scholarly journals Size Effect in Compressive Strength Tests of Cored Specimens of Lightweight Aggregate Concrete

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1187 ◽  
Author(s):  
Lucyna Domagała
Keyword(s):  
Compressive Strength ◽  
Scale Effect ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Cement Matrix ◽  
Lightweight Aggregate Concrete ◽  
Core Diameter ◽  
Aggregate Concrete ◽  
Normal Weight Concrete ◽  
Strength Tests

The aim of this paper is to discuss the unrecognized problem of the scale effect in compressive strength tests determined for cored specimens of lightweight aggregate concrete (LWAC) against the background of available data on the effect for normal-weight concrete (NWAC). The scale effect was analyzed taking into consideration the influence of slenderness (λ = 1.0, 1.5, 2.0) and diameter (d = 80, 100, 125, and 150 mm) of cored specimens, as well as the type of lightweight aggregate (expanded clay and sintered fly ash) and the type of cement matrix (w/c = 0.55 and 0.37). The analysis of the results for four lightweight aggregate concretes revealed no scale effect in compressive strength tests determined on cored specimens. Neither the slenderness, nor the core diameter seemed to affect the strength results. This fact should be explained by the considerably better structural homogeneity of the tested lightweight concretes in comparison to normal-weight ones. Nevertheless, there were clear differences between the results obtained on molded and cored specimens of the same shape and size.

scholarly journals Efficiency factor and modulus of elasticity of lightweight concrete with expanded clay aggregate

2010 ◽  
Vol 3 (2) ◽  
pp. 195-204 ◽  
Author(s):  
W.G Moravia ◽  
A. G. Gumieri ◽  
W. L. Vasconcelos
Keyword(s):  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
Large Scale ◽  
Lightweight Concrete ◽  
Weight Ratio ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Lightweight Aggregate Concrete ◽  
Empirical Methods ◽  
Normal Weight Concrete

Nowadays lightweight concrete is used on a large scale for structural purposes and to reduce the self-weight of structures. Specific grav- ity, compressive strength, strength/weight ratio and modulus of elasticity are important factors in the mechanical behavior of structures. This work studies these properties in lightweight aggregate concrete (LWAC) and normal-weight concrete (NWC), comparing them. Spe- cific gravity was evaluated in the fresh and hardened states. Four mixture proportions were adopted to evaluate compressive strength. For each proposed mixture proportion of the two concretes, cylindrical specimens were molded and tested at ages of 3, 7 and 28 days. The modulus of elasticity of the NWC and LWAC was analyzed by static, dynamic and empirical methods. The results show a larger strength/ weight ratio for LWAC, although this concrete presented lower compressive strength.

scholarly journals Influence of Aggregate Gradation on the Engineering Properties of Lightweight Aggregate Concrete

2018 ◽  
Vol 8 (8) ◽  
pp. 1324 ◽  
Author(s):  
How-Ji Chen ◽  
Chung-Hao Wu
Keyword(s):  
Compressive Strength ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Engineering Properties ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Gradation ◽  
Aggregate Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Expanded Shale

Expanded shale lightweight aggregates, as the coarse aggregates, were used to produce lightweight aggregate concrete (LWAC) in this research. At the fixed water-cement ratio, paste quantity, and aggregate volume, the effects of various aggregate gradations on the engineering properties of LWAC were investigated. Comparisons to normal-weight concrete (NWC) made under the same conditions were carried out. From the experimental results, using normal weight aggregates that follow the specification requirements (standard gradation) obtained similar NWC compressive strength to that using uniform-sized aggregates. However, the compressive strength of LWAC made using small uniform-sized aggregates was superior to that made from standard-grade aggregates. This is especially conspicuous under the low water-cement ratio. Even though the workability was affected, this problem could be overcome with developed chemical additive technology. The durability properties of concrete were approximately equal. Therefore, it is suggested that the aggregate gradation requirement of LWAC should be distinct from that of NWC. In high strength LWAC proportioning, following the standard gradation suggested by American Society for Testing and Materials (ASTM) is optional.

