scholarly journals The Effect of Elevated Temperature on the Lightweight Aggregate Concrete

2017 ◽  
Vol 2 (3) ◽  
pp. 193-196
Author(s):  
Rahel Khalid Ibrahim
Keyword(s):  
Elevated Temperature ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
Lightweight Concrete ◽  
Concrete Structures ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Weight Losses ◽  
Before And After

The use of lightweight concrete has become widely spread in concrete structures in the last years. Fire can be considered as a destructive hazard that attack concrete structures. In this research the effect of elevated temperature on lightweight aggregate concretes is studied. For this purpose, 81 cube shaped specimens were prepared from three different lightweight aggregate concrete mixes. After moist curing periods for 3, 7 and28 days, the specimens were subjected to ambient and elevated temperatures of 450⁰C and 650⁰C for 2hrs.The weight of the specimens before and after exposure to elevated temperatures was determined and the residual strength results for the specimens were compared. The results showed that, the elevated temperature induces a decrease in strength and significant weight losses in lightweight aggregate concrete.

Permeability of Lightweight Aggregate Concrete with Mineral Admixture

2013 ◽  
Vol 857 ◽  
pp. 105-109
Author(s):  
Xiu Hua Zheng ◽  
Shu Jie Song ◽  
Yong Quan Zhang
Keyword(s):  
Pore Structure ◽  
Lightweight Concrete ◽  
Chloride Ion ◽  
Lightweight Aggregate ◽  
Total Porosity ◽  
Normal Weight ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete

This paper presents an experimental study on the permeability and the pore structure of lightweight concrete with fly ash, zeolite powder, or silica fume, in comparison to that of normal weight aggregate concrete. The results showed that the mineral admixtures can improve the anti-permeability performance of lightweight aggregate concrete, and mixed with compound mineral admixtures further more. The resistance to chloride-ion permeability of light weight concrete was higher than that of At the same strength grade, the anti-permeability performance of lightweight aggregate concrete is better than that of normal weight aggregate concrete. The anti-permeability performance of LC40 was similar to that of C60. Mineral admixtures can obviously improve the pore structure of lightweight aggregate concrete, the total porosity reduced while the pore size decreased.

Lightweight Aggregate Concrete as an Alternative for Dense Concrete in Post-Tensioned Concrete Slab

2018 ◽  
Vol 926 ◽  
pp. 140-145 ◽  
Author(s):  
Małgorzata Mieszczak ◽  
Lucyna Domagała
Keyword(s):  
Mechanical Properties ◽  
Lightweight Concrete ◽  
Concrete Slab ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Large Span ◽  
Shrinkage And Creep ◽  
Theoretical Results ◽  
Post Tensioned

The paper presents the results of tests conducted on two lightweight aggregate concretes made of new national Certyd artificial aggregate. This research is intended to first application of lightweight concrete to construct large-span post-tensioned slab. In addition to mechanical properties development, shrinkage and creep during 3 months of loading were tested. The obtained results are compared with theoretical results predicted by standard. Conducted tests indicated, that measured values of shrinkage and creep are significantly lower than predicted ones. This is promise for application of tested concrete in construction of post-tensioned slabs.

Evaluation of fire performance of lightweight concrete wall panels using finite element analysis

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Irindu Upasiri ◽  
Chaminda Konthesingha ◽  
Anura Nanayakkara ◽  
Keerthan Poologanathan ◽  
Brabha Nagaratnam ◽  
...  
Keyword(s):  
Finite Element ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Fire Performance ◽  
Concrete Wall ◽  
Aggregate Concrete ◽  
Content Type ◽  
Wall Panels ◽  
Foamed Concrete

Purpose In this study, the insulation fire ratings of lightweight foamed concrete, autoclaved aerated concrete and lightweight aggregate concrete were investigated using finite element modelling. Design/methodology/approach Lightweight aggregate concrete containing various aggregate types, i.e. expanded slag, pumice, expanded clay and expanded shale were studied under standard fire and hydro–carbon fire situations using validated finite element models. Results were used to derive empirical equations for determining the insulation fire ratings of lightweight concrete wall panels. Findings It was observed that autoclaved aerated concrete and foamed lightweight concrete have better insulation fire ratings compared with lightweight aggregate concrete. Depending on the insulation fire rating requirement of 15%–30% of material saving could be achieved when lightweight aggregate concrete wall panels are replaced with the autoclaved aerated or foamed concrete wall panels. Lightweight aggregate concrete fire performance depends on the type of lightweight aggregate. Lightweight concrete with pumice aggregate showed better fire performance among the normal lightweight aggregate concretes. Material saving of 9%–14% could be obtained when pumice aggregate is used as the lightweight aggregate material. Hydrocarbon fire has shown aggressive effect during the first two hours of fire exposure; hence, wall panels with lesser thickness were adversely affected. Originality/value Finding of this study could be used to determine the optimum lightweight concrete wall type and the optimum thickness requirement of the wall panels for a required application.

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.

