Investigating Alternates to Flexural Beams for Airport Concrete Strength Compliance

2021 ◽  
Author(s):  
Greg White ◽  
Matthew Johnson

Concrete for airport rigid pavement construction is generally specified to achieve a minimum characteristic flexural strength of 4.5 MPa and acceptance testing during construction aims to verify this key design assumption. The large flexural beam specimens are cumbersome and the testing is expensive. Consequently, industry desires a more convenient test and a laboratory-based conversion to an estimated flexural strength for acceptance testing during production. This research developed and trialed a protocol for the conversion of indirect tensile strength and compressive strength to estimate the flexural strength. The laboratory correlation was encouraging. However, when trialed on a real construction project, the conversions significantly underestimated the measured flexural strength and the risk of rejecting compliant batches of concrete was significantly higher. Further research is required to understand why the reliable conversions developed in the laboratory failed in the field. This may be related to the effect of ambient temperature on 28 day flexural strength, despite the constant curing condition.

2015 ◽  
Vol 773-774 ◽  
pp. 949-953 ◽  
Author(s):  
Izni Syahrizal Ibrahim ◽  
Wan Amizah Wan Jusoh ◽  
Abdul Rahman Mohd Sam ◽  
Nur Ain Mustapa ◽  
Sk Muiz Sk Abdul Razak

This paper discusses the experimental results on the mechanical properties of hybrid fibre reinforced composite concrete (HyFRCC) containing different proportions of steel fibre (SF) and polypropylene fibre (PPF). The mechanical properties include compressive strength, tensile strength, and flexural strength. SF is known to enhance the flexural and tensile strengths, and at the same time is able to resist the formation of macro cracking. Meanwhile, PPF contributes to the tensile strain capacity and compressive strength, and also delay the formation of micro cracks. Hooked-end deformed type SF fibre with 60 mm length and fibrillated virgin type PPF fibre with 19 mm length are used in this study. Meanwhile, the concrete strength is maintained for grade C30. The percentage proportion of SF-PPF fibres are varied in the range of 100-0%, 75-25%, 50-50%, 25-75% and 0-100% of which the total fibre volume fraction (Vf) is fixed at 0.5%. The experimental results reveal that the percentage proportion of SF-PPF fibres with 75-25% produced the maximum performance of flexural strength, tensile strength and flexural toughness. Meanwhile, the percentage proportion of SF-PPF fibres with 100-0% contributes to the improvement of the compressive strength compared to that of plain concrete.


2021 ◽  
Vol 878 (1) ◽  
pp. 012052
Author(s):  
H Ndruru ◽  
R M Simanjuntak ◽  
S P Tampubolon

Abstract The rigid pavement is a pavement construction in which a concrete slab is used as the top layer, which is located above the foundation or directly above the subgrade, without or with an asphalt surface layer. One type of rigid pavement used in Indonesia is rigid pavement without using reinforcement which is usually used in areas with low traffic or residential areas. Pavement without using reinforcement is the small split tensile strength so that the part of the plate will experience cracks due to stresses that cannot be avoided from traffic loads. Therefore, it is necessary to have reinforcement on the concrete slab so that the cracks do not extend. In this research, the use of copper fiber waste from electronic cables as a substitute solution for reinforcement to be used as a mixture in concrete. The experiments were carried out using fiber with variations of 0%, 0.5%, 1%, and 1.5% of the total weight of concrete mixture material and then tested at 28 days of concrete age. This research showed the variation of fiber weight until 1,5% increase the split tensile strength up to 32,46% and the compressive strength up to 9,16%.


