Autoclaved Lightweight Concrete Research Articles

Composite Building Materials Prepared from Bioresources: Use of Rice Husk for Autoclaved Lightweight Concrete Production

Composite Building Materials Prepared from Bioresources: Use of Rice Husk for Autoclaved Lightweight Concrete Production

Study on prefabricated composite shear wall cladding anti-shedding connection structure

Fabricated steel structure systems have undergone significant advancements. However, problems associated with exterior wall panel systems have become increasingly prominent, particularly the issue of exterior wall panel shedding. Three full-scale fabricated composite shear wall exterior panel components were designed and tested under quasi-static conditions. The failure sequence and characteristics of the exterior wall panels at different displacement angles, including their out-of-plane displacement and stiffness degradation, were evaluated to assess their seismic and connection performance in different building construction methods. The results indicated that drilling holes near the centre of autoclaved lightweight concrete (ALC) boards improved the seismic performance of wall panels. Long round holes in the ALC boards allowed the dissipation of sliding energy during the initial deformation of wall panels. Furthermore, wall panels with bonded anchorage connections for rockwool boards exhibited better seismic performance than those with pure anchorage connections. To verify the accuracy of the findings, a structural finite element model was established, and the influences of various parameters, such as the position of ALC board connecting bolts, length of ALC board holes, and bonding rate of rockwool boards, on the stress and deformation of the exterior wall panel system were analyzed. Based on the test results and finite element simulation analysis, an anti-shedding connection construction method was proposed.

A scheme of installing ALC wall panels based on autonomous mobile robot

Autoclaved lightweight concrete (ALC) wall panels are widely used in building envelope structures. Due to the limitations of their sizes and architectural environment, installing ALC wall panels is very complex, requiring significant labor and time costs. Construction robots provide enhanced efficiency, yet current façade installation robots lack comprehensive on-site automation. In this study, an on-site wallboard installation robot with sensors, a mobile base, and a mechanical gripper was self-designed. Based on this robot, an automated installation scheme with integrated functions was proposed for the multiple steps from grasping to installing the wall panel. The robot could recognize and judge the posture of the wall panel through a robot vision algorithm and was able to navigate according to the simultaneous localization and mapping (SLAM). The proposed scheme achieved good results in both simulation and field testing. The robot automatically completed multiple tasks, from grasping to placing ALC wall panels, significantly reducing the difficulty of manually installing ALC wall panels and avoiding construction hazards.

Wind load resistance of prefabricated ALC-rock wool external wall panel system

Exterior wall enclosure systems in steel-frame residential buildings are prone to extensive cracking and detachment under wind loads. This study, through research and comparison of commonly used materials, identified the exterior wall panel system with the optimal comprehensive performance. To assess the wind load resistance of this system, 11 sets of tensile tests were conducted considering anchor bolt quantity and the bonding rate parameters between autoclaved lightweight concrete (ALC) panels and rock wool boards. The research investigated the failure modes, load-bearing capacity, and failure mechanisms of the external wall panel system under wind suction loads. Based on the experimental findings, a simplified finite element simulation method was proposed and subjected to parameter analysis. This analysis explored the impact of anchor bolt quantity and layout. The research indicates that under tensile loads, the external wall panel system primarily experiences interfacial damage between rock wool boards and coating mortars. Its load-bearing capacity consists of the net bonding force between rock wool boards and finishing layers, as well as the mechanical force between fiberglass mesh and anchors. The load bearing capacity can be enhanced by strengthening the overall integrity of the system and by expanding the contact area between the fiberglass mesh and the anchor plate, with specific structural measures such as increasing the number of anchor, the bond ratio, and the diameter of the anchor plate. The arrangement of anchors has a minor impact on the load-bearing capacity of the external wall panel system but significantly affects the deformation of rock wool boards. Based on experimental and finite element studies, a simplified calculation method for the tensile load-bearing capacity of external wall panels for engineering applications was further developed and proven to be accurate through comparison with experimental results.

