1788
DOI: 10.30684/etj.v39i12.1984

The production process of cement is the main binder material in concrete usually accompanied by carbon dioxide emission. Therefore, geopolymer concrete (GPC) an alternative binder material was developed as a replacement for cement. In order to make this promising material more common in constructions and applicable for different design purposes further investigations for GPC mechanical properties were needed. This work aims to predicate the splitting tensile strength, modulus of elasticity and flexural strength for normal and high strength GPC by deriving new equations covering a wide range of compressive strength based on data available from previous work. Equations behavior along the changes in compressive strength from normal to high is adopted in comparisons as illustrated. The results show that the proposed equations, as compared with other equations established by previous works, provide a steady behavior for the various values of compressive strength especially for high strength. The coefficient of variation (COV) used as additional comparison criteria, and shows that the proposed equations provide better estimation of GPC mechanical properties.

Optimum Steel Fiber Content of High Strength Pozzolime Concrete

Sabreen M. Hamza; Ahmed Sh. J. Al-Zuheriy; Sabreen M. Hamza

Engineering and Technology Journal, 2021, Volume 39, Issue 12, Pages 1869-1874
DOI: 10.30684/etj.v39i12.2213

Pozzolime is a promising alternative binder, compared to Portland cement because of its low CO2 emission. it is produced by mixing hydrated lime, silica fume, and fly ash. Fiber is added to concrete to improve the durability, mechanical properties of the structure, and others. In this study, high-strength Pozzolime concrete was reinforced with hooked-end steel fiber which was added as fractions of volume of 0.5, 1, 1.5, and 2%. Optimization for fiber content was performed according to the workability and strength of the fiber-reinforced mixture. Obtained results showed that the compressive strengths at 14d and 90d increased by 71.4% and 58.3% respectively when adding 1.5% steel fiber. Correspondingly, the 14d, 28d, and 90d flexural strength of pozzolime concrete increased by 170.4%, 203.2%, and 191.4% respectively at 1.5% and a further increase in fiber content caused a reduction in strength. The finding presented in this research confirmed that the volume fraction (1.5%) can be considered as the optimum content.

A Study of Some Mechanical and Physical Properties for Palm Fiber/Polyester Composite

Samah M. Hussein

Engineering and Technology Journal, 2020, Volume 38, Issue 3B, Pages 104-114
DOI: 10.30684/etj.v38i3B.598

This research has been done by reinforcing the matrix (unsaturated polyester) resin with natural material (date palm fiber (DPF)). The fibers were exposure to alkali treatment before reinforcement. The samples have been prepared by using hand lay-up technique with fiber volume fraction of (10%, 20% and 30%). After preparation of the mechanical and physical properties have been studied such as, compression, flexural, impact strength, thermal conductivity, Dielectric constant and dielectric strength. The polyester composite reinforced with date palm fiber at volume fraction (10% and 20%) has good mechanical properties rather than pure unsaturated polyester material, while the composite reinforced with 30% Vf present poor mechanical properties. Thermal conductivity results indicated insulator composite behavior. The effect of present fiber polar group induces of decreasing in dielectric strength, and increasing dielectric constant. The reinforcement composite 20% Vf showed the best results in mechanical, thermal and electrical properties.

Influence of Minimum Tension Steel Reinforcement on the Behavior of Singly Reinforced Concrete Beams in Flexure

Ali A. Abdulsada; Raid I. Khalel; Kaiss F. Sarsam

Engineering and Technology Journal, 2020, Volume 38, Issue 7, Pages 1034-1046
DOI: 10.30684/etj.v38i7A.902

The requirements of minimum flexural reinforcement in the last decades have been a reason for controversy. The structural behavior of beams in bending is the best way of investigating and evaluating the minimum reinforcement in flexure. For this purpose, twelve singly reinforced concrete beams with a rectangular cross-section of (125 mm) width by (250 mm) height and (1800 mm) length were cast and tested under two-point loads up to failure. These beams were divided into three groups with different compressive strengths (25, 50, and 80 MPa). Each group consists of four beams with different amounts of tension steel reinforcement approximately equal to (0% Asmin, 50% Asmin, 100% Asmin and 150% Asmin), two bar diameters (Ø6 mm and Ø8 mm) were used as the longitudinal tension reinforcement with different yield and ultimate strengths, the minimum amount of reinforcement required is calculated based on ACI 318M-2014 code. The results show that for the reinforced concrete beams, the flexural reinforcement in NSC beams increases the first cracking load and the increment increased with an increasing amount of reinforcement, while for HSC beams the increasing in first cracking load are very little when the quantity of reinforcement less than the minimum flexural reinforcement and increased with the increasing amount above the minimum flexural reinforcement. The equation of ACI 318M-14 code gives adequate minimum flexural reinforcement for NSC and overestimate value for HSC up to (83 MPa), A new formula is proposed for HSC rectangular beams up to (90 MPa) concrete compressive strength by reducing the equation of ACI 318M-14 code for minimum flexural reinforcement by a factor depending on concrete compressive strength.

