STRENGTH OF LIGHTWEIGHT AGGREGATE FOAMED CONCRETE EXPOSED TO ELEVATED TEMPERATURES (original) (raw)
Related papers
IOP Conference Series: Earth and Environmental Science, 2018
Concrete is the chief material of construction and it is non-combustible in nature. However, the exposure to the high temperature such as fire can lead to change in the concrete properties. Due to the higher temperature, several changes in terms of mechanical properties were observed in concrete such as compressive strength, modulus of elasticity, tensile strength and durability of concrete will decrease significantly at high temperature. The exceptional fireproof achievement of concrete is might be due to the constituent materials of concrete such as its aggregates. The extensive use of aggregate in concrete will leads to depletion of natural resources. Hence, the use of waste and other recycled and by-product material as aggregates replacements becomes a leading research. This review has been made on the utilization of waste materials in concrete and critically evaluates its effects on the concrete performances during the fire exposure. Therefore, the objective of this paper is to review the previous search work regarding the concrete containing waste material as aggregates replacement when exposed to elevated temperature and come up with different design recommendations to improve the fire resistance of structures.
Effect of additives on mechanical and thermal properties of lightweight foamed concrete
This paper reports the results of experimental works that have been performed to investigate the mechanical and thermal properties of lightweight foamed concrete (LFC) with different additives. LFC with three different densities of 600, 1000 and 1400 kg/m 3 were cast and tested. Fly ash, lime and polypropylene fiber were incorporated with the LFC at different proportions. Compressive, flexural and drying shrinkage tests were carried out up to 180 days to evaluate the mechanical properties. The Hot Disk Thermal Constants Analyzer was used to establish different thermal conductivity values of LFC of different densities and additives. Scanning electron microscopy was used to give a detail view on each of particles produced by the reaction of additives in hydration process. The addition of additives in LFC showed no contribution on compressive strength but improvement in the flexural and shrinkage test results. LFC integrating various additives only contribute slight increase for therma...
Journal of Thermal Analysis and Calorimetry, 2021
The residual compressive strength of eight lightweight concrete mixtures containing three commercial grading (Liapor HD 5 N, Liapor HD 7 N, and Liapor 8F) of coarse lightweight aggregate (LWA) were determined after to expose at high temperatures. Eight mixes were produced, two by normal weight aggregate and the rest by different types of LWA. The produced concrete was analyzed after high temperature exposure and the effect of using LWA, the type of LWA, and compaction method was studied. To do so, visual inspection, residual compressive strength, crack pattern, spalling, and thermoanalytical analysis were conducted. Generally, it could be concluded that concrete formulations with LWA behave more advantageous up to 500 °C, compared to those with quartz gravel aggregates. Moreover, this study found that an ideal type of LWA to produce structural concrete was Liapor HD 5 N, which was used for producing the mixes L1 and L3.
Influence of the nature of aggregates on the behaviour of concrete subjected to elevated temperature
An experimental study is carried out on concretes composed of three different types of aggregates: semi crushed silico-calcareous, crushed calcareous and rolled siliceous. For each aggregate type, two water/cement ratios (W/C), 0.6 and 0.3 are studied. Aggregates and concrete specimens were subjected to 300, 600 and 750 °C heating–cooling cycles. We analyse the evolution of thermal, physical and mechanical properties of concrete in terms of behaviour and physical characteristic evolutions of aggregates with temperature. The study of thermal behaviour of aggregates showed the importance of initial moisture state for the flints. The crystallisation and microstructure of quartz play an important role in the thermal stability of siliceous aggregates. The residual mechanical behaviour of concrete varies depending on the aggregate and the influence of aggregates is also dependent on paste composition. This study allowed to better understand the influence of chemical and mineralogical characteristics of aggregates on the thermomechanical behaviour of concrete.
The effect of pumice as aggregate on the mechanical and thermal properties of foam concrete
Arabian Journal of Geosciences, 2018
Pumice is a porous rock, which is formed as a result of volcanic activity and does not include any crystal water. Its porous structure makes it lightweight and provides advantage for heat and sound isolation. Foam concrete is a type of lightweight concrete. Foam concrete is obtained by adding the foam obtained from the agent to the mixture of cement, water, and aggregate. Foam concrete is an environmentally friendly structure and insulation material which provides light, heat, and impact sound insulation that can be used in place of the building elements used in the interior-exterior walls and floors of all buildings. Because of the lack of coarse aggregate in the foam concrete mix, it has some structural problems and this limits its usage area. In this study, four different types of pumice aggregates and stone powder were used to overcome the structural problems of foam. The cement dosages (250 kg/m 3), aggregate amounts (250 kg/m 3), fresh concrete densities and w/c ratio (0.45) were kept constant in all foamed concrete mixtures. Then, physical, mechanical, and thermal conductivity properties of the resulting foam concretes were investigated. When the findings were evaluated, the most suitable type of lightweight aggregates for use in foam concrete have been determined in terms of compressive strength and thermal conductivity properties. In all aggregate groups, Nevsehir Pumice has the highest compressive strength while Karaman Pumice has the lowest thermal conductivity. However, when both properties were evaluated together, it was determined that the most favorable lightweight aggregate was Nevsehir Pumice.
