Autoclaved Aerated Concrete Panels Research Articles

Numerical investigation on composite enclosure walls of RC frames infilled with autoclaved aerated concrete panels under cyclic loads

To promote the application of prefabricated walls and autoclaved aerated concrete (AAC) panels in the Metro industry, the seismic resistance investigations on composite enclosure walls (CEWs) of reinforced concrete (RC) frames infilled with AAC panels suitable for the Metro station were performed. Based on the field test arrangement, the corresponding finite element (FE) models were established and verified according to the experimental results. Moreover, the parametric studies, including with or without AAC infill panels, the compressive strength and thickness of the AAC panels, the compressive strength of frame concrete, and the door opening location and width, were further investigated to explore the structural behavior under cycle loads. The results indicate the seismic performance of CEWs can be effectively improved by infilling AAC panels. The increase in the strength and thickness of AAC panels could enhance the load-bearing capacity and ductility of CEWs. The structural stiffness and cumulative energy dissipation of CEWs are increased with the increasing thickness of AAC panels. The increased range of the peak load, ductility, initial stiffness, and cumulative energy dissipation of CEWs would be maintained within 20.5 % when the concrete strength of the RC frame increases from 35 MPa to 45 MPa. With increasing distance between the constructional column and the door opening, the load-bearing capacity of CEWs is significantly decreased, while the ductility is enhanced. The high initial stiffness could be obtained when the door opens near the constructional column. The load-bearing capacity and initial stiffness of CEWs would be decreased with increasing width of the door opening, while the insignificant effect of the changed door opening width on the ductility.

The modern Autoclaved Aerated Concrete (AAC) plant of today for a sustainable tomorrow

AbstractAAC, already produced since the 1920's, has been subject to continuous innovation and evolution over the history of its product life. The same applies to the AAC production process. Recently, the need for innovation has become more apparent than ever, driven by a serious energy crisis in Europe, combined with an increasing shortage of available labor and an increasing awareness of workers safety. Since the 70's, Aircrete Europe founding roots were highly involved in driving innovation in the AAC industry, with an emphasis on AAC panels. In every project designed by Aircrete top‐class innovation and the highest level of sustainability are always a top priority and are considered already from the very early design phase. As a result of this, Aircrete factories can be operated with the highest level of automation and energy‐saving initiatives to ensure higher operator safety, larger operating efficiency, and a minimized carbon footprint. This paper outlines how decades of experience from being involved in its own AAC operations result in how Aircrete can design a factory that is not only able to meet today's highest safety, regulatory, and environmental standards but is also future‐proof for the anticipated global trends in the industrial manufacturing and construction markets.

Performance of reinforced lightweight geopolymer composite panels subjected to windborne debris impacts

Lightweight panels have been widely employed as building envelopes in construction. As a result of the rising demand for environmentally friendly building materials, the authors recently developed a lightweight geopolymer composite (LGC) material and investigated the performance of reinforced LGC panels under static loading. Superior performance of LGC panels as compared to conventional panels such as autoclaved aerated concrete (AAC) panels has been observed, demonstrating their potential applications. During strong winds, building envelopes might be subjected to windborne debris impact, which could threaten residents and facilities and lead to structural failure. To explore the application potentials of LGC panels in strong wind regions, in this study, the performances of LGC panels subjected to windborne debris impact were investigated and compared with those of AAC panels by using a pneumatic cannon testing system. The failure modes and damage levels under different impact scenarios of LGC and AAC panels and their impact resistance capacities were obtained, compared and quantified in terms of the projectile residual velocity, penetration length and opening size. The effects of matrix materials, panel thicknesses, impact locations, reinforcement spacings and projectile impact velocities on their impact resistance performance were analyzed. For comparison, the punching shear capacities of the panels were also quasi-statically tested and analyzed subjected to the same projectile employed in the impact tests.

