Time-Dependent Properties of Lightweight Concrete Using Sedimentary Lightweight Aggregate

2010 ◽  
Vol 168-170 ◽  
pp. 2235-2240
Author(s):  
How Ji Chen ◽  
Wen Po Tsai ◽  
Ming Der Yang
Keyword(s):  
Lightweight Concrete ◽  
Drying Shrinkage ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Time Dependent ◽  
Test Results ◽  
Fine Sediments ◽  
Normal Weight Concrete ◽  
Shrinkage And Creep ◽  
Shihmen Reservoir

A kind of lightweight aggregate (LWA) has been successfully developed in Taiwan, which was made by expanding under heat fine sediments dredged from the Shihmen Reservoir. In this study the performances of concrete made from the aforementioned LWA were tested and compared with those of the companion normal weight concrete (NC). The test results show that the so produced lightweight concrete (LWAC) exhibited a comparable time-dependent properties (i.e., compressive strength, elastic modulus, drying shrinkage, and creep) as compared with those of the companion NC. Based on the results, it can be concluded that the use of prewetted LWAs and the incorporation of pozzolan materials can effectively control the drying shrinkage of LWAC. The specific creep of the LC mixture was obviously higher than that of the NC mixture at the same curing time.

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 The influence of OPC and PPC on compressive strength of ALWA concrete

2018 ◽  
Vol 195 ◽  
pp. 01021
Author(s):  
Fedya Diajeng Aryani ◽  
Tavio ◽  
I Gusti Putu Raka ◽  
Puryanto
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Structural Members ◽  
Concrete Composition ◽  
Normal Weight Concrete ◽  
To Come ◽  
Seismic Forces

Lightweight concrete is one of the options used in construction in lieu of the traditional normal-weight concrete. Due to its lightweight, it provides lighter structural members and thus, it reduces the total weight of the structures. The reduction in weight resulting in the reduction of the seismic forces since its density is less than 1840 kg/m3. Among all of the concrete constituents, coarse aggregate takes the highest portion of the concrete composition. To produce the lightweight characteristics, it requires innovation on the coarse aggregate to come up with low density of concrete. One possible way is to introduce the use of the artificial lightweight aggregate (ALWA). This study proposes the use of polystyrene as the main ingredient to form the ALWA. The ALWA concrete in the study also used two types of Portland cements, i.e. OPC and PPC. The ALWA introduced in the concrete comprises various percentages, namely 0%, 15%, 50%, and 100% replacement to the coarse aggregate by volume. From the results of the study, it can be found that the compressive strength and the modulus of elasticity of concrete decreased with the increase of the percentage of the ALWA used to replace the natural coarse aggregate.

scholarly journals Optimum Oil Palm Shell Content as Coarse Aggregate in Concrete Based on Mechanical and Durability Properties

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Mehdi Maghfouri ◽  
Payam Shafigh ◽  
Muhammad Aslam
Keyword(s):  
Oil Palm ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Drying Shrinkage ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Normal Weight ◽  
Concrete Mixture ◽  
Palm Shell ◽  
Oil Palm Shell

Oil palm shell (OPS) is a biosolid waste in palm oil industry in the tropical countries which could be used as aggregate in concrete mixture. Since 1984, OPS has been experimented as natural lightweight aggregate in research studies to produce lightweight concrete (LWC). Medium and high-strength LWCs using OPS as coarse aggregate were successfully produced. However, higher drying shrinkage and lower mechanical properties for concretes containing higher volume of OPS are reported in previous studies. Therefore, OPS is not fit to be used as full coarse aggregate in concrete mixture and therefore, there should be an optimum OPS content in concrete. In this study, in a normal-weight concrete, normal coarse aggregate was replaced with OPS from zero to 100% with an interval of 20%. Tests such as slump, density, compressive strength in different curing conditions, splitting tensile strength, initial and final water absorptions, and drying shrinkage of cured and uncured specimens were conducted to find out optimum OPS content in concrete. From the test results, it could be summarized that OPS content should not exceed 60% of total volume of coarse aggregate.