2018 ◽  
Vol 12 (1) ◽  
pp. 441-457 ◽  
Author(s):  
Sahar Jabbar Alserai ◽  
Wissam Kadhim Alsaraj ◽  
Zina Waleed Abass

Introduction:One of Iraq’s major environmental problems is a large amount of residual iron produced by the industrial sector, which is stored in domestic waste and landfills. The reuse of construction waste gives two aims, the first is to remove large quantities of pollution resulted from these waste, the second provides cheap resources for concrete aggregates.Methods:This study conducted a series of experiments and tests to test the feasibility of reusing this iron slag and recycled concrete aggregate in concrete mixtures. Different percentages of iron filings were used in the concrete mixture at 0, 0.5%, 0.75% and 1%. Tests are done to evaluate the quality of cast iron concrete which include compressive strength (fcu), flexural strength (fr), indirect tensile strength (ft), SEM and modulus of elasticity (Ec) for four sustainable concretes.Results and Conclusion:The results show that the iron filings amount is increased to 1.0% which resulted in increasing percentage of compressive strength (fcu), flexural strength (fr), indirect tensile strength (ft), SEM and modulus of elasticity (Ec) with 10%, 32%, 42% and 11% for Geopolymer Concrete with Recycled Aggregate (GCRA), 9%, 52%,31% and 17% for geopolymer concrete with natural aggregate (GCNA), 10%, 19%,26% and 12% for Normal Concrete with Natural Aggregate (NCNA) and 23%, 19%, 67% and 14% for Normal Concrete with Recycled Aggregate (NCRA), respectively.


2021 ◽  
Vol 3 (1) ◽  
pp. 1-5
Author(s):  
Saad Issa Sarsam

Prediction of the strength properties of roller compacted concrete from mathematical models is significant for rapid decision of the quality of the pavement. In the present assessment, roller compacted concrete slab samples have been prepared in the laboratory using 12 percentage of Portland cement by weight of aggregates. Cube, core, and beam specimens were extracted from the slab samples and tested for compressive, indirect tensile, and flexural strength at the age of 28 days. Strength test results were corelated among each other and mathematical models were obtained. It was observed that low significance of aggregates gradation type on the compressive and tensile strength exists. However, high influence of dense gradation on flexural strength could be detected. The flexural strength of dense graded mixture is higher than that of gap graded mixtures. The compressive strength of gap graded mixture is higher than that of dense graded mixture. It can be concluded that the flexural strength is higher than the tensile strength by (2.17 and 1.24) folds for dense and gap graded mixtures respectively. The compressive strength is higher than tensile strength by (5.72 and 4.87) folds for dense and gap graded mixtures respectively. The compressive strength is higher than the flexural strength by (3.4 and 2.49) folds for dense and gap graded roller compacted concrete respectively. The obtained mathematical models exhibit high coefficient of determination and may be implemented in verification of the specific strength property based on other measured strength properties of roller compacted concrete.


2018 ◽  
Vol 13 (4) ◽  
pp. 447-474 ◽  
Author(s):  
Ali Ghorbani ◽  
Maysam Salimzadehshooiili ◽  
Jurgis Medzvieckas ◽  
Romualdas Kliukas

In this paper, stress-strain behaviour of sand-clay mixture stabilised with different cement and rice husk ash percentages, and reinforced with different polypropylene fibre lengths are evaluated. Mixtures are widely used in road construction for soil stabilisation. It is observed that replacing half of the cement percentage (in high cement contents) with rice husk ash will result in a higher unconfined compressive strength. In addition, the presence of 6 mm polypropylene fibres will help to increase the unconfined compressive strength of stabilised samples, while larger fibres cause reverse behaviour. In addition, introducing a new index for assessing the effect of curing days. Curing Improvement Index it is obtained that larger fibres show higher Curing Improvement Index values. Results gained for the effects of curing days, and fibre lengths are further discussed and interpreted using Scanning Electron Microscopy photos. Based on the conducted Unconfined Compressive Strength, Indirect Tensile Strength, and Flexural Strength tests and using evolutionary polynomial regression modelling, some simple relations for prediction of unconfined compressive strength, indirect tensile strength, and flexural strength of cement-rice husk ash stabilised, and fibre reinforced samples are presented. High coefficients of determination of developed equations with experimental data show the accuracy of proposed relationships. Moreover, using a sensitivity analysis based on Cosine Amplitude Method, cement percentage and the length of polypropylene fibres used to reinforce the stabilised samples are respectively reported as the most and the least effective parameters on the unconfined compressive strength of specimens.