Field testing of blast responses and strengthening methods of reinforced autoclaved aerated concrete panels

Autoclaved aerated concrete (AAC) is a type of lightweight cellular concrete with a homogeneous void or cell structure. Because of its physical characteristics, AAC has many advantages, such as heat insulation, sound insulation, and fire resistance. AAC masonry blocks or reinforced AAC elements are widely used in public and civil buildings. Reinforced AAC panels, also known as autoclaved lightweight concrete panels, are made of AAC and steel reinforcing cages and are commonly used as panels. Explosions due to accidents or warfare have occurred more frequently in recent years, which often threaten the safety of building structures. In order to protect personnel and buildings, it is crucial to understand the dynamic response and damage of the reinforced AAC panels under blast loadings and find effective strengthening methods. In this study, 12 TNT blast tests were carried out on reinforced AAC panels, considering two strength classes of AAC and different strengthening materials. Various scaled distances were considered to investigate the blast resistance performance of reinforced AAC panels. The corresponding displacement responses of reinforced AAC panels were recorded. The damage characteristics and damage modes of the panels were compared and analyzed. The test results show that reinforced AAC panels have poor blast resistance performance and the damage mode changed as the scaled distances decreased. Increasing the strength of AAC or adding 5 mm strengthening layers significantly reduced the displacement response of reinforced AAC panels. Polyurea-strengthened and engineered geopolymer composites (EGC)-strengthened panels had similar displacement responses at the same scaled distance. Double-layer EGC prevented the fragmentation both on the front and rear faces. EGC strengthening is a very economical approach for reinforced AAC panels.

Experimental investigation of engineered geopolymer composite for structural strengthening against blast loads

The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures. Engineered geopolymer composite (EGC) is a promising material featured by eco-friendly, fast-setting and strain-hardening characteristics for emergent strengthening and construction. However, the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain. In this study, laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability, dry shrinkage, and mechanical properties in compression, tension and flexure. The experimental results showed that EGC containing PE fiber exhibited suitable workability, acceptable dry shrinkage and superior mechanical properties compared with other types of fibers. After that, a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements. The tests include autoclaved aerated concrete (AAC) masonry walls subjected to vented gas explosion, reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion. It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios. For AAC masonry walls and panels, with the existence of EGC, the integrity of specimens could be maintained, and their deflections and damage were significantly reduced. For plain concrete slabs, the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.

Experimental and analytical study on structural performance of reinforced lightweight geopolymer composites panels

Various lightweight panels such as autoclaved aerated concrete (AAC) panels have been widely used in the prefabricated construction. With the growing demand for eco-friendly building materials, geopolymer as cementitious material has been extensively studied. A novel ambient-cured lightweight geopolymer composite (LGC) with expanded polystyrene (EPS) was recently developed by the authors and demonstrated sound static and dynamic mechanical properties. In this study, a new lightweight reinforced panel made of LGC is proposed for prefabricated structures. Five full-scale panels, including one AAC panel and four LGC panels with different configurations, were prepared and tested under four-point bending to investigate the effects of panel thickness and reinforcement configuration on the structural performance. The test results showed that the LGC panels demonstrated better structural performance, with the characteristic ultimate bending capacity 57%-110% higher than that of the corresponding AAC panel. An analytical study was also conducted, and empirical formulae were proposed to predict the ultimate bending capacity of LGC panels.

Blast responses of BFRP-bar reinforced AAC panels

Basalt fiber reinforced plastic (BFRP) bars can replace steel bars in concrete protective structures because of their advantages of corrosion resistance and high load-bearing capacity. In this paper, the BFRP-bar reinforced autoclaved aerated concrete (AAC) panels (BFRP-AACPs) were designed and prepared. Based on close-in explosion experiments, the dynamic responses and failure modes of the BFRP-AACPs were revealed. Through the quasi-static three-point bending experiment, the residual load capacity of each BFRP-AACP was evaluated, which can quantitatively reveal the damage degree of the BFRP-AACP after explosion. Calculated by the equivalent static load method, the critical scaled distance of the designed panel is 2.08 m/kg1/3, which provides a design basis for the application of the BFRP-AACP.

Cyclic Behavior of Autoclaved Aerated Concrete External Panel with New Connector.

