Experimental study on mechanical properties of different lightweight aggregate concretes

The concrete type known as high-strength concrete (HSC) has a high level of strength. HSC provides increased strength by the utilization of superplasticizers and silica fume. HSC is found to be very difficult to handle because of its high density. The density of HSC could be lowered with the use of lightweight aggregates. High Strength Light Weight Concrete (HSLWC) includes the behavior of both high-strength concrete and lightweight concrete. The lightweight aggregate used for HSLWC is Exfoliated Vermiculite (EV). It is a byproduct obtained from hydrous phyllosilicate minerals by heating. This provides various applications in the construction industry. This is an environmentally friendly material. Glass fibres will work as a strengthening element in concrete to make it strong and lightweight. The inclusion of glass fibers in HSLWC can raise its mechanical properties. Exfoliated vermiculite and glass fibres are integrated in this study to examine the mechanical characteristics of High Strength Lightweight Concrete (HSLWC).

Structural lightweight concrete is a very versatile material and Haydite and Minergy lightweight aggregates can be utilized in the mixture development of concrete for use in girders and decks in bridges. More widespread use of lightweight aggregates (LWA) would result in savings in construction cost due to considerable dead load reduction. The materials phase of this research study evaluated the fresh concrete properties (slump, unit weight, and air content), the mechanical properties of hardened concrete (compressive strength, tensile strength, flexural strength, static and dynamic modulus of elasticity, Poisson’s Ratio, and temperature development), and durability related parameters (air void distribution, freeze-that resistance, chloride permeability, resistance to scaling, and drying shrinkage). In addition, selected properties (24-hour, absorption, bulk, specific gravity, size distribution, and internal pore structure) of the lightweight aggregates were also determined. Lightweight aggregate mixes used in this study were proportioned using water-cement ratio/strength method in order to better address the issue of producing mixes that would satisfy both durability and strength requirements. Target compressive strengths for bridge girder concrete were 42 and 60 MPa (6000 and 10,000 psi) and 31 MPa (4500 psi_ in the case of bridge deck concrete. In the structural phase of the study the shear strength of reinforced and prestressed concrete lightweight concrete (LWC) beams was evaluated. In the Kettelhut Structural Engineering Laboratory twelve reinforced and four prestressed concrete beams were tested to failure. The experimental shear capacities were compared to calculated shear strength values from the 1995 American Concrete Institute Building Code and the 1994 AASHTO LRFD Stand Specifications. Based on the test results from this study it is recommended that water-cementitious ratio be used for proportioning of lightweight concrete mixes and that trial batches be prepared and tested before actual field application. To ensure adequate durability, lightweight aggregate concrete should be allowed to dry before exposing to the cycles of freezing and thawing. On the structural side, both the ACI and the AASHTO LRFD Specifications were found to yield conservative estimates of the shear strength of LWC reinforced and prestressed reinforcement for high strength light concrete beams.

PurposeIn 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/approachLightweight 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.FindingsIt 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/valueFinding 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.

This research studies the effect of high temperature which is reached to 600 °C onstructural lightweight and normal weight concrete. Lightweight concrete mix designedaccording to ACI committee 211-2-82 with mix proportion 1:1.12 :3.35 by volume .Thewc ratio equal to 0.5 by weight and cement content 550 kgm3. Mix proportions ofnormal weight concrete were 1:2:3 by weight with cement content 400 kgm3 and samewc. The design compressive strength at 28 days of normal weight concrete (NWC) andlightweight concrete (LWC) were 34.7 MPa and 22.62 MPa respectively. Compressivestrength tests were performed on 100 mm cubes exposed to high temperature 100,200,400and 600 °C. The normal weight concrete and light weight concrete test specimens wereexposed to high temperature for 10 minute suddenly at the required degree. Moreover,light weight concrete test specimens tested after graduate exposure to high temperaturereaching to the required degree with and without drying to examine the effect of moisturecontent.The results indicated that the structural lightweight concrete exhibits approximatelysimilar compressive strength loss compared to normal weight concrete up to 600 °C at 28days in graduate exposure .The percentage of reduction on compressive strength was30% in lightweight concrete compared to 28% in normal weight concrete at 600 °C .Insudden exposure to high temperature ,the opposite behavior was noticed .The percentageof reduction on compressive strength was 64.4% in lightweight concrete at 600°C .Drying of lightweight concrete specimens before graduate exposure to high temperaturessignificantly reduce the loss of compressive strength.

The objective of this study is to assess the shear friction characteristics of lightweight aggregate concrete (LWAC) prepared using artificially expanded bottom ash and dredged soil granules. A total of 37 concrete mixtures were prepared under the classification of three series. In the first and second series, the natural sand content for replacing lightweight fine aggregates and the water-to-cement ratio varied to obtain different densities and compressive strengths of concrete. The third series was designed to estimate the effect of the maximum aggregate size on the friction resistance along the shear crack plane of the monolithic interfaces. The frictional angle of the LWAC tested was formulated as a function of the ratio of the effective tensile and compressive strengths of concrete through the expansion of the integrated mathematical models proposed by Kwon et al., based on the upper-bound theorem of concrete plasticity. When predicting the shear friction strength of LWAC, the present mathematical model exhibits relatively good accuracy, yielding the mean and standard deviation of the ratios between experiments and predictions of 1.06 and 0.14, respectively, whereas the empirical equations proposed by the AASHTO provision and Mattock underestimated the results. Ultimately, an advanced modification factor for shear design of LWAC is proposed as a function of the density and compressive strength of concrete and the maximum size of aggregates.