COMPRESSIVE STRENGTH EVALUATION OF LIGHTWEIGHT CONCRETE WITH EXPANDED GLASS AGGREGATE BY ULTRASONIC PULSE VELOCITY METHOD

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Christopher Collins ◽  
Saman Hedjazi
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Normal Weight ◽  
Unit Weight ◽  
Normal Weight Concrete

In the present study, a non-destructive testing method was utilized to assess the mechanical properties of lightweight and normal-weight concrete specimens. The experiment program consisted of more than a hundred concrete specimens with the unit weight ranging from around 850 to 2250 kg/m3. Compressive strength tests were performed at the age of seven and twenty eight days. Ultrasonic Pulse Velocity (UPV) was the NDT that was implemented in this study to investigate the significance of the correlation between UPV and compressive strength of lightweight concrete specimens. Water to cement ratio (w/c), mix designs, aggregate volume, and the amount of normal weight coarse and fine aggregates replaced with lightweight aggregate, are the variables in this work. The lightweight aggregate used in this study, Poraver®, is a product of recycled glass materials. Furthermore, the validity of the current prediction methods in the literature was investigated including comparison between this study and an available expression in the literature on similar materials, for calculation of mechanical properties of lightweight concrete based on pulse velocity. It was observed that the recently developed empirical equation would better predict the compressive strength of lightweight concrete specimens in terms of the pulse velocity.

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.

Evaluation of Silica Fume Effect on Compressive Strength of Structural Lightweight Concrete Containing LECA as Lightweight Aggregate

2012 ◽  
Vol 626 ◽  
pp. 344-349 ◽  
Author(s):  
Maryam Mortazavi ◽  
Mojtaba Majlessi
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Considerable Increase ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Mix Design ◽  
Strength Gain ◽  
Experimental Phase ◽  
Normal Weight Concrete

The purpose of this paper is to evaluate the effect of silica fume on compressive strength of structural lightweight concrete, containing saturated LECA (Light Expanded Clay Aggregate) as lightweight aggregate (LWA). In experimental phase of study 120 cubic specimens (10*10*10) were made and cured. For every mix design, different cement percentages were replaced with silica fume, containing same amount of saturated LECA. The mixes incorporate 0%, 5%, 10%, 15%, 20%, 25% silica fume. Constant level of Water/Cement ratio (0.37) was considered. For each mix design 20 specimens were prepared and cured for 7, 14, 28, 42 days in standard 20 C water. Also 20 specimens with the same mix design of 0% silica fume as normal weight concrete were prepared and cured to compare the results. For these specimens LECA were replaced with same volume and size of sand. The testing results showed; increasing silica fume causes considerable increase in compressive strength. The rate of strength gain slows down at high percentage of silica fume. Also silica fume leads concrete to get higher initial compressive strength at certain time compared with normal weight concrete.

Development of a Specification for Low-Cracking Bridge Deck Concrete in Virginia

2017 ◽  
Vol 2629 (1) ◽  
pp. 83-90
Author(s):  
Harikrishnan Nair ◽  
H. Celik Ozyildirim ◽  
Michael M. Sprinkel
Keyword(s):  
Modulus Of Elasticity ◽  
Bridge Deck ◽  
Lightweight Concrete ◽  
Coefficient Of Thermal Expansion ◽  
Bridge Decks ◽  
Drying Shrinkage ◽  
Normal Weight ◽  
Continuous Contact ◽  
Normal Weight Concrete ◽  
Virginia Department

Cracking continues to be the number one concern about bridge deck construction. Rarely is a deck without cracks constructed. Transverse cracking mainly attributable to drying shrinkage is common in bridge decks and has been observed in many bridge decks newly constructed by the Virginia Department of Transportation (DOT). Shrinkage-reducing admixtures (SRAs) in concrete reduce shrinkage and are one of the most effective ways of reducing shrinkage cracking. A low modulus of elasticity and high creep also help minimize cracking. Lightweight concrete (LWC) has a lower modulus of elasticity, higher inelastic strains, a lower coefficient of thermal expansion, a more continuous contact zone between the aggregate and the paste, and more water in the pores of aggregates for continued internal curing than normal weight concrete: all these factors help reduce cracking in LWC. Drying shrinkage can also be counteracted with the use of shrinkage-compensating concrete (SC). When properly restrained by reinforcement, SC can expand an amount equal to or slightly greater than the anticipated drying shrinkage. The research in this paper investigated the effectiveness of SC, LWC, and concrete with SRA in reducing cracks in bridge decks and to develop a low-cracking bridge deck specification for use in future Virginia DOT bridge decks. The study showed that bridges with fewer and narrower cracks could be constructed with SRA, LWC, and SC and that proper construction practices were needed to reduce bridge deck cracking. This study resulted in the Virginia DOT implementing a low-cracking bridge deck specification.

