A Biaxial Fracture Criterion for Porous Brittle Materials

1968 ◽  
Vol 90 (2) ◽  
pp. 285-291 ◽  
Author(s):  
H. W. Babel ◽  
G. Sines

The Griffith criterion for fracture of brittle materials is based on a model of a continuum in which infinitely sharp cracks are distributed with random orientations. This study extends the Griffith analysis to cracks of finite sharpness. While the Griffith criterion predicts a compressive strength of eight times the tensile strength, the extended criterion predicts a compressive strength of any value from three to eight times the tensile strength depending on the sharpness of the cracks. To test the validity of the extended criterion, tests were conducted on porous zirconia under ratios of compressive to tensile stress of 0, 3, and 5, and under compressive stress. A specimen was designed and test procedures developed so that the average bending stress was 1.99 percent. A test program was designed so that a statistical confidence limit could be assigned to the test results. The test results of the proposed criterion fell within a 99 percent confidence band, while all other criteria fell outside of the band for many combinations of tensile and compressive stress. The average compressive strength of the porous zirconia was approximately 7.1 times the tensile strength.

2018 ◽  
Vol 9 (2) ◽  
pp. 67-73
Author(s):  
M Zainul Arifin

This research was conducted to determine the value of the highest compressive strength from the ratio of normal concrete to normal concrete plus additive types of Sika Cim with a composition variation of 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1 , 50% and 1.75% of the weight of cement besides that in this study also aims to find the highest tensile strength from the ratio of normal concrete to normal concrete in the mixture of sika cim composition at the highest compressive strength above and after that added fiber wire with a size diameter of 1 mm in length 100 mm with a ratio of 1% of material weight. The concrete mix plan was calculated using the ASTM method, the matrial composition of the normal concrete mixture as follows, 314 kg / m3 cement, 789 kg / m3 sand, 1125 kg / m3 gravel and 189 liters / m3 of water at 10 cm slump, then normal concrete added variations of the composition of sika cim 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1.5%, 1.75% by weight of cement and fiber, the tests carried out were compressive strength of concrete and tensile strength of concrete, normal maintenance is soaked in fresh water for 28 days at 30oC. From the test results it was found that the normal concrete compressive strength at the age of 28 days was fc1 30 Mpa, the variation in the addition of the sika cim additive type mineral was achieved in composition 0.75% of the cement weight of fc1 40.2 Mpa 30C. Besides that the tensile strength test results were 28 days old with the addition of 1% fiber wire mineral to the weight of the material at a curing temperature of 30oC of 7.5%.


2014 ◽  
Vol 887-888 ◽  
pp. 824-829
Author(s):  
Qing Fang Lv ◽  
Ji Hong Qin ◽  
Ran Zhu

Laminated veneer lumber is taken as an object of study, and use LVL specimens of different sizes for compression test and tensile test. The goal of the experiment is to investigate the size effect on compressive strength and tensile strength as well as the influence of the secondary glued laminated face, which appears in the secondary molding processes. The results show that both compressive strength and tensile strength have the size effect apparently and the existence of the secondary glued laminated face lower the compressive strength of LVL specimens. Afterwards, the relationship between compressive strength and volume along with tensile strength and area are obtained by the test results.


2019 ◽  
Vol 2 (1) ◽  
pp. 1
Author(s):  
Agil Dwi Krisna ◽  
Sigit Winarto ◽  
Ahmad Ridwan

Concrete has the disadvantage of having a low tensile strength and convincing brittle beams with steel inscriptions to anticipate. In this study, the concrete mixture was given additional bagasse and additives of cycacim bonding. This addition was carried out to study and study the effect of bagasse on the compressive strength of normal k300 concrete by replacing bagasse by 0%, 5%, 10% and 15% in compressive loads. Compressive strength specimens in the form of cubes with a size of 15 cm x 15 cm x 15 cm. Testing is done after 28 days. Concrete with increased bagasse of 5% is better able to produce high compressive strength values than others. The addition of bagasse resulted in an average compressive strength of 5%, 229.64 kg / cm2, 10%, 190.35 kg / cm2, 15%, 160.87 kg / cm2.Beton mempunyai kelemahan yaitu mempunyai kuat tarik yang rendah dan bersifat getas sehingga beton diberi tulangan baja untuk mengantisipasinya. Pada penelitian ini, campuran beton diberi bahan tambahan ampas tebu dan zat additif sikacim bonding adhesive. Penambahan ini dilakukan untuk mempelajari dan mengetahui pengaruh ampas tebu terhadap kuat tekan pada beton mutu normal k300 dengan penambahan ampas tebu sebesar 0%, 5%, 10% dan 15% pada beban tekan. Benda uji kuat tekan berbentuk kubus dengan ukuran 15 cm x 15 cm x 15 cm. Pengujian dilakukan setelah 28 hari. Beton dengan penambahan ampas tebu 5% lebih mampu menghasilkan nilai kuat tekan tinggi dari pada yang lainya. Penambahan ampas tebu menghasilakan kuat tekan rata-rata yaitu 5%,229,64 kg/cm2, 10%,190,35 kg/cm2, 15%,160,87kg/cm2.