The influence of infill ALC walls on the seismic performance of prefabricated PEC T-column frames

Autoclaved lightweight concrete (ALC) is characterized by its light weight, high strength, fire resistance, and sound insulation, and has been widely used in industrial and civil construction. Partially encased concrete (PEC) columns exhibit good load-bearing performance, energy dissipation performance, and outstanding prefabrication performance. In order to study the influence of embedded prefabricated ALC wall panels on the seismic performance of assembled PEC T-shaped column frames, this study conducted low-cycle reversed loading tests on a two-story PEC T-shaped column pure frame and a two-story assembled PEC T-shaped column frame with ALC wall panels. This paper draws detailed comparisons between the failure modes and skeleton curves of the two frames. Analysis of the experimental results indicates that the stiffness contribution of infill walls is primarily affected by local compression and exhibits a negative correlation with the wall-frame lateral stiffness ratio. Furthermore, the presence of ALC walls can significantly increase the initial stiffness of the assembled frame. Therefore, based on the existing theoretical basis, a calculation model and method based on the interaction between infill wall panels and frames are proposed. The frame was numerically simulated using finite element software to study the factors affecting the initial stiffness of the frame, and a relationship formula for the wall stiffness reduction coefficient aw was obtained. The calculated lateral stiffness obtained from the formula was compared with the experimental results of this paper and other studies, proving that the model provides a safe result for the design and application of PEC T-shaped column frames filled with ALC walls, and can provide a reference for engineering practice.

Sound insulation performances of the wall profiles using autoclaved lightweight concrete block

This study aimed to predict the sound insulation performance of wall profiles made of autoclaved lightweight concrete (ALC) blocks using computer simulations. The single wall structures made of ALC were evaluated based on variations in density and thickness, with densities ranging from 0.3 g/cm³ to 1.2 g/cm³ and thicknesses from 20 mm to 350 mm. The results showed that there was a reduction in sound insulation performance between 200 Hz and 400 Hz due to the coincident effects of ALC materials. Although increasing density and thickness could have improved sound insulation, the overall performance did not meet legal standards. The study then explored the effect of composite structures, which incorporated reinforcing materials in the ALC blocks, and found that the sound insulation performance was improved by up to 5 dB compared to single structures. The predicted results were verified through laboratory testing and measurement of the composite structures made of ALC.

Seismic behaviors of CFT-column frame-four-corner bolted connected buckling-restrained steel plate shear walls using ALC/RAC panels

A Frame-Buckling Restrained Steel Plate Shear Walls (BRSPSWs) system has been designed, featuring a steel plate connected to frame elements, to withstand lateral loads like seismic or wind forces. This system incorporates recycled aggregate concrete (RAC) to create concrete-filled and concrete panels, promoting eco-friendly and sustainable construction materials. Two single-span, two-floor specimens were tested under cyclic quasi-static load. A four-corner bolted connection was used to connect the steel plate to the square concrete-filled steel tubes (CFTs) column and H-section beam, minimizing the potential deformation of the frame elements produced by the tension field of the steel plate after high-order bucking. The steel plate was sandwiched using either autoclaved lightweight concrete (ALC) or RAC panels. The study analyzed failure modes, load-displacement responses, and characteristic capacities. Test results inferred that BRSPSWs exhibited favorable cyclic behavior, with similar failure modes observed using both ALC and RAC panels. The buckling of steel plates was reduced, and the type of restrained panels had a negligible impact on buckling. Consequently, ALC panels can effectively replace RAC panels. Furthermore, bearing capacities and yield stiffness were primarily determined by the bolted connection forms. A finite element (FE) modeling was developed using ABAQUS software and validated against test results. This FE modeling method successfully simulated failure modes and load-displacement curves. Parametric analyses were conducted and revealed that bearing capacity and yield stiffness positively correlated with steel plate thickness, bolt diameter, and the number of bolts but negatively correlated with the axial compression ratio. In contrast, the panel thickness and span length had a minor impact due to shear deformation in the bolted connection. Based on the test results and parametric studies, an equation for the yield-bearing capacity of BRSPSWs was proposed and verified.

