Density Of Lightweight Concrete Research Articles

Preparation and Compression Resistance of Lightweight Concrete Filled with Lightweight Calcium Carbonate Reinforced Expanded Polystyrene Foam.

Lightweight concrete is widely used in the construction industry due to its low density and high strength. In this paper, lightweight concrete was prepared by a simple two-step method. Firstly, the light calcium carbonate reinforced epoxy macrospheres (LCR-EMS) material was obtained by adhering calcium lighter carbonate powder to the expanded polystyrene foam spheres (EPS) material using the "balling method". In the second step, the LCR-EMS was mixed with water, cement, and the hollow glass microspheres (HGMS) material using the "molding method" to obtain lightweight concrete. The combination of macroscopic photographs and microscopic morphology shows that the LCR-EMS material itself is uniformly encapsulated and well bonded to the matrix. Test results show that the density of the lightweight concrete decreases with an increase in the volume fraction of stacked LCR-EMS, the diameter, and the proportion of HGMS in the matrix, but it decreases with a decrease in the number of layers of LCR-EMS. The compressive strength of lightweight concrete exhibits a completely opposite trend. When three layers of LCR-EMS were used as filler material, the density and compressive strength of the concrete were 1.246 g/cm3 and 8.19 MPa, respectively. The density and maximum compressive strength of lightweight concrete were 1.146 g/cm3 and 6.37 Mpa, respectively, when filled with 8-9 mm-2L-90 svol% of LCR-EMS and 40 wt% of HGMS in the matrix. Compared with lightweight concrete filled with 90% EPS, the density increased by 20% while the compressive strength increased by 300%.

A REVIEW OF THE EFFECT OF ADDITIVES ON THE MECHANICAL PROPERTIES OF LIGHTWEIGHT CONCRETE

Many organizations around the world have recognized lightweight, long-lasting, cost and environmentally-friendly construction materials as a future necessity. The lightweight concrete is manufactured mainly either by replacing the original aggregate with lightweight aggregate or addition foam production materials to concrete mixtures. These additions lead to a decrease in the lightweight concrete density and change mechanical properties such as compressive strength. Therefore, there is much experimental research has been conducted to add different material types that can improve lightweight concrete compressive strength while maintaining low density. In this review, the effect of various additions such as steel fiber, product waste materials, and nano-materials on the lightweight concrete compressive strength and density have been explained. The various effects of these additive materials on lightweight concrete properties, some additives lead to improving the properties of lightweight concrete, while other materials lead to a decrease in those properties, and this depends on the type and amount of material additive, the method lightweight concrete manufacturing, and their mixture composition.

Shear and Flexural Behavior of Lightweight Concrete Beams Containing Hybrid Fibers

Abstract Due to the low density of lightweight concrete, work has been done in this research to develop it by adding fibers of more than one type to improve its properties. Basic tests were conducted to determine the properties of concrete before and after the addition of fibers. The variables of the models were beams in two groups (shear and flexural). The variables of these two groups included the type of fibers (steel and polypropylene) and the size of the added fibers 0 %, 0.05 %, 0.1 % for polypropylene fibers 0 %, 0.75 %, 1 % for steel fibers. This study presented an examination of 18 beam specimens and discussed the results, which included mechanical properties (air dry density, slump test, compressive strength, modulus of elasticity, flexural strength, and splitting tensile strength). The results showed that the addition of fibers had an effective effect on the compressive strength, and this led to an increase in the resistance to shear forces and flexural forces, as the highest load capacity was shown by adding polypropylene fibers at a rate of 0.1 % in both groups, and the fibers played an important role in reducing the width of cracks and controlling their spread due to modulus of elasticity of the fiber.

The Effect of Expanded Glass and Crushed Expanded Polystyrene on the Performance Characteristics of Lightweight Concrete

This paper describes the production and performance characteristics of lightweight concrete (LWC) made from porous aggregates, such as expanded glass (EG), made from glass waste, and crushed expanded polystyrene waste (CEPW), obtained by crushing packaging waste from household appliances and ordinary Portland cement (OPC). During the study, the LWC density, thermal conductivity, compressive strength, bending strength, water absorption, deformations, composite structure, and freeze–thaw resistance were evaluated. By changing the amount of OPC and replacing part of the EG with CEPW, it was possible to reduce the thermal conductivity from 0.0977 to 0.0720 W/(mK). The presence of CEPW did not degrade compressive and bending strength or long-term water absorption of LWC. The influence of the amount of porous aggregates and OPC on the resistance to freezing and thawing was investigated by two methods. In one case, the freezing resistance was studied by the method of one-sided freezing of LWC structural indicators and, in the other case, the freezing resistance was determined by the decrease in compressive strength after 25, 100, and 200 freeze–thaw cycles. By modifying the structure with CEPW aggregate the durability of LWC products was increased and deformations were decreased.

