Surface Properties of Lightweight Aggregate Concrete and its Correlation with Durability

2015 ◽  
Vol 812 ◽  
pp. 207-212 ◽  
Author(s):  
Rita Nemes
Keyword(s):  
Compressive Strength ◽  
Abrasion Resistance ◽  
Cement Mortar ◽  
Gas Permeability ◽  
Concrete Strength ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Conventional Concrete ◽  
Aggregate Concrete ◽  
Mortar Matrix

Durability is one of most important requirements of concrete design. From this aspect is arising the required minimal compressive strength class of conventional concrete in order to ensure durability. The porosity of cement mortar matrix and consequently the liquid and gas permeability of concrete may be reduced. But the strength of lightweight aggregate concrete depends primarily on the crushing resistance of lightweight aggregate (LWA). With low strength LWA may be achieved higher concrete strength by high strength cement mortar matrix. Therefore we can not consider durability simply on the basis of the compressive strength of concrete. The most important durability factors are closely related to the porosity and strength of the cement mortar matrix but for example the abrasion resistance depends more significantly on the aggregate type. Lightweight aggregates usually do not have high abrasion resistance, but they can be advantageous in case of restoration of bridge pavement. The most important factors of durability regarding pavements are frost scaling and abrasion resistance. These parameters (especially abrasion resistance) are not available in the literature when using LWA.

Development of Lightweight Aggregate Concrete Containing Pulverized Fly Ash and Bottom Ash

2008 ◽  
Vol 400-402 ◽  
pp. 379-384 ◽  
Author(s):  
Theradej Litsomboon ◽  
Pichai Nimityongskul ◽  
Naveed Anwar
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Apparent Density ◽  
Abrasion Resistance ◽  
Bottom Ash ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Lightweight Materials ◽  
Aggregate Concrete ◽  
Compressive Strength Of Concrete

This study examines the feasibility of using different lightweight aggregates (LA) and bottom ash as coarse and fine aggregates in concrete with fly ash. The lightweight materials were composed of 3 types, namely pumice, cellular lightweight aggregate and MTEC lightweight aggregate. The tests for physical and mechanical properties of lightweight aggregate concretes (LWAC) were conducted in terms of workability, compressive strength, apparent density, abrasion resistance and absorption. Test results showed that compressive strength of LWAC increased with an increase in apparent density, which is mainly depending on the type of aggregate. The replacement of normal weight sand with bottom ash resulted in a decrease both in density of concrete by 180-225 kg/m3 and 28-day compressive strength of concrete by 16-26%. Moreover, the use of bottom ash to replace sand in concrete increased the demand for mixing water due to its porosity and shape and to further obtain the required workability. The type and absorption of LA influenced predominantly the water absorption of LWAC. Total replacement of natural sand by bottom ash increased the absorption of the concrete by 63-90%. With regard to abrasion resistance, the abrasion resistance of lightweight aggregate concrete was mainly dependent on the compressive strength of concrete: the higher the strength, the higher the abrasion resistance of LWAC. In addition, the use of bottom ash as a fine aggregate resulted in a lower abrasion resistance of lightweight aggregate concrete due to its porosity. Of the three types of lightweight materials, MTEC LA had achieved both low density and high compressive strength.

Study of Prediction Model for Compressive Strength of Lightweight Aggregate Concrete

2011 ◽  
Vol 335-336 ◽  
pp. 1204-1209 ◽  
Author(s):  
H. Z. Cui
Keyword(s):  
Compressive Strength ◽  
Prediction Model ◽  
Volume Content ◽  
Particle Density ◽  
Lightweight Aggregate ◽  
Shape Index ◽  
Lightweight Aggregate Concrete ◽  
Crushing Strength ◽  
Aggregate Concrete ◽  
Mortar Matrix

This paper presents studies of prediction of compressive strength of lightweight aggregate concrete (LWAC). In order to choose the optimized prediction model, the prediction models based on different parameters, which included compressive strength of mortar matrix, volume content of lightweight aggregate (LWA), crushing strength of LWA, particle density of LWA and shape index of LWA, were analyzed and compared. For LWAC, due to the effect of LWA on LWAC is more obvious than the effect of mortar matrix, therefore, a prediction model that just used LWA properties to serve as parameters of prediction model can predict LWAC strength. The LWA properties included volume content, crushing strength, particle density and shape index. As long as the LWA properties are known, the advantage of the model is that LWAC strength can be predicted. The best prediction discrepancy of 12.9% compared with the experimental results.

Study on the Curve of Lightweight Aggregate Concrete Compressive Strength by Rebound Method

2011 ◽  
Vol 477 ◽  
pp. 268-273
Author(s):  
Li Xiong Gao ◽  
Li Juan Kong ◽  
Xue Gang Du
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Technical Specification ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Relative Standard Error ◽  
Concrete Compressive Strength ◽  
Aggregate Concrete ◽  
Relative Standard ◽  
Strength Curve

Testing strength curve of 1400~1900 density grade lightweight aggregate concrete by rebound method was studied systematically. Results show that, adopting the Chinese national unified testing strength curve, specified by JGJ/T 23-2001 of Technical Specification for Detection of Concrete Compressive Strength by Rebound Method, to detect the lightweight aggregate concrete strength, the strength scaled value obtained is higher, which would reduce the structure assurance coefficient. The special testing strength curve of 1400~1900 density grade and LC15~LC50 strength grade lightweight aggregate concrete were built, and the computed mean relative error and relative standard error are less than 12.0% and 14.0% respectively, meet the error requirement of special curve that specified by JGJ/T 23-2001 of Technical Specification for Detection of Concrete Compressive Strength by Rebound Method.