Evaluation of seismic performance and design of AAC building systems (autoclaved aerated concrete) with different reinforcement methods

Autoclaved lightweight concrete was produced for the first time in Sweden and after several decades, it has been widely used in most of the industrialized countries of the world, especially in the construction industry. Lightness, effect in reducing forces caused by earthquakes, ease of implementation, low thermal coefficient, fire resistance and sound insulation are among the undeniable advantages of this product. The use of this concrete is very effective in optimizing fuel and energy consumption, and its high compressive strength is considered an important feature, to the extent that it has been recognized as a desirable and suitable product in the construction industry. Obviously, with the growth of demand increasingly, using traditional methods and materials for housing production in Iran is not very effective. Compilation of criteria for the design and implementation of a gravity-bearing and lateral structural system made of AAC autoclaved aerated concrete products (including reinforced blocks and panels) The structure is made based on valid international regulations and considering Iran's seismic standards as follows. Roof and floor design using reinforced AAC roof panels and the combination of AAC roof blocks and regular concrete in place reinforced with steel reinforcements after examining the principles and foundations and modeling based on logical engineering principles and assumptions to compare the results and the outputs of the software have paid. Based on the available results, we can see the effect of the number of floors, plan and height of the floor on the behavior of the structure. According to the values in the table, the probability of the structure passing through the threshold of minor, moderate, and advanced damage is examined in different states. 1- The probability of passing a 1-story structure compared to a 2-story structure from the threshold of partial, moderate, and advanced damage has decreased by 59.7%, 94.5%, 99.3, and 99.8%, respectively. 2- The probability of passing a 2-story structure compared to a 3-story structure It reduces the threshold of partial, moderate, and advanced damage by 55.7%, 93.2%, 99.0%, and 99.7%, respectively.

Damage Detection in ALC Exterior Walls in Steel Structural Frames Subjected to Earthquakes Using Acceleration Sensors

ABSTRACT To establish a practical method to detect damage to autoclaved lightweight concrete (ALC) exterior walls subjected to earthquakes, a cyclic loading test of steel structural frames equipped with ALC exterior walls was performed. In the test, several compact and cost-effective MEMS accelerometers were placed on the ALC panels and steel structural frames to evaluate their effectiveness in damage assessment. The results showed that the MEMS acceleration sensors could measure the residual in-plane and out-of-plane rotation angle of each element including ALC panels with sufficient accuracy and was concluded to be the most promising instrument for application to damage detection.

Production of autoclaved lightweight concretes using pottery stone and bagasse ash

This study investigated the influence of pottery stone and bagasse ash on the mechanical features of autoclaved lightweight concrete. Pottery stone is a natural resource of igneous rock weathering commonly exists with white clay, feldspar and limestone. This raw material is mainly composed of quartz and mica that has been used for the production of ceramic products. Bagasse ash is a waste product of the sugar refining process that causes serious environmental pollution. Pottery stone and bagasse ash waste were physically characterized and partially substituted by the weight of cement in lightweight concrete with the addition of aluminium powder at a certain amount. The use of aluminium powder showed a positive effect on the porosity of lightweight bodies. Compressive strength, density and thermal conductivity were determined. Pottery stone can be used as a natural pozzolan for the production of lightweight concrete. Lightweight concrete manufactured with 17.5% pottery stone and 17.5% bagasse ash showed low density and good compressive strength. Autoclaved lightweight concrete is considered an economy in the consumption of pottery stone and bagasse ash waste as cement replacement, therefore enhancing the possibility of its reuse in a sustainable way.

Seismic behavior of concrete-filled steel tubes column frame-buckling restrained steel plate shear walls connected with bolt/weld

In this study, a buckling restrained steel plate shear wall (BRSPSW) system, consisting of a steel plate linked to frame elements using a double-sides connection bolt/weld and sandwiched by autoclaved lightweight concrete (ALC) panels, was designed to resist the lateral load. Concrete-filled steel tubes (CFTs) and H-section beams were adopted to build the vertical and horizontal frame elements. Three single-bay, two-floor specimens were tested under lateral cyclic load. Besides, this study offered an eco-friendly and sustainable application for recycled aggregate concrete (RAC) as concrete infills. The hysteretic load–displacement response associated with failure patterns was deeply reported and analyzed. The three tested specimens were evaluated based on characteristic capacities. The experimental outcomes demonstrated that all specimens have excellent cyclic performance, and buckling of the steel plates was significantly reduced using bolts connection. Although yield-bearing capacity and stiffness with weld connection were relatively higher than with bolt connection, the peak-bearing capacity was almost the same with bolt or weld. In addition, the ductility, energy consumption, and displacement characteristics were improved using bolts compared with weld. Finite element (FE) models were generated and verified to analyze out-of-displacement and equivalent plastic strain. Based on validated FE models, parametric analyses were performed to examine the impact of five crucial parameters on characteristic capacities. The parametric studies presented considerable indications for the seismic behavior of BRSPSWs. The findings of this study serve as a valuable point of reference for the implementation of engineering applications.

