Compressive Strength Of Concrete Cubes Research Articles

Experimental investigation on the floating of rubber particles of crumb rubber concrete

Crumb rubber concrete has been reported to possess many favorable qualities for engineering applications, such as higher ability of deformation, higher toughness, damping ratio and good performance of freeze-thaw, anti-cracking and resistance to water or chloride ion penetration. However, still there exists a major problem at this stage of applications of crumb rubber concrete, which is the floating of rubber particles when vibrating and compacting fresh Crumb rubber concrete. In order to investigate this “floating problem”, a series of experiments were conducted which utilize Crumb rubber concrete cube compressive strength, density and rubber particle distribution inside Crumb rubber concrete specimens as measures of floating of rubber particles. 20 groups of prismatic specimens were casted, among which 11 groups were proportioned with different slump values by adjusting content of water and water-reducing agent, 4 groups were proportioned on basis of one of the 11 groups mentioned above with different sand ratio and vibrating time and the last 5 were controlled groups with no rubber particles. The results show that the floating of rubber particles is not apparent when the slump test value of concrete is low. However, if the slump value is high, and keeps increasing, the floating effect tends to be more apparently and when the slump surpasses a certain value (near 18 cm), the floating develops sharply and abruptly. The floating is more evident with an increased vibrating time. With the sand ratio at a certain value, the floating phenomenon is well-controlled. Sand ratios that are too high or too low can lead to significant floating.

Research on Mechanical Properties of Polymer Regenerative Concrete

This paper designed and completed the different polymer dosage of recycled concrete, was prepared by adding amount was 7%, 14%, 21%, 14% styrene butadiene latex recycled concrete, recycled rubber powder recycled concrete and ordinary concrete block, the cube compressive strength and damping performance test. The cube compressive strength of concrete test according to the ordinary concrete mechanics performance test methods, specimen is 150×150×150 mm cube specimens, pressure testing machine loading speed is 0.5 MPa per second. The concrete damping performance test is carried out according to the free attenuation method, with the hammer vibration test device, the test piece is T type. Based on the damage form of specimens, the compressive strength and damping performance analysis, and compared with ordinary concrete as the benchmark analysis test results show that the polymer recycled concrete cube compressive strength failure process and failure pattern basic consistent with common concrete; In the water/cement ratio, sand ratio, and amount of material per unit volume is the same, under the condition of polymer recycled concrete cube compressive strength is lower than normal concrete, damping performance is higher than that of ordinary concrete, the compressive strength is inversely proportional to the damping sexual relations.

Bond strength between steel and self-compacting lower expansion concrete in composite columns

In order to study the bond behavior between the steel tube and the concrete infill, a total of 17 self-compacting lower expansion CFST columns were prepared and tested. Cross-sectional dimension, dosage of concrete expansive agent, concrete compressive strength, steel tube fabrication method and interface condition were varied to assess their effect on the ultimate average bond strength. The push-out load-slip curves for each specimen are obtained and the distribution of the interface bond stress along the member axial direction and around the cross-section for various load levels are reported. The test results indicate that the steel tube interface roughness, influenced by both the steel tube fabrication method and the interface condition, the maximum flat width-to-thickness ratio (D/t), the concrete compressive strength, and the dosage of expansion agent are the main influence factors for interface bond strength. Then, regression analysis was performed to examine the bond strength of the test results of 19 square and 13 rectangular CFST columns with cold-formed steel tubes from this investigation and other additional references. Considering the influences of the dosage of concrete expansion agent, concrete cube compressive strength and D/t ratio to the bond stress, two empirical equations have been proposed for predicting the ultimate average bond strength for square and rectangular self-compacting lower expansion CFST columns with cold-formed steel tube respectively. Finally, by the analysis of the test data and the previous four segments bond stress-slip curve model, a new bond strength-slip model fitting equation has been proposed to predict the bond stress development.

Characteristics of Cement Concrete with Nano Alumina Particles

Concrete can be nano-engineered by incorporating nano sized building blocks or objects (e.g., nano particles and nano tubes) to control material behaviour and add novel properties. In this work an attempt has been made to study the effect of nano alumina on the properties of concrete composite. In order to investigate the effect of nano-alumina on the mechanical strength of cement composite, the specimens with different volume percentages (0%, 0.5%, 0.75% and 1%) nano-alumina, in each proportion three sample were cast totally making 58 specimens and after 28 days of curing they were tested. Based on experiment, the compressive strength of concrete cubes was all increased by incorporating nano alumina into matrix, when the fraction of nano alumina was 1% of the cement by weight the compressive strength of composites increased by 33.14% at 28 days. The test results showed that addition of nano alumina enhanced the compressive strength and reduced the initial setting time of concrete composite. Micro analysis was carried out by Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS).The studies indicated that nano particle was uniformly distributed by improving the microstructure of concrete.

