Properties Of Lightweight Aggregate Concrete Research Articles

Research on A Kind of Lightweight Heat-insulating, Sound-insulating and Light-transmitting Concrete Interior Partition Wall Block

The new composite concrete with both lightweight, thermal insulation, heat insulation and light transmission properties is a new type of building The new composite concrete with both lightweight, thermal insulation, heat insulation and light transmission properties is a new type of building material with energy saving and consumption reduction functions. This paper integrates the research status of scholars in this field at home and abroad, realises the lightweight of blocks by studying the properties of lightweight aggregate concrete and porous concrete, and selects suitable light- transmitting materials, tests the light transmittance and mechanical properties of concrete blocks after adding light-transmitting materials, then analyzes the advantages and disadvantages of the sound insulation effect produced by adding soundproofing materials made from different materials to concrete blocks, and selects the best sound insulation effect by adding soundproofing materials to concrete blocks. concrete blocks, and selects the best soundproofing material for the comprehensive performance. Then we analyze the advantages and disadvantages of Then we analyze the advantages and disadvantages of adding different sound insulation materials into concrete blocks, and select the best sound insulation material with comprehensive performance. the same time of realising the three properties of light weight, sound insulation and light transmittance, we further study the effect of adding different thermal insulation materials on the thermal insulation effect of the blocks, and select the concrete blocks with the best thermal insulation performance.

Effect of Fine Steel Fiber on Mechanical Properties of Light-weight Aggregate Concrete

Effect of Fine Steel Fiber on Mechanical Properties of Light-weight Aggregate Concrete

Self-healing properties of lightweight aggregate concrete with mineral additions and water-absorbing resins

Self-healing properties of lightweight aggregate concrete with mineral additions and water-absorbing resins

Assessment of Properties of Structural Lightweight Concrete with Sintered Fly Ash Aggregate in Terms of Its Suitability for Use in Prestressed Members.

The main aim of the paper was to assess whether the lightweight concrete with a new type of sintered fly ash aggregate can be used as a structural material for post-tensioned elements subject to high effort. This purpose was achieved by comparison of the properties of lightweight aggregate concrete with Certyd aggregate (LWAC) and normal-weight concrete with dolomite aggregate (NWAC) of similar strength in terms of their suitability for use in prestressed members. Special emphasis was placed on long-term, relatively rarely performed tests of rheological properties such as shrinkage and creep. The research was conducted on standard specimens as well as on plain and post-tensioned beams of bigger scale, which could reflect better the behavior of the materials in a destined type of structural members. The carried out tests showed that, despite the expected lower density and modulus of elasticity, LWAC revealed comparable tensile strength and lower shrinkage and creep in the whole time of observations (ca 1.5 years) in comparison to NWAC. Moreover, the total loss of prestressing force for beams made of LWAC was slightly lower than for NWAC. Estimations of tensile strength and modulus of elasticity values according to the standard Eurocode EN-1992-1-1 for both concrete types turned out to be satisfactory. However, the rheological properties of the tested lightweight concrete seemed to be considerably overestimated.

Analysis of Mechanical Properties and Failure Mechanism of Lightweight Aggregate Concrete Based on Meso Level.

The relationship between the macroscopic mechanical properties of lightweight aggregate concrete and its microstructure is a hot topic in the discipline of concrete materials. It is very meaningful to provide an efficient numerical analysis method to conduct a meso-level analysis. This study proposes an automatic dissection algorithm and adapts the calculation program of the base force element method to conduct a non-linear damage analysis. In the numerical simulation, three groups of 100 mm × 100 mm × 100 mm specimens were selected for the uniaxial compression experiment and uniaxial tensile experiment, respectively. The average tensile strength of the numerical simulation for the uniaxial compression test was 21.86 MPa. The stress-strain softening curve, stress contour plot, strain contour plot, and damage plot of the light aggregate concrete were also analyzed. These research results provide data for analyzing the failure mechanism of light aggregate concrete and reveal the failure mechanism of light aggregate concrete. At the same time, the reliability of the proposed algorithm is verified. Our aim is to provide a more efficient and accurate analysis of meso-damage in lightweight aggregate concrete, which benefits industries involved in production, construction, and structural engineering.