Flexural and Impact Properties of Epoxy Composites Reinforced with Peanut Shell Particles

Hwazen Fadhil

Engineering and Technology Journal, 2020, Volume 38, Issue 7, Pages 1026-1033
DOI: 10.30684/etj.v38i7A.584

Natural materials have been extensively used as reinforcements in polymer matrices instead of non-degradable synthetic reinforcement such as carbon, glass or aramid. The use is because of their low density, good mechanical properties, availability, and biodegradability. Peanut shell is one such natural waste filler used, and it contains cellulose, hemicellulose, and lignin. Natural fiber/particle sources are not only strong and lightweight but are relatively very cheap. This paper offers the comparison of the flexural, and impact energy test properties of the peanut shell reinforced with the epoxy resin matrix. Peanut shells add into the epoxy resin matrix with various weight fractions (2%, 4%, 6%, and 8%) and have been fabricated by hand lay-up procedure. Flexural strength and flexural modulus changed from (140MPa) to (160 MPa), and from (2 GPa) to (7.79 GPa) respectively, impact strength, and fracture toughness changed from (2.5 KJ/m2) to (7 KJ/m2), and from (2.23 MPa.m1/2) to (7.07 MPa.m1/2), respectively as a function of the particle weight fraction. The highest flexural strength and modulus obtained samples (reinforced 4% wt. peanut shell), while samples (reinforced +8% wt. peanut shell) provided the highest impact strength and fracture toughness.

Properties of Self-Compacting Cementitious Composite Materials Containing Cement Kiln Dust Powder

Ahmed S. Kadhim; Alaa A. Atiyah; Shakir A. Salih

Engineering and Technology Journal, 2020, Volume 38, Issue 6, Pages 879-886
DOI: 10.30684/etj.v38i6A.592

This paper aims to investigate the influence of utilization micro cement kiln dust as a sustainable materials additive in order to reduce the voids and micro cracks in the cementitious mortar materials which cause a drastic reduction in the load carrying capacity of the element. Its therefore very important to decrease the pores and enhance the mechanical strength of the cementitious composite materials. In this article, the properties of self-compacting mortar containing micro cement dust additive was experimentally assessed. Micro cement dust powder was added to the self-compacting mortar in (1, 2, 3, 4 and 5 %) percentage by weight of cement to be used as cementitious sustainable materials. The experimental results indicated that the modification and enhancement of the workability of fresh mixture and the mechanical strengths of self-compacting mortar were increased as micro cement dust additives increases. Also; the water absorption and total porosity were decreased with increases of micro cement dust powder.

Influence of Recycled Fine Aggregates on Strength Properties of Reactive Powder Mortar

Doaa H. Nayyef; Shatha S. Hasan

Engineering and Technology Journal, 2020, Volume 38, Issue 3A, Pages 288-294
DOI: 10.30684/etj.v38i3A.265

Although many researchers have done many studies on recycled aggregate concrete, information is very little about the influence of utilizing recycled aggregate in the production of reactive powder concrete. Experimental work was executed to investigate the influence of utilizing recycled concrete as fine aggregate in reactive powder concrete. Five different mixes were prepared, the first mix, or control mix, was prepared with natural sand, four additional mixes were prepared with different percentage of substitution of fine aggregates(20%,40%,60%, and 80%). The investigation was carried out using compressive strength test, direct tensile strength test and flexural strength test, and two methods of curing were used standard curing at 20 °C and steam curing at 90°C. the results indicated that the strength decreases with increased the percentage of recycled fine aggregate, and the best percentage was 40% replacement where the percentages of decrease at this percentage at 28-day steam curing were 2.46, 6.66, and 2.14 for compressive strength, flexural strength, and direct tensile strength respectively.

Analysing Some Mechanical Properties of Cinnamon Powder Reinforced with Polymeric Materials Used in Dental Application

Ahamed M. AlGhabban; Reem A. Mohammed; Jumaah R. Mahmood

Engineering and Technology Journal, 2019, Volume 37, Issue 3A, Pages 96-105
DOI: 10.30684/etj.37.3A.4

In the dentures industry, materials must be chosen to have good mechanical properties in order to resist the conditions that may occur in the mouth. A study was conducted to assess tensile strength, elasticity coefficient, elongation, flexural strength, flexural modulus with impact properties of poly methyl methacrylate resin as matrix strengthened with cinnamon powder and also analysing these mechanical properties by using (OriginLab) software program. The samples of Poly Methyl methacrylate bio composites which containing 2%, 4%, 6%, and 8% weight fractions of cinnamon powder and an unfilled as control sample were fabricated using “hand lay up” method. The results indicate that the addition of 8% weight fraction cinnamon powder into Poly Methyl methacrylate resin improved of ultimate tensile strength, modulus elasticity ,flexural strength, flexural modulus (62 MPa, 3.7 GPa, 96 MPa, 6.4 GPa) respectively, compared with the values of pure Poly Methyl methacrylate (51 MPa, 1.5 GPa, 78MPa, 2.0 GPa) respectively. Also can be noted that the elongation at break values decreases with an increase in weight fractions of filler, where the sample (Poly Methyl methacrylate +2% cinnamon) has the best value for elongation compared with samples reinforced (4%, 6% and 8% wt). The impact strength results observe the maximum value was present in the sample (Poly Methyl methacrylate+6% cinnamon). From the results, descriptive, One Way ANOVA statistical analysis and means comparison by used (Scheffe test and Tukey test) for all mechanical properties indicated, turns out if Sig equals 1 shows that the variance in mean is significant at the level of 0.05, whereas Sig is 0 designates that the mean variance is not significant at the level 0.05.