Case study on fire resistance of fire stopping system in Ultrahigh-voltage Direct current converter station

In this study, two existing fire stopping systems of the valve hall in the converter station were selected, and the heat transfer process in the key areas was simulated by the ANSYS software under the condition of a hydrocarbon temperature rise curve. The main thermal parameters, such as temperature field, thermal flux, and thermal gradient, were obtained, and the temperature rise characteristics of measuring points were tested through the Fire Test Furnace and the one-dimensional heat conduction model. The simulation results show that Model 2 exhibits superior thermal resistance performance compared to Model 1, and the maximum heat flux density occurs at the square steel (keel) position. During the fire resistance test, it is observed that the fireproof mortar at the connection of Autoclaved Lightweight Concrete board in Model 1 exhibits significant detachment and cracking, accompanied by the emission of white smoke. Compared with the temperature rise of the measuring points in Model 1 and Model 2, the heating rate of measuring points f1 and f2 is 0.0471 °C/s and 0.0159 °C/s, respectively. The temperature value obtained from the fire resistance test exceeds that calculated by the one-dimensional heat conduction model.

Effect of the mixing procedure on the properties of lightweight EPS mortar

The management of thermocol wastage has become a major problem in developing countries like Nepal. This paper describes the physical, mechanical, and durability properties of lightweight mortar using expanded polystyrene (EPS) beads, extracted from thermocol wastage, as aggregates. The content of EPS was 0, 20, 30, 40, 50, and 60 percentages by the total volume. The effectiveness of the High Ductile Mortar (HDM) mixing method was compared with the conventional (CON) mixing method on those properties of EPS mortar. The HDM method refers to the addition of EPS in the viscous mortar mixed with the first part of the water and then increasing its workability with the remaining water. The HDM method enhanced compressive strength and Modulus of elasticity by a minimum of 20%, and with a minimum of 10% enhancement in flexural and splitting tensile strengths to the CON method. With the assessment of drying shrinkage, freezing and thawing, and water absorption tests, the durability properties of EPS mortar were found less effective on mixing methods and percentage of EPS. The empirical models were proposed for different strengths and Modulus of elasticity. As result, the structural EPS mortar can be developed with the HDM method up to 30% of EPS but it is limited to 20% with the CON method. Up to 60% of EPS can be used to produce the non-structural mortar with both methods which can replace autoclaved lightweight concrete (ALC) for use in non-load bearing infill and partition walls. EPS beads extracted from thermocol wastage can be re-used to produce structural and non-structural mortar depending on their percentages. It can easily solve the never-decomposing problems of thermocol wastage.

Effects of Hygrothermal Environment on Tensile Capacity of Adhesive-injected Anchor Bolt of ALC Panel and ETICS

The connection between the autoclaved lightweight concrete (ALC) and an external thermal insulation composite system (ETICS) is accomplished by anchors. The anchor is consisted of a connector and an anchor bolt, where the anchor bolt is an important force transmission element. Adhesive is used to install an anchor bolt, and significantly improves the anchoring force of the anchor bolt. However, the hygrothermal environment influences the adhesion of the anchor adhesive, which adversely affects the reliability and security of the ALC panel and ETICS connection. To investigate the effect of high temperature and a humid environment on the anchor bonding performance, 5 sets of durability tests were conducted. Each group of 15 specimens was tested for 0, 15, 30, 45, and 60 thermal rain cycles. The test results reveal that, as the number of cycles increased, the tensile capacity of the adhesive-injected anchor bolts decreased, and the capacity's discount factor decreased. The discount factors of the anchor bolt tensile load capacity values after 15, 30, 45 and 60 cycles were 85.5%, 72.1%, 56.2%, and 50.4%, respectively. A prediction model was established based on the relationship between the number of thermal rain cycles and the tensile capacity. Based on the anchor bolt tensile capacity requirements, the model can calculate the number of cycles over which the adhesive-injected anchor bolts need in a hygrothermal environment must be tested, reinforced, and replaced to ensure a good connection between the ALC panel and an ETICS.

