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 Sustainable Green Lightweight Concrete Containing Plastic-Based Green Lightweight Aggregate

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3304
Author(s):  
Fahad K. Alqahtani
Keyword(s):  
Natural Resources ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Plastic Waste ◽  
Unit Weight ◽  
Lightweight Aggregate Concrete ◽  
Dry Density ◽  
Study Results

Nowadays the environment and its natural resources face many issues, related to the depletion of natural resources beside the increase in environmental pollution resulted from uncontrolled plastic waste disposal. Therefore, it is important to find effective and feasible solutions to utilize these wastes, such as using them to produce environmentally friendly green concrete. In this study, plastic-based green lightweight aggregates (PGLAs) containing PET plastic waste and by product additives were developed, and their subsequent physical and mechanical properties were compared with those of reference aggregates. Then, green lightweight aggregate concrete mixes (GLACs) were produced at 100% replacement of normal weight and lightweight coarse aggregate with developed PGLAs; and their fresh, hardened, microscopic and durability-related properties were compared to those of control mixes. Study results revealed that the unit weight of PGLAs were 21% to 29% less than that of normal coarse aggregate. Additionally, PGLAs had low water absorption that varied between 1.2% and 1.6%. The developed aggregates had 45% higher strength compared to that of lightweight coarse aggregate. Study results confirmed that structural green lightweight aggregate concretes (GLACs), that satisfied the dry density, compressive and splitting tensile strength requirements specified in ASTM C330, were feasibly produced. Finally, GLACs had low-to-moderate chloride penetration in accordance with ASTM C1202, thus it can be used in those areas exposed to the risk of chloride attack.

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.

Properties of Lightweight Concrete Masonry Units Made from Lightweight Aggregates

2010 ◽  
Vol 150-151 ◽  
pp. 1588-1594
Author(s):  
Chao Wei Tang ◽  
Kuo Haung Fan ◽  
Wen Po Tsai ◽  
How Ji Chen
Keyword(s):  
High Performance ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Filling Ratio ◽  
National Standards ◽  
Unit Weight ◽  
Concrete Masonry ◽  
Research Findings

In the paper the properties of concrete masonry unit (CMU) made from sedimentary lightweight aggregate (LWA) were investigated. The main variables include water to cementitious material ratio (W/CM), filling ratio of paste or mortar in voids between coarse aggregate particles (Fv), filling ratio of sand in mortar (Fm), and cement replacement level by slag (Sc). Test results of representative CMU specimens show that unit weight ranged from 1585 to 1743 kg/m3, which was 30-25% lower than that for a normal weight CMU (2300 kg/m3); compressive strengths ranged from 8.4 to 18.7 MPa; water absorption was found to vary between 0.05 to 0.13 g/cm3; and thermal conductivity ranged from 0.27 to 0.41 W/mK. The research findings demonstrate that the use of sedimentary LWA as coarse aggregate in various concrete mixtures could produce high performance lightweight CMU, which comply with the requirements of Chinese National Standards (CNS) standards.

Preparation Test Study on High Strength Lightweight Concrete in Engineering Materials

2013 ◽  
Vol 648 ◽  
pp. 55-58
Author(s):  
Xiao Qing Yu ◽  
Mao Lin ◽  
Guang Long Geng ◽  
Yue Han Li ◽  
Li Jia
Keyword(s):  
Rate Ratio ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Cement Ratio ◽  
Test Study ◽  
Aggregate Rate

Low and easy brittle characteristics of lightweight aggregate concrete tensile strength, shear strength, combined with high strength lightweight concrete requirements in the selection select strength Lytag, silica fume, superplasticizer material, preparationhigh strength lightweight aggregate concrete. Experimental study on the water-cement ratio, coarse aggregate rate ratio factors on the strength of lightweight aggregate concrete.

scholarly journals Influence of Coarse Aggregate Gradation on the Mechnical Properties of Concrete, Part II: No-Fines Vs. Ordinary Concrete

