Autoclaved Lightweight Concrete Research Articles

Bond strength of autoclaved aerated concrete manufactured using partial replacement of flyash with fibers – A review

Autoclaved aerated concrete is widely attracted because of its excellent environmentally friendly characteristics and thermal insulation property. Autoclaved lightweight concrete (ALC), autoclaved cellular concrete (ACC), cellular concrete, autoclaved concrete, porous concrete, Ytong, hebel block, aircrete, and thermalite are some of the other names for AAC. AAC is a cent percent green construction material that has been used to construct the highest rated green structure. It consumes the least amount of energy and material per cubic meter of product, making it the most energy and resource efficient. Unlike brick manufacturing, which wastes valuable agricultural soil, AAC uses fly ash as the most beneficial answer to the country's fly-ash use problem. AAC's unrivalled strength-to-weight ratio, which is even higher than M150 concrete and greatly exceeds Indian building code standards, is achieved by a high-pressure steam-curing autoclaving process. In this article physical, mechanical and microstructural properties of AAC on replacing fly ash with various additives are studied. Comparison of properties for AAC manufactured using different additives were made and explained. AAC is a versatile building material. Fiber reinforced aerated concrete (FRAC) is a form of light weight aerated concrete which consist of internal reinforcement with small polymer fibers. Numerous materials such as basalt, rice husk, granite, graphite, zeolite, municipal solid waste, iron ore tailings, silica fume were used as fibers and incorporated (especially organic and industrial wastes) in manufacturing process of AAC. The mechanical (drying shrinkage), physical (compressive strength, flexural strength, thermal insulation, modulus of elasticity) and microstructural analysis (XRD, SEM) were done for different fiber incorporated AAC and results were studied an d compared. Above study indicates that all the properties depend on main factors such as condition during autoclaving process. Thus by the use of autoclaving, various industrial wastes, industrial byproducts and organic wastes are used in manufacturing AAC leads to reduction in wastes and widening the application of AAC.

Full-scale fire and postearthquake fire experiments of CFS walls with new configurations

In this paper, autoclaved lightweight concrete (ALC) boards, steel sheets and calcium-silicate (CS) boards were adopted to form a new sheathing configuration of cold-formed steel (CFS) walls. Full-scale fire and postearthquake fire experiments with such walls were carried out. The results showed that the steel sheets improved the mechanical behavior of the screw connectors, and the shear strength of specimen S2 with the new sheathing configuration was 14.7% higher than that of the CFS walls lined with base-layer CS boards and face-layer gypsum plasterboards (GP) on either side. Meanwhile, under the horizontal cyclic load with a drift ratio of 3.0%, obvious residual in-plane deflection and local buckling at the stud bottom of specimen S2 were detected, which caused the residual fire resistance (FR) to drop by 17.7% compared to the FR of specimen S1 without earthquake damage. Moreover, both specimens S1 and S2 with new sheathing configurations showed excellent fire and postearthquake fire performance, and the corresponding FR was at least 120 min longer than the FR of the CFS walls sheathed with double-layer GP or CS boards on either side, which could be attributed to the new sheathing configuration effectively mitigating the damage to the sheathing under earthquake motion, so that the effect exerted by seismic action on the heat transfer of CFS walls was insignificant under postearthquake fire conditions. In addition, both steel sheets and steel strips could protect the joints of the base-layer boards and achieve almost the same insulation performance as sheathing without board joints.

Experimental study on full-scale steel moment-resisting frames with nonstructural walls subjected to multiple earthquakes