Measurement and Improvement the Quality of the Compressive Strength of Product Concrete

The research dealt with studying path technology to manufacture of concrete cubes according to specification design of Iraq to the degree of concrete C20 No. 52 of 1984, and in which sample was cubic shape and the dimensions (150 × 150 × 150) mm for each dimensions and the proportion of mixing of the concrete is (1:2:4) using in the casting floor. For concrete resistance required that achieve the degree of confidence of 100%, were examined compressive strength 40 samples of concrete cubes of age 28 days in the Labs section of Civil Department – Technical Institute of Babylon, all made from the same mixing concrete. Where, these samples classified within the acceptable tests were adopted in the implementation of investment projects in the construction sector. The research aims first, to measure the compressive strength of concrete cubes because the decrease or increase the compressive strength from specification design contributes to the failure of investment projects in the construction sector therefore, test was classified units that produced within damaged units. Second, to study an improvement the quality of compressive strength of concrete cubes. Results show that the proportion of damaged cubes are 0.00685, compressive strength was achieve confidence level 99.5% and producing of concrete cubes within the acceptable level of quality (3 Sigma). The quality of compressive strength was improved to good level use advanced sigma levels . DOI: http://dx.doi.org/10.25130/tjes.24.2017.20

Effect of Partial Replacement of Slag and Nano Silica Infused Slag on Properties of Concrete

Investigations were carried out on the changes in properties of concrete when steel slag is used in concrete in its normal form and after modifying its properties by infusing it with nano-silica. The sand is replaced by steel slag and modified steel slag by 10%, 20% and 30% in M30 grade concrete. Tests results on compressive strength and workability of concrete revealed that compressive strength of concrete cubes after 28 days increased by 25.4%, 26.4% and 45.2% for 10%, 20% and 30% respectively after replacing sand by steel slag. After modification of steel slag properties by infusing it with nano silica, the 28 days compressive strength was observed to be increased by 38.19%, 35.80% and 27.89% for 10%, 20% and 30% as compared to traditional concrete mix respectively after replacement. Infusing steel slag with nano silica increased the compressive strength of concrete mix by 20.17%, 25.74% and 49.64% for 10%, 20% and 30% respectively when compared to normal steel slag concrete mix. It was also observed that using steel slag in concrete mix also influences on water consumption in concrete mix. Workability tests conducted using 0.45 and 0.5 w/c ratio and the inference was that the workability increased with the increase in percentage of steel slag but workability decreases with the increase in percentage of modified steel slag.

Investigation of aggregate size effects on the compressive behavior of concrete by electromechanical and mechanical impedance spectroscopy

Concrete is a composite material that is composed of cement mortar and aggregate. The size of the aggregates in the internal structure of concrete affects the mechanical properties and compressive strength of the concrete. In this study, three-dimensional concrete models are created by idealizing the material properties such as modulus of elasticity and mass density which were experimentally acquired in order to investigate the effect of varying size of the aggregates on the compressive strength of concrete cubes in the age of 28 days. Piezoelectric ceramic patches (PZT) are embedded in the core of the concrete cube models with aggregates in fine, medium, and coarse sizes and the harmonic analyses are simulated in commercial software, ABAQUS® using the multi-physics finite element method (MP-FEA). Eventually, electromechanical impedance spectroscopy (EMIS) results as well as mechanical impedance spectroscopy (MIS) results are obtained to highlight the relative changes in the impedance results depending on the aggregate sizes. Thus, EMIS and MIS simulation results are employed in order to predict the effects of varying aggregate sizes on the compressive strengths of the concrete models.