2019 ◽  
Vol 9 (5) ◽  
pp. 4623-4626
Author(s):  
A. S. Buller ◽  
Z. A. Tunio ◽  
F. U. R. Abro ◽  
T. Ali ◽  
K. A. Jamali
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Coarse Aggregate ◽  
Substantial Effect ◽  
Strength Properties ◽  
Minimum Size ◽  
Split Tensile Strength ◽  
Aggregate Gradation ◽  
Coarse Aggregates ◽  
Water Curing

This study aims to investigate the effect of different gradations of coarse aggregates on mechanical properties of no-fines concrete (NFC). NFC reduces a structure’s self-weight, thus minimizing cost. The effects of coarse aggregate gradation on mechanical properties such as compressive strength, split tensile strength, and flexural strength were studied and compared at the end of 28-day water curing. A fixed cement- to-aggregate proportion 1:6 with 0.5 water/cement (w/c) ratio was adopted. Four gradations of coarse aggregates ranging between specific maximum and minimum size were used, namely 5mm-4mm, 10mm-4mm, 20mm-4mm and 20mm-15mm. The results of this study reveal the substantial effect of the gradation of coarse aggregates on strength properties compressive and tensile strength of NFC.

Mixed Proportion Design of Lightweight Concrete Using the Sludge Kilned Coarse Aggregate from Reservoir

2012 ◽  
Vol 430-432 ◽  
pp. 602-608 ◽  
Author(s):  
Hsi Chi Yang ◽  
Jung Pin Wang ◽  
Jiun Wei Wu
Keyword(s):  
Water Consumption ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Quality Characteristics ◽  
Unit Weight ◽  
Control Factors ◽  
Operational Life ◽  
Binder Ratio ◽  
Water Binder Ratio

The sludge dramatically causes the water pollution and storage reduction of a reservoir, threatening its functionality and operational life span. One strategy is to add sludge into lightweight concrete, thus, recycling the sludge and making it one of the valuable natural resources. This study intends to use the Design of Experiment (DOE) and Taguchi Method to ensure the stability of quality and to reduce the production cost of lightweight concrete using the sludge kilned coarse aggregate from the Shihmen reservoir in Taiwan. Based on literature reviews as well as past experimental results, the research selects four control factors including lightweight aggregate unit weight, water content, water-binder ratio (W/B), and interactions among these factors. By using Analysis of Variance (ANOVA), this study discusses the significant degree of these control factors and their interactions, affecting the quality characteristics of lightweight concrete such as compressive strength, ultrasonic wave, and electric resistance at different ages. The significant levels and contribution ratios from each ANOVA analysis are placed in a Cross Table to obtain the overall evaluation, giving the optimal mix proportions. On the basis of the results, the optimal parameter setting are: the unit weight of lightweight aggregate at 0.378 g/cm3, the water consumption at 160 kg/m3, and the water-binder ratio at 0.28 for the 14 and 28-day age lightweight aggregate concrete, and the unit weight of lightweight aggregate at 0.378 g/cm3, the water consumption at 140 kg/m3, and the water-binder ratio at 0.28 for the 91-day age. Furthermore, considering the mean and variance, the research find out the optimal design according to the combination of ages and quality characteristics using the Type III Signal to Noise Ratio of Taguchi’s nominal-is-the-best quality characteristics. The obtained result includes the unit weight of lightweight aggregate at 0.378 g/cm3, the water consumption at 160 kg/m3, and the water-binder ratio at 0.28.

Bond-Slip Behavior of Steel Bar Embedded in Lightweight Concrete Using Sand Coated Polypropylene Coarse Aggregate

2018 ◽  
Vol 929 ◽  
pp. 103-108 ◽  
Author(s):  
Pamudji Gandjar ◽  
Heribowo Bimasena ◽  
Prayoga Adam Yuta ◽  
Purnomo Heru
Keyword(s):  
Bond Strength ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Aggregate Gradation ◽  
Bond Slip ◽  
Coarse Aggregates ◽  
Pull Out ◽  
Steel Bar ◽  
Fine Aggregates ◽  
Natural Aggregates