A cyclic loading test of a steel moment-resisting frame (SMRF) with nonstructural components was conducted to evaluate the seismic performance of steel buildings subjected to multiple earthquakes. The specimen is a single-floor, one-span substructure of the intermediate story of typical current middle- or low-rise steel building in Japan. Two specimens were tested. The structural systems of these two specimens were the same, but the nonstructural components attached to the steel frame were different. The light gauge steel (LGS) partition wall and the autoclaved lightweight concrete (ALC) exterior wall were used as the nonstructural components of each specimen. One typical set of loading history that corresponds to one earthquake was created based on the response analysis results, and multiple sets of loadings with various levels were loaded to consider the effect of multiple earthquakes. Based on the observed visible damages, it was found that the structural component performed well under multiple earthquakes with a maximum story drift angle less than 1/50, while for the nonstructural component, the ALC wall performed better than the LGS wall. From the obtained load–deformation relationship, it was found that the strength of the structural component and the strength contribution of the LGS wall gradually decreased when subjected to multiple earthquakes, while the strength contribution of the ALC wall fluctuates within a close range. Moreover, the elastic stiffness of the structural component subjected to multiple earthquakes was almost constant, while the stiffness contribution of the nonstructural components decreased.

Full-scale experimental investigation of external-insulated cold-formed steel load-bearing walls under fire conditions

This paper presented a detailed experimental investigation on three full-scale external-insulated cold-formed steel (CFS) load-bearing wall specimens under ISO 834 fire exposure. The load ratio of each specimen was 0.55. The results showed that using autoclaved lightweight concrete (ALC) board as the external-insulation was more reasonable than the configuration of rock wool cavity-insulation and rock wool external-insulation under fire conditions. The specimens S2 and S3, which adopted ALC board as the external-insulated sheathing and calcium-silicate (CS) board as the base-layer sheathing on both sides, demonstrated desirable thermal insulation and integrity in fire. The corresponding fire resistance was longer than 3 h, meeting the highest requirement of the fire resistance rating specified in Chinese codes. Moreover, the fire-induced structural failure of specimen S3 was significant different from that of the non-cavity-insulated specimen of S1, which adopted the rock wool as the external insulation and was lined with gypsum plasterboards (GP) and CS boards on either side. This was attributed to the constraint effect of different sheathing configurations on the out-of-plane deflection of the wall studs. At the final stage of fire experiment, specimen S1 experienced significant out-of-plane deflection towards the furnace and the local buckling occurred on the cold flanges, which eventually led to the flexural–torsional buckling of the wall studs towards furnace. For specimen S3, the out-of-plane deflection was invisible through the experiment and the structural failure tended to be described as the local buckling of the whole cross section of wall studs. Additionally, compared with specimen S2, the cavity depth of specimen S3 was increased from 89 mm to 150 mm by increasing the stud web depth. It was found that for the non-cavity-insulated CFS walls, the increased cavity depth had insignificant effect on the temperature rise of wall cavity, wall studs and the ambient surface, if the possible change of heat transfer path caused by the cracking and falling-off of fire-side sheathing was not considered.

Improved fire resistance of cold-formed steel walls by using super absorbent polymers

Fire resistance is an important concern in the design of steel structures. The fire protection mechanism of traditional methods is to cover the external surface of steel members and delay fire-induced heat transfer. This paper develops an innovative solution to improve the structural fire resistance using super absorbent polymers (SAPs) with an experimental study to successfully demonstrate the effect of SAPs on cold-formed steel (CFS) walls. The SAP insulation material was filled in the cavity of CFS walls to provide thermal insulation and absorb heat. Six 1.1 m × 1.1 m CFS walls with SAP insulation materials inside were prepared and subjected to the ISO 834 time-temperature curve. During the experiments, a large amount of water vapor was observed from the SAP insulation materials, effectively removing heat and providing fire protection. The effects of various combinations of SAP insulation materials and steel studs and different configurations of CFS walls on the fire resistance are discussed. The results show that increasing the stud web depth, using autoclaved lightweight concrete (ALC) boards and SAP insulation materials can substantially improve the fire resistance of CFS walls. An optimal configuration of CFS walls with ALC boards as the face-layer sheathing and SAP insulation materials in the cavity of the rectangle hollow section studs was proposed and showed high heat consumption and low damage during fire exposure, which was supported by the maximum temperature of the steel studs being less than 150 °C after exposure to ISO 834 fire for 2 h. Finally, a possible application scenario for the SAP material was proposed for the fire protection of steel structures.