Study of the Compressive Properties of Heavy Calcium Carbonate-Reinforced Epoxy Composite Spheres (HC-R-EMS) Composite Lightweight Concrete.

Lightweight concrete is one of the effective means to solve the problems of structural component weight, energy efficiency, and fire safety in modern civil engineering. Heavy calcium carbonate-reinforced epoxy composite spheres (HC-R-EMS) were prepared by the ball milling method, and HC-R-EMS, cement, and hollow glass microspheres (HGMS) were mixed into the mold by the molding method to prepare composite lightweight concrete. The relationship between the HC-R-EMS volumetric fraction, the initial inner diameter of the HC-R-EMS, the number of layers of HC-R-EMS, the HGMS volume ratio, the basalt fiber length and content, and the multi-phase composite lightweight concrete density and compressive strength was studied. The experimental results show that the density of the lightweight concrete ranges between 0.953-1.679 g/cm3 and the compressive strength ranges between 1.59-17.26 MPa, where the volume fraction of HC-R-EMS is 90%, the initial internal diameter is 8-9 mm, and the number of layers of HC-R-EMS is three. The lightweight concrete can meet the requirements of high strength (12.67 MPa) and low density (0.953 g/cm3). In addition, the addition of basalt fiber (BF) can effectively improve the compressive strength of the material without changing the density of the material. From a micro-level perspective, HC-R-EMS is closely combined with the cement matrix, which is conducive to increasing the compressive strength of concrete. Basalt fibers connect the matrix into a network, improving the maximum limit force of the concrete.

Experimental Study on Light Weight Concrete by Using Light Expanded Clay Aggregate (LECA)

Abstract: This study examined the structural behavior of Lightweight concrete (LWAC) using lightweight aggregates (Light expanded clay aggregates LECA) and normal weight aggregates, aims to investigate on concrete mix M25 by the effect of partially and fully replacement of the coarse aggregate by LECA with various percentage such as 20%, 40%, 60%, 80% and 100%. Analysis of this concrete was done in fresh state as well in hardened state to evaluate mechanical properties of concrete. This paper concentrated on performance parameters such as compressive strength, splitting tensile strength of the light weight concrete using LECA. The Lightweight concrete density varies from 40% - 100% replacement of LECA such as 1996kg/m3- 1597kg/m3. It reduces the weight of concrete and cost of concrete by reducing the aggregate cost and produces economical system.

Physical and mechanical properties of lightweight concrete based on gypsum binders and peat vermiculite granules

Introduction. An analysis of the literature and experimental data on the resource provision of the construction market has shown that the development of new and effective materials with improved quality parameters is an urgent task, and in the long term will serve as an impetus for the development of the building materials market. Currently, the peat industry in Russia is experiencing a serious decline in the extraction of peat raw materials, the reserves of which are practically inexhaustible. One of the possible ways to develop this industry in the Tomsk region can be the organisation of the production of competitive structural, heat-insulating and heat-insulating materials using local raw materials, namely lowland peat and vermiculite, which will improve the economic prestige of the region, create new enterprises and jobs.Materials and methods. The studies using the methods and tests set out in national standards were carried out. The measurement of the obtained material density was carried out in accordance with GOST 17177-94. The determination of the samples strength in compression and in bending was carried out in accordance with GOST 23789-2018. The determination of the moisture content percentage of the samples was carried out in accordance with GOST 23789-2018.Results. The results of the research made it possible to determine the basic requirements for the designed composition of lightweight concrete based on gypsum binders and peat vermiculite granules. The relationship between the strength characteristics and density of lightweight concrete has been studied, it has been established that at average density values in the range of 530-850 kg/m3, the resulting material meets the basic technical requirements of heat-insulating lightweight concrete (GOST 25820-2014).Discussion and conclusions. In the work, experimental studies determined the rational ratio of the components of lightweight concrete based on gypsum binder and peat vermiculite granules, at which the maximum value of their strength is achieved at a minimum average density. Based on the data obtained, it was found that in order to achieve the necessary physical and mechanical properties of lightweight concretes based on gypsum binders, the optimal size of peat-vermiculite granules should be no more than 5 mm.