2010 ◽  
Vol 168-170 ◽  
pp. 1325-1329
Author(s):  
Ye Ran Zhu ◽  
Jun Cai ◽  
Dong Wang ◽  
Guo Hong Huang

This paper investigates the mechanical properties (compressive strength, splitting tensile strength and flexural toughness) of polypropylene fiber reinforced self-compacting concrete (PFRSCC). The effect of the incorporation of polypropylene fiber on the mechanical properties of PFRSCC is determined. Four point bending tests on beam specimens were performed to evaluate the flexural properties of PFRSCC. Test results indicate that flexural toughness and ductility are remarkably improved by the addition of polypropylene fiber.


2014 ◽  
Vol 980 ◽  
pp. 132-136 ◽  
Author(s):  
Ahmad Baharuddin Abd Rahman ◽  
Jen Hua Ling ◽  
Zuhairi Abd Hamid ◽  
Mohd Hanim Osman ◽  
Shahrin Mohammad ◽  
...  

This paper presents the test results of proposed grouted sleeve connections under increasing tensile load. The objective of this research was to investigate splice connections that could provide tensile strength similar to the full tensile strength of the connected rebars. The parameters varied were splice types, splice length and rebar embedment length. The performance of the splice connection was evaluated based on the load-displacement, ultimate load, displacements and failure modes. The results show that the strength of splice connection depends on the bond strength between sleeve-to-grout and grout-to-rebar; the tensile strength of spliced steel bars and also the tensile strength of sleeve. It is observed that when the grout compressive strength is more than 60N/mm2and bar embedded length is at least 10 bar diameter, the splice connection in BS series is able to provide full tensile strength of the connected rebars.


1994 ◽  
Vol 370 ◽  
Author(s):  
Manouchehr Hassanzadeh

AbstractThis study has determined the fracture mechanical properties of 9 types of rock, namely fine-, medium- and coarse-grained granites, gneiss, quartzite, diabase, gabbro, and fine- and coarse-grained limestones. Test results show among other things that quartzite has the highest compressive strength and fracture energy, while diabase has the highest splitting tensile strength and modulus of elasticity. Furthermore, the strength and fracture energy of the interfacial zone between the rocks and 6 different mortars have been determined. The results showed that, in this investigation, the mortar/rock interfaces are in most cases weaker than both mortars and rocks.


2018 ◽  
Vol 9 (4) ◽  
pp. 560-571
Author(s):  
Hamed Hemmati Pourghashti ◽  
Malek Mohammad Ranjbar ◽  
Rahmat Madandoust

Purpose The purpose of this paper is to conduct a laboratory investigation on measuring the tensile strength of recycled concrete using a double punch test. Furthermore, one of the main goals of this study is to compare the tensile and compressive strengths of recycled concrete samples. Design/methodology/approach Recycled concrete samples were made with variables such as aggregate type (natural stone and aggregate recycled concrete), different water-to-cement ratios and different treatment conditions in the first stage. In the next stage, the double punch test was performed on them, and finally the results obtained from experiments were analyzed and investigated. Findings According to the above tests, it was concluded that: first, according to the laboratory results, the strength of concrete containing recycled aggregates becomes closer to the strength of concrete containing natural aggregates whenever the water-to-cement ratio is higher. Second, upon investigating the treatment conditions, it was observed that the treatment had a greater effect on the strength of the recycled concrete. However, this effect was less tangible in tensile strength. Third, upon investigating the results of tensile strength, it can be said that the Barcelona test results were closer to the direct tensile test results compared to the Brazilian test results. This indicates the higher viability of Barcelona’s test results. Fourth, the results obtained from the Barcelona tensile test for recycled concrete were closer to the results of the direct tensile test compared to the concrete containing natural aggregates, which suggests that the Barcelona test is more suitable as a tensile test for recycled concrete. Fifth, the effects of various factors on tensile strength were somewhat less compared to the compressive strength, although very close. Sixth, the relationships provided by the regulation for concrete tensile strength on compressive strength were highly inconsistent with the results obtained from the direct tensile test, for which the consistency was higher for concrete containing natural aggregates compared to recycled concrete. Seventh, the dispersion of results obtained from tensile tests was higher for recycled concrete compared to concrete containing natural aggregates, but lesser of this dispersion was observed in the compressive strength. Originality/value According to the laboratory results, the strength of concrete containing recycled aggregates becomes closer to the strength of concrete containing natural aggregates whenever the water-to-cement ratio is higher. Upon investigating the treatment conditions, it was observed that the treatment had a greater effect on the strength of the recycled concrete. However, this effect was less tangible in tensile strength. On the basis on the results of the tensile strength, it can be said that the Barcelona test results were closer to the results of the direct tensile test compared to those of the Brazilian test. This indicates the higher viability of Barcelona’s test results. The results obtained from the Barcelona tensile test for recycled concrete were closer to the results of direct tensile test compared to the concrete containing natural aggregates, which suggests that the Barcelona test is more suitable as a tensile test for recycled concrete. The effects of various factors on tensile strength were somewhat less compared to the compressive strength, although very close. The relationships provided by the regulation for concrete tensile strength on compressive strength were highly inconsistent with the results obtained from the direct tensile test, for which the consistency was higher for concrete containing natural aggregate compared to recycled concrete. The dispersion of results obtained from tensile tests was higher for recycled concrete compared to concrete containing natural aggregate, but lesser of this dispersion was observed in the compressive strength.


