Effect of Autoclave Curing on the Compressive Strength and Elastic Modulus of Lightweight Aggregate Concrete

2009 ◽  
Vol 6 (6) ◽  
pp. 101644
Author(s):  
S. W. Dean ◽  
Her-Yung Wang ◽  
Jing-Jie Shie
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Autoclave Curing

scholarly journals Mechanical Properties and Conversion Relations of Strength Indexes for Stone/Sand-Lightweight Aggregate Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xianggang Zhang ◽  
Dapeng Deng ◽  
Jianhui Yang
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Lightweight Aggregate ◽  
Poisson's Ratio ◽  
Lightweight Aggregate Concrete ◽  
Replacement Rate ◽  
River Sand ◽  
Aggregate Concrete ◽  
Axial Compressive Strength

This is a study of the basic mechanical properties of specified density shale aggregate concrete, which is based on different replacement rates in stone-lightweight aggregate concrete (stone-LAC) and sand-lightweight aggregate concrete (sand-LAC). They were prepared by replacing the ceramsite and pottery sand with stone and river sand, respectively. Many tests were performed regarding the basic mechanical property indexes, including tests of cube compressive strength, axial compressive strength, splitting tensile strength, flexural strength, elastic modulus and Poisson’s ratio. The failure modes of specified density shale aggregate concrete were obtained. The effects of replacement rates on the mechanical property indexes of specified density shale aggregate concrete were analyzed. Calculation models were implemented for elastic modulus, for the conversion relations between the axial compressive strength and the cube compressive strength, and for the relations between the tension-compression ratio and Poisson’s ratio. It was shown that when the replacement rate of stone or river sand increased from 0% to 100%, the cube compressive strength of stone-LAC and sand-LAC increased, respectively, by 55% and 25%, the axial compressive strength increased, respectively, by 91% and 72%, splitting tensile strength increased, respectively, by 99% and 44%, and the flexural strength increased, respectively, by 46% and 26%. Similarly, the elastic modulus of stone-LAC and sand-LAC increased, respectively, by 16% and 30%. However, Poisson’s ratio for stone-LAC decreased first and then increased, eventually increased by 11%; Poisson’s ratio for sand-LAC only reduced gradually, eventually reduced by 67%. After introducing the influence parameter for the replacement rate, the established calculation models become simple and practical, and the calculation accuracies are favorable.

Compressive Strength Variations in Lightweight Aggregate Concrete Samples Affected by Segregation Caused by Excessive Vibration

2019 ◽  
Vol 821 ◽  
pp. 493-499 ◽  
Author(s):  
Afonso Miguel Solak ◽  
Antonio José Tenza-Abril
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniform Distribution ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Global Properties ◽  
Concrete Failure ◽  
Good Homogeneity ◽  
Cylindrical Samples

Lightweight aggregates used in lightweight aggregate concrete (LWAC) exert an important influence on the compressive strength and elastic modulus of concrete. A good homogeneity of the material is essential in this type of concrete once a non-uniform distribution of aggregates in the mixture may strongly affect the concrete global properties, which are commonly considered as homogenous values for design purposes. LWAC, due to density differences among its components, are susceptive to segregation. The separation of the aggregates from the rest of the mixture increases the risk of cracking and areas where segregation or insufficient compaction occur are mostly the areas where the concrete failure begins. The aim of this study is analysing possible variations caused by segregation on compressive strength (fc) along the height of cylindrical samples, comparing results of four sections extracted from samples segregated intentionally.

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.