Cyclic behavior tests and evaluation of CFS truss composite floors

The cold-formed steel (CFS) composite floors have used widely in engineering practice owing to their benefits of lightweight, high strength and fast construction. Previously published literatures mainly focused on the flexural behavior of this type of composite floor, while there was little guidance on the cyclic behavior and design method. Therefore, it was necessary to study the cyclic behaviors of CFS composite floors with various lightweight slabs. This paper employed the CFS truss beam, commonly used profiled steel sheeting-concrete (PSSC) slab and novel type of autoclaved lightweight concrete (ALC) slab. A series of experimental and analytical studies on the hysteretic behaviors of CFS truss composite floors with PSSC slab and ALC slab were reported in this paper. The typical failure modes, hysteresis curves, envelope curves, characteristic values, ductility ratios, stiffness, and energy dissipation capacities of this composite floor type were systematically studied and estimated. The results indicated that the using of shear connectors could restrict the separation of concrete slab and profiled steel sheet, and improve the shear capacity and ductility ratio of CFS truss composite floor with PSSC slab. Besides, the CFS truss composite floor with ALC slab exhibited reliable hysteretic behavior accompanied by relatively poor integral rigidity owing to its assembly. Finally, the shear capacity and initial stiffness of CFS truss composite floor with PSSC slab were predicted based on a simplified model. The predicted results were agreed well with the experimental data. The studies in this paper could be adopted in the design and application of the CFS composite floor.

318 外装仕上塗材によるALCの凍害防止に関する研究 : その1 全体計画と室内実験結果

318 外装仕上塗材によるALCの凍害防止に関する研究 : その1 全体計画と室内実験結果

319 外装仕上塗材によるALC建築物の凍害防止に関する研究 : その2 実大構造物暴露試験結果

319 外装仕上塗材によるALC建築物の凍害防止に関する研究 : その2 実大構造物暴露試験結果

고온고압 증기양생 기포 콘크리트 블록의 역학적 특성

고온고압 증기양생 기포 콘크리트(ALC)는 기포제를 사용하여 콘크리트 내부에 무수한 기포를 형성시켜 콘크리트보다 밀도를 낮게 하고 열전도율을 낮춰 단열성능을 개선한 콘크리트이다. 본 연구에서는 국내에서 사용 중인 ALC 블록의 역학적 특성에 관해 살펴보았다. 재료시험을 통해 ALC 블록의 압축강도, 탄성계수, 휨인장강도, ALC 모르타르의 압축강도를 평가하였고, 현행 국내외 설계기준과 비교･분석하였다. 재료 시험결과, ALC 블록의 압축강도, 탄성계수, 휨인장강도는 블록의 밀도에 비례하여 증가하였다. ACI 523의 탄성계수식과 휨인장강도식은 압축강도에 대한 함수로 제시되어 있고, 본 연구의 시험결과를 잘 예측하는 것으로 나타났다.

Effect of Curing Age on Material Properties of Autoclaved Light-Weight Concrete Wallboard

The curing age of Autoclaved Light-weight Concrete (ALC) wallboards generally is not long enough in actual application, which may affect its material properties. By testing of various specimens for ALC with different curing ages, the relationship between the curing age of ALC and the dry density, moisture content, waterabsorption, compressive strength, splitting tensile strength, flexural strength, axial compressive strength and thermal conductivity is proposed, and the mathematic models were given. The results show that the growth of curing age is beneficial to most of the material properties of ALC, which are significantly different between those of 13 days and 10 days. In actual situation, the curing age should be 13 days at least while it cannot reach enough time.

