Effect Of Coarse Aggregate Size Research Articles

Effects of coarse aggregate size on thickness and micro-properties of ITZ and the mechanical properties of concrete

This research delves into the impact of coarse aggregate particle size on the mechanical properties of concrete. Nano-indentation and scanning electron microscope (SEM) techniques were applied to characterize the micro-properties and thickness the Interfacial Transition Zone (ITZ). The effect of coarse aggregate size on concrete's compressive strength (σc) and elastic modulus (E) and the relationship between the micro properties of the ITZ and the macro properties of concrete were discussed. In addition, Griffith's microcrack theory was adopted to explain related mechanisms. The relationship between the microscopic properties of the ITZ and the macroscopic properties of concrete was discussed. The results show that, in concrete with a low water cement-ratio w/c (0.3), thickness of ITZ increased with the coarse aggregate size and concrete properties decreased. While, in concrete with a higher w/c (0.4), there exists an optimum coarse aggregate size for the lowest thickness of ITZ and highest strength. Taking the ITZ as the initial crack in concrete failure, concrete properties can be linked to ITZ thickness from Griffith's microcrack theory.

Variation of aggregate size using sensors based on impact strength of pervious concrete

Pervious concrete is a high porosity concrete and this focussed on the effect of coarse aggregate size on the mechanical and impact strength of pervious concrete. Compressive and split tensile strengths are considered for mechanical properties. Porosity as hydraulic and impact strengths were evaluated. The coarse aggregate used in this was grouped in three categories based on the size of M1, M2, and M3 with 16 mm, 12 mm, and 10 mm respectively. Fly ash as secondary cementitious material replaced cement from 0 to 30%, and a total of twenty-one mixes were considered using sensorsfor this study. The various mineral phases available in the concrete was identified with XRD analysis. The results concluded that the M3 mix with 20% FA enhanced the mechanical properties and lower in impact strength. M1 mix with 20% FA can be a sustainable pervious concrete mix.

Effect of Coarse Aggregate Size on the Performance of PE/HPP Hybrid Fiber Concrete

Three kinds of continuously graded coarse aggregates with maximum particle sizes of 10mm, 16mm and 20mm were selected from pebble and gravel respectively, then, Slump test, compressive strength test and bending toughness test were carried out to study the influence of maximum particle size of coarse aggregate on the workability, compressive strength, wear resistance and bending behaviour of PE/HPP hybrid fiber concrete. The results show that with the increase of the maximum particle size of coarse aggregate, the work performance, compressive strength and bending toughness of hybrid fiber concrete are improved.

Requirements of specimen dimension considering maximum coarse aggregate size for concrete split Hopkinson pressure bar tests

Dynamic increase factors (DIF) of concrete compressive strength have been proposed through experiments on specimens including small aggregates without considering the effect of the coarse aggregate size, which was due to the limitations in the size of specimens and test apparatus. Therefore, this study conducted an experimental investigation of the effect of the maximum coarse aggregate size (Gmax) on the DIF of normal-strength concrete. Split Hopkinson pressure bar (SHPB) tests were performed for mortar and concrete specimens with various sizes of Gmax, and the apparent and pure rate DIFs were obtained. Moreover, the pure rate DIF of each Gmax was verified through numerical analysis of the SHPB tests. The test and analysis results indicated that Gmax affected the dispersion of the apparent DIF and the values of the pure rate DIF. Based on these results, a guideline for the fabrication of specimens considering Gmax for concrete SHPB tests was suggested.

Effect of coarse aggregate size on corrosion of reinforced concrete exposed to carbonation and chloride ingress by electrochemical measurements

This article evaluated the application of electrochemical techniques to assess the degree of corrosion of reinforcement steel in concrete exposed simultaneously to carbonation and chloride ingress. After carbonation accelerated at 3 different levels, the reinforcement corrosion was accelerated by the ionic migration of chlorides. Subsequently, the electrochemical techniques (Rp, cyclic voltammetry, EIS) were applied to the specimens at 40 months of age. Chloride penetrations above 20 mm showed a remarkable drop in steel durability. In this condition, the disappearance of the stability region in the voltammograms and an increase in the capacitive arc of the impedance spectra were identified. The intensification of carbonation reduced the Rp. Concretes with 25 mm coarse aggregate had the worst results in the electrochemical tests since the sharp drop in the phase angle during EIS tests indicates a concrete/reinforcement interface incapable of retaining electrical charges, with a low resistance to corrosion progress. The results of mass loss supported this statement.

Effect of Fine Aggregate Particle Size on Mortar Shrinkage Properties

The materials used and mix proportion for repair materials differ depending on the required performance such as shrinkage. In general, repair materials have a lower water-cement ratio than regular ready-mixed concrete. In addition, the particle size of the fine aggregate used for repair materials has been adjusted in consideration of workability. Aggregate has the effect of restraining the shrinkage of cement-based materials. Although the effect of coarse aggregate size on the shrinkage characteristics of concrete has been reported, the effect of fine aggregate size on the shrinkage characteristics of mortar has hardly been investigated. Therefore, we investigated the effect of the particle size of the fine aggregate on the autogenous shrinkage and drying shrinkage of the mortar with W/C=35% assuming the repair materials. As a result, it was clarified that the particle size of fine aggregate affects the autogenous shrinkage strain and drying shrinkage strain of mortar. In the range of S/C=1-1.5, it was clarified that the larger the F.M., the smaller the autogenous shrinkage strain. It was also clarified that the larger the S/C and the larger the FM, the smaller the drying shrinkage strain tends to be.

The Effect of Coarse Aggregate Size On Pervious Concrete Mixture

Along with the development progress in Indonesia, it causes the reduction of green areas. Coupled with the lack of public awareness of the environment is a problem that must be considered. Pervious concrete that be as one of the solutions in pavement construction, concrete sheet piles, retaining walls is a product that can be considered successfully in meeting expectations as an environmentally friendly construction. For road pavement, pervious concrete must have a strength of 30 MPa. Therefore, there is a need for research for the mix design of pervious concrete using the ACI 522R-10 Report on Pervious Concrete method with an initial design compressive strength of 25 MPa. The method is to vary the coarse aggregate used in the pervious concrete mixture. In this research, it is divided into 5 variations to find a mixture that is in accordance with the plan or which exceeds the initial plan, and its permeability still meets the requirements for pervious concrete. Testing of the specimens includes the volume weight test, compressive strength, split tensile strength, modulus of elasticity of concrete, porosity, absorption, and permeability. From the research, the results of the volume weight of pervious concrete are 1,974.14 - 2,187.83 kg/m3 that pervious concrete is included in the lightweight concrete group due to it has a weight below 2,200 kg/m3 . The average compressive strength of pervious concrete is 20.089 – 46.978 MPa. The value of the split tensile strength of pervious concrete is 8,968-19,127 MPa. The average value of porosity is between 8,307 – 13,097%. The average value of absorption is between 3.452 – 5.444%. The average value of the permeability is between 0.0025-0.487 cm3/sec. From this research, it can be concluded that the use of different coarse aggregates size will produce pervious concrete with different compressive strengths. The compressive strength with aggregate size 0.5x0.5 without sieving, it closed to the initial plan of 27.72 MPa, whereas the highest compressive strength is for a mixed aggregate size of 1/1 and 0.5/0.5 cm with sieving that the compressive strength achieved 46.978 MPa

The Effect of Coarse Aggregate Size On Pervious Concrete Mixture

Along with the development progress in Indonesia, it causes the reduction of green areas. Coupled with the lack of public awareness of the environment is a problem that must be considered. Pervious concrete that be as one of the solutions in pavement construction, concrete sheet piles, retaining walls is a product that can be considered successfully in meeting expectations as an environmentally friendly construction. For road pavement, pervious concrete must have a strength of 30 MPa. Therefore, there is a need for research for the mix design of pervious concrete using the ACI 522R-10 Report on Pervious Concrete method with an initial design compressive strength of 25 MPa. The method is to vary the coarse aggregate used in the pervious concrete mixture. In this research, it is divided into 5 variations to find a mixture that is in accordance with the plan or which exceeds the initial plan, and its permeability still meets the requirements for pervious concrete. Testing of the specimens includes the volume weight test, compressive strength, split tensile strength, modulus of elasticity of concrete, porosity, absorption, and permeability. From the research, the results of the volume weight of pervious concrete are 1,974.14 - 2,187.83 kg/m3 that pervious concrete is included in the lightweight concrete group due to it has a weight below 2,200 kg/m3 . The average compressive strength of pervious concrete is 20.089 – 46.978 MPa. The value of the split tensile strength of pervious concrete is 8,968-19,127 MPa. The average value of porosity is between 8,307 – 13,097%. The average value of absorption is between 3.452 – 5.444%. The average value of the permeability is between 0.0025-0.487 cm3/sec. From this research, it can be concluded that the use of different coarse aggregates size will produce pervious concrete with different compressive strengths. The compressive strength with aggregate size 0.5x0.5 without sieving, it closed to the initial plan of 27.72 MPa, whereas the highest compressive strength is for a mixed aggregate size of 1/1 and 0.5/0.5 cm with sieving that the compressive strength achieved 46.978 MPa