Recycling of waste expanded polystyrene concrete in lightweight sandwich panels and structural applications

The recycling of waste expanded polystyrene (EPS) concrete in the lightweight construction sector is not yet explored. The complexity of recycling resides from concrete crushing that creates two distinct, yet inseparable phases including the hardened mortar fraction and recycled EPS beads. This study investigates the feasibility of using the waste EPS-based concrete in two different lightweight applications; i.e., sandwich panels and structural concrete complying with ACI 213 requirements. Test results showed that the lightweight concrete density and mechanical properties remain unaltered when the virgin EPS beads are replaced by recycled ones at relatively low rates not exceeding 2 kg/m3. The strength degradation becomes evident at higher rates, given the inseparable mortar fraction that weakens the aggregate skeleton due to higher porosity and water absorption. The bond to embedded reinforcement and shear strength of beams without stirrups decreased by about 20% when 3 kg/m3 of virgin EPS are replaced by recycled ones. The incorporation of 0.5% steel fibers, by volume, was efficient to mitigate the detrimental effect of such wastes and restore the lightweight concrete structural properties.

Study of The Mechanical and Absorbent Properties of Lightweight Concrete (Foam Concrete) Reinforced with Waste Fillers

This research included the production and study of the mechanical properties (compression resistance), absorption and density of lightweight concrete (foam concrete), where different proportions of the raw materials used in the production of this type of concrete. The obtained results showed that the addition of waste paper filling powder reduces the spaces between the concrete chains, which reflects the high concrete ability to withstand the pressure imposed on it, and that the degree of homogeneity between both concrete and waste paper is high, and that this increases the compressive strength of the prepared models by an increase of (44.6 %), while the addition of waste iron wire fillers reduces the compressive strength of the samples prepared for light concrete. Several engineering and physical tests were conducted on lightweight concrete models in this research, where it was reached to produce light concrete with a compressive strength ranging between (1.18 – 2.43) MPa, and the density was measured and the recorded values ranged between (718-917) kg / m 3, the water absorbency of the models was recorded, and the recorded values ranged between (18.6-56.6)%. The research aims to produce lightweight concrete with good physico-mechanical properties that can be used in the manufacture of building units, with a focus on the economic aspect of producing this type of concrete from available materials and at the lowest possible cost. Various fillers and foam were used as a percentage of cement weight for the purpose of improving the properties properties mechanical.

Mechanical Properties of Barchip Polypropylene Fibre-reinforced Lightweight Concrete Made With Recycled Crushed Lightweight Expanded Clay Aggregate

Concrete is one of the broadly used construction materials in the construction industry. This research intends to recommend the replacement of conventional coarse aggregates with recycled lightweight expanded clay aggregate (LECA) which offers several advantages such as lightweight, low cost, and easy availability. Lightweight concrete (LWC) offers numerous benefits; therefore, many researchers are using lightweight aggregate to produce lightweight structural composites concrete to compensate heavy loads by reducing the concrete self-weight due to lower density of lightweight concrete, improving in thermal properties and fire resistance, saving the cost of transportation and handling of precast units in the site. Different percentages (0, 0.15, 0.30, and 0.45%) of volume fraction of barchip polypropylene (BPP) fibre have been incorporated to improve the mechanical properties of lightweight aggregate concrete (LWA) concrete. In this study, the mixture of crushed lightweight expanded clay aggregate (CLECA) and barchip polypropylene (BPP) fibre have been used to achieve compressive strength between 28 and 37 MPa at 28-days with an oven-dry density ranged between 1900 and 2000 kg/m3. It is found that the inclusion of BPP fibres at an optimum volume fraction concrete enhances the compressive strength, splitting tensile strength and modulus of rupture. The compressive strength of the lightweight aggregate concrete containing 0.45% volume fraction of BPP fibre (CLLWAC-BPP0.45%) had achieved the highest compressive strength of 37 MPa at 28-days with a significant increment of about 31% compared to plain concrete. Hence, the findings of this research showed that the development of eco-friendly lightweight structural composites can be used as an alternative solution for conventional lightweight concrete, infrastructure and marine fields application.

The relationships between compressive strength and density of polystyrene lightweight concrete and their component ratios

The research deals with the compressive strength and density of lightweight concrete, made from polystyrene, cement, sand and water. This type of lightweight concrete is characterized by good thermal insulation, low density and good compressive strength and it is used as a lining material in inclination surfaces and in the production of unloaded building units and elements. The aim of this paper is to suggest mathematical relationships between compressive strength, density and mix proportions. An intensive experimental program has been implemented for this purpose. The investigated variables were the mix proportions, namely, polystyrene to cement ratio (P/C), sand to cement ratio (S/C) and water to cement ratio (W/C). Sixty mixes were produced and tested using five polystyrene to cement ratios (P/C), 0.02, 0.03, 0.04, 0.05, 0.06 four sand to cement ratios (S/C), 2.5, 3, 3.5, 4 , and three water to cement ratios (W/C), 0.35, 0.40, 0.45. From the test results, mathematical relationships were suggested that can be of use in determining mix proportions of polystyrene lightweight concrete based on the required compressive strength or based on the required dry density.