In this paper, a new slip-type crossing connector is proposed for autoclaved aerated concrete (ALC) panels with steel frames, and the proposed connector is also studied deeply in terms of seismic performance. The research included pseudo-static tests and finite element simulations. First, the seismic performance of slip-type crossing connectors and standard L-hooked bolts was studied comparatively, including the stability, bearing capacity, stiffness, energy dissipation, and hysteresis performance. ABAQUS 2020 software was used to establish finite element models, and the results of the experiments were verified with simulations on the basis. According to the simulations, a parameter analysis of connector optimization was carried out. The effects of connector thickness and connector plate length on the seismic performance were further investigated. From the experimental and simulation results, the slip-type crossing connector has excellent performance and good assembly efficiency, it can improve the deficiencies of the existing connectors. The comparison demonstrated that the slip-type crossing connector has a complete hysteresis curve, a high energy dissipation capacity, and a 9.7% increase in bearing capacity. The appropriate reduction in connector thickness and plate length can ensure superior seismic performance while saving resources. The finite analysis method can guide the design and implementation of new external ALC panel connectors.

Experimental and Numerical Studies on the Behaviors of Autoclaved Aerated Concrete Panels with Insulation Boards Subjected to Wind Loading.

Autoclaved aerated concrete panels (AACP) are lightweight elements in civil engineering design. In this paper, experiments and numerical analyses were conducted to study the flexural behavior of an enclosure system that consisted of AACPs and a decorative plate. A full-scale test was conducted to investigate the behavior of the enclosure system under wind suction. Load–deflection curves and load–strain relationships under different wind pressures were recorded and discussed. The effects of thickness, reinforcement ratio, and strength grade on the flexural behavior of AACPs were numerically investigated. Based on the numerical results, we found that the flexural behavior of AACPs can be improved by increasing the thickness or the reinforcement ratio. A comparison of finite element and theoretical results calculated using American and Chinese design formulae was conducted, and the results indicated the existing design formulae can conservatively estimate the major mechanical indices of AACPs.

Thermal insulation performance evaluation of autoclaved aerated concrete panels and sandwich panels based on temperature fields: Experiments and simulations

The thermal performance of wall materials has a profound influence on the energy consumption and thermal comfort of the buildings. The thermal performance can be evaluated by various indexes, such as thermal conductivity, decrement factor, delay time lag, etc., which are obtained by different methods. To more comprehensively characterize the thermal insulation performance of wall materials, a thermal inertia factor was proposed in this study based on the temperature fields of the wall materials. The autoclaved aerated concrete (AAC) panels with different densities and thicknesses were prepared, and also a kind of AAC - calcium silicate board (CSB) composite sandwich wall panels were designed to be compared. It was found that the low density (i.e. low thermal conductivity) alone did not equivalent to high thermal inertia, that is, both the decrement factor and the time lag were proportional to the density of the panels. Thickening of the AAC panels significantly hindered the heat transfer, and the designed sandwich structure also had this enhanced hindering effect. The thermal inertia factor was calculated based on the simulations of temperature fields by ANSYS software. It was concluded that the comprehensive thermal inertia of AAC panels was favorable when the density of AAC was in the range of 700–900 kg/m3. The heat flux through the AAC panels reached equilibrium at a position of 55%–75% panel thickness away from the high-temperature surface facing the hot box. These achievements contribute to better understanding of the thermal insulation performance of AAC and are desirable for proper modeling and design of AAC or other insulation materials.

Fire resistance of external light gauge steel framed walls clad with autoclaved aerated concrete panels

This paper presents an investigation into the fire resistance of external light gauge steel framed (LSF) walls clad with autoclaved aerated concrete (AAC) panels exposed to fire on the external side. Past research has been limited to the fire resistance of internal LSF walls clad with gypsum plasterboard on both sides. A series of experimental studies including thermal material property tests, a full-scale (3 m × 3 m) ambient capacity test of LSF wall and full-scale standard fire tests of non-load bearing and load bearing LSF walls were conducted to investigate the fire resistance of external LSF walls clad with AAC panels. Finally, a small-scale (1.2 m × 1.2 m) fire test of a wall made of AAC panels was also conducted to investigate the performance of joints between AAC panels. AAC panels with very low thermal conductivity performed exceptionally well by keeping the temperatures low for 160 min achieving a fire resistance level (FRL) of 204 min in load bearing conditions and 240 min in non-load bearing conditions. Hence, LSF walls clad with AAC panels can be used when higher FRLs are required. Experimental studies such as these on the whole system enable a good understanding of the overall fire performance of external wall systems in terms of structural adequacy and integrity instead of focusing only on the cladding.