Thermo-physical properties of light-weight aggregate concrete integrated with micro-encapsulation phase change materials: Experimental investigation and theoretical model

The experimental and theoretical determination method of thermo-physical properties of light-weight aggregate concrete integrated with micro-encapsulation phase change materials (MPCM-LWAC) has always been a crucial issue, but severely lacking the study on its theoretical determination method in previous researches. This work aims to construct the theoretical models for thermo-physical properties of MPCM-LWAC. For this purpose, we firstly established the theoretical models of enthalpy, specific heat capacity, and thermal conductivity according to the characteristics of phase transition and pore structure of MPCM-LWAC, and then validated these models by comparing with the experimental data. Results exhibit that (1) In case of the effective thermal conductivity of MPCM-LWAC, the improved two-step Reconstruction Maxwell Model considering the porosity is shown to fit excellently to experimental data. The difference is not more than 3%. (2) The newly constructed theoretical model of enthalpy with liquid phase ratio as a fitting parameter effectivity reflects the effect of temperature on enthalpy. (3) The theoretical model of specific heat capacity is constructed by the assumption that MPCM-LWAC satisfies the proportional mixing law. The theoretical results of specific heat capacity fit to the experimental results with excellent agreement in the range of phase-transition temperature, and the change is less than 5.160%.

The size of portlandite crystals in ITZ and its relation with ratios of ingredients and properties of LWAC

In this experimental study, nine different lightweight aggregate concrete (LWAC) specimens - in which natural lightweight scoria aggregate was used as coarse aggregate - were prepared for investigating the size of portlandite crystals in their interfacial transition zone (ITZ). Scanning Electron Microscope (SEM) was used to determine the size of portlandite crystals in ITZ of LWAC specimens. The size of portlandite crystals in ITZ of these LWAC specimens was determined quantitatively in order to identify its relation with ratios of ingredients and properties of LWAC that were investigated. It was determined that the size of portlandite crystals in ITZ of nine LWAC specimens is in the range of (0.91-2.047) µm. The size of portlandite crystals in ITZ is found to be increased when the water/cement (W/C) and coarse aggregate/total aggregate (Ac/A) ratios of LWAC get increased. On the other hand, the compressive strength and the oven-dry density of LWAC are found to be decreased when the size of portlandite crystals in ITZ gets increased. The best way to make portlandite beneficial from mechanical, physical and durability points of view is to transform it into so-called secondary hydration products by making it react with materials that have proper chemical properties for this transformation. In this case, the small portlandite crystals dissolve entirely, and the large portlandite crystals become smaller. Lightweight scoria aggregate used in this study is thought to have chemical properties to assist such a transformation in ITZ.

Estimating the permeability of porous aggregate concretes using electrical resistivity based tests

The established relationships between concrete's electrical resistivity and permeation properties are not applicable and might differ when porous aggregates are used. In this study, the relationships of electrical resistivity with the permeation properties of lightweight aggregate concrete (LWAC) and normal weight aggregate concrete (NWAC) were determined and compared to the permeation properties of recycled aggregate concrete (RAC). Differences in the regression slope of the three concrete types were found. At the same electrical resistivity, RAC has higher chloride permeability than LWAC and NWAC. But at the same formation factor, LWAC has higher water permeability than RAC and NWAC.

Experimental Investigation on Mechanical Properties of Lightweight Aggregate Concrete

Abstract This present research work mainly focusses on an investigation of the workability and strength properties of lightweight aggregates, particularly Palm oil shell and pumice aggregate, used in the production of concrete with (PA) and (POS), which were substituted for conventional Hard Broken Stone (HBG) coarse aggregate. Through the use of lightweight aggregate (POS and PA) in place of some of the coarse aggregate, the properties of a lightweight concrete M30 have been concentrated in this experimental study. The lab tests that were conducted include the compaction factor test, Schmidt Hammer test (rebound hammer test), and compressive strength. A total of 108 numbers of cube specimen were employed of size 2400 kg/m3. As part of a parametric study, the total number of cube specimens was divided into two groups according to various percentages: palm oil shell and pumice aggregate. In order to cast the cube specimens, dry weight of coarse aggregate was substituted for 0, 10 %, 20 %, 30 %, 40 %, and 50 % of POS and PA lightweight aggregate, respectively. A total of 9 cube specimens were cast and tested for 3, 7, and 28 days after successful curing in order to obtain accurate results. Average values were obtained from the test program and are shown in the corresponding Tables. Slump, compaction factor, rebound hammer compressive strength, and compressive strength values with different amounts of light aggregate were used to assess how well concrete performed when coarse aggregate was partially replaced with light aggregate. The test findings revealed that when the amount of conventional aggregates substituted by POS and PA increased, the slump test, compaction factor test, and strength of the lightweight aggregate concrete (LWAC) rapidly diminished. With an increase in the amount of aggregates replaced by POS and PA, the LWAC’s absorption has gradually increased as water. It is stated at the outset that the POS has shown to perform better than the PA when construction is done using structural lightweight concrete.