2019 ◽  
Vol 3 (1) ◽  
pp. 11-23
Author(s):  
Helwiyah Zain

Aggregate is a natural mineral grains that serve as filler in concrete mix, and the greatest material contained in the concrete. These material influence on the properties of concrete, so that the diameter size selection is essential in making the concrete. This study aims to determine the effect of variations of aggregate maximum diameter to the compressive strength of concrete. In this study used 15 specimens, were divided into 3 groups witch each of 5 specimens. Each group is distinguished aggregate maximum diameter: 31.5 mm, 16 mm, and 8 mm. Specimens used in this study is the specimen cylinder with a diameter of 15 cm and 30 cm high. Speciment tested done at age of concrete 28 days. The average compressive strength of concrete for each group of test based on variations of  the aggregate maximum diameter is: for the aggregate maximum diameter of 31.5 mm = 249.67 kg / cm2; the aggregate maximum diameter 16 mm = 274.91 kg / cm2; and the aggregate maximum diameter of 8 mm = 326.74 kg / cm2. Based on these test results, show that the average compressive strength of the concrete for the aggregate maximum diameter of 16 mm is 10.11% stronger than the concrete with the aggregate maximum diameter of 31.5 mm; and the strength of concrete aggregate maximum diameter of 8 mm, 30.87% stronger than the concrete with aggregate maximum diameter of 31.5 mm.


Author(s):  
S.E Ubi ◽  
P.O Nkra ◽  
R.B Agbor ◽  
D.E Ewa ◽  
M. Nuchal

This present research was on the comparison of the efficacious use of basalt and granite as coarse aggregates in concrete work. In order to obtain the basis for comparison, physical and structural tests were conducted on the different materials of the concrete and the concrete samples respectively. Physical test results revealed that basalt have a specific gravity of 2.8 and 2.5, while granite have a specific gravity of 2.9 and 2.6. In density, basalt have a density of 1554.55kg/m3 while granite had a density of 1463.64kg/m3. Aggregate impact test conducted on both aggregates revealed a percentage of 11.05% for basalt and 12.63% for granite. The following structural tests were carried out: compressive strength tests, flexural and tensile strength test and the comparative results are as follows. Compressive strength for basalt 36.39N/mm2 while 37.16N/mm2 for granite. 24.81N/mm2 tensile strength for basalt while 12.57N/mm2 for granite, 31.83N/mm2 flexural strength for basalt while 27.97N/mm2 for granite. From the above results, it can be deduced that basalt has higher strength properties than granite. Therefore, more suitable for coarse aggregate in achieving higher strength with some quantity of other composition of the concrete mix when compared to granite.


Author(s):  
Denny Meisandy Hutauruk ◽  
Muhammad Irwansyah ◽  
Akbar Alfa

The waste problem continues to be a complex issue. On the one hand, the use of plastic still cannot be abandoned by humans, but on the other hand the waste produced is very difficult to decompose. In Indonesia, in 2015 the amount of waste reached 64 million tons / year. Palm fiber is one of the materials that can be used as composite fiber. In this study, a research will be conducted on the manufacture of paving blocks made from HDPE plastic combined with variations of 0%, 1%, 2% and 3% palm fiber. Plastic waste is melted and put into a mold and then combined with palm fiber. From the test results, the highest compressive strength (2% fiber variation) was 45.91 kg/cm2 and the average compressive strength was 45.28 kg/cm2. This compressive strength is under the minimum compressive strength standard of SNI   Permasalahan sampah masih terus menjadi isu kompleks. Di satu sisi, penggunaan plastik masih belum bisa ditinggalkan manusia, namun di sisi lain sampah yang dihasilkan sangat sulit terurai. Di indonesia, pada tahun 2015 tercatat banyaknya sampah mencapai 64 juta ton/tahun. Ijuk merupakan salah satu material yang dapat digunakan sebagai serat komposit. Pda penelitian ini akan dilakukan penelitian mengenai pembuatan paving block berbahan dasar plastik HDPE yang dikombinasikan dengan variasi serat ijuk 0%, 1%, 2 % dan 3%. Limbah plastik dilelehkan dan dimasukkan ke dalam cetakan lalu dipadukan dengan serat ijuk. Dari hasil pengujian, didapatkan kuat tekan tertinggi (variasi serat 2%) sebesar 45,91 kg/cm2 dan kuat tekan rata-ratanya sebesar 45,28 kg/cm2. Kuat tekan ini berada di bawah standar kuat tekan minimal dari SNI.


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