Bond Performance of Fiber Reinforced Polymer （FRP） Bars in Autoclaved Aerated Concrete （AAC）

This paper concerns the bond strength of FRP bars in AAC by the concentric pullout test. Specimens were subjected to compare with mild steel bars. The bond performance including the mode of failure and bond strength was investigated with varying embedment length and surface treatment. Regarding the bond performance, embedment depth has influenced on bond strength as well as the sanded surface. Carbon fiber reinforced polymer （CFRP） pronounced the most promising results with the highest bond strength attained.

Synthesis and Microstructure Analysis of Autoclaved Aerated Concrete with Carbide Slag Addition

Synthesis of autoclaved aerated concrete （AAC） has been carried out with carbide slag addition, and the carbide slag could be used as a main material to produce the AAC with the compressive strength about 2 MPa and the density below 0.6 g.cm-3. In this study, quartz sand acted as frame structure phase in the matrix, and quartz addition also influenced the Si/Ca of starting material. Tobermorite and CSH gel were formed readily at 62%, which seemed to enhance the compressive strength of samples. Curing time seemed to affect the morphology of phase produced, and specimen with the plate-like tobermorite formed at 10 h appeared to have a better compressive strength development than the fiber-like one at 18 h. The higher curing temperature seemed to favor the tobermorite and CSH gel formation, which also exerted a significant effect on the strength development of the samples. On the micro-scale, the formed CSH gel was filled in the interface of the matrix, and the tobermorite appeared to grow in internal-surface of the pores and interstices. The tobermorite or/and CSH formation seemed to densify the matrix, and therefore enhanced the strength of the samples.

A Review on the Utilization of Waste Material for Autoclaved Aerated Concrete Production

Autoclaved aerated concrete(AAC)has become more attractive due to its excellent and environmental-friendly properties in building construction.AAC is relatively lightweight,possesses lower thermal conductivity,higher heat resistance,lower shrinkage,and fasten construction than normal concrete.AAC is a combination of silica sand,cement,gypsum,lime,water,and an expansion agent.To improve its physical and mechanical properties and reduce its production cost,tremendous innovations where waste materials were utilized as partial replacement of AAC materials were done.This paper is intended to present the literature on the utilization of waste materials as a means of a partial replacement in AAC materials to enhance its physical and mechanical properties and thermal performance.The physical properties such as microstructure and mechanical properties such as density,compressive strength,water absorption are presented to classify the investigation that has been done in such innovations.Apart from that,the discussion on innovations to improve its thermal performance was also presented.Based on the review,an increase of AAC application causes much waste at construction sites and recycling concrete waste powder into wall concrete;particularly,an AAC was not frequently practiced in construction.

Preparation of New Cementitious System using Fly Ash and Dehydrated Autoclaved Aerated Concrete

We experimentally studied the interaction between pozzolanic material（fly ash） and dehydrated autoclaved aerated concrete（DAAC）. The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner than 75μm and was then heated to temperatures up to 900 ℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction（XRD） was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content（Wn）. The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700 ℃ and the dehydrated products are mainly β-C2 S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fl y ash, increasing the replacement level of fl y ash lowered them in AF. The strength contribution rates on pozzolanic effect of fl y ash in AF are always negative, showing a contrary tendency of that of cement-fl y ash system.

Experimental Study on Improving Seismic Behavior of Load-Bearing Masonry Wall Made of Autoclaved Aerated Concrete

To investigate the seismic behavior of autoclaved aerated concrete load-bearing masonry wall(AACLMW), a piece of control block wall without constructional measures and five pieces of block walls with different constructional measures were tested under low reversed cyclic loading which imitated low to moderate earthquake force. The seismic behavior of AACLMW with different constructional measures in terms of failure mode, hysteretic curve, deformation capacity and displacement ductility was studied and compared with that without constructional measures. The experimental results indicate that the constructional measures comprising constructional columns and horizontal concrete strips are effective for improving the seismic behavior of AACLMW. The study in this paper can provide a reliable experimental basis for further analysis and engineering application of AACLMW in the future.

Research on Preparation and Influencing Fctors of High Calcium High Sulfate Ash to Autoclaved Aerated Concrete

In this paper, a high calcium high sulfate ash as the main material, adding fly ash, lime, cement, gypsum and some modifiers to prepