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

2018 ◽  
Vol 8 (3) ◽  
pp. 2882-2886 ◽  
Author(s):  
M. A. Memon ◽  
M. A. Bhutto ◽  
N. A. Lakho ◽  
I. A. Halepoto ◽  
A. N. Memon
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Aggregate Size ◽  
Unit Weight ◽  
Conventional Concrete ◽  
Major Aspect ◽  
Coarse Aggregates ◽  
Cellular 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.

scholarly journals Effect of Coarse Aggregate Gradation and Water-Cement Ratio on Unit Weight and Compressive Strength of No-fines Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 3786-3789
Author(s):  
Z. A. Tunio ◽  
B. A. Memon ◽  
N. A. Memon ◽  
N. A. Lakho ◽  
M. Oad ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Substantial Effect ◽  
Normal Weight ◽  
Structure Design ◽  
Unit Weight ◽  
Uniform Size ◽  
Aggregate Gradation ◽  
Coarse Aggregates

Self-weight of a structure comprises a major portion of the overall structural load which causes conservative structure design. Reduction of structures’ self-weight is an active area of research today. One of the options is to use lightweight concrete and no-fines concrete is one of its types. This type of concrete is made with coarse aggregates, cement, and water. From the density point of view, it is the lighter concrete compared to normal weight concrete but it exhibits less strength. Normally no-fines concrete is manufactured with uniform size aggregates. The performance of no-fines concrete depends on the cement-aggregate ratio and water-cement (w/c) ratio. This study focuses on investigating experimentally the effect of gradation of coarse aggregates and the w/c ratio on unit weight and compressive strength of no-fines concrete. NFC with two cement-aggregate ratios (1:6 and 1:8) having seven combinations of coarse aggregate gradations (10-5 mm, 16-13mm, 20-16mm, 20-13mm, 20-10mm, 16-10mm and 20-5mm) were studied. Two w/c ratios are considered 0.38 and 0.42. The effect of coarse aggregate gradation, cement-aggregate ratio and w/c ratio are studied in terms of unit weight and compressive strength of NFC. The results reveal the pronounced effect of aggregate gradation on the compressive strength and unit weight of the concrete. Also, a substantial effect on the unit weight and compressive strength is observed with the variation in cement-aggregate ration and the w/c ratio.

scholarly journals Effect of Recycled Coarse Aggregate and Bagasse Ash on Two-Stage Concrete

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 556
Author(s):  
Muhammad Faisal Javed ◽  
Afaq Ahmad Durrani ◽  
Sardar Kashif Ur Rehman ◽  
Fahid Aslam ◽  
Hisham Alabduljabbar ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Coarse Aggregate ◽  
Construction Material ◽  
Strength Reduction ◽  
Recycled Aggregate ◽  
Two Stage ◽  
Conventional Concrete ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates

Numerous research studies have been conducted to improve the weak properties of recycled aggregate as a construction material over the last few decades. In two-stage concrete (TSC), coarse aggregates are placed in formwork, and then grout is injected with high pressure to fill up the voids between the coarse aggregates. In this experimental research, TSC was made with 100% recycled coarse aggregate (RCA). Ten percent and twenty percent bagasse ash was used as a fractional substitution of cement along with the RCA. Conventional concrete with 100% natural coarse aggregate (NCA) and 100% RCA was made to determine compressive strength only. Compressive strength reduction in the TSC was 14.36% when 100% RCA was used. Tensile strength in the TSC decreased when 100% RCA was used. The increase in compressive strength was 8.47% when 20% bagasse ash was used compared to the TSC mix that had 100% RCA. The compressive strength of the TSC at 250 °C was also determined to find the reduction in strength at high temperature. Moreover, the compressive and tensile strength of the TSC that had RCA was improved by the addition of bagasse ash.

Analysis and optimization of mechanical properties of recycled concrete based on aggregate characteristics

2021 ◽  
Vol 28 (1) ◽  
pp. 516-527
Author(s):  
Jiangwei Bian ◽  
Wenbing Zhang ◽  
Zhenzhong Shen ◽  
Song Li ◽  
Zhanglan Chen
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Coarse Aggregate ◽  
Aggregate Size ◽  
Peak Stress ◽  
Recycled Concrete ◽  
Maximum Aggregate Size ◽  
Coarse Aggregates ◽  
Aggregate Content ◽  
Aggregate Shape

Abstract The most significant difference between recycled and natural concretes lies in aggregates. The performance of recycled coarse aggregates directly affects the characteristics of recycled concrete. Therefore, an in-depth study of aggregate characteristics is of great significance for improving the quality of recycled concrete. Based on the coarse aggregate content, maximum aggregate size, and aggregate shape, this study uses experiments, theoretical analysis, and numerical simulation to reveal the impact of aggregate characteristics on the mechanical properties of recycled concrete. In this study, we selected the coarse aggregate content, maximum aggregate size, and the aggregate shape as design variables to establish the regression equations of the peak stress and elastic modulus of recycled concrete using the response surface methodology. The results showed that the peak stress and elastic modulus of recycled concrete reach the best when the coarse aggregate content is 45%, the maximum coarse aggregate size is 16 mm, and the regular round coarse aggregates occupy 75%. Such results provide a theoretical basis for the resource utilization and engineering design of recycled aggregates.

Investigation on Improvement of Flexural Behavior of Low-Density Cellular Concrete through Fiber Reinforcement for Non-Structural Applications

2019 ◽  
Vol 2673 (10) ◽  
pp. 641-651
Author(s):  
Arman Abdigaliyev ◽  
Jiong Hu
Keyword(s):  
Mechanical Properties ◽  
Lightweight Concrete ◽  
Construction Material ◽  
Flexural Behavior ◽  
Unit Weight ◽  
Slight Reduction ◽  
Low Density ◽  
Hybrid Fibers ◽  
Structural Applications ◽  
Cellular Concrete

During the last decades, cellular lightweight concrete (CLC), or foamed concrete, has been experiencing greater interest in geotechnical, structural, and non-structural applications. The low density and high flowability makes it a favorable construction material in relation to handling, placing, and construction costs. However, the applications of low-density cellular concrete (LDCC), the category of CLC with a unit weight less than 50 pounds per cubic foot (801 kg/m3) and generally without fine aggregates, are limited mostly to backfill applications in geotechnical engineering. The main reason lies in the brittleness of the material and low to zero resistance to flexural loads. Fiber-reinforced LDCC may be a reasonable solution to improve mechanical properties and expand the application range of the material. This study investigated the effects of adding polypropylene and hybrid fibers on physical and mechanical properties of LDCC and the feasibility of expanding LDCC utilization to non-structural applications. Results showed that although there is a slight reduction of flowability and compressive strength, the flexural behavior of LDCC can be significantly improved with the incorporation of fibers. The flexural strength and flexural toughness of LDCC was found to increase from 26.8 pounds per square inch (psi) (0.18 MPa) to 217.5 psi (1.48 MPa), and from 5.67 lb-in. (0.64 kN-mm) to 292 lb-in. (33.0 kN-mm) respectively at a 1.0% addition rate of a fibrillated polypropylene fiber selected in this study, which makes it a feasible material for non-structural applications.

scholarly journals PENGARUH CANGKANG KEMIRI SEBAGAI PENGGANTI AGREGAT KASAR TERHADAP SIFAT MEKANIK BETON (EFFECT OF CANDLENUT SHELL AS SUBTITUTE COARSE AGGREGATE TO THE MECHANICAL PROPERTIES OF CONCRETE)

2018 ◽  
Author(s):  
Erniati Bachtiar
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Coarse Aggregate ◽  
Concrete Mixture ◽  
Construction Technology ◽  
Concrete Compressive Strength ◽  
Coarse Aggregates ◽  
Volume Weight ◽  
Compressive Strength Test

Concrete construction technology is directed to be sustainable and ecofriendly. The waste of the candlenut shell as a substitute for the coarse aggregate of concrete mixture is known that the candlenut shell has a hard texture so it may be used as a substitute for coarse aggregates in concrete. The purpose of the research was to determine the effect of Candlenut shell as a substitute of coarse aggregate on physical properties (slump test, bleeding, segregation, volume weight) and mechanical properties (compressive strength and tensile strength) of concrete using Candlenut shell as replacement material of the coarse aggregate. The variation of the research was percentage of the Candlenut shell in the concrete mixture, that was 0%, 25%, 50%, 75% and 100% to the coarse aggregate volume in the concrete mixture. Number of specimens in reseach was each 5 pieces each variation. Testing of mechanical properties of concrete (compressive strength and tensile strength) was performed at 28 days. Testing of the concrete for compressive strength test and tensile strength on age 28 days. Concrete using candlenut shell as a substitute of coarse aggregates has decreased compressive strength respectively 11.72 MPa (37.71%) for 25% candlenut shell; 15.54 MPa (50.00%) for 50% candlenut shell; 18.35 MPa (59.02%) for 75% candlenut shell; And 18,85 MPa (60,66%) for 100% candlenut shell from of the 0% candlenut shell with compressive strength of 31.08 Mpa. Concrete using for 25% candlenut shell as a substitute for coarse aggregates decreased tensile strength respectively of 0.95 MPa (28.70%) for 25% candlenut shell; 1.21 MPa (36.56%) for 50% candlenut shell; 1.27 MPa (38.37%) for 75% candlenut shell; And 1.40 MPa (42.30%) for 100% candlenut shell from of the 0% candlenut shell with the tensile strength of BN of 3.31 MPa. The decrease in the value of compressive strength and tensile strength is strongly influenced by the increasing percentage of Candlenut shells on concrete

scholarly journals Influence of Coarse Aggregate Gradation on the Mechnical Properties of Concrete, Part I: No-Fines Concrete

2019 ◽  
Vol 9 (5) ◽  
pp. 4612-4615 ◽  
Author(s):  
Z. A. Tunio ◽  
F. U. R. Abro ◽  
T. Ali ◽  
A. S. Buller ◽  
M. A. Abbasi
Keyword(s):  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Fine Sand ◽  
Minimum Size ◽  
Unit Weight ◽  
Lightweight Aggregate Concrete ◽  
Total Load ◽  
Aggregate Gradation ◽  
Coarse Aggregates

It is well-accepted fact that in concrete construction, the self-weight of the structure is a major part of its total load. Reduction in the unit weight of the concrete results in many advantages. The structural lightweight aggregate concrete (LWAC) of adequate strength is now very common in use. In frame structures, the partition walls are free of any loading, where the construction of these non-structural elements with lightweight concrete of low strength would lead to the subsequent reduction of the overall weight of the structure. No-fines concrete is one of the forms of lightweight concrete and it is porous in nature. It can be manufactured similarly as normal concrete but with only coarse aggregates and without the sand. Thus, it has only two main ingredients; the coarse aggregates and the cement. The coarse aggregates are coated with a thin cement paste layer without fine sand. This is a detailed experimental study carried on NFC with fixed cement to the aggregate proportion of 1:6 with w/c 0.40 ratio. In this study, coarse aggregate of  various gradations (7-4.75) mm, (10-4.75) mm, (10-7) mm, (13-4.74) mm, (10-7) mm, (13-4.75) mm, (13-10) mm, (13-7) mm, (20-4.75) mm, (20-7) mm, (20-10) mm, (20-13) mm, are used, where prefix and suffix show the maximum and minimum size of the aggregate. The cube and cylinder specimens of standard sizes are cast to determine the compressive strength and splitting tensile and the specimens are cured in water up to the age of testing (28 days).

scholarly journals Evaluation of the Effects of Coarse Aggregate Sizes on Concrete Quality

2017 ◽  
Vol 2 (10) ◽  
pp. 1 ◽  
Author(s):  
Lawrence Echefulechukwu Obi
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Aggregate Size ◽  
Test Results ◽  
Construction Sites ◽  
Coarse Aggregates ◽  
Appreciable Increase ◽  
Concrete Production ◽  
Concrete Quality

This work was necessitated by the observations made at construction sites where artisans and craftsmen were left alone in concrete production. It was discovered that they used inadequate quantity and size of coarse aggregates due to difficulty associated in the mixing as if the coarse aggregates were not needed in concrete production. The research has established that the coarse aggregates and their sizes play critical roles in the development of adequate strength in concrete. It was observed that with proper mixing, the slump test results did not witness shear or collapse type of slump rather there were true slump in all cases of the test. The workability decreased with slight differences when the coarse aggregate size was increased. The increase in the coarse aggregates yielded appreciable increase in the compressive strength. It can therefore be inferred that the quality of concrete in terms of strength can be enhanced through an increase in the coarse aggregate size when proper mix ratio, batching, mixing, transporting, placing and finishings are employed in concrete productions.

scholarly journals Effects of the Variety and Content of Natural Pozzolan Coarse Aggregate on the Thermo-Mechanical Properties of Concrete

2021 ◽  
Vol 12 (4) ◽  
pp. 5405-5415
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Coarse Aggregate ◽  
The Other ◽  
Natural Pozzolan ◽  
Coarse Aggregates ◽  
Natural Aggregate ◽  
Middle Atlas