Effects of aggregate types and softening effect on multiaxial mechanical properties of lightweight aggregate concrete

Softening effect refers to the inherent property of porous media materials of having their strength decrease over time under water saturation compared with that under dry condition. Typical porous media materials, such as ceramsite and ceramsite-based concrete, exhibit a softening effect. This study investigated the softening effect of shale ceramsite (SC) and different types of lightweight aggregate concrete (LWACs). Mix ratios of LC30 all-lightweight shale ceramsite concrete (also known as all-lightweight concrete, ALWC) whose SC and shale pottery (SP) were selectively or simultaneously replaced with limestone gravel (LSG) and river sand (RS) with the same volume fraction, respectively, were prepared for comparison with gravel lightweight concrete (GLWC), sand lightweight concrete (SLWC) and hybrid aggregate lightweight concrete (HALWC) were formed. The four kinds of LWACs (ALWC, GLWC, SLWC and HALWC) were cast into their corresponding specification and size specimens and demoulded after indoor curing for 24 h, with their target ages (7–180 d) maintained under standard and hydrostatic curing. Then, the strength and initial elastic modulus under uniaxial stress, ultimate compressive strength and stress–strain curves under triaxial stress of the specimens were tested to analyse the influence of aggregate types and curing methods on the mechanical properties and softening effect of LWACs. According to the test results, the cube compression, prism compression, splitting tensile, conventional triaxial compression and elastic modulus decreased after 180 d of hydrostatic curing; the experimental age of the conventional triaxial compression test was after 90 d. ALWC demonstrated the most evident decrease, followed by SLWC, HALWC and GLWC. The trend indicates that normal aggregates can significantly improve the softening effect of LWACs. The failure modes of the triaxial compression specimens changed from splitting failure to shear failure, and a plastic platform phenomenon was apparent on the stress–strain curves, with their descending section appearing gentler than those in the uniaxial compression test with the increase in confining pressure. The relationship between ultimate compressive strength and confining pressure of the LWACs can be accurately described by the Mohr–Coulomb single-parameter failure criterion, Hsieh–Ting–Chen four-parameter failure criterion and Willam–Warnke five-parameter failure criterion. However, the three failure criteria demonstrated application limitations based on meridian equation and deviatoric plane analysis. The extension trend of the compression meridian of the LWACs after 90 d of hydrostatic curing was generally the same, and the types of aggregates exerted a minimal effect on the meridian and deviatoric plane limit trace. The softening effect of LWACs was mainly caused by the softening effect of the SC itself and the influence of pore water on the matrix concrete.

Effect of Steel Inorganic Fiber on Mechanical Properties of Lightweight Aggregate Concrete

In order to study the influence of steel-inorganic fiber on the mechanical properties of lightweight aggregate concrete, test parameters including single ceramic fiber and basalt fiber with different dosage and mixed steel-basalt fiber and steel-ceramic fiber reinforced lightweight aggregate concrete specimens with different doping methods were designed, and compared with the non-fiber reference group. The test results show that the compressive strength of cube is improved most obviously by steel-basalt fiber, with the maximum increase of 14.5%. Adding 1.35kg/m3 basalt fiber can increase the flexural strength of lightweight aggregate concrete by 62.2%. Adding ceramic fiber reduces the compressive strength of lightweight aggregate concrete, but improves the flexural strength.

Mechanical Properties of Lightweight Aggregate Concrete Reinforced with Various Steel Fibers

The objective of the present study is to examine the effects of different types and content of steel fibers on the workability, mechanical properties, and ductility enhancement of lightweight aggregate concrete (LWAC). Thirteen LWAC mixtures were prepared using different types of steel fibers including conventional hooked-end macro steel fibers (SF(H)), straight (CSF(S)), crimp-shaped (CSF(C)), and hooked-end (CSF(H)) copper-coated micro steel fibers at the designed compressive strength of 40 MPa. The fiber volume fraction varied from 0% to 1.5% at an interval of 0.5%. Test results showed that CSF(H) type possesses a better potential than the other types in enhancing the tensile resistance and toughness at the post-peak branch of the load–deflection curve of beams. The bond characteristics of fibers with cement matrix were one of critical parameters that needs to be considered in designing the fiber reinforced concrete. Thus, the splitting strength, modulus of rupture, and modulus of elasticity of fiber reinforced LWAC were formulated as a function of volume fraction, aspect ratio, and bond strength of fibers from the regression analysis using the present test data.