Formulation and characterization of geopolymer and conventional lightweight green concrete by incorporating synthetic lightweight aggregate

The present work was designed to develop green lightweight aggregates (LWA) using; coal fly ash, granulated blast furnace slag and small amount of cement (10–20%). Two types of lightweight concrete (LWC) were formulated using developed synthetic LWAs i.e. (i) geopolymer (GC), and (ii) Portland cement concrete (PC). Physical and mechanical properties of both LWAs and LWCs were examined for their suitability to produce LWC. Test results indicated that, density of LWA was increased and water absorption value was decreased with higher cement percentage in the developed pellet, which were complying with the ASTM requirements for LWA. Mechanical strength of produced LWAs was approximately 50% of the natural coarse aggregate. Considering LWC results, the density of LWCs was less than the threshold value (<2000 kg/m3). The compressive strength, ultrasonic pulse velocity and split tensile strength of GC were higher than PC and they were more for concretes containing LWA with higher cement percentage. Experimental strength was also compared with predicted strength from different empirical models. Overall, the properties of LWA and resulting LWC were appropriately acceptable and can offer sustainable solution to the construction industry, especially for green concrete.

Predictive to Monitor Modified Lightweight Concrete Density Influenced by Variation of Aggregate Size and Void Ratios

This paper predicts the rate of lightweight concrete density influenced by variation of heterogeneous aggregate deposition and void ratios. The study try to monitor the behaviour of this material under slight modification in concrete formations, variation of mixed designs output were observed to determined most concrete densities in structures, the basis for light weight concrete is to ensure imposed loads are reduced, this include other structural elements such column size, footings and other load bearing elements, such significant condition expressed the imperative of light weight concrete density in concrete structures, the study developed this element of concrete parameter to monitor the growth rate of the element under the slight modification from addictive material, such mixed design are applied to achieve all the required target parameters, such strength and other required characteristics in concrete structure are based on the these parameters, the study provided plate form for mechanical and durability performance that is required, the standard for efficient strength-to- weight ratio in structural element are achieved, this condition explained the advantage it has in the reduction of less reinforced steel including reduction of volume concrete. The study were developed to monitor light weight concrete density based on these factors, this were observed to determine the application of lightweight concrete density. This condition implies that the rate of lightweight concrete density modified will always attained such required status, the lightweight concrete simulation parameter are within the specification that can be achieved in such required rate. The study has express the significant of light weight concrete density based on the required level in other relevant area advantage of structural elements.

Slip modulus of screws in timber and lightweight concrete composite structures

The use of lightweight concrete in timber-concrete composite structures for the purposes of reconstruction, upgrading, and strengthening has increasing application potential. The correct combination of mechanical properties of both materials can preserve the beneficial aspects of timber in tension and concrete in compression, while reducing the weight of the structure. This paper experimentally evaluated the slip modulus of screw connectors as one of the key issues in the structural design of these types of composite structures. The results of four groups of push-out tests, which were performed on composite samples, are presented. All of the samples had identical cross sections, but each group was made with a different lightweight concrete density class according to Eurocode 2. The obtained results were compared with the values recommended by Eurocode 5. The analysis showed that the code recommendations yielded slip modulus values that were considerably higher than the ones obtained experimentally, which could lead to unsafe timber and lightweight concrete structures.

Assessment the thermal properties lightweight concreteproduced by using local industrial waste materials

In this research study of the thermal properties of light weight concrete produced from using two locally industrial wastes materials, to evaluate the thermal insulation, and some physical properties like strength of concrete (compressive and flexural tensile strength and variation of density of light weight concrete. Two types of wastes admixtures were used in this study, (chopped rubber, and wood sawdust) with (5%, 10%, 15% and 20%) percent of each one. Thermal conductivity, compressive strength, flexural tensile strength and variation of density have been examined for each specimen at all percentages of admixtures, and compare with the reference concrete specimens. Experimental test results indicated that using these types of wastes as replacement of fine aggregate in concrete significantly affects the thermal conductivity, compressive strength, flexural tensile strength (rise or fall out), especially at (5%) of adding materials, as well as utilization of additives in concrete to produce low density mixture with wood sawdust or as high density concrete when using rubber chopped in the concrete mixture.