Experimental study on the seismic performance of steel frames with infill ALC wall panels

To explore the seismic performance of H-shaped steel frames with infill precast autoclaved lightweight concrete (ALC) wall panels, the horizontal low-cyclic loading tests were conducted under vertical load. The influence of the connector style, the arrangement, and the integrity of the wall panels on the seismic performance of the structure were analyzed depending on four specimens of H-shaped steel frames with ALC wall panels and one hollow H-shaped steel frame. The failure mode, bearing capacity, rigidity and strength degradation, and energy dissipation performance were compared and discussed. The results showed that the steel frame with infill wall panels had better ductility and energy-dissipating capacity than the hollow frame. The infill ALC wall panels greatly enhanced the seismic performance of the frames and had a significant influence on the bearing capacity, stiffness, energy dissipation capacity, and ductility performance of the specimens. The maximum ductility factors and total energy dissipation of the steel frame with ordinary infill wall panels were 1.58 times and 2.27 times larger than those of the hollow frame. Due to cooperation with the steel frame, the panels delayed the buckling and in-plane deformation of the frame. The sliding connector improved the bearing capacity, displacement ductility, and energy dissipation of the overall structure compared with the hooking connector. Moreover, the bearing capacity of the frames with the reinforced wall panels was improved further. Additionally, the equivalent compression bar model was developed to estimate the bearing capacity of the steel frames with the infill ALC wall panels. The experimental conclusions and the proposed analytical model improve the practical design of the steel frames with the infill ALC wall panels in high-rise buildings.

Fire Resistance of an Assembled Integrated Enclosure Panel System

Due to increasing economic development in recent years, large-scale prefabricated structures have been used for substations. However, the assembly of steel structures suffers from technical problems, such as the mismatch between the fire protection level of the main structure and the enclosure system. This paper proposes an assembled integrated enclosure panel system for covering and fireproofing steel structures, such as beams and columns, consisting of sandwich wall panels and autoclaved lightweight concrete (ALC) wall panels covering the main steel structure. Fire resistance tests were carried out for each part and the entire integrated enclosure panel system to fully investigate its fire resistance performance. ALC and gypsum were selected as the external fire protection materials for the sandwich wall panel test for theoretical analysis and fire resistance test. The fire resistance test results show that the designed solutions of sandwich wall panels and ALC panels covering steel beams and columns meet the fire protection requirements of the ISO-834 standard fire test. The proposed size scheme of the integrated enclosure panel system is an integrated sandwich wall panel composed of 50 mm thick ALC board + 50 mm thick rock wool layer + 50 mm thick ALC board and the integrated structure of 100 mm thick ALC board covering beams and columns. The designed U-shaped connectors between the wall panels are suitable for the assembled integrated enclosure panel system.

Fire performance of superabsorbent polymers protecting cold-formed steel walls with high load ratios

Superabsorbent polymers (SAPs) have great potential in the fire protection of steel structures due to their high absorbency and water-holding capacity. In this paper, SAP is applied to the full-scale cold-formed steel (CFS) wall studs to investigation the fire performance of the CFS walls. An axial compression experiment of CFS wall specimen at ambient temperature and three experiments at elevated temperature were conducted. Meanwhile, considering the effect of thermal expansion load, the actual load of CFS walls may increase significantly under fire condition. Hence, the load ratio of the specimens was 0.85 in the fire experiments. The specimens use an autoclaved lightweight concrete (ALC) board and calcium-silicate (CS) board as the face and base layers of sheathings, respectively. The effect of SAP insulation material, high load ratios and thermal expansion load on the fire resistance of walls are discussed. The results indicate that SAP insulation materials can improve the structural and insulation performance of CFS walls under fire exposure. This is because the dehydration and heat absorption process of the SAP insulation material removes the heat inside the wall cavity, maintaining the maximum temperature of the wall studs below 140 °C. Hence, the fire resistance time (FRT) is extended by 41 min after using the SAP insulation material. In addition, neither a high load ratio nor SAP insulation material changes the failure mode of the wall studs. For the present specimens at ambient and elevated temperature, local buckling was identified on the whole section of stud ends. However, the SAP insulation material will change the fire-induced failure position of wall studs. Specimen W3 with SAP insulation material fails at the top of the studs. Furthermore, a thermal expansion load will significantly speed up the fire-induced structural failure of CFS walls with a high load ratio. The FRT of specimen W4 decreases by 79 min after considering the effect of thermal expansion load.