The project study with the special concrete such as light weight concrete by using pumice aggregate (Natural aggregate). One of the disadvantages of conventional concrete is having high self weight. This heavy self-weight will make it to some extent an uneconomical structural material. Light weight concrete having low density reduces dead load and increase the thermal insulation. The reduction in density is produced by using it as a replacement of coarse aggregate partially in concrete. In this Study an attempt has been made to find the compressive strength of light weight aggregate concrete using mix M25 with poly carboxyl ether admixture under the application of axial load on short wall panel. Light weight concrete is made by replacement of Coarse Aggregate of Pumice aggregates.

In this study, the compressive strength, unit weight and chemical structure of light weight concrete (LWC) containing crumb rubber after exposure to high temperature are investigated. The crumb rubber was used as light weight aggregate in place of normal aggregate at the content of 3-15 wt% of LWC. For all mixtures, the water/cement ratio and sand/cement ratio were fixed at 0.5 and 0.2, respectively. The experimental results showed that the unit weight of LWC containing crumb rubber decreased with increasing crumb rubber content. The unit weight and compressive strength values are in range of 1566-1761 kg/m3, 12-29 MPa, respectively. The LWCs containing 3-7 wt% and 15 wt% crumb rubber can meet the requirement of ASTM standards for structural light weight concrete and masonry, respectively. After high temperature exposure, the unit weight loss and compressive strength loss were 25% and 75%, respectively. All specimens still complied with the requirement of ASTM standard for masonry.

Comparison of lightweight aggregate and foamed concrete with the same density level using image-based characterizations

The wide spread of lightweight concrete due to its properties like low density, good thermal insulation, and the economic feasibility of low cost for buildings constructed with this type of concrete. The studies in this field of construction materials have varied, in this research, one types of the lightweight concrete was produced. It is a lightweight aggregate concrete. Crushed attapulgite rocks was used as aggregate which fired at temperature of 700°C and used as partially or completely replacement with ordinary aggregates to production low-density concrete blocks both structural and insulating, The properties of the concrete produced which tested for (density, compressive strength, thermal conductivity, linear shrinkage, splitting strength) is conformed to the requirements of international specifications, the mix (GP) which contain 50% fine attapulgite aggregate and 50% ordinary fine aggregate with 100% coarse attapulgite aggregate conforms to the properties of structural lightweight concrete according to ASTM C330 and its gave a density about 1668Kg/m3 and compression strength of 17.5 N/mm2, while the two mixtures (H, HP) consisting of fine and coarse attapulgite aggregate with 100% of the total aggregate in mixture, with weight of 10% from cement as a pozzolana material in the mix HP is identical to the properties of the insulating lightweight aggregate concrete according to ASTM C332 with density about (1380,1432)Kg/m3 and thermal insulation (0.37,0.41)w/mk°, respectively.

Investigating lightweight recycled brick aggregate concrete incorporating EPS beads: Application to masonry units

초록·키워드 목차 오류제보하기 등록된 정보가 없습니다. Abstract1. 서론2. 실험개요3. 실험결과에 대한 고찰4. 결론참고문헌요약

One of the most crucial ecological challenges is the removal of the ever increasing enormous quantities of Fly Ash (FA) generated from various industries and its reduction in landfill spaces. Light-Weight Aggregate Concrete (LWAC) is utilized in the construction industry as it can decrease the unit weight leading to lower dead load, thermos-insulation, and resistance against earthquakes. A number of researchers have implemented experimental programs on the use of large amounts of FA as a substitute for cement in various lightweight concrete mixtures. This study aims to present the recent efforts of adding attapulgite in LWAC and highlight its effects and the influence of its mixture with High Volume FA Light-Weight Concrete (HVFALC) in terms of compressibility resistance, tensile strength, and rupture resistance.

Although the nano modification has been considered as a promising approach to enhance the mechanical properties of cement-based concrete, the investigation of low dosage nano modification on lightweight cement-based concrete is still very limited. In this study, the lightweight concrete, which was modified with low dosage nano-silica particles, were investigated. Non-prewetting and prewetting methods were used to prepare the lightweight concrete samples. The compressive and flexural strengths were tested to evaluate the modification effects of low dosage nano-silica on lightweight concrete. The microstructure analyses demonstrate that the hydration process of the cement paste can be changed with addition of nano-silica, and new types of hydration products have been observed in nano modified cementitious matrix. The interface between the lightweight aggregates and the cement paste can be reinforced by low dosage of nano-silica due to the new types of hydration products. However, relatively high dosage of nano-silica will reduce the modification effect because of the internal stress, which is resulted from the volume expansion of the new types of hydration product, at the interface of the lightweight aggregates and the cement paste. This study not only shows the possibility of low dosage nano modification on the mechanical properties enhancement of lightweight concrete but also provides potential modification mechanisms, which help to design and fabricate high-performance lightweight concrete materials.

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%.

Properties of lightweight aggregate for lightweight concrete production