Experimental Study on Size Effect and Fracture Properties of Polypropylene Fiber Reinforced Lightweight Aggregate Concrete

In this experimental research, the effects of polypropylene fibers on size effect and fracture properties of lightweight aggregate concrete were studied. Two methods, including size effect method and work of fracture method, were used to investigate and analyze the size effect and fracture properties on different sizes of notched beams. The polypropylene fiber contents were 0.5%, 0.75%, and 1% by volume fraction. The obtained results revealed that increasing the polypropylene fibers in lightweight aggregate concrete relatively decreased the dependence of strength on the size effect parameter, while the addition of polypropylene fibers exhibited significant influence on decreasing the size dependency of ductility and fracture energy in lightweight aggregate concrete. Moreover, the increase of polypropylene fibers improved the total fracture energy (GF), initial fracture energy (Gf), characteristic length (lch), length of fracture process zone (cf), and critical stress intensity factor (KIc) of lightweight aggregate concrete in both size effect method and work of fracture method. This increase was more significant in work of fracture method because of considering the post-peak behavior. The size effect method was suitable and accurate for plain lightweight aggregate concrete. The GF ⁄ Gf ratio increased from 2.88 in plain lightweight aggregate concrete to 12.26 in polypropylene fiber reinforced lightweight aggregate concrete.

Influence of Lightweight Aggregates and Supplementary Cementitious Materials on the Properties of Lightweight Aggregate Concretes

Influence of Lightweight Aggregates and Supplementary Cementitious Materials on the Properties of Lightweight Aggregate Concretes

Correlation Analysis of Ultrasonic Pulse Velocity and Mechanical Properties of Normal Aggregate and Lightweight Aggregate Concretes in 30-60 MPa Range.

This study classified the strength of normal aggregate concrete (NC) and lightweight aggregate concrete (LC) into three levels (30, 45, and 60 MPa). In particular, the compressive strength, ultrasonic pulse velocity, and elastic modulus were measured and analyzed at the ages of 1, 3, 7, and 28 days to establish the correlation between the compressive strength and the ultrasonic pulse velocity and between the elastic modulus and the ultrasonic pulse velocity. In addition, this study proposed strength and elastic modulus prediction equations as functions of the ultrasonic pulse velocity. The developed equations were compared with previously proposed strength prediction equations. The results showed that the measured mechanical properties of NC tended to be higher at all ages than in LC. However, LC45 exhibited relatively high compressive strength compared to NC45. The relative mechanical properties of LC compared to NC were the highest at 45 MPa and the lowest at 60 MPa. The relative ultrasonic pulse velocity converged at all levels as the age increased. Moreover, the correlation between the compressive strength and the ultrasonic pulse velocity in LC exceeded that of NC, and in LC, the correlation coefficient decreased as the strength increased. The correlation coefficients between the elastic modulus and the ultrasonic pulse velocity were high at all levels except for LC45. Finally, this study proposed compressive strength and elastic modulus prediction equations as an exponential function of LC. The proposed equations outperformed the previously proposed strength prediction equations.

Performance of surface modification on bio-based aggregate for high strength lightweight concrete

The utilization of wastes in concrete as bio-based aggregate can alleviate disposal issues as well as preserve precious natural resources. This research highlights the wet grout binder derived from different water-cement ratios (0.65, 0.85, 1.05, and 1.25) in modifying the surface of lightweight bio-based coarse aggregate (LWBCA). In this research, the strength properties of lightweight aggregate concrete (LWAC) mixed with modified LWBCA were evaluated. The outcomes showed that through the replacement of non-treated bio-based aggregate with that of pre-treated grout coating bio-based aggregate, the density of the samples slightly increased. The results indicated that the slump value of the treated LWBCA showed a significant enhancement by almost 45% at 10 min for treated dura oil palm shell at 0.65 water-cement ratios (TDOPS/0.65), as compared to the non-treated bio-based aggregate. In addition, the strength of the TDOPS/0.65 mix shows more appropriate quality enhancement of pre-treated LWBCA when compared to non-treated, and correspondingly the strength properties of the concrete, particularly the significant increment of compressive strength and elastic modulus were recorded at 21% and 31%, respectively. Based on the water absorption test assessment, the LWBCA concrete indicated that good concrete was obtained for all the mixes. Therefore, a new technique of surface modification on bio-based aggregate has shown to be a highly suggested method, which performs as one of the most promising solutions to enhance the interfacial bonding strength. Thus, treatment improves the bio-aggregates to a level without scarifying the quality of the LWAC and substantially mitigating the environmental impact in concrete.

