Effect of size on nominal strength of self-compacting lightweight concrete and self-compacting normal weight concrete: A stress-based approach

2017 ◽  
Vol 13 ◽  
pp. 36-45 ◽  
Author(s):  
Mohammad Karamloo ◽  
Moosa Mazloom ◽  
Gholamhassan Payganeh
Keyword(s):  
Lightweight Concrete ◽  
Normal Weight ◽  
Normal Weight Concrete ◽  
Nominal Strength

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 Rehabilitation of Hybrid RC-I Beams with Openings Using CFRP Sheets

2022 ◽  
Vol 8 (1) ◽  
pp. 155-166
Author(s):  
Ali I. Salahaldin ◽  
Muyasser M. Jomaa’h ◽  
Nazar A. Oukaili ◽  
Diyaree J. Ghaidan
Keyword(s):  
Lightweight Concrete ◽  
Normal Weight ◽  
Reinforced Concrete Beams ◽  
Bottom Flange ◽  
Normal Concrete ◽  
Normal Weight Concrete ◽  
Concrete Members ◽  
Hybrid Beams ◽  
The Difference ◽  
Total Capacity

This research presents an experimental investigation of the rehabilitation efficiency of the damaged hybrid reinforced concrete beams with openings in the shear region. The study investigates the difference in retrofitting ability of hybrid beams compared to traditional beams and the effect of two openings compared with one opening equalized to two holes in the area. Five RC beams classified into two groups, A and B, were primarily tested to full-failure under two-point loads. The first group (A) contained beams with normal weight concrete. The second group (hybrid) included beams with lightweight concrete for web and bottom flange, whereas the top flange was made from normal concrete. Two types of openings were considered in this study, rectangular, with dimensions of 100×200 mm, and two square openings with a side dimension of 100 mm. A full wrapping configuration system for the shear region (failure zone) was adopted in this research. Based on the test results, the repaired beams managed to recover their load carrying capacity, stiffness, and structural performance in different degrees. The normal concrete beam regains its total capacity for all types of openings, while the hybrid beams gain 84% of their strength. The strength of hybrid concrete members compared with normal concrete is 81 and 88% for beams of one opening and two openings, respectively. Doi: 10.28991/CEJ-2022-08-01-012 Full Text: PDF

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.

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.

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.

BOND BEHAVIOR OF LIGHTWEIGHT FIBER REINFORCED CONCRETE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Klaus Holschemacher ◽  
Ahsan Ali ◽  
Shahid Iqbal
Keyword(s):  
Reinforced Concrete ◽  
Lightweight Concrete ◽  
Normal Weight ◽  
Fiber Reinforced Concrete ◽  
Experimental Program ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Normal Weight Concrete ◽  
Air Content ◽  
Pull Out

In construction industry lightweight concrete and fiber reinforced concrete are being used for many years. The former is known for brittle nature, light in weight and low thermal conductivity properties. It also offers better workability when compared to the normal weight concrete for the same slump value. These properties are however affected by addition of discrete fibers. Among the affected properties is also the bond between steel and concrete surrounding it. The integrity of a reinforced concrete member is not ensured in the absence of adequate bond. Due to limited literature on the subject matter, an experimental program was carried out to understand the bond behavior in lightweight concrete after fiber inclusion. For the purpose modified pull-out specimens made of Lightweight Fiber Reinforced Concrete (LWFC) were tested. Hooked end steel fibers having length 35 mm and diameter 0.5 mm (l/d = 0.7) were incorporated in dosages of 0, 20, and 40 kg/m3. Besides pull-out specimens, testes were also carried out for fresh and hardened properties of LWFC. Tests results indicate higher pull-out loads for higher fiber contents. The average increase in ultimate bond strength was observed at 28% and 2% for 40 kg/m3 and 20 kg/m3 fiber contents respectively. The fresh concrete density, compressive strength of mixes reduced and air-content values increased with increase in fiber content.

Study of Lightweight Concrete for Roof Insulation Materials

2012 ◽  
Vol 174-177 ◽  
pp. 795-801
Author(s):  
H. Z. Cui ◽  
X. Shi
Keyword(s):  
Experimental Study ◽  
Lightweight Concrete ◽  
Normal Weight ◽  
Insulation Material ◽  
Insulation Property ◽  
Aggregate Concrete ◽  
Thermal Transmittance ◽  
Insulation Materials ◽  
Normal Weight Concrete

This paper presents an experimental study to determine the thermal transmittance of various types of lightweight concrete with an objective to assess the applicability of lightweight concrete as a roof insulation material. The lightweight concrete ranging in density from 400 kg/m3 to 1700 kg/m3 was investigated. The results were also compared with normal weight concrete. It was found that the expanded clay aggregate concrete with density of 700 to 900 kg/m3 had adequate insulation property and enough strength to be applied without the use of surface tiles. Lightweight concrete with Perlite provided better insulation than expanded clay aggregate concrete. Because of its lower in strengths, Perlite concrete required the use of surface tiles to permit maintenance access to roof.

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.

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