In this research, the properties of Structural lightweight aggregate concrete (LWAC) made of local lightweight aggregates in East Azarbaijan-Iran were investigated. Considering Iran earthquake zone, the weight of structures is of high importance. Reducing the weight of building using lightweight aggregates is one of the methods to decrease the harmful effects of earthquake on structures. In this study two different types of lightweight aggregates, Scoria and Pumice, provided from Azarbaijan-Iran, were used in concrete mixes. Mechanical properties of LWAC, including compressive strength, tensile strength, modulus of rupture, modulus of elasticity and stress-strain relationship were studied. In spite of NWC, the results show that at the same conditions, strength of aggregates is the main factor controlling the compressive strength of LWAC. Twenty-seven different concrete mixes with different 28 days compressive strengths varying from 24 to 51 Mpa were used in this study to measure the compressive strength, tensile strength, modulus of rupture, modulus of elasticity and strain at maximum stress which were compared with those of NWC. It was found that for the same compressive strength (24-51 Mpa) the modulus of elasticity of LWAC (10.92-18.77 Gpa) was less than that of NWC (17.53-28.31 Gpa) and tensile strength and modulus of rupture of LWAC was also less than NWC. The corresponding strain of the maximum stress in LWAC was found to be in the range of 2.55-3.78 mm/m, whereas for the same compressive strength, it was at range of 2.28-3.41 mm/m in NWC, this imply to lower modules of elasticity in LWAC compared with NWC.

lightweight aggregate concretes are widely incorporated in construction and development.This study, presents an experimental investigation on the properties of volcanic pumice lightweight aggregates concretes. To this end, two groups of lightweight concretes (lightweight coarse with natural fine aggregates concrete, and lightweight coarse and fine aggregates concrete) are built and the physical/mechanical and durability aspects of them are studied. The results of compressive strength, tensile strength and drying shrinkage show that these lightweight concretes meet the requirements of the Structural lightweight concrete.Also, the cement content is recognized as a paramount parameter in the performance of lightweight aggregate concretes.

In this research the mechanical properties of Structural lightweight concrete including compressive, tensile and flexural strengths and energy absorption using five types of fibres (industrial and scrap steel, glass, polypropylene and straw) in the form of single type of fibre or combination of two or three types of fibres have been studied. At the first stage, two reference samples of lightweight concrete and normal concrete without fibres are produced. At the second stage, samples of lightweight concrete with single type of fibres with volume percentages of 0.1, 0.25, 0.4, and 0.5 are made. At the third stage, samples of lightweight concrete containing twin combination forms of fibres with volume percentages of (0.1, 0.4), (0.4, 0.1) and (0.25, 0.25) are produced. At last stage, samples of lightweight concrete with triad combination forms of fibres with volume percentages of (0.1, 0.1, 0.3), (0.1,0.3,0.1) and (0.3, 0.1, 0.1) are produced. Obtained results indicated that samples with combination of two types of fibres had the best behaviour compared to other samples. The highest compressive strength have been resulted from the combination of industrial steel and polypropylene fibres and the highest tensile and flexural strengths have been obtained from the combination of glass and polypropylene fibres. The highest energy absorption is related to the combination of industrial steel and glass fibres.

concrete is one of the most widely used materials in the current century. At high temperatures, due to high thermal stresses and low tensile strength, this material suffers from problems such as cracking, crumbling, or disintegration. In this research, concrete samples have been reinforced using steel and polypropylene fibers and subjected to different temperatures from 25 degrees to 800 °C, and compressive and tensile strength tests have been performed on the samples. In order to better examine the results, a concrete sample containing lightweight aggregate was also prepared and tested along with other samples. The test results showed that with the addition of steel and polypropylene fibers, the compressive strength up to the temperature of 200 °C is higher or similar to the control sample. Also, the tensile strength test results showed that samples containing steel fibers had the highest tensile strength at all temperatures. The results of the compressive and tensile strength test also displayed that at temperatures of 600 °C and above, the lightweight concrete sample has a higher or similar strength to the control sample. Polypropylene fibers start to melt at 400 °C, which has caused a drop in compressive and tensile strength in samples containing this type of fibers at temperatures above 400 °C.