Experimental investigation for partial replacement of fine aggregates in concrete with sandstone

This research study focuses on utilizing sandstone which is overburden waste rock in coal mines to use in concrete as a replacement of fine aggregate. Physical properties of sandstone like water absorption, moisture content, fineness modulus etc., were found to be similar to conventional fine aggregate. Scanning Electron Microscope (SEM) analysis was carried out for analysing elemental composition of sandstone. There was no sulphur content in sandstone which is a good sign to carry the replacement. Fine aggregate was replaced with sandstone at 25%, 50%, 75% and 100% by volume and moulds of concrete cubes and cylinders were prepared. Compressive strength of concrete cubes was tested after 3, 7 and 28 days and split tensile & flexural strength was determined after 28 days. The strength was found to be increasing marginally with increase in sandstone content. Fine aggregate that was replaced by 100% sandstone gave highest strength among all the replacements for the compressive, split tensile and flexural strengths. Though increase in strength was marginal, still sandstone can be an effective replacement for sand in order to save the natural resource and utilize the waste sandstone.

Comparative Studies on Calculation Methods of Shear Behavior of ReinforcedConcrete Beams of Chinese Modern Reinforced Concrete Buildings

In order to study the calculation methods of shear behavior of reinforced concrete beams of Chinese modern reinforced concrete buildings, this paper carried out tests on the concrete compressive strength of 12 Chinese modern concrete buildings, the mechanical properties of 66 rebars from different Chinese modern concrete buildings, and the concrete cover thickness of 9 Chinese modern concrete buildings, and the actual material properties and structural configurations have been obtained. Then, the comparison on calculation methods include the Chinese original calculation method, the Chinese present calculation method, the American present calculation method and the European present calculation method is studied with case analysis method. The results show that the Chinese original calculation method of shear behavior of reinforced concrete beams is based on the allowable stress calculation method, and the design safety factors are 3.55-4.00. The standard value of the compressive strength of concrete cubes is 8.48 MPa, the standard value of the concrete tensile strength is 1.20 MPa, the standard value of the yield strength of rectangular rebars is 229.56 MPa, and the standard value of the yield strength of round rebars is 276.82 MPa. The average value of the concrete cover thickness of beams and columns is 35.96 mm. In term of calculation area of hoop rebars of reinforced concrete beams, without considering earthquake loads, the Chinese original structural calculation method is safer than the Chinese present structural calculation method, but is more unsafe than the American present structural calculation method and the European present structural calculation method. The results can provide the support for structural safety assessments and repair designs of Chinese modern reinforced concrete buildings.

Study on the Effect of the Strength Grade on the Creep Behavior of Concrete

The internal factors which influenced the concrete creep behavior have been mostly divided by the creep model at home and abroad, but the computing is complex. In order to directly use the creep model in engineering conveniently, it is necessary to consider the effect of concrete strength grade on concrete creep. 302 creep test data with a loading age of 28 d, a lasting age of 360 d, and meet certain environmental conditions were collected. The strength of prism with different aspect ratio and high ratio of cylinder specimen was equivalent to the standard cube strength. The relationship between the creep compliance and creep degree and the cube compressive strength of concrete was fitted, and influence coefficient of the strength grade on the creep degree and creep coefficient were obtained. The influence coefficient can be used to determine creep value, creep coefficient, creep degree of concrete. In this paper, the effect of the strength grade on creep was considered directly, which involves the cube compressive strength of concrete from 15 MPa to 180MPa. The research results can be used in broad scope and has certain practical value.

EFFECT OF AGGREGATE FLAKINESS ON THE COMPRESSIVE STRENGTH OF CONCRETE CUBES

In this paper effects of aggregate flakiness on the compressive strength of concrete cubes have been studied using experiments. Total 30 cubes have been cast using normal, 5% of 8 mm, 10 mm and 12 mm size of flaky aggregates and 10% of 12mm size of flaky aggregate. NDT of the cast cubes using rebound hammer and ultrasonic pulse velocity have been also carried out. Aall the cubes were tested for compressive strength. Based on these data, comparative studies have been carried out to quantify the effect of flakiness and salient conclusions are drawn. Most Searchable Keywords what is flaky aggregate, flaky aggregate, the flaky aggregate is when flaky aggregate size,flaky aggregates,flaky aggregate is when, the flaky aggregates is when, mean dimension of aggregate, the flaky aggregate, flakiness of aggregate, flakiness index, effect of flaky aggregates on concrete, flakiness, factors affecting aggregate impact value, flaky shape aggregate, flakiness and elongation test procedure, flakiness and elongation, shape test of aggregate, flakiness and elongation test, flaky aggregate least dimension

Effect of Sugar Cane Juice on Slump Values, Setting Times and Strength of Concrete