2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Chaohua Jiang ◽  
Yizhi Wang ◽  
Wenwen Guo ◽  
Chen Jin ◽  
Min Wei

With great mechanical properties and corrosion resistance, amorphous alloy fiber (AAF) is a highly anticipated material in the fiber-reinforced concrete (FRC) field. In this study, the mechanical properties of AAFRC such as compressive strength, tensile strength, and flexural strength were examined. The comparison and analysis between AAFRC and steel fiber-reinforced concrete (SFRC) were also carried out. The results show that adding fibers significantly improves the concrete strength and toughness index. Compared with plain concrete, the compressive strength, splitting tensile strength, and flexural strength of AAFRC increase by 8.21–16.72%, 10.4–32.8%, and 18.12–45.21%, respectively. Meanwhile, the addition of AAF with a greater tensile strength and larger unit volume quantity improves the splitting tensile strength and flexural strength of concrete more noticeably than that of SF. Adding AAF improves the ductility of concrete more significantly in comparison to the SF. AAFRC shows great interfacial bonding performance as well. A prediction equation for the strength of AAFRC was proposed, which verified good accuracy calibrated based on the test results.


2021 ◽  
Vol 921 (1) ◽  
pp. 012063
Author(s):  
D Sandy ◽  
S R Tonapa

Abstract One of the most widely used construction materials is concrete. Concrete technology is currently developing, one of which is looking for alternative materials concrete forming. This research focuses on the use of slag as a fine aggregate in concrete, especially in environments containing sulfuric and chloride acid. Observations were made by testing compressive strength, indirect tensile strength, and flexural strength, with 171 cylindrical specimens and 27 sample beam specimens. The test results show that the relative percentage of compressive strength of normal concrete on H2SO4 curing against normal curing decreased 1.85% and 2.58% on HCl curing. The biggest reduction in the percentage of concrete compressive strength was found in 30% slag substitution with a value 8.42%, while the percentage reduction in the relative strength of the indirect tensile strength concrete is found in concrete with a slag substitution of 35% with a value 9.26%. As well as the decrease in relative percentage of flexural strength was found in 35% slag substitution with a value 12.84%. Although there is a decrease in each characteristic of concrete, slag material can be used as a constituent for concrete under environmental conditions of sulfuric acid and chloride acid.


2019 ◽  
Vol 276 ◽  
pp. 01020 ◽  
Author(s):  
Habib Abdurrahman ◽  
Mia Qoryati ◽  
Muklisin Olivia ◽  
Monita Olivia

A waste tyre is an inorganic rubber waste that is difficult to decompose since it has a complex structure. Utilization of waste tyre as a material to improve elastic properties in rigid pavement construction in peat environment has not investigated yet. The rigid pavement in peat environment needs to be impermeable and posses high elastic properties. This paper presents mechanical properties and porosity of concrete incorporating crumb rubber as an additive in concrete mixture with a variation of 10%, 20%, and 30% by fine aggregates volume. Rice husk ash is added as a filler in various percentage (5%, 10%, and 15%) by cement volume in the mixture. Concrete is produced with a target strength of 35 MPa. In this research, the OPC concrete mix is used as a control mix. Mechanical properties taken were the compressive strength, tensile strength, flexural strength, modulus of elasticity, and porosity at 7, 14 and 28 days. Results show that crumb rubber and rice husk ash addition increases compressive strength, improves elastic properties, i.e., tensile strength, flexural strength, modulus of elasticity, and reduce the porosity of the concrete. It can be concluded that the crumb rubber is potential as an environmentally friendly additive as rigid pavement material in peat environment.


2020 ◽  
Vol 14 (2) ◽  
pp. 6734-6742
Author(s):  
A. Syamsir ◽  
S. M. Mubin ◽  
N. M. Nor ◽  
V. Anggraini ◽  
S. Nagappan ◽  
...  

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study.  The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.    


2011 ◽  
Vol 243-249 ◽  
pp. 494-498
Author(s):  
Hui Ming Bao

By means of the tests on the mechanics performance of the reinforcing concrete mixed with sisal fibers or rubber powder of certain content are investigated. The compressive strength, tensile strength and flexural strength, etc. are compared. The test indicates that when the test condition is same, the compressive strength, tensile strength and flexural strength of the sisal fibers concrete are better than those of the rubber powder’s. The sisal fiber concrete is environment friendly than the rubber powder concrete. And it has widely value of spread and utilization.


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