Some Properties of No-Fines Concrete Produced by Using Demolished Concrete as Recycled Coarse Aggregate

Sh. A. Salih; I.N. Gorgis; W.F. Abd

Engineering and Technology Journal, 2017, Volume 35, Issue 7, Pages 741-748

This paper investigate some mechanical properties of no-fines concrete produced by using demolished concrete as coarse aggregate after crushing to different sizes. Different no-fine mixes were considered using Portland cement type I with two types of coarse aggregates, crushed natural gravel and crushed demolished concrete were used with two ratios by weight (1:5 and 1:7) cement/aggregate. Single size and graded aggregate were used with a maximum size of 20 mm. W /C ratio was kept as 0.4 for all mixes and supper plasticizer was used to keep the same flow and compaction factor value for all mixes . Using demolished concrete as coarse aggregate in no fine concrete led to decrease in the workability. As a comparison with natural coarse aggregate mixes, the average percentages of decreases for the flow, compaction factor and the fresh density were 2%, 2.3% and 6.4%, respectively. As well as the test results indicated that the compressive strength, splitting tensile strength, flexural strength and oven dry density for no fine made with crushed demolished concrete at age 28 days were decreased by about 29%, 22 %, 21% and 4% respectively as compared with no fine made by natural crushed aggregate.

Effect of Al2O3 Powder on Some Mechanical and Physical Properties for Unsaturated Polyester Resin Hybrid Composites Materials Reinforced by Carbon and Glass Fibers

Reem Alaa Mohammed

Engineering and Technology Journal, 2016, Volume 34, Issue 12, Pages 2371-2379

This research is a study of the effect of Al2O3 powder on physical and mechanical properties of the polymer hybrid composites based on unsaturated polyester resin reinforced with carbon and glass fibers. The samples were made by a hand lay-up method according to ASTM standard for various volume fractions of additives. The polymer composites materials reinforced with carbon and glass fibers are the most used in manufacture of components such as pip, part of aerospace, and leisure industries and automotive.The polyester resin matrixwas strengthened with 3% carbon and glass fibers with 1%, 3%, 5%, 7% Al2O3 powders. The water absorption, hardness (shore D), impact test, and flexural strength properties are studied. The results show the specimens (UP+3%C.F+7%Al2O3) and(UP+3%G.F+7%Al2O3) had the maximum hardness (shore D) and water absorptionwhen compared withunfilledpolyester resinspecimen, it can be observed that the specimens(UP+3%C.F+5%Al2O3) and (UP+3%G.F+5%Al2O3) have maximum impact strength and flexural strengthcompared with specimens (UP+3%C.F+7%Al2O3)and (UP+3%G.F+7%Al2O3) .

Effect of Micro Powder on Mechanical and Physical Properties of Glass Fiber Reinforced Epoxy Composite

Aseel Basim Abdul-Hussein; Fadhel Abbas Hashim; Tamara Raad Kadhim

Engineering and Technology Journal, 2016, Volume 34, Issue 7, Pages 1402-1414

In the present study, composites were prepared by Hand lay-up molding. The composites constituents were epoxy resin as the matrix, 3% volume fractions of Glass Fibers (G.F) as re enforcement and 2%, 4%, 6% volume fraction of micro powder (Aluminum Oxide Al2O3, Silicon Oxide SiO2 and Titanium Oxide TiO2) as filler. Studied the, hardness test, flexural strength, density, water absorption measurements and tests were conducted to reveal their values for each type of composite material. The results showed that the non – reinforced epoxy have lower properties than nano composites material. Measured density results had show an incremental increase with volume fraction increase and water absorption, hardness, and flexural strength had show an incremental increase with volume fraction increase and with smaller particle size.

Effect of Nature Materials Powders on Mechanical and Physical Properties of Glass Fiber / Epoxy Composite

Aseel Basim Abdul-Hussein; Emad Saadi AL-Hassani; Reem Alaa Mohammed

Engineering and Technology Journal, 2015, Volume 33, Issue 1, Pages 175-197

In the present study composites were prepared by Hand lay-up molding. The composites constituents were epoxy resin as the matrix, 6% volume fractions of Glass Fibers (G.F) as reinforcement and 3%, 6% of nature material (Rice Husk Ash, Carrot Powder, and Sawdust) as filler. Density, water absorption, hardness test, flexural strength, shear stress measurements and tests were conducted to reveal their values for each type of composite. True density results had shown an incremental increase with volume fraction increasing and water absorption, hardness, flexural strength and shear stress results had shown an incremental increase with volume fraction increasing with smaller particle size.