The effect of sugar cane juice, (SCJ) on slump values, setting time and compressive strength of concrete cubes was investigated. A total of 32 concrete cubes of size 150x150x150mm with a mix ratio of 1:2:4 were cast with different percentages of unfermented sugar cane juice replacing some proportion of water in the concrete mix. Water/Sugar Cane Juice/cement ratio was held constant at 0.45. The concrete cubes were prepared by replacing water with SCJ in the following proportions 0, 25, 50 and 100%. The cubes were cured, tested and the physical properties of interest in this study were determined. The slump values of the concrete decreased from 40mm at 100: 0 (water:SCJ) to 18mm at 50:50 (water:SCJ) and to 0mm (collapse) at (0:100) (water :SCJ). The final setting time of concrete increased with increase in proportion of SCJ. The highest final setting time of 42 hours (considered excessive), occurred at 75:25 (water:SCJ) proportion. The compressive strength of the (water:SCJ) concrete decreased as the percentage of SCJ increased up to 25% SCJ. Thereafter, an increase in compressive strength was noticed up till 100% SCJ, with a maximum strength of 13.08N/mm2 occurring at 100% SCJ at 28 days. The early strength reduction is due to quick-setting of the concrete, at 25% SCJ, retardation commences and the strength of concrete increases. The study has been carried out at 0, 25, 50 and 100% replacement by weight of potable water with SCJ. A comparative study has been done between concrete made with potable water and those made with water/sugar cane juice.http://dx.doi.org/10.4314/njt.v34i2.6

Properties of pull-out bond strength and concept to assess ultimate bond stress of NSC and HSC

This study was conducted in two phases. The first phase was a study of bond behaviour using two different tests – the single pull-out (SPO) test, in which a concrete specimen was subjected to compressive stresses, and the double pull-out (DPO) test, in which a concrete specimen was subjected to tensile stresses. This phase of the study aimed to make a comparison of the SPO and DPO tests. To compare the behaviour of these tests, different levels of cube compressive strength (from 18·0 to 96·8 MPa) were considered through the use of different types of coarse aggregate (pink limestone, gravel and dolomite), different water/cement ratios and different cement contents. The second phase of the study focused on the bond strength of high-strength concrete (HSC) using the DPO test to assess the ultimate bond stress. This phase considered the effects of concrete cube compressive strength, bar diameter, concrete cover, embedded length and pre-flexural crack length. The cube compressive strengths of the concretes used were 30, 50, 70 and 90 MPa, the bar diameters used were 16 and 18 mm and the concrete covers were 67, 66 and 42 mm. Based on the test results, a concept to assess the ultimate stress of normal-strength concrete (NSC) and HSC was developed. Equations to calculate the ultimate bond stress and the required development length are also suggested.

Impact of Admixture and Rice Husk Ash in Concrete Mix Design

In this paper an attempt has been made to show the impact of Admixtures and Rice husk on concrete structures by conducting an experimental study in the laboratory to improve the cubic strength of concrete structures. Super plasticizer Conplast 430: G-8 as an Admixture is added in concrete mix design. Compressive strength of concrete cubes with Admixture at 7 and 28 days for M-20 grade has been found to be Superior as compare to without Admixture. Similarly, Rice husk ash as a partial replacement of cement is added in the concrete mix design and a detailed parametric study for 5% and 15% Rice husk has been carried out on compressive strength of concrete cubes for M-20 mix at 7 and 28 days. The results shows that compressive strength of concrete cubes has been improved by adding Admixture and Rice husk (as a partial replacement of cement) in the concrete mix design.

Study the Influence of Waste Glass Powder on the Properties of Concrete

The amount of waste glass has gradually increased over the recent years due to an ever-growing use of glass products. Most of the waste glasses are being dumped into landfill sites. The land filling of waste glasses is undesirable because they are not biodegradable, which makes them environmentally less friendly. There is huge potential for using waste glass in the concrete construction sector. When waste glasses are reused in making concrete products, the production cost of concrete will come down. Crushed glass or cullet, if properly sized and processed, can exhibit characteristics similar to that of gravel or sand. In this report we are going to discuss how the waste glass will have its significant effect on concrete and its properties. Fine aggregate replacement levels by waste glass powder 10, 20, and 30 %. The compressive strength of concrete cubes is tested for 3, 7, 28, days were found. The highest replacement level is 20% by WGP. The results are presented in tables and graphs. The performance of design mixes is good and results are reported in this report.

