Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Flexural strength


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.

A Comparative Investigation on Mechanical Properties of Various Fibers Reinforced Concrete

Ahmed M. Al-Ghaban; Hussein A. Jaber; Aya A. Shaher

Engineering and Technology Journal, 2019, Volume 37, Issue 1A, Pages 28-36
DOI: 10.30684/etj.37.1A.5

The present work presents an investigation the effect of adding various fiber materials such as (glass, nylon, and carbon) into the concrete mix for inspecting and compare the mechanical properties of different fibers reinforced concrete. Two different fiber length states of (short=3cm and long=10cm) are used in this work. The concrete of ordinary Portland cement of (1:1.5:3), (cement: sand: gravel), were mixed with each of the fiber materials at four different weight percentages (0, 0.4, 0.8, and 1.2) wt% per cement content. Compressive strength and flexural strength were experimentally investigated of different fibers reinforced concrete specimens after curing for 28 days. The results showed that the incorporation of various fibers with the concrete mix generally improved the strength of concrete by improving the toughness. The flexural strength of concrete with addition of various fibers was strongly enhanced than compression. Addition 0.8% of nylon fiber to concrete resulted in the maximum increase of its compressive strength, reaching the rate of increasing to 11.08% for short fiber and 20.75% for long fiber. Addition 1.2% of nylon fiber to concrete mix resulted in the maximum increase of the flexural strength, reaching rate of increasing to 120.02% for short fiber and 211.49% for long fiber. Increasing the length of fibers increases the strength of the concrete but a little extent. Among these fibers, nylon containing concrete composite exhibits promising mechanical strength that could be easily used as low-cost partitioning wall, false ceiling, and other household purposes.

Effect of Using Windows Waste Glass as Coarse Aggregate on Some Properties of Concrete

Abdelmaseeh Bakos Keryou; Gailan Jibrael Ibrahim

Engineering and Technology Journal, 2014, Volume 32, Issue 6, Pages 1519-1529

In this experimental study, local waste glass (WG) gathered from Turkey-made windows glass has been used as a partial replacement of coarse aggregates with 0, 20, 25, and 30% percentages of replacement by weight. Some mechanical and other properties of the concrete, produced this way have been studied at both fresh and hardened stages.
The experimental results obtained from testing the specimens prepared from concrete mixes with water/cement ratio equal to 0.5, showed that using WG resulted in decreasing the slump and fresh density due to angular grain shape, whereas the compressive, splitting, and flexural strengths noticeably enhanced. Tests revealed that with increasing the WG percentage the strengths gradually increase up to a given limit beyond which they decrease. The maximum effect was reached at 25% percentage of replacement. At this percentage the increases in the compressive, splitting tensile and flexural strengths at 28-day age were 30, 38 and 31 %, respectively. The results of this study indicate a considerable economical effect from using the optimum percentage of WG (25%) as partial replacement of coarse aggregate.