Effect of Coarse Aggregate Size and Gradation on Workability and Compressive Strength of Plain Concrete

In this study effect of coarse aggregate size and gradation on workability and compressive strength of concrete was investigated. A mix ratio of 1:2:4 with a target strength of 20/25MPa, was adopted with a water-cement ratio of 0.6. Concrete cubes were produced with uniform coarse aggregate size of 4.75, 6.7, 9.5, 13.2 and 19mm respectively, with another set of samples produced with all the coarse aggregate sizes. Slump tests were carried out for all mixes and all sets of samples were tested for compressive strength after, 7, 14 and 28 days of curing. It was observed that workability was similar for all mixes with no well-defined pattern of relationship with size of coarse aggregate used. Compressive strength was observed to increase with increase in coarse aggregate size. Authors attributed this to the less quantity of water absorbed by larger size coarse aggregate during mixing which results in lesser quantity of capillary pores after curing. Maximum compressive strength was recorded for samples with 9.5mm coarse aggregate size. These show that quality concrete can still be produced with single-sized coarse aggregate as long as the optimum size can be determined for the particular mix.

Assessing the Effect of Coarse Aggregate Size on Self-Compacting Fibre Reinforced Concrete Mix

Assessing the Effect of Coarse Aggregate Size on Self-Compacting Fibre Reinforced Concrete Mix

Effects of Coarse Aggregate Shape and Texture on Engineering Properties of Roller Compacted Concrete Prepared for High Traffic Routes

Abstract Use of roller-compacted concrete in pavement construction is increasing. Roller compacted concrete is a zero-slump, highly compacted concrete that is placed by equipment similar to that used in asphalt pavement construction. This investigation was conducted to collect the state-of-the-art information on effects of coarse aggregate size and texture on the strength and workability of roller-compacted concrete (RCC) for pavement construction and maintenance. Concrete specimens containing cubical and rough coarse aggregate, irregular and rough coarse aggregate, angular and rough coarse aggregate, rounded/spherical and smooth coarse aggregate, and flaky/elongated and rough coarse aggregate were prepared at 1:3:3 concrete mix ratio and 0.4 water cement ratio. Laboratory testing of specimens derived from the concrete specimens showed excellent results for cubical and rough coarse aggregate, irregular and rough coarse aggregate, and angular and rough coarse aggregate. Specimens from the rounded/spherical and smooth coarse aggregate, and flaky/elongated and rough coarse aggregate performed poorly in laboratory. The study therefore recommends the use of cubical and rough coarse aggregate, and irregular and rough coarse aggregate in the production of roller-compacted concrete for pavement construction and maintenance.

Effect of coarse aggregate size on non-uniform stress/strain and drying-induced microcracking in concrete

Non-uniform stresses, strains and microcracking of the concretes with three coarse aggregate sizes (5–10 mm, 10–16 mm, 16–20 mm) dried under 40% relative humidity (RH) for 60 days were quantified using digital image correlation and lattice fracture modelling. The influencing mechanism of coarse aggregate size on the drying-induced microcracking of concrete was clarified: (1) As the coarse aggregate size decreases, propagation paths of microcracking are increased, which increase the number of small microcracks and release the drying shrinkage force from mortar phase. (2) Tensile stress shells surrounding the coarse aggregates become thinner, thereby decreasing the area of large microcracks. As the coarse aggregate size decreased from 16-20 mm to 5–10 mm, the average thickness of tensile stress shells decreased from 2.13 mm to 1.09 mm at the beginning of drying, and the area of the microcracks >5 μm in width decreased from 796.6 mm2/m2 to 340.2 mm2/m2 at 60 days since drying.