Plastic waste as coarse aggregates in concrete making is part of efforts to reduce environmental pollution. In one hand the use of plastic as aggregates can provide lighter weight of concrete than those using natural aggregates. Accordingly, a comprehensive experimental study on the concrete-steel bond behavior of structural waste polypropylene (PP) lightweight coarse aggregate concrete (WPPLAC) was carried out using different composition, aggregate gradation, type of bar and size diameter of bar. Pull out tests are conducted for three kind of plain and deformed steel bars having diameter 10, 12 and 16 mm respectively, which are embedded in concrete cubes made by the two mixtures to know local bond-slip relation. Two mixtures of sand coated polypropylene (PP) coarse plastic aggregates, sand as fine aggregates, water and Portland Composite Cement with a water-cement ratio of 0.264 are conducted. The first mixture contains 100% of 25 mm sand coated coarse aggregate while the second mixture contains 70% of 25 mm and 30% of 20 mm sand coated coarse aggregates. Bond strength versus steel displacements results in general show that higher bond strength is found for steel bar having larger diameter while steel displacements approximately follow the scale of bar diameter.

scholarly journals Quality Improvement on Properties of Concrete by using Lightweight Aggregates

2019 ◽  
Vol 8 (2) ◽  
pp. 4550-4554
Keyword(s):  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Partial Replacement ◽  
Lightweight Aggregate Concrete ◽  
Lightweight Aggregates ◽  
Slump Test ◽  
Test Compaction ◽  
Compaction Factor

This paper presents an investigation to make the study on workability and strength properties of concrete which is made by Lightweight Aggregates {i.e. Palm Oil Shell (POS) and Pumice Aggregate (PA)}as coarse aggregate. A series of tests conducted in lab containing Slump test, Compaction Factor test, Schmidt Hammer test and Compressive Strength test was led on concrete made by ordinary aggregate as normal weight sample and concrete formed by different ratios of POS and PA separately i.e. 10% to 50% of dry weight of coarse aggregate. All the specimens were underwater for 3, 7 and 28 days as curing stage. In this experimental study, an effort has been made to concentrate the properties of a lightweight concrete M30 using the lightweight aggregate (POS and PA) as a partial replacement to coarse aggregate. The test results indicate that with the increasing amounts of normal aggregates replaced by POS and PA, the slump test, compaction factor test and strength of the Lightweight Aggregate Concrete (LWAC) has reduced gradually. As water absorption of the LWAC has been increased step by step with the increasing amounts of aggregates replaced by POS and PA. Lastly, it is concluded that the use of POS has great future than compared to PA in the construction of structural lightweight concrete.

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 Effects of carbon nanotubes on expanded glass and silica aerogel based lightweight concrete

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Suman Kumar Adhikary ◽  
Žymantas Rudžionis ◽  
Simona Tučkutė ◽  
Deepankar Kumar Ashish
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Silica Aerogel ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Cementitious Materials ◽  
Lightweight Aggregate Concrete ◽  
Multi Wall Carbon Nanotubes ◽  
Sem Image ◽  
Study Results

AbstractThis study is aimed to investigate the effect of carbon nanotubes on the properties of lightweight aggregate concrete containing expanded glass and silica aerogel. Combinations of expanded glass (55%) and hydrophobic silica aerogel particles (45%) were used as lightweight aggregates. Carbon nanotubes were sonicated in the water with polycarboxylate superplasticizer by ultrasonication energy for 3 min. Study results show that incorporating multi-wall carbon nanotubes significantly influences the compressive strength and microstructural performance of aerogel based lightweight concrete. The addition of carbon nanotubes gained almost 41% improvement in compressive strength. SEM image of lightweight concrete shows a homogeneous dispersal of carbon nanotubes within the concrete structure. SEM image of the composite shows presence of C–S–H gel surrounding the carbon nanotubes, which confirms the cites of nanotubes for the higher growth of C–S–H gel. Besides, agglomeration of carbon nanotubes and the presence of ettringites was observed in the transition zone between the silica aerogel and cementitious materials. Additionally, flowability, water absorption, microscopy, X-ray powder diffraction, and semi-adiabatic calorimetry results were analyzed in this study.

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