Experimental Study of Non- Autoclaved Lightweight Concrete Prepared by Bagasse Ash

Experimental Study of Non- Autoclaved Lightweight Concrete Prepared by Bagasse Ash

Fire experiments of cold-formed steel non-load-bearing composite assemblies lined with different boards

At present, fire-resistant boards have become the most common fire protection productions in cold-formed steel (CFS) structures. In this paper, a fire experimental investigation of 12 CFS composite assemblies is carried out and the effects of different boards and insulation material are discussed. For non-load-bearing CFS composite assemblies lined with only GP board on the fire side, significant flexural deflection of CFS frame towards the furnace and local buckling of steel web is observed, due to the thermal bowing and fall off of fire-side GP board. Compared to the GP board, the low-bulk-density calcium-silicate (CS) board is not prone to fall off during the fire exposure. Replacing the fire-side base-layer GP board with CS board generates an effective fire protection on the cavity and ambient-side of assemblies. Therefore, the buckling of steel frame becomes insignificant and the testing fire resistance time of insulation failure is extended by 9 min to 46 min. The thermal insulation performance of aluminum silicate wool is obviously superior to that of rock wool in fire. For the present assemblies using aluminum silicate wool as external insulation instead of rock wool, the fire resistance time of insulation failure is extended by 18 min. Meanwhile, the composite panel and autoclaved lightweight concrete (ALC) board display excellent thermal insulation performance. For the CFS assemblies using aluminum silicate wool as external insulation, GP and CS boards as fire-side composite panel and ALC board as ambient-side base-layer sheathing, the fire resistance time of insulation failure becomes more than 171 min.

Experimental and analytical assessments on flexural behaviour of CTLST composite beams

This paper reports a series of experimental and analytical assessments on the flexural behaviour of cold-formed thin-walled lipped-channel section truss (CTLST) beams with profiled steel sheeting-concrete (PSSC) slabs or autoclaved lightweight concrete (ALC) slabs. Three test parameters were studied, including the floor type, the U-shaped shear connector, and the connection type among CTLST members. Besides, testing phenomena, failure modes, load versus deflection curves, and strain response for these CTLST composite beams were also analyzed. The experimental data showed that flexural strength of CTLST composite beam was significantly increased by adopting reliable connection type; bond performance of the interface between the profiled steel sheeting (PSS) and concrete slab was improved by erecting U-shaped shear connectors. These CTLST composite beams were in accordance with specification recommendations of deflection limits. In addition, three-dimensional finite element (FE) modelling of CTLST composite beams were developed and verified by test data. Effect of material and geometrical parameters on the flexural feature of the CTLST beams with PSSC slabs was explored. Finally, a simplified method, which was verified by the tested and simulated results, was proposed to predict the mid-span deflection of the CTLST composite beam using reliable connection type under serviceability loads.

Sustainable building solutions with new generation autoclaved aerated concrete panel applications

AbstractUntil now, autoclaved aerated concrete (AAC) was widely used in the construction industry mainly as a relatively simple (commodity) wall building material. The need and regulatory pressure for green, energy neutral buildings for residential housing and nonresidential constructions is becoming stronger every day. Consequently, we must challenge our construction designs and way of building to deal with increasing regulations, climatic and seismic conditions around world's geographical areas. This article presents new generation panel construction methods and a realized case study for a passive residential housing project designed with mid‐size modular AAC panels. The role and importance of this building method, applied with light‐ and heavy‐reinforcement panels, is also highlighted. The structural AAC panel design will be complemented and finished with autoclaved lightweight concrete (ALC) blocks, drywall sheets, and AAC partition panels. This partnership of building materials with installation integration at early stage of the construction process results in excellent insulation, efficient building, and supports HVAC.

습식 및 온수 바닥 복사 난방 시스템에서 PCM 적용을 위한 상변화온도 영향 분석

This study aims to design the PCM radiant floor heating system and to calculate optimal temperature of the PCM. The results of this study is as following. A existing radiant floor heating system have some problems to use a lot of hot water and energy owing to low heat storage performance of autoclaved lightweight concrete and mortar. for this problem, this study suggested the design of PCM radiant floor heating system applied to PCM, which is a heat storage material. The PCM radiant floor system consists of 210 mm concrete slab, 20 mm cushioning material, 15 mm mortar, 10 mm PCM aluminum case, 55 mm mortar, and a finishing material. It was analyzed that the PCM temperature (Melting point) scope for the PCM radiant floor heating system is 32-39℃ through the heat transfer model if a finishing material of 5 mm thickness is used.