Suitability of Surface Water for Concrete Mix (Case Study of Kwanar - Are Reservoir, Katsina, Nigeria)

Kwanar-Are reservoir is located along Katsina Kano Federal road (Northern Nigeria). It has been used for over two decades as a source of water for irrigation and infrastructural development in Kasina city and environs.This study is intended to determine the quality of water in the reservoir to establish its suitability or otherwise for use in mixing concrete. The investigation is very necessary having in mind that the irrigarion activities take place on substantial portion within the reservoir for which the long term application of fertilizer and pesticides might have negetive impact on it. Samples of water were collected and examined. Parameters such as pH value, chlorides, sulphates, alkalies, and solids as well as organic impurities were determined which essentially affect the setting time of cement, strength, durability and other properties of the concrete. Result obtained shows the tested parameters in negligible quantities. Metals are in trace quantities also. The determined compressive strength of concrete cubes of the diamension 150x150x150 made from water in the reservoir for 7 and 28 days after curing are within normal range. Frequent monitoring of the reservoir is necessary by all stake holders especially the Regulatory Bodies of water resources in Katsina state.

Investigation on concrete filled double skin steel tubes (CFDSTs) under pure torsion

This paper presents a series of tests on concrete filled double skin steel tubular (CFDST) members subjected to pure torsion. Two types of combinations are included, i.e., CFDST section with circular hollow section (CHS) as both inner and outer tubes, and section with CHS as the inner tube and square hollow section (SHS) as the outer tube. Finite element method was used to analyze typical failure mode and complete torque–rotation curve of the specimens, as well as interaction between the steel tubes and the sandwiched concrete of CFDSTs. It was found that the results calculated by finite element method show reasonable agreement with those of the test results. Six important parameters influencing the torque versus torsional rotation curves are identified, i.e. nominal steel ratio, yield strength of outer steel tubes and inner steel tubes, concrete cube compressive strength, width to thickness ratio of inner steel tubes and hollow section ratio. Finally, design formulas are proposed for calculating torsional capacities of CFDSTs.

EFFECT OF CORROSION INHIBITOR ON PROPERTIES OF CONCRETE AND MORTAR MADE WITH DIFFERENT ADMIXTURES

The effect of corrosion inhibiting admixture on concrete and mortar properties is investigated experimentally. Two reference concretes and mortars are considered, based on ordinary Portland cement (OPC) and slag cement. The effect of corrosion inhibiting admixture (a sodium nitrite-based inhibitor) is evaluated. The properties of the fresh concrete (setting time, density and workability) and of the hardened concrete (compressive strength, bending tensile strength and splitting tensile strength) are evaluated. From experimental results, it has been observed that addition of sodium nitrite as corrosion inhibitor (CI) decreases the compressive strength of OPC mortar at all ages i.e. 7 and 28 days, while an increasing trend is observed for addition of CI in slag cement mortars. There is no remarkable change in density observed for addition of CI for both types of mortars made with OPC and slag cement. 7 days compressive strength decreases with addition of CI to concrete cube made with OPC, while an increasing trend is observed for concrete made with slag cement. 28 days compressive strength of concrete cubes made with both type of cements decreases with addition of CI. Further addition of silica fume (10%) with combination of CI improves the compressive strength.

Effect of Water-Cement Ratio on Carbonation and Steel-Corrosion Resistance of Recycled Concrete

This paper studies the effects of different water-cement ratio on recycled concrete strength, anti-carbonation capability, and protecting reinforce steel bar capability. Select the water-cement ratio 0.6,0.55,0.5,0.45,0.4 five cases of the pilot study.It shows that: recycled concrete cube compressive strength, anti-carbonation capacity and protecting reinforce steel bar capability are less than ordinary concrete.

Compressive strength performance of low- and high-strength concrete soaked in mineral oil

This study focused on the impact of used engine oil on the compressive strength of concrete. The compressive strengths of concrete cubes soaked in used mineral oil for 6months were compared with those of oil-free concrete cubes. Five different concrete mixes were adopted to investigate the negative impact of mineral oil on low- and high-strength concrete. Furthermore, this paper describes an investigation into the effect of oil absorption on concrete frame foundations used for large machines at Assiut cement factory, CEMEX, in Egypt. It is concluded that the evaluation of the aggressive effect of mineral oil on concrete by experimentally comparing the strengths of oil-free concrete and oiled concrete at the same age is the most optimal and most reliable of the existing methods. The aggressiveness of oil is very clearly observed for low- and high-strength concrete, and the reductions in compressive strength were observed to be 17% and 11.8%, respectively. Additionally, based on this field study, the degree of oil absorption in concrete is an important determinant of compressive strength.