The behavior of light weight concrete at elevated temperature is of significant importance in providing safety of structures in response to certain accidents or particular service conditions. Thispaper deals with the physical and mechanical properties of light weight concrete “containing leca” such as: compressive strength, water absorption, mass loss and spalling. Specimens with different amount of Nano Silica by applying the Taguchi method for an optimal mix design had been made and after curing for 28 days and being subjected to 200, 400 and 600oC specimens had been compared with the specimen without Nano silica and cured at room temperature. It was found that by increase temperature to 600oC physical properties of light weight concrete like water absorption goes bad and in some condition an improvement in mechanical properties like compressive strength had been emerged surprisingly.

1. Introduction: In order to reduce dead loads of structures in earthquake prone areas such as Iran, lightweight concretes have several advantages which could be used as a substitution of ordinary concretes. One of the challenges in construction industry is producing an economical and environmental structures which could be able to fulfil requirements of Structural and durability properties both. Thus, this industry needs a sustainability evaluation to find sustainable materials in engineering, environmental and economical aspects which this is one of the keys to achieving sustainable development. The main purpose of this research is to investigate economical, environmental and durability properties of lightweight concretes and fiber reinforced lightweight concretes and compare them with ordinary concretes. . .

In this study, the stress-strain behavior of lightweight aggregates concrete (LWAC) made of local Scoria and Pumice aggregates in Azarbaijan-Iran has been studied. Fourteen different concrete mixes with different mix proportions were used in this work. Forty-two cylindrical specimens made of different concrete mixes were prepared for uniaxial compression test to determine the stress-strain behavior of the LWAC. The trend of the experimental results were compared with the existent mathematical relationship defined by other researchers .There were some differences between the experimental results and existing equations which can be related to different properties of the LWAC in comparison with those of normal and high strength concrete (HSC). The experimental results can result in lower flexural strength of the beams than that of the existing relation by other researcher, which implies more attention to be paid on it.

In this papers, the punching shear strength of flat plate lightweight concrete slabs, using natural lightweight aggregates, is studied. In the experimental part of the study, six specimens of rectangular lightweight concrete slabs have been manufactured and tested. The strength of concrete and reinforcement varied in different tests. The slab dimensions and the area of reinforcing bars in slabs have been carefully designed so that the slabs failed due to punching shear. In each test, load and displacement were measured using a computer data acquisition system. The behavior of slabs, cracking pattern and the slab stiffness were studied from the test results. The experimental results have been compared with the provisions of different codes. The comparison shows that the BS-8110 Code estimates the punching shear of lightweight slabs most accurately. The slabs made of natural lightweight aggregates can be used in structures by providing good concrete mixture designs.    

In this paper a new system of precast concrete sandwich panels (PCSP) is introduced. Finite element analyses (FEA) were carried out to study the behavior of composite precast concrete sandwich panels (PCSP) in order to examine feasibility of their usage as slab elements in the construction industry. The panels are composed of three layers; an ordinary reinforced concrete or fiber-reinforced concrete as top layer، a thick layer of light-weight concrete as a middle layer or core and the third layer or lowest layer is a tensile resistant reinforced concrete or reinforced light-weight concrete. In this research, the Structural behavior of precast concrete sandwich panels (PCSP) under flexure is studied. For this purpose, at first four model of one-way sandwich panels with the ABAQUS software was modeled and in terms of Structural performance have been studied. The effect of steel shear connector’s stiffness as measured by its diameter on the ultimate strength and composite action of the panels was investigated. In addition, the effect and orientation of the shear connectors in one or two directions were also investigated. According to the results, the sandwich panels with two concrete layers had a smaller linear region stiffness than those with three concrete layers. When the prefabricated sandwich panels behave as one-way slabs, placing shear connectors parallel to the x-axis (larger dimension) is sufficient to bond two concrete layers for them to act as a single unit, The ultimate strength and the composite action of desired were found to depend to a large extent upon the stiffness of the shear connector used.