Effects of Precast Cladding Systems on Dynamic Characteristics of Steel Frame Buildings by Ambient and Free Vibration Tests

Full-scale tests on a one-story steel frame structure with a typical precast cladding system using ambient and free vibration methods are described in detail. The cladding system is primarily composed of ALC (Autoclaved Lightweight Concrete) external wall cladding panels, gypsum plasterboard interior linings, and window glazing systems. Ten test cases including the bare steel frame and the steel frame with addition of different parts of the precast cladding system are prepared for detailed investigations. The amplitude-dependent dynamic characteristics of the test cases including natural frequencies and damping ratios determined from the tests are presented. The effects of the ALC external wall cladding panels, the gypsum plasterboard interior linings, and the window glazing systems on the stiffness and structural damping of the steel frame are discussed in detail. The effect of the precast cladding systems on the amplitude dependency of the dynamic characteristics and the tendencies of the dynamic parameters with respect to the structural response amplitude are investigated over a wide range. Furthermore, results estimated from the ambient vibration method are compared with those from the free vibration tests to evaluate the feasibility of the ambient vibration method.

Improvement of Sound Insulation Performance of ALC Walls Using Mock-up Experiments

AbstractMulti-unit dwelling has comprised the largest part of living in modern society where noise problems have become a social issue. Autoclaved lightweight concrete (ALC) panel and blocks have been widely used in residential, commercial and industrial buildings as its lightness and workability. However, the sound insulation performance of ALC is not high due to its light weight and the porousness. This study aimed to improve the sound insulation performance of ALC walls between housing units by changing the structure of the walls including layer of material, thickness of the air cavity, and connecting materials. In order to this, computer modeling and laboratory mock-up tests were undertaken to measure the STC of four different structures. As a result, the single-number quantities (Rw+C) of 61-68 dB, the first grade of sound insulation performance, can be acquired when ALC blocks were constructed with gypsum board and air cavity connected with metal or resilient channel.

Effect of Autoclaved Lightweight Concrete(ALC) on Growth and Flowering in Three Species of Cymbidium and Doritaenopsis Plants as a Potting Medium

Effect of Autoclaved Lightweight Concrete(ALC) on Growth and Flowering in Three Species of Cymbidium and Doritaenopsis Plants as a Potting Medium

폴리프로필렌 섬유 혼입 슬러리와 미네랄 하이드레이트 단열소재의 물리적 특성에 관한 연구

The fabrication method used for mineral hydrate is similar to that of ALC (autoclaved lightweight concrete), but the fabrication of normal slurry with a considerable amount of a foaming agent is difficult due to material separation and collapse of the slurry. Therefore, the development of fabrication methods for normal slurry is necessary. The final product, mineral hydrate insulation, has excellent thermal properties but poor strength characteristic given the many pores. In this study, in order to fabricate normal slurry, the viscosity and foaming time of the slurry were controlled. The mixing ratio of the starting material and the polypropylene fiber was controlled to improve the strength. Mineral hydrate with polypropylene fiber showed a higher strength than that without this type of fiber. Specifically, the compressive strength of mineral hydrate with 2% polypropylene fiber added to it was more than 40% higher than that without the fiber.

塩を含むALCの平衡含水率の測定とモデリング

This paper reports on measurements of water sorption isotherm of AAC (Autoclaved Aerated Concrete), commonly called ALC (Autoclaved Light-weight Concrete) in Japan, that contains salt (sodium chloride or magnesium chloride) water with a concentration that is low to saturated with undissolved salt in the material. The definitions of important parameters of porous materials that contain salt are clearly described. Measurement results confirm significant impacts of salt on sorption isotherm particularly at high salt concentrations. The measured sorption isotherm is modeled with the existing model that considers vapor pressure depression and the density of salt water. It is shown that differences between the measurement and the model increase with an increase of the amount of undissolved salt. Therefore, a modified model of water sorption isotherm for materials that do not only contain salt water but also undissolved salt is proposed and discussed. The modified model shows better agreement with the measurement.