Effect of Lightweight Concrete Density on Bond Strength

The main objective of this paper is connected with the search of an optimal anchorage length of reinforcement in lightweight and ultra-lightweight concretes. Experimentally obtained values of the bond stress between lightweight concrete and reinforcing bars are presented. The density classes of lightweight concrete were D1,0, D1,2 and D1,4. The results are compared with equal ones of normal density concrete. The tests with ordinary reinforcement and with non-metallic hybrid reinforcement C-GFPR (30% portion of carbon fibres) were conducted.

Lightweight Concrete Produced Using a Two-Stage Casting Process.

The type of lightweight aggregate and its volume fraction in a mix determine the density of lightweight concrete. Minimizing the density obviously requires a higher volume fraction, but this usually causes aggregates segregation in a conventional mixing process. This paper proposes a two-stage casting process to produce a lightweight concrete. This process involves placing lightweight aggregates in a frame and then filling in the remaining interstitial voids with cementitious grout. The casting process results in the lowest density of lightweight concrete, which consequently has low compressive strength. The irregularly shaped aggregates compensate for the weak point in terms of strength while the round-shape aggregates provide a strength of 20 MPa. Therefore, the proposed casting process can be applied for manufacturing non-structural elements and structural composites requiring a very low density and a strength of at most 20 MPa.

Mechanical Properties of Structural Lightweight Aggregate Concrete Containing Low Volume Steel Fiber

The use of steel fibers is a good solution for compensating lower mechanical properties of lightweight concrete. However, due to the high specific gravity, the addition of steel fiber increases the density of lightweight concrete. Therefore, there is some reluctance regarding the use of this fiber in lightweight concrete. In this study, to prevent a significant increase in density, low volume fractions of steel fiber (\({\leq}\) 1 %) were used to produce grade 20 structural lightweight aggregate concrete with a dry density of 1,650 kg/m3. Effect of low volume steel fiber on the compressive strength in different curing environments, splitting tensile strength and flexural strength was studied. The test results show that the addition of steel fiber in volume fractions of 0, 0.25, 0.5, 0.75 and 1 % increased its 28-day compressive strength between 14 and 32 %, splitting tensile strength between 21 and 77 % and flexural strength between 6 and 69 %. The effectiveness of steel fiber to increase the compressive strength was more pronounced at later ages than at early age. It was observed that 3 days moist curing is sufficient to gain equivalent compressive strength under standard curing. Adding even a small amount of steel fiber (i.e. 1 % volume fraction) increased the density; however, it was still within the ACI structural lightweight concrete specification. The flexural crack patternsin steel fiber-reinforced concrete beams showed excellent performance of low volume steel fibers in arresting the propagation of cracks.

Properties of Lightweight Concrete Composites with Mixture of Fly Ash and Concrete Sludge Aggregate

Lightweight foamed concrete is a concrete made by cement slurry mixed with foam so that foamed concrete that is much lighter than conventional concrete can be produced. The objectives of this study is to develop optimal pre-foamed lightweight foamed concrete and to achieve desired density of lightweight concrete that is below 2400 kg/m3. Three samples of concrete were batching with 0%, 25% and 50% of foam respectively under mixing ratio of 1:1:2 and foam dilution ratio 1:5 to obtain optimum result. Based on the result attained, the samples achieved the bulk density ranged from 1943 kg/m3 to 2305 kg/m3. In addition, other physical characteristics of this mixture of materials show that its water absorption for all the samples was increased from 6.508% to 11.889%. This trend of results was obtained if the volume of foam presented in the concrete were increased. Furthermore, the samples achieved compression strength ranged from 22.418 MPa to 32.229 MPa with presence of foam. In summary, with additional of fly ash and concrete sludge as aggregate it can help to produce comparable concrete composites with lighter density.

Using of Porcelinite as Coarse Aggregate in Concrete

In this research the ability of using porcelinite as coarse aggregate to produce light weight concrete was investigated. The experimental program consists of preparing and testing a mixes to investigate mechanical properties of concrete, with a total of 15 cubes (100×100×100) mm, 30 cylinders (100×200) mm. The tests include compressive strength, splitting tensile strength, fresh and hardened density of light weight concrete for different porcelinite percentages ranged between(0% to 100%) of the coarse aggregate weight. The obtained results for tested specimens were compared to control one. Test results indicated that using of porcelinite in concrete mix reduces the strength of concrete Porcelinite aggregate represents a reduction in density ranging between (10%-36%) of normal weight concrete, therefore there is an advantage using this type of light weight aggregate in this country where soil bearing capacity is low in most construction sites.