BOD and COD reduction using porous concrete pavements

Many places in the world suffer from a shortage in potable water because of the population growth, contamination of water supplies and the problems related with global warming issue. The contamination of drinking water is a considerable problem in the world. In this study, the possibility of using a Pervious Concrete Pavement (PCP) in wastewater clarification was studied. Twenty-four Portland cement mixtures were prepared and tested in order to estimate the effect of coarse aggregate size, water-to-cement ratio and cement content as well as the relationships between compressive strength, porosity, and permeability. Two gravel grades were used (G1 and G2), G1 includes the aggregate size between 4.75–9 mm, while the aggregate size between 9−19 mm was represented by G2. Three water cement ratios (W1 = 0.28, W2 = 0.30, W3 = 0.32) and four cement contents (C1 = 275, C2 = 300, C3 = 325 and C4 = 350 kg/m3) were used. The maximum compressive strength obtained in this study was 17.75 Mpa, which resulted from gravel size of G1 and the highest W/C ratio and cement content. The evaluation of water treatment properties of PCP involved pavement samples of 300 × 300 mm with three different thicknesses of 100, 150 and 200 mm that subjected to synthetic wastewater flow with volume of 5 L. Removal efficiencies of several pollutants such as the chemical oxygen demand (COD), biological oxygen demand (BOD) were inspected. The removal percentage of such pollutants increased with the increment of gravel size and pavement thickness. Maximum removal for COD and BOD were 54 % and 68 %, respectively, they were obtained using the aggregate size of G2, water cement ratio of W3 and pavement thickness of 20 cm. The modification in pollutants removal percentages can be done depending on the enhancement and refreshment of the bacterial growth by adding the required feed for the bacteria in wastewater in form of mineral salt solution MSM. The resulted removals due to this process also occurred when the large gravel size of G2, water cement ratio of 0.32 and pavement thickness of 20 cm were used, the removal percentages were increased in this case to be 61 % and 79 % for COD and BOD, respectively.

Effect of aggregate size on the dynamic interfacial bond behaviour between basalt fiber reinforced polymer sheets and concrete

This experimental investigation examines the influence of coarse aggregate size (i.e. 5–10 mm, 10–15 mm, and 15–20 mm) on the dynamic interfacial bond behaviour between BFRP and concrete under various loading speeds (i.e. 8.33E−6, 0.1, 1.0, 3.0, 5.0, and 8.0 m/s). The testing results including the interfacial bond strength and bond-slip responses are evaluated and discussed. For the specimens with the same coarse aggregate size under different loading speeds, the ultimate debonding strain of the BFRP sheets subjected to dynamic loading is higher than that under static loading, and the debonding load and peak shear stress increase with the rising loading speed. For the specimens with different coarse aggregate sizes under the same loading speed, the peak interfacial shear stress slightly reduces with the rising coarse aggregate size. However, the variation of the interfacial shear stress is marginal when the loading speed is over 3 m/s due to the debonding surface shifted from concrete substrate to the concrete-epoxy interface. The proposed bond-slip model by incorporating the effects of coarse aggregate size and strain rate matches well with the testing results.

Effect of micro silica and aggregate size on cracking of self-compacting concrete

In the evaluation of long-term serviceability leading to prevention of damage of self-compacting concrete (SCC) structures, a thorough understanding on fracture parameters and cracking performance from initial stage to hardened stage is important. This paper reports the effect of coarse aggregate size and micro silica addition on fracture characteristics and ductility of SCC. Experiments were performed by conducting three-point bending tests on notched beams as per recommendations by Rilem standards. For all mixes, the parameters are analysed by the size-effect method. The tests proved that an increase in the size of the coarse aggregates can increase the fracture energy and ductility due to changing fractal dimensions and the fracture process zone length. A 10% addition of micro silica showed better fracture properties. Equations for assessing the fracture energy and length of the fracture process zone using a statistical approach were then developed.