Meso-scale analysis of failure characteristics and mechanical properties of lightweight aggregate concrete (LWAC) with different aggregate volume fractions and shapes under axial tension

LWAC is a concrete prepared by the natural or artificial lightweight aggregates (LWAs). It has been receiving much interest in construction engineering field due to its outstanding properties including lightweight, heat preservation and shock absorption. A cohesive crack model of LWAC with random aggregates was established in this paper, and failure characteristics and mechanical properties of the concrete with different aggregate shapes and with volume fractions between 0.3 and 0.8 were analyzed by numerical simulation under axial tension. Results show that the LWAC crack starts from the inside of LWA, penetrates through interfacial transition zones (ITZs) and mortar to other LWAs to form the main crack.An increase in aggregate volume fraction decreases the slope of the ascending section of the stress–strain curve and tensile strength of LWAC. The crack initiation time of LWAC with polygonal LWAs is earlier, and the strength is slightly lower than them of circular aggregate LWAC. However, its time and strain of penetrating crack are larger, and it is more suitable for structural engineering with seismic requirements. The finite element model can effectively describe the two-dimensional failure process of LWAC.

Effects of Aggregate Types and Softening Effect on Multiaxial Mechanics Properties of Lightweight Aggregate Concrete

Effects of Aggregate Types and Softening Effect on Multiaxial Mechanics Properties of Lightweight Aggregate Concrete

Dynamic Properties Test and Constitutive Relation Study of Lightweight Aggregate Concrete under Uniaxial Compression

For the purpose of studying the dynamic properties of lightweight aggregate concrete, dynamic performance tests under uniaxial compression were conducted by considering 10 different strain rates ranging from 10−5/s to 10−1/s, from which the stress-strain curves under various compressive loads were obtained. From the stress-strain curves, parameters including peak stress, peak strain, and elastic modulus of lightweight aggregate concrete, as well as the concrete failure mode, were determined and examined. By reviewing the relevant literature on ordinary concrete, the dynamic properties of lightweight aggregate concrete were analyzed accordingly. Meanwhile, by applying the dynamic elastoplastic damage constitutive model, the effect of dynamic rate on lightweight aggregate concrete was calculated. The experimental results showed that the damage mode of lightweight aggregate concrete under the static and dynamic strain rates belonged to shear failure, which is different from that of ordinary concrete (binding material failure). On the other hand, it was also found that the peak stress and elastic modulus of lightweight aggregate concrete could be increased by 54.48% and 28.75%, respectively, with the increase of strain rate, suggesting that the loading strain rate has a stronger influence on lightweight aggregate concrete than on ordinary concrete. Based on the experimental data, both the peak stress and nondimensionalized elastic modulus are in linear relationship with the logarithm of the nondimensionalized strain rate. Moreover, the established constitutive model had been verified as an effective and reliable tool for simulating the dynamic rate effect of lightweight aggregate concrete.

Experimental investigation on the mechanical and chemical properties of lightweight aggregate concrete with CO2 curing

In the cement and concrete industry, enormous amounts of Carbon Dioxide (CO2) are emitted during their production processes. Carbon dioxide emission significantly contributes to the global climate change, which has been one of the biggest challenges of our times. Some novel solutions have been proposed for CO2 capture and storage, as well as reducing CO2 emission in concrete production. Carbonation curing is an effective alternative for conventional water curing for concrete. It can store CO2 in the hardened concrete and meanwhile improve early mechanical properties of concrete. Partial replacement of cement with fly ash shows environmental benefits, such as reducing greenhouse gas emissions and industrial waste destined for landfills. There has been some previous research studying on the effect of carbonation curing on normal Portland concrete in the past decade. Nevertheless, few studies have focused on the CO2 curing for lightweight aggregate concrete (LWAC). In this paper, the influence of early carbonation curing on LWAC is studied. LWAC specimens with two different water-to-cement ratios are cast and cured for a series of experimental investigations. The mechanical and chemical properties including the 1-day compressive strength, 28-day compressive strength, flexural strength, CO2 uptake, heat development, and pH level are investigated. Specimens with ordinary Portland cement are also tested as references in terms of compressive strength and CO2 uptake.