The present study investigated the effects of the variety and content of three natural pozzolan coarse aggregates on concrete. Natural pozzolan aggregates have been obtained from three volcanoes (Boutagrouine, Timahdite, and Jbel Hebri) located in the Middle Atlas region in Morocco. The three pozzolans studied were characterized, and then a comparison was made by replacing the natural aggregate with the pozzolan aggregate in the concrete in different percentages, namely 25, 50, and 100 % in volume. The results showed that the variety and content of pozzolan aggregate have a significant impact on the properties of concrete, primarily caused by the characterization of pozzolan aggregate. The density of concrete decreases with the addition of pozzolan aggregate, which decreases depending on the type of pozzolan aggregate used. The highest compressive strength was measured in the concrete specimens prepared with aggregate BP while the lowest compressive strength was noted in the concrete specimens prepared with aggregate RP. On the other hand, the substitution of NA at 100% by BP, GP, and RP aggregates leads to a decrease in the thermal conductivity of about 67%, 62%, and 55% respectively.

scholarly journals Mechanical and Structural Properties of a Lightweight Concrete with Different Types of Recycling Coarse Aggregate

2019 ◽  
Vol 26 (1) ◽  
pp. 33-40
Author(s):  
Muyasser M. Jomaa’h ◽  
Baraa Thaer Kamil ◽  
Omer S. Baghabra
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
High Efficiency ◽  
Coarse Aggregate ◽  
Splitting Tensile Strength ◽  
Modulus Of Rupture ◽  
Unit Weight ◽  
Dry Density ◽  
Total Density

The light of the world’s technological development in the construction field and the continuous need to apply of a high-efficiency building materials because old methods is no longer is used after the advent of the solutions that characterized by fast applications and maximum protection in addition to reducing costs and increase the sustainability of the establishment and its design age. The lightweights of various installations are an urgent need to decrease the dead loads. Therefore, this study is specie locally focus on replacing the normal coarse aggregate with lightweight coarse aggregate (claystone (bonza), rubber, thermostone and polystyrene) in various volumetric ratios of (25, 50 and 75) % in addition to a preparation reference mix. For the purpose identifying and studying the important specifications the new concrete which contributes to the self-load reduction of the concrete by reducing the total density of the mixture, were prepared models of cylinders and standard prisms, to evaluate the compressive strength and the splitting tensile strength respectively, Also the modulus of rupture and the unit weight, where carried out. The results tests indicated that a drop in the mechanical properties of the concrete with increasing the lightweight coarse aggregate , mechanical properties values : compressive strength , rupture modulus, splitting tensile strength and flexural strength were between (10.66-28.99) MPa (1.122-3.372) MPa, (3.606-6.83) MPa and (20.101-25.874)MPa compared with a reference mixes (38.44MPa), (3.969MPa), (10.476MPa) and (26.940)MPa respectively for mixes of (25, 50 and75)% with different light coarse aggregate , also the values of an oven dry density were between (1665.5-2287.58)kg/m3 compared with reference mixes (2426.41kg/m³). The best concrete mix was (M7, M10) of low density (1598.4 kg/m3) and (1580.4) kg /m3 and the compression strength within the permissible limits (15.47) MPa.

Developing Porous Concrete Interlocking Pavement Blocks Utilizing Recycled Concrete Aggregate for Rainfall Harvesting Use

2021 ◽  
Vol 28 (3) ◽  
pp. 48-60
Author(s):  
Mahdi Mahdi ◽  
Raad Irzooki ◽  
Mazin Abdulrahman
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Coarse Aggregate ◽  
Concrete Pavement ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Unit Weight ◽  
Conventional Concrete ◽  
Porous Concrete ◽  
Porous Pavement

Rainwater harvesting and flood prevention in cities are significant urban hydrological concerns. The use of porous pavement is one of the most effective solutions to handle this matter. Thus, this study aims to develop Porous Interlocking Concrete Pavement (PICP) using recycled aggregate from concrete waste. This porous pavement, then later, can be utilized in low traffic areas and parking lots to harvest water by infiltration and reduce surface runoff. First, the physical properties of the porous concrete blocks, such as density (unit weight), absorption, coefficient of permeability, and porosity, were studied. Also, the mechanical properties of concrete mixtures like compressive strength and flexural strength were tested. This study used two types of PICP, the first one with ordinary coarse aggregate (P1) and the second with recycled crushed concrete coarse aggregate (P2), and then compared their performance to the conventional concrete pavement blocks used the two types of coarse aggregate (R1 and R2). The results show that the unit weight (density) of porous types was reduced by 25% and 26%, and the total porosity increases by around 2.4 times and 18 times respectively, as compared to conventional concrete pavement types. However, the compressive strength and flexural strength of porous concrete types decreased by (55% and 71%), respectively, compared to conventional types. Overall, the infiltration test results showed that the infiltrated water through porous concrete increased by about 83% in comparison to conventional concrete. From the results, utilizing porous concrete pavement can be considered a promising material in terms of water harvesting and decreasing rainwater flooding. Additionally, using recycled concrete can bring economical and environmental benefits.

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