MATEC Web of Conferences, 2016
The production and characteristic of lightweight bubble aggregates (LBA) are presented in this paper. The LBA are produced by mixing between the foam and ordinary Portland cement according to the composition which has been set. Then, the characteristics of LBA such as density, water absorption, specific gravity, compressive strength, aggregate impact value and microscopic analysis of the LBA are analyzed. Those characteristics are identified in order to ensure that the LBA are successfully categorized into lightweight aggregate. The loose bulk density is obtained at 812.5 kg/m3 which can be categorized under lightweight aggregate group. For water absorption the value obtained is 9.7 % which is slightly higher compared to normal aggregate. Meanwhile the average specific gravity obtained for the samples of LBAis 1.75. Compressive strength for the aggregates was 17.76 MPa. The highest compressive strength for LBA foamed concrete was obtained at 25% replacement with 7.83MPa. Thus, the LBA have a significant features and characteristics that can be used as coarse aggregates in concrete.
INFLUENCE OF BIOMASS AGGREGATE ON STRENGTH OF FOAM CONCRETE
Light weight concrete was initially used for nonstructural purposes but now due to advancement of new materials such as recycled biomass aggregates this concrete can be used for structural purposes as well. In past, different materials have been used in making foam concrete but this work utilized particularly recycled biomass aggregate as a filler. This research is aimed to study the effect of biomass aggregates on strength of concrete. The biomass aggregate was crushed into fine aggregate of size lesser than 2mm. A total of 72 foam concrete cubes of size 100mmx100mmx100mm were cast for this research. The foam concrete cubes were air-cured in outdoor environment and in the concrete curing chamber for 28, 56 and 91 days. The foam concrete achieved highest compressive strength by using biomass aggregate at 91 days of air curing as compared to normal sand at indoor environment. The study is a new step towards utilization of recycled material. The possible utilization of such material would reduce the consumption of natural resources and also reduces the carbon footprint from the industries
Residual Compressive Strength of Lightweight Foamed Concrete after Exposure to High Temperatures
Applied Mechanics and Materials, 2015
Even though lightweight foamed concrete has low mechanical properties compared to normal weight concrete, there is a potential of using this material as partition or load-bearing wall in low-rise residential construction. Before it can be considered for use as a load-bearing element in the building industry, it is necessary to acquire reliable information of its mechanical properties at ambient and high temperatures for quantification of its fire resistance performance. This paper will present the results of experiments that have been carried out to examine and characterize the residual compressive strength of foamed concrete after high temperatures. Foamed concrete with 700 kg/m 3 and 1000 kg/m 3 density were cast and tested. The compression tests were carried out at ambient temperature, 100, 200, 300, 400, 500 and 600°C.
2017
Concrete is a building material commonly used in the construction structures. There are many reasons why concrete is preferred. One of these reasons is fire resistance of concrete. Concrete is not a combustible material, but it behaves differently under high temperature. Aggregates constitute an important part of concrete volume. Differences in aggregate properties significantly affect the performance of the concrete during heating. Differences in these properties also cause cracks and breakages in parts of the concrete and significant losses in adherence. When we look at these effects, we have seen that high temperature creates a threatening environment for concrete. Therefore, it is necessary to investigate the behavior of the concrete caused by the high temperature. In this study, we investigated the effect of high temperature on the compressive strength of concrete specimens prepared using different aggregate types. For this purpose, 10 × 10 × 10 cm and 15 × 15 × 15 cm cube samp...
Fire and Materials, 2015
This paper presents the results of an experimental study on the behaviour of high-performance concretes after high temperature exposure. The high temperature exposure is related to the potential risk of fire, and mechanical properties analysis is needed afterwards to assess the residual strength of the material. The results presented in the paper show the properties evolution of four concretes made with four different aggregate types: basalt, granite, dolomite and riverbed gravel. The mix compositions allow comparisons, because the cement paste and mortar compositions and their volumes remain the same for all the four concretes. Moreover, the aggregate particle size distribution was chosen to be quasi identical so that this factor does not affect the concrete behaviour. The decrease of tensile strength value with the increase of temperature is more pronounced than compressive strength reduction thus, the exponential and power function equations were proposed to describe f tT -f cT relationship. The change of modulus of elasticity in relative values is similar, although the initial values of modulus are different and correspond to the aggregate type.