Pre-Failure Deflection and Residual Load Capacity of Reinforced Lightweight Aggregate Concrete Beams under High-Cycle Fatigue

2010 ◽  
Vol 146-147 ◽  
pp. 926-936 ◽  
Author(s):  
How Ji Chen ◽  
Te Hung Liu ◽  
Chao Wei Tang
Keyword(s):  
Fatigue Testing ◽  
Load Capacity ◽  
Fatigue Behavior ◽  
Lightweight Aggregate ◽  
Fatigue Loading ◽  
Normal Weight ◽  
Lightweight Aggregate Concrete ◽  
Rc Beams ◽  
Aggregate Concrete ◽  
Normal Weight Concrete

The present study experimentally investigated the pre-failure and post-fatigue behavior of reinforced concrete (RC) beams constructed with lightweight aggregate concrete (LWAC) in comparison with that constructed of normal weight concrete (NWC) of the same compressive strength (40 MPa). A total of twelve RC beams were tested under different fatigue loadings. Based on the experimental observations, the midspan total deflection measured in the fatigue testing consisted of the elastic and plastic components. The mechanismof the two deflection components developed with load cycles was different. The experimental results showed that the fatigue resistance of LWAC beams was better than that of NWC beams for the same fatigue loading levels. It was reflected in both the lower evolution of fatigue damage and the smaller growth of midspan residual deflection. After 2 million cycles, an average increase in residual load capacity of about 8% was found in the NWC beams, while that in the LWA beams remained virtually unchanged.

scholarly journals Experimental Evaluation of Shrinkage, Creep and Prestress Losses in Lightweight Aggregate Concrete with Sintered Fly Ash

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3895
Author(s):  
Rafał Stanisław Szydłowski ◽  
Barbara Łabuzek
Keyword(s):  
Fly Ash ◽  
Prestressed Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Lightweight Aggregate Concrete ◽  
Clear Correlation ◽  
Aggregate Concrete ◽  
Normal Weight Concrete ◽  
Creep Coefficient ◽  
Shrinkage And Creep

The paper presents the experimental results of shrinkage, creep, and prestress loss in concrete with lightweight aggregate obtained by sintering of fly ash. Two concrete mixtures with different proportions of components were tested. Concrete with a density of 1810 and 1820 kg/m3, and a 28-day strength of 56.9 and 58.4 MPa was obtained. Shrinkage and creep were tested on 150 × 250 × 1000 mm3 beams. Creep was tested under prestressing load for 539 days and concrete shrinkage for 900 days. The measurement results were compared with the calculations carried out according to the Eurocode 2 as well as with the results of other research. A very low creep coefficient and lower shrinkage in relation to the calculation results and the results of other research were found. It was also revealed that there is a clear correlation between shrinkage and creep, and the amount of water in the concrete. The value of the creep coefficient during the load holding period was 0.610 and 0.537, which is 56.0 and 49.3% of the value determined from the standard. The prestressing losses in the analyzed period amounted to an average of 13.0%. Based on the obtained test results, it was found that the tested lightweight aggregate concrete is well suited for prestressed concrete structures. Shrinkage was not greater than that calculated for normal weight concrete of a similar strength class, which will not result in increased loss of prestress. Low creep guarantees low deflection increments over time.

scholarly journals The Structural Characteristics of Lightweight Aggregate Concrete Beams

2019 ◽  
Vol 27 (2) ◽  
pp. 64-73
Author(s):  
Sajjad abdulameer Badar ◽  
Laith Shakir Rasheed ◽  
Shakir Ahmed Salih
Keyword(s):  
Compressive Strength ◽  
Ultimate Load ◽  
Lightweight Concrete ◽  
Concrete Beams ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Lightweight Aggregate Concrete ◽  
Dry Density ◽  
Aggregate Concrete ◽  
Clay Bricks