Seismic Performance of Panel Connectors with Steel Frame Based on Autoclaved Lightweight Concrete (ALC)

This paper proposes new prefabricated autoclaved lightweight concrete (ALC) connectors which allow limited sliding. The seismic performance of the proposed connectors and a traditional connector (L-hooked bolt) were investigated in depth. Three specimens of full-scale steel frames with ALC panel and connectors were subjected to horizontal low-cyclic loading. The failure modes, hysteretic behavior, strength and deterioration of stiffness and energy-dissipating performance of all specimens were analyzed and discussed. The experimental results indicated that the frames of the new connectors were more reliable than the traditional connector. The energy-dissipating capacity of the specimen frames with new connectors increased by 23.0% and 24.4%, and deterioration of stiffness increased by 10.6% and 13.0%. The new ALC panel connectors not only increased elastic stiffness in the early stage, but also provided some stiffness in the elastoplastic and plastic stages. Using relevant construction measures, the frames with new connectors displayed good cooperative behavior and safety reliability. To summarize, the new ALC connectors tested showed excellent performance in resisting seismic loading and had good assembly efficiency and could provide a basis for the development and application of a new type of ALC steel frame connector.

Hysteresis Behavior and Design of the New Autoclaved Lightweight Concrete (ALC) External Panel Connector with the Steel Frame

This paper proposes a new flexible connector for the autoclaved lightweight concrete (ALC) panel with the steel beam. It is a universal upper and lower crossing connector, with load-bearing and limitation holes; then, the seismic capacity of this connector is investigated in the simulations and full-scale tests. Firstly, the finite element simulations of the new connector and traditional connector (L-hooked bolt) were made by ABAQUS, which proved the reliability of the new connector by comparing them in low-cyclic loading. Secondly, in order to analyze the phenomenon and data of the two connectors which are in the same test conditions of simulation, the full-scale tests of the steel frame were conducted. The damage of the ALC panel at different connectors and at different test load displacements is described in detail. The contribution of the connectors to the steel frame and the ALC panel is investigated in depth during the elastic, elastoplastic, and plastic stages of the steel frames. The test result is similar to the simulation result roughly, in which the new connector has better seismic capability. In minor earthquakes, the ALC panel frame with the new connector has better synergistic capacity of panels, while in large earthquakes, it can provide certain stiffness to the structure. Compared with the L-hooked bolt, the maximum bearing capacity of the structure with the new connector increases by 5.2%, and the yield displacement delays by 27.5%, which results in the increase of ductility by 9.8%. In terms of energy consumption capacity, the equivalent damping factor of the new connector increases by 10.2% and 35.3% at the yield and ultimate state, respectively. The FEM simulation results can represent the actual test results well. To summarize, the new ALC panel connector in this paper has excellent seismic capacity and good synergistic, which can provide a reference for the development and application of new types of the ALC connector.

Performance of Prefabricated Foam Concrete as Infilled Wall Under Cyclic Lateral Loading

Every year earthquakes occur in various regions in Indonesia because Indonesia is located near earthquake faults. The cyclic lateral loading test in the laboratory has been widely used to simulate lateral loads caused by earthquake events. This research is an experimental study on the behavior of prefabricated foam concrete as an infill wall against lateral cyclic loads. Prefabricated foam concrete was used in this study to make it an alternative to brick and autoclaved lightweight concrete (ALC) blocks that have been widely used as infill walls. This study analyzes the relationship between performance levels, lateral loads and drifts ratio on RC infilled prefabricated foam concrete. Lateral cyclic loading with displacement control method was applied to evaluate the structural behavior where the test refers to ASTM E2126-02a. This study adopts FEMA 273, which regulates the performance levels to be achieved by the structure of a building. The results showed that at performance levels Operational Level (OL), Immediate Occupancy (IO) and Life Safety (LS), the RC frame infilled with prefabricated foam concrete blocks had a drift ratio of 0.2%, 1.2% and 2.4%, respectively. Damage to the RC frame infilled with prefabricated foam concrete blocks was similar to the masonry infilled RC frame.