scholarly journals A Parametric Study to Assess Lightweight Aggregate Concrete for Future Sustainable Construction of Reinforced Concrete Beams

2021 ◽  
Vol 13 (24) ◽  
pp. 13893
Author(s):  
Ismael Vives ◽  
Francisco B. Varona ◽  
Antonio J. Tenza-Abril ◽  
Javier Pereiro-Barceló
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Emissions ◽  
Concrete Strength ◽  
Lightweight Aggregate ◽  
Reinforced Concrete Beams ◽  
Design Parameters ◽  
Lightweight Aggregate Concrete ◽  
Attractive Alternative ◽  
Conventional Concrete ◽  
Aggregate Concrete

Lightweight aggregate concrete (LWC) is an attractive alternative to conventional concrete in building construction. It leads to lighter self-weight in beams and floor slabs and thus might have a positive impact on reinforcing steel consumption, also reducing the loads withstood by columns and foundations. However, LWC may increase cement consumption to maintain the required concrete compressive strength. This study presents compact equations for the design of reinforced LWC beams and subsequently applies them to a parametric analysis programmed in MATLAB. The aim of this analysis is to obtain an estimation of the equivalent carbon dioxide emissions associated with steel and cement consumption if using LWC instead of conventional concrete. The analysis involves more than 3 million beams simulating real scenarios by varying different design parameters, such as mix design, concrete strength, span length and applied loads and verifying both Ultimate and Serviceability Limit States. Whereas LWC of density equal or below 1600 kg/m3 does not seem to be feasible when trying adequately control cement content, the study shows that LWC with densities of 1800 and 2000 kg/m3 would not have a negative impact on the carbon dioxide emissions and would adequately comply with the various design restrictions.

Research on Porous Properties of Air-Entrained Lightweight Aggregate Concrete

2013 ◽  
Vol 652-654 ◽  
pp. 1209-1212
Author(s):  
Wei Xin Hu ◽  
Abulitipu. Abudula
Keyword(s):  
Thermal Conductivity ◽  
Porous Structure ◽  
Concrete Strength ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Materials Properties ◽  
Porous Properties ◽  
Concrete Materials ◽  
The Right

Lightweight aggregate concrete with bleed air : the air-entraining agent added to the lightweight aggregate concrete , cement paste to form the porous structure of the porous structure of the right amount of artificial lightweight aggregate concrete . Reduce the density of the concrete to improve the insulation properties of the concrete . Applied to structural insulation concrete strength than 20Mpa, the thermal conductivity is less than 0.36W / ( m • K) . Of lightweight aggregate structure insulation concrete materials properties and microstructure of variation with air entraining agent .

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 Shrinkage and Strength Properties of Coal Gangue Ceramsite Lightweight Aggregate Concrete

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yunsen Wang ◽  
Jingping Qiu ◽  
Chao Zeng
Keyword(s):  
Waste Treatment ◽  
Concrete Strength ◽  
Lightweight Aggregate ◽  
Strength Properties ◽  
Coal Gangue ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Concrete Shrinkage ◽  
Strength Tests ◽  
The Stability

It is a promising and effective method for waste treatment by using coal gangue to make lightweight aggregate concrete. However, lightweight aggregate concrete with low-density coal gangue ceramsite is prone to cracking during volume shrinkage, which limits its application in the construction industry. In an attempt to resolve the problem of cracking in shrinkage, this study investigated the effect of prewetting time and shrinkage reducing agents on shrinkage volume and concrete strength through a series of concrete shrinkage and strength tests. The experimental results show that shrinkage volume reduced at a prewetting time of 12 hrs or with a 2% addition of D-230 polyether amine reductant. With the optimal conditions of 12 hrs prewetting time and 2% addition of the reductant, the concrete shrinkage volume significantly decreased with a negligible impact on its strength. Appropriate amount of shrinkage reducing agent and adjustment of prewetting time of coal gangue ceramsite are necessary to reduce the shrinkage rate and improve the stability of the specimen. This is of great significance to wide application of lightweight aggregate concrete with coal gangue ceramsite.

Effect of confinement on the behaviour of high-strength lightweight concrete columns

1986 ◽  
Vol 13 (6) ◽  
pp. 741-751 ◽  
Author(s):  
R. Basset ◽  
S. M. Uzumeri
Keyword(s):  
Experimental Investigation ◽  
Lightweight Concrete ◽  
Concrete Strength ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Concrete Columns ◽  
Lightweight Aggregate Concrete ◽  
Test Results ◽  
Aggregate Concrete ◽  
Concrete Confinement

This paper summarizes an experimental investigation into the behaviour of high strength sand – lightweight concrete columns confined with rectangular ties. Fifteen reinforced and three unreinforced specimens were tested under monotonically increasing axial compression. Variables considered in this study were the longitudinal steel distribution and tie configuration, the tie steel spacing, the amount of tie steel, and the amount of longitudinal steel.The results indicated that unconfined high-strength lightweight aggregate concrete is a brittle material. The addition of lateral confining steel significantly improved the behaviour of this material, with a large amount of lateral steel resulting in very ductile behaviour. The tie configuration and resulting distribution of longitudinal steel contributed significantly to the confinement of concrete, with well-distributed steel resulting in improved behaviour. The ratio of specimen to cylinder concrete strength was observed to be 0.98, which is much higher than the commonly assumed value of 0.85.The test results were compared with results from selected theoretical confinement models. Based on the results of this investigation, existing models for concrete confinement give unconservative results for high-strength lightweight aggregate concrete and overestimate the ductility that can be achieved with this material. Key words: columns, confinement, ductility, high-strength concretes, lightweight aggregate concretes, reinforcement, stress–strain relationships, tests, ties, toughness.

Sign in / Sign up

Export Citation Format

Share Document