Polyurea coating for foamed concrete panel: An efficient way to resist explosion

Abstract Autoclaved aerated concrete (AAC) panels have ultra-light weight, excellent thermal insulation and energy absorption, so it is an ideal building material for protective structures. To improve the blast resistance of the AAC panels, three schemes are applied to strengthen the AAC panels through spraying 4 mm thick polyurea coating from top, bottom and double-sides. In three-point bending tests, the polyurea-coated AAC panels have much higher ultimate loads than the un-coated panels, but slightly lower than those strengthened by the carbon fiber reinforced plastics (CFRPs). Close-in explosion experiments reveal the dynamic strengthening effect of the polyurea coating. Critical scaled distances of the strengthened AAC panels are acquired, which are valuable for the engineering application of the AAC panels in the extreme loading conditions. Polyurea coatings efficiently enhance the blast resistance of the bottom and double-sided polyurea-coated AAC panels. It is interesting that the polyurea-coated AAC panels have much more excellent blast resistance than the CFRP reinforced AAC panels, although the latter have better static mechanical properties.

Seismic behavior of autoclaved aerated concrete low rise buildings with reinforced wall panels

Reinforced Autoclaved Aerated Concrete (AAC) wall panels are more commonly used to construct load-bearing walls in low-rise prefabricated buildings located in seismic zones. In the scope of this study, the seismic response of buildings constructed with reinforced AAC wall panels was investigated. To this end, an in situ test was conducted on a two-story test building under reversed cyclic displacement excursions. It was determined that the test building could carry a lateral load of 60% more than its weight and has a global displacement ductility of about 3.5. The first story of the building was observed to be critical and the failure of the building was due to overturning response of the whole system. In addition, the proposed numerical models for simulating the behavior of the AAC wall panels were validated. These calibrated numerical models were utilized to conduct nonlinear static analysis of the test building and a reasonably good agreement was observed between the test results and simulations. The results of the incremental dynamic analyses demonstrated that i) the two-story test building could resist strong ground motions with PGA values up to 0.6 g without undergoing significant plastic deformations and ii) a reserve of ductility and over strength is available for the AAC panel building to survive earthquakes with PGAs reaching nearly 0.6 g. Based on these numerical results, reinforced AAC wall panel buildings appear to be good alternatives for low-rise construction in seismic regions.

Highly automated versatile volume production of autoclaved aerated panels

AbstractThe need for better and quicker building is growing every day. The shortage for craftsmanship with high costs is pushing building activities toward innovative, industrialized prefab elements and even to a complete casing production. New and affordable autoclaved aerated concrete (AAC) building concepts with its related production technology is a serious request from markets worldwide. AAC panels still have a limited or no market share in most of the countries in the construction industry. Exceptions to this case are Japan, Australia, the Netherlands, Denmark, Belgium, and Germany. The reasons are too many to mention. But the fact is that there are only a very few facilities fit for the future to produce predictable, versatile, high volume “quality” panels, lintels, cladding panels, and AAC boards. This paper presents an image collage and figurative views of our studies and 68 years of panel production experience with information about the lessons learned. Highlighted subjects will be the technology, plant automation, rebar and AAC, the smooth cutting, curing regimes, and handling.

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.

Shaking table test study on a steel frame with autoclaved aerated concrete walls

AbstractThis paper studies the seismic performance of a steel frame with autoclaved aerated concrete (AAC) walls through full‐scale shaking table tests. In the tested single‐span two‐storey steel frame, two types of AAC walls, AAC panel, and AAC block masonry wall, were adopted. Damage distribution and progress, acceleration and displacement responses, and the effect of window openings and corresponding strengthening methods were investigated. Test results showed that good seismic performance of the model structure was achieved with using both types of AAC walls, the connection used between AAC walls and steel structure was reliable and the reinforcement applied for the wall near window openings was found effective.