Influence of the Steel Fiber Length on the Properties of Lightweight Concrete

2013 ◽  
Vol 739 ◽  
pp. 251-254
Author(s):  
Ru Jie Huang ◽  
Chen Shi ◽  
Guo Xin Li
Keyword(s):  
Tensile Strength ◽  
Fiber Length ◽  
Elasticity Modulus ◽  
Steel Fiber ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Earthquake Resistance ◽  
Lightweight Aggregate Concrete ◽  
Light Weight ◽  
Aggregate Concrete

Lightweight aggregate concrete has lower density and lower elasticity modulus, so it has better earthquake resistance. But the low strength limited the application of lightweight concrete. Steel fiber can improve the strength of lightweight aggregate concrete. In this paper, the influences of different lengths of steel fiber on the slump, compressive strength, splitting tensile strength and antiflex cracking strength are investigated. The results show that adding steel fiber reduces the workability of the concrete mixture, but it improved the each strength of light weight concrete and different lengths have the different regularity of effects.

scholarly journals Experimental Research on High Temperature Resistance of Modified Lightweight Concrete after Exposure to Elevated Temperatures

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Ke-cheng He ◽  
Rong-xin Guo ◽  
Qian-min Ma ◽  
Feng Yan ◽  
Zhi-wei Lin ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Modification Method ◽  
Superior Mechanical Properties ◽  
Axial Compressive Strength ◽  
Crushed Limestone

In order to improve the spalling resistance of lightweight aggregate concrete at high temperature, two types of modified materials were used to modify clay ceramsite lightweight aggregates by adopting the surface coating modification method. Spalling of the concrete specimens manufactured by using the modified aggregates was observed during a temperature elevation. Mass loss and residual axial compressive strength of the modified concrete specimens after exposure to elevated temperatures were also tested. Concrete specimens consisting of ordinary clay ceramsites and crushed limestone were manufactured as references for comparison. The results showed that the ordinary lightweight concrete specimens and the crushed limestone concrete specimens were completely spalled after exposure to target temperatures above 400°C and 1000°C, respectively, whereas the modified concrete specimens remained intact at 1200°C, at which approximately 25% to 38% of the residual compressive strength was retained. The results indicated that the modified lightweight concrete specimens have exhibited superior mechanical properties and resistance to thermal spalling after exposure to elevated temperatures.

Surface Modification for Porous Artificial Lightweight Aggregate and Mechanical Properties of the Resulting Concrete

2011 ◽  
Vol 117-119 ◽  
pp. 1302-1305
Author(s):  
Ning Liao ◽  
Hong Zhi Cui
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Water Absorption ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
High Water ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
High Water Absorption ◽  
Change Material

This research is one part of preliminary work for integrated structural-functional energy storage concrete by using porous artificial lightweight aggregate and phase change material. Lightweight aggregate concrete (LWAC) has been applied more and more extensively in recent years, but high water absorption of porous artificial lightweight aggregate (LWA) is inconvenient for LWAC production. In order to improve LWA application, in this paper, two aspects of lightweight aggregate (LWA) study have been carried out, namely, a) LWA surface modification. The effects of different concentration of surface modifier on water absorption of modified LWA were studied. b) Mechanical properties of lightweight aggregate concrete made of the unmodified and modified LWAs Through comparing the water absorption of unmodified and modified LWAs, it can be known that the surface modification for LWA can reduce the water absorption obviously. The three kinds of lightweight concrete possess nearly same strength at 7-day and, at 28-day, the strength of LWAC using 1:20 modified LWA is highest and that of LWAC using 1:5 modified LWA is lowest. 28 days compressive strength of LWAC using 1:20 modified LWA could be up to 46.1MPa.

scholarly journals Novel Core-Shell Non-Sintered Lightweight Aggregate Concrete for Better Properties in Wallboard

2021 ◽  
Author(s):  
Chaoming PANG ◽  
Xinxin MENG ◽  
Chunpeng ZHANG ◽  
Jinlong PAN
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Insulation ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Dry Density ◽  
Core Shell ◽  
Aggregate Concrete ◽  
The Core

Abstract Shrinkage of foam concrete can easily cause cracking and thus makes it difficult for a manufacturer to maintain quality. The density of lightweight aggregate concrete is too high to meet specifications for lightweight and thermal insulation for wallboard. Two types of concrete with dry density in the range 1000–1200 kg/m3 for use in wallboard were designed and prepared using foam and lightweight aggregate. The properties of porous lightweight aggregate concrete with core-shell non-sintered lightweight aggregate were compared with sintered lightweight aggregate concrete along with several dimensions. The two aggregates were similar in particle size, density, and strength. The effects of each aggregate on the workability, compressive strength, dry shrinkage, and thermal conductivity of the lightweight concrete were analyzed and compared. Pore structures were determined by mercury intrusion porosimetry and X-ray computed tomography. Compressive strength ranged from 7.8 to 11.8 MPa, and thermal conductivity coefficients ranged from 0.193 to 0.219 W/m/K for both types of concrete. The results showed that the core-shell non-sintered lightweight aggregate bonded better with the paste matrix at the interface transition zone and had a better pore structure than the sintered lightweight aggregate concrete. Slump flow of the core-shell non-sintered lightweight aggregate concrete was about 20% greater than that of the sintered lightweight aggregate concrete, 28d compressive strength was about 10% greater, drying shrinkage was about 10% less, and thermal conductivity was less. Porous lightweight aggregate concrete using core-shell non-sintered lightweight aggregate performs well when used in wallboard because of its low density, high thermal insulation, and improved strength.

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