Effect of Coarse Aggregate Size on Shear Behavior of Self-Compacting Concrete and Conventional Concrete Beams

This research presents an experimental study to investigate the effect of coarse aggregate maximum size on the shear behavior of self-compacting concrete (SCC) and conventional concrete (CC) slender beams having the same compressive strength and make a comparison between the shear behavior of concrete beams. The experimental program included casting and testing eight beams with a constant size of 150mm height ×125mm width×1000mm length. Two coarse aggregate maximum sizes were used (10mm and 20mm) with SCC and CC in normal and high strength concrete. The results showed that increasing the coarse aggregate maximum size from 10mm to 20mm results in a slight increase in the diagonal cracking load and ultimate shear strength of SCC beams, while for CC beams the result was more significant. Also, it was found that the effect of increasing the coarse aggregate maximum size was more significant for normal strength as compared with high strength beams for both concrete types. Furthermore, the comparison between the shear behavior of SCC and CC beams having the same compressive strength and a concrete with the same coarse aggregate maximum size revealed that the SCC exhibited less diagonal cracking load and less ultimate strength compared with CC.

Effect of maximum coarse aggregate size on dynamic compressive strength of high-strength concrete

Dynamic increase factor (DIF) is a measure of the rate effect in the analysis and design of structures subjected to impact or impulsive loads. A variety of DIFs have been suggested based on the results of split Hopkinson pressure bar (SHPB) tests, which is the test technique most commonly used to obtain dynamic material properties. However, due to the lack of a standard test method and some limitations in the SHPB equipment, most SHPB tests have been conducted for mortar or concrete specimens containing small size coarse aggregate that is very different from the actual concrete used in construction. The DIFs that are provided in most structural design codes are based on these test results. Therefore, it is necessary to investigate the effect of coarse aggregate size on the dynamic concrete compressive strength. In this study, a series of SHPB tests were conducted for mortar and concrete specimens with various maximum aggregate sizes. The test results indicated that the larger maximum coarse aggregate sizes induce larger heterogeneity of specimens. On the other hand, the pure rate DIFs did not exhibit a dependency on the maximum coarse aggregate size. Based on these results, guidance as to the maximum coarse aggregate size of concrete specimens for SHPB tests is provided.

Effects of Uncrushed Aggregate on the Mechanical Properties of No-Fines Concrete

Concrete’s self-weight is a major aspect of a structure’s overall weight. Recently, the use of lightweight concrete (no-fines, foamed and cellular concrete) has been increased. Normally no-fines concrete is produced with crushed coarse aggregate of uniform gradation. This study aims to investigate experimentally the effects of the use of uncrushed coarse aggregates on unit weight, compressive and tensile strength of the no-fines (NFC) as well as conventional concrete (CC). In addition, the effects of coarse aggregate size on the mechanical properties were also studied. Four gradations of uncrushed coarse aggregates ranging between (5.5-4.75) mm, (10-4.75) mm, (20-4.75) mm and (25-4.75) mm were used for preparing the concretes. The fixed cement-aggregate ratios of 1:6 (with w/c ratio=0.4) and 1:2:4 (with w/c ratio=0.5) were adopted for NFC and CC respectively. It was found that the gradation of uncrushed coarse aggregate has a significant effect on the mechanical properties of NFC. A maximum of 16% reduction in self-weight of the concrete without fines was obtained, as compared to that with fines. Moreover, the compressive strength of no-fines concrete significantly improved by replacing crushed with uncrushed coarse aggregate. The compressive strength increased by 16% for the batch of (25-4.75) mm.

Effect of Coarse Aggregate Size on the Shear Behavior of Beams without Shear Reinforcement

Effect of Coarse Aggregate Size on the Shear Behavior of Beams without Shear Reinforcement

Effect of coarse aggregate size on the compressive behaviour of geopolymer concrete

The utilisation of ordinary Portland cement not only consumes significant amount of natural resources but also causes pollution to the environment due to Carbon emission. As a result, a replacement material for cement including the use of fly ash becomes a solution to this environmental concern. Accordingly, the compressive strength of cement-based concrete depends primarily on several factors such as the size of gravel. Therefore, it is worth studying to find out whether this factor likewise influences the compressive behaviour of geopolymer concrete. This study experimentally investigated the effect of the particle size of coarse aggregate on the compressive behaviour of fly ash geopolymer concrete. Compressive tests have been carried out on a 100 mm × 200 mm cylindrical specimen using a compression testing machine. The results showed that the fly ash geopolymer concrete specimens exhibited brittle failure mode characterised by splitting, shear, columnar and conical type of failure. It was found that the size of the coarse aggregate that offered a maximum compressive strength is in the range of 12.5–25 mm. Furthermore, the size of the coarse aggregate does not affect the trend results on ambient vs. oven-cured specimen, as well as the days of curing.