From experiments to seismic design rules for structures built with reinforced autoclaved aerated concrete panels

AbstractIn the last few decades, many destructive earthquakes have taken place all around the world, causing fatal injuries, loss of lives, and severe damages on structures. A number of innovative construction techniques have been developed over the past years to mitigate these casualties. Autoclaved aerated concrete (AAC) is a lightweight, energy efficient building material with satisfactory mechanical properties. Therefore, the use of reinforced AAC panels as load‐bearing structural elements in low‐rise buildings is a potentially viable alternative to traditional construction practices to build cost‐effective structures with adequate seismic performance. In this paper, preliminary results of a number of experimental tests which were executed through a project led by the Turkish Autoclaved Aerated Concrete Association are presented. The experiments include AAC material tests, AAC member tests, and a seismic test of a full‐scale building constructed with AAC panel walls and floors. Finally, design provisions included in the new version of the Turkish Seismic Design Code 2018, which were adopted based on these experimental findings, are outlined.

Seismic behavior of reinforced autoclaved aerated concrete wall panels

AbstractVertical reinforced autoclaved aerated concrete (AAC) panel systems are among attractive alternatives for low‐rise buildings. The popularity of AAC panels in building construction is increasing due to their unique material properties, such as being light weight, good insulator, fire resistant combined with having high speed of erection and ease of quality control. However, past experimental evidence on the seismic response of reinforced vertical panels is rather limited with few tests on multi‐panel specimens. To overcome this issue, an experimental program was initiated to test six full‐scale AAC wall panel specimens. In the scope of this study, the in‐plane seismic behavior of AAC vertical load‐bearing wall panels was examined under constant axial load and two‐way cyclic lateral displacement excursions. First, the effect of axial loads on lateral behavior of reinforced AAC walls was investigated. For this purpose, four specimens composed of two and four AAC panels with and without axial loads were tested. Then, the effect of window opening was examined by conducting two more tests. The results of the experiments clearly indicated that the axial loads had a positive effect on the load carrying capacity. The window openings reduced the lateral strength and caused localization of the damage. The ultimate drift of the tested panels was found to be around 1%. The ability of estimating the measured moment versus curvature response of the tested specimens were examined for different adjacent panel assemblages. Finally, the code‐proposed equations to determine the lateral load capacity of AAC walls were critically reviewed in light of the experimental results.

The design of storey height elements for the inner leaf of masonry cavity walls

AbstractHistorically, codes of practice, such as the United Kingdom code CP111, dealt with walling rather than concrete or masonry as separate materials. CP111 was withdrawn in 1985 following the publication of BS5628 Part 2 but other European standards do still indicate that masonry design procedures may be used for the design of cavity walls constructed with a prefabricated inner leaf. Reinforced and unreinforced panels of autoclaved aerated concrete (AAC) have been manufactured for many years in Europe but have never proved to be particularly popular in the United Kingdom except for specialist applications, such as mansard roofs. In 2008, BS EN 12602, dealing with prefabricated reinforced components of AAC and which covers plain AAC panels containing reinforcement for handling, was published. EN 1996‐1‐1 (Eurocode 6), which is the current structural design code for masonry, does not directly limit the size of unit that can be considered as masonry but does require masonry units to be manufactured in accordance with the relevant BS EN 771 series standard, which in the case of AAC is BS EN 771‐4. This paper looks at the issues involved in designing the inner leaf of an external cavity wall using storey height elements in accordance with EN 1996‐1‐1.

Aluminum silicate recycling raw materials for production of autoclaved aerated concrete

AbstractAluminum silicate recycling raw materials such as tiles and pot shards waste, in which the main phases were Al‐Si‐O amorphous with Mullite and α‐Quartz, were subjected to the utilization for the production of autoclaved aerated concrete (AAC). In case of adding silica gel or fine‐grinded quartz sand for production of AAC, tobermorite formation is declined. By adding tiles waste up to 33% substitution for silica sand, tobermorite formation is improved. Tobermorite formation is not altered by fineness of tiles waste. The possibility of replacing silica sand by tiles and pod shards waste at the amount of up to 27% for AAC panels and blocks is confirmed.