Risk of Thermal Cracking from Use of Lightweight Aggregate in Mass Concrete

2017 ◽  
Vol 2629 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Aravind Tankasala ◽  
Anton K. Schindler ◽  
Kyle A. Riding
Keyword(s):  
Cross Sections ◽  
Lightweight Concrete ◽  
Coefficient Of Thermal Expansion ◽  
Concrete Structures ◽  
Lightweight Aggregate ◽  
Thermal Cracking ◽  
Normal Weight ◽  
Mass Concrete ◽  
Normal Weight Concrete ◽  
Cracking Risk

This paper describes the results of a numerical investigation of incorporating lightweight aggregate (LWA) in mass concrete structures. Numerical simulation was performed with ConcreteWorks software on three rectangular piers for normal weight concrete, internally cured concrete, sand–lightweight concrete, and all–lightweight concrete. Results show that temperature differences greater than 35°F may not necessarily introduce thermal cracking in mass concrete made with LWA. Maximum core temperatures and temperature differences increased with decreasing concrete density; however, the cracking risk of the mass concrete elements decreased as a greater quantity of LWA was used, regardless of element size. This trend occurred because other properties, such as coefficient of thermal expansion, creep, modulus of elasticity, tensile strength, and geometrical conditions, influenced the risk of thermal cracking. Additionally, the identification of the cross-section locations involved in measuring the critical temperature difference in a mass concrete structure are presented. The results of this work can be helpful in identifying critical stress locations in cross sections and assessing the cracking risk for mass concrete structures. A temperature and stress analysis is recommended before mass concrete construction involving LWA is begun.

scholarly journals Self-Consolidating Lightweight Concrete Incorporating Limestone Powder and Fly Ash as Supplementary Cementing Material

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3050 ◽  
Author(s):  
Khan ◽  
Usman ◽  
Rizwan ◽  
Hanif
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Limestone Powder ◽  
Normal Weight Concrete ◽  
Supplementary Cementing Materials ◽  
Fresh State ◽  
Cementing Material

This paper assesses the mechanical and structural behavior of self-consolidating lightweight concrete (SCLWC) incorporating bloated shale aggregate (BSA). BSA was manufactured by expanding shale pellets of varying sizes by heating them up to a temperature of 1200 °C using natural gas as fuel in the rotary kiln. Fly ash (FA) and limestone powder (LSP) were used as supplementary cementing materials (10% replacement of cement, each for LSP and FA) for improved properties of the resulting concrete. The main parameters studied in this experimental study were compressive strength, elastic modulus, and microstructure. The fresh-state properties (Slump flow, V-funnel, J-Ring, and L-box) showed adequate rheological behavior of SCLWC in comparison with self-consolidating normal weight concrete (SCNWC). There was meager (2%–4%) compressive strength reduction of SCLWC. Lightweight aggregate tended to shift concrete behavior from ductile to brittle, causing reduced strain capacity and flexural toughness. FA and LSP addition significantly improved the strength and microstructure at all ages. The study is encouraging for the structural use of lightweight concrete, which could reduce the overall construction cost.

scholarly journals Lightweight Concrete—From Basics to Innovations

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1120 ◽  
Author(s):  
Karl-Christian Thienel ◽  
Timo Haller ◽  
Nancy Beuntner
Keyword(s):  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Unintended Consequences ◽  
Special Focus ◽  
Normal Weight Concrete ◽  
Stage Of Development ◽  
Technical Potential ◽  
Wide Range ◽  
History Of

Lightweight concrete has a history of more than two-thousand years and its technical development is still proceeding. This review starts with a retrospective that gives an idea of the wide range of applications covered by lightweight concrete during the last century. Although lightweight concrete is well known and has proven its technical potential in a wide range of applications over the past decades, there are still hesitations and uncertainties in practice. For that reason, lightweight aggregate properties and the various types of lightweight concrete are discussed in detail with a special focus on current standards. The review is based on a background of 25 years of practical and theoretical experience in this field. One of the main challenges in designing lightweight concrete is to adapt most of design, production and execution rules since they often deviate from normal weight concrete. Therefore, aspects are highlighted that often are the cause of misunderstandings, such as nomenclature or the informational value of certain tests. Frequently occurring problems regarding the mix design and production of lightweight concrete are addressed and the unintended consequences are described. A critical view is provided on some information given in existing European concrete standards regarding the mechanical properties of structural lightweight concrete. Finally, the latest stage of development of very light lightweight concretes is presented. Infra-lightweight concrete is introduced as an innovative approach for further extending the range of applications of lightweight concrete by providing background knowledge and experiences from case records.

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