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 Fresh and Mechanical Properties of Self-Compacting Rubber Lightweight Aggregate Concrete and Corresponding Mortar

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Jing Lv ◽  
Qiang Du ◽  
Tianhua Zhou ◽  
Zuoqian He ◽  
Kunlun Li
Keyword(s):  
Compressive Strength ◽  
Shear Stress ◽  
Lightweight Aggregate ◽  
Segregation Ratio ◽  
Plastic Viscosity ◽  
Lightweight Aggregate Concrete ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Waste Tires ◽  
Rubber Particles

Increasing amount of waste tires caused huge environment issues in recent years. Recycling concrete is an effective way. In this paper, waste tires are crushed into particles and incorporated in lightweight aggregate concrete to prepare a special concrete (self-compacting rubber lightweight aggregate concrete (SCRLC)). A detailed experimental research of effects of rubber particles on the properties of SCRLC and corresponding mortar is conducted. The results show that increasing the rubber particles replacement ratio leads to a raising of yield stress and plastic viscosity of mortar pastes. Flowability, filling capacity, and passing ability of SCRLC decline and the segregation resistance property of SCRLC improves as the rubber particles replacement ratio increases. Well, linear correlations between slump flow of SCRLC and shear stress of corresponding mortar pastes and segregation ratio of SCRLC and plastic viscosity of corresponding mortar pastes are obtained. In order to ensure that rubber lightweight aggregate concrete can compact by itself, the upper limit of shear stress of corresponding mortar pastes is 231.7 Pa and the lower limit of plastic viscosity of corresponding mortar pastes is 3.72 Pa·s. Compressive strength, splitting tensile strength, flexural strength, and elastic modulus of SCRLC and compressive strength of corresponding mortar decrease as the rubber particles replacement ratio increases. The 28-day compressive strength of SCRLC can meet the requirements of lightweight aggregate concrete structures until the rubber particles replacement ratio reaches 50%.

Experimental Study of the Foam Agent in Lightweight Aggregate Concrete

2012 ◽  
Vol 226-228 ◽  
pp. 1776-1779
Author(s):  
Yong Wei Wang ◽  
Bai Xiao Tang
Keyword(s):  
Compressive Strength ◽  
Apparent Density ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Optimal Dosage ◽  
Foaming Agent ◽  
Aggregate Concrete ◽  
Wall Strength ◽  
Different Content ◽  
Good Range

Different content of foaming agent in the lightweight aggregate concrete test, the apparent density and compressive strength of concrete assessment indicators. Studies have shown that, with the dosage increase, the variation of the apparent density of the concrete is first decreases and then increases when the content is 0.8kg/m3 dry apparent density minimum; as the foaming agent content continues to grow, dry apparent density continues to increase, but the magnitude of increase is less obvious. At this point, its 28 days compressive strength of only 0.7MPa, the wall strength of the material does not meet the insulation requirements. Taking into account the apparent density and strength of wall insulation materials, requirements, test data to determine the optimal dosage of the foaming agent should be 0.4 ~ 0.6kg, to determine the content of foaming agent in the lightweight aggregate concrete of the most good range.

scholarly journals THE EFFECT OF EXPANDED GLASS AND POLYSTYRENE WASTE ON THE PROPERTIES OF LIGHTWEIGHT AGGREGATE CONCRETE

2016 ◽  
Vol 8 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Jurga Šeputytė-Jucikė ◽  
Marijonas Sinica
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Conductivity Coefficient ◽  
Lightweight Aggregate ◽  
Expanded Polystyrene ◽  
Partial Replacement ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Low Thermal Conductivity ◽  
Polystyrene Waste

The main objective of this study is to create a lightweight aggregate concrete (LWAC) with a low thermal conductivity coefficient using expanded glass (EG) aggregate, produced from waste glass or crushed expanded polystyrene waste, obtained by crushing waste packing tare of household appliances. Research related to the effects of the amount of Portland cement (PC) as well as EG aggregates and crushed expanded polystyrene waste on physical (density, thermal conductivity coefficient, water absorption and capillary coefficient) and mechanical (compressive strength) properties of LWAC samples are provided. Insulating LWAC based on a small amount of PC and lightweight EG aggregates and crushed expanded polystyrene waste, with especially low thermal conductivity coefficient values (from 0.070 to 0.098 W/ (m·K)) has been developed. A strong relationship between thermal conductivity coefficient and density of LWAC samples was obtained. The density of LWAC samples depending on the amount of PC ranged between 225 and 335 kg/m3. A partial replacement of EG aggregate by crushed expanded polystyrene waste, results in relative density decrease of LWAC samples. In LWAC samples the increased amount of PC results in increased compressive strength.

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