This paper aims to investigate the structural behavior of reinforced lightweight concrete beams. Attapulgite aggregate and crushed clay brick aggregate were used as coarse lightweight aggregate to produce structural lightweight aggregate concrete with 25 Mpa and 43.6 Mpa cube compressive strength and 1805 Kg/m3 and 1977 Kg/m3 oven dry density respectively. The result of reinforced lightweight concrete beams compared with reinforced normal weight concrete beams, which have 50.5 Mpa cylinder compressive strength and 2317 Kg/m3 oven dry density. For each type of concrete two reinforced concrete beams with (1200 mm length × 180 mm height × 140 mm width), one of them tested under symmetrical two-points load STPL (a/d = 2.2) and another one tested under one-point load OPL (a/d=3.3) at 28 days. The experimental program shows that a structural lightweight aggregate concrete can be produced by using Attapulgite aggregate with 25 MPa cube compressive strength and 1805 Kg/m3 oven dry density and by using crushed clay brick aggregate with 43.6 MPa cube compressive strength and 1977 Kg/m3 oven dry density. The weight of Attapulgite aggregate concrete and crushed clay bricks aggregate concrete beam specimens were lower than normal weight aggregate concrete beams by about 20.56% and 13.65% respectively at 28 days.  As for the ultimate load capacities of beam specimens, the ultimate load of Attapulgite aggregate concrete beams tested under STPL were lower than that of crushed clay bricks aggregate concrete beams and normal weight aggregate concrete beams by about 4.85% and 5% respectively. While the ultimate load capacities of reinforced Attapulgite concrete beams tested under OPL were lower than that of reinforced crushed clay bricks aggregate concrete beams and reinforced normal weight aggregate concrete beams by about 10.3% and 10.5% respectively. Finally, Attapulgite aggregate concrete and crushed clay bricks aggregate concrete showed ductility and toughness less than that of Normal weight aggregate concrete.

On the Durability of Concrete under the Action of Ultra-Low (up to -196 °C) Technological Temperatures

2021 ◽  
Vol 887 ◽  
pp. 406-414
Author(s):  
V.N. Yarmakovsky ◽  
D. Kadiev
Keyword(s):  
Lightweight Aggregate ◽  
Normal Weight ◽  
Air Separation ◽  
Inert Gases ◽  
Lightweight Aggregate Concrete ◽  
Experimental Investigations ◽  
Cryogenic Temperatures ◽  
Aggregate Concrete ◽  
Normal Weight Concrete ◽  
Structural Lightweight Aggregate Concrete

The article presents the physical-chemical bases and as result – the technological bases of concrete resistance to ultra-low cryogenic (up to-196 °C) technical (engineering) temperatures, which is applied to the reinforced concrete structures of engineering constructions such as storage tanks for liquefied gases (in particular, liquid nitrogen and oxygen with cryogenic temperatures), as well as the enclosing structures of blocks (units) for air separation for various inert gases. The above-mentioned physical and chemical bases of concrete resistance to the ultralow cryogenic technical temperatures are developed, using the results of the analysis of modern ideas (hypotheses and theories) about the mechanism of low negative temperatures exposure on structural lightweight aggregate concrete and normal weight concrete due to the characteristics of their macro-and microstructure. The resistance of structural lightweight aggregate concrete in comparison with equal-strength normal weight concrete to the cyclic exposure of cryogenic temperatures was performed by the authors based on the results of the relevant analytical and experimental investigations. The results of these investigations are considered in the article as a modern scientific basis for the development of the main provisions for the manufacturing technology of structural lightweight aggregate concrete and normal weight concrete with high durability (frost resistance and water resistance) in conditions of cyclic exposure to cryogenic temperatures. The results of changes in strength and deformative characteristics of concrete in the process of cyclic freezing and thawing are accepted as evaluation criteria of the resistance of concrete, manufactured using the above-mentioned technologies, to such temperature exposure.

Compressive Strength of Organic Lightweight Aggregate Concrete

2011 ◽  
Vol 374-377 ◽  
pp. 1531-1536
Author(s):  
Cong Mi Cheng ◽  
Da Gen Su ◽  
Juan He ◽  
Chu Jie Jiao
Keyword(s):  
Compressive Strength ◽  
Relative Density ◽  
Lightweight Aggregate ◽  
Cement Matrix ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Slowing Down ◽  
Density Relationship ◽  
The Difference ◽  
Relationship Of

Organic lightweight aggregate concrete (OAC) is produced by replacing normal aggregate with organic aggregate in concrete or mortar either partially or fully, depending on the requirements of the strength and density. The study aims to investigate the compressive strength of OAC containing virgin EPS beads, recycled EPS granules and rubber granules with diameter 3-5 mm, and the influence of cement matrix on compressive strength of OAC. The results show that compressive strength of OAC decreases as organic aggregate content increases; furthermore, the decreasing rate of the strength is slowing down. The dimensionless compress strength-density relationship of EPS lightweight aggregate concrete (PAC) containing virgin EPS, recycled EPS and different cement matrix has uniform law. It can be modeled as σ*pl/σs=0.916(ρ*/ρs)3.04. The experimental compressive strength of ultra-lightweight EPS concrete with density lower than 900 kg/m3is much higher than the value calculated by Gibson formula. The larger the relative density is, the greater the difference between the two is. The dimensionless compressive strength-density relationship of rubcrete can be modeled as σ*pl/σs=0.956(ρ*/ρs)8.66. The compressive strength of rubcrete, compared with PAC, is more sensitive to the relative density.

scholarly journals A Review on the Carbonation and Chloride Penetration Resistance of Structural Lightweight Aggregate Concrete

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3456 ◽  
Author(s):  
José Alexandre Bogas ◽  
Sofia Real
Keyword(s):  
Service Life ◽  
Life Prediction ◽  
Current Knowledge ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Service Life Prediction ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Normal Weight Concrete ◽  
Structural Lightweight Aggregate Concrete

This paper presents a comprehensive review on structural lightweight aggregate concrete (SLWAC) durability. The main transport properties and degradation mechanisms of reinforced concrete are addressed, namely, carbonation and chloride attack. The influence of the main composition parameters, such as type of aggregate, type of binder and water/binder ratio, as well as the influence of cracking, are also analysed. Finally, the current knowledge of SLWAC’s service life prediction is assessed. Although the knowledge of SLWAC’s durability behaviour is still limited, investigation works performed either in laboratory or in real environments indicate that SLWAC can have similar to better durability performance than normal weight concrete, especially when the same strength level is considered. The importance of the quality of the paste over the characteristics of the lightweight aggregates is highlighted. Durability standardization regarding SLWAC is still insufficient and is one of the main gaps of current knowledge. The objective of this review is to foster a better understanding on the durability and service life prediction of SLWAC, contributing to a greater confidence in using this type of concrete.

Performance of Lightweight Aggregate Concrete Containing Expanded Polystyrene, Cinder and Silica Fume

2020 ◽  
Vol 17 (9) ◽  
pp. 4311-4317
Author(s):  
M. L. Harish ◽  
H. Narendra ◽  
Md. Rizwan Tahashildar
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Silica Fume ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Expanded Polystyrene ◽  
Lightweight Aggregate Concrete ◽  
Split Tensile Strength ◽  
Aggregate Concrete ◽  
Optimal Mix

Lightweight aggregate concrete is developed by substituting normal weight aggregate either fully or partially based on required strength and density. Expanded polystyrene (EPS) bead is a type of low density material, which also has good energy-absorbing characteristics and can be used as light weight aggregate in concrete. In the present study, Structural lightweight aggregate concrete (SLWAC) was produced by fully replacing normal weight aggregate with combinations of EPS beads to Cinder by the ratio 20:80, 40:60, 60:40, 80:20 respectively and Silica fume was used as supplementary cementitious material. The resulting concrete had strength variation between 24.85 to 12.01 MPa, and the density variation of 1896 to 1664 kg/m3. Considering strength and density criteria 40:60 ratios was observed as the optimal mix. The Compressive strength acquired by concrete was inversely proportional to the volume of EPS beads. Effect of fibres on mechanical properties such as flexural strength, compressive strength, and split-tensile strength was investigated on optimal mix by using polypropylene fibres, it was observed that a 13.24% increase in flexural strength at 1% fibres, 8.41% increase in Compressive strength at 1% fibres and 23.11% increase in split-tensile strength at 1% fibres. Along with these, durability tests such as water absorption and permeability tests were performed, the performance of this concrete in water absorption test and permeability is well within the acceptable limits as the EPS ratio in the concrete increased, the absorption and depth of penetration values increased considerably. Microscopic observations were also made to study the interface amongst the cement paste and aggregates. It was revealed that silica fume has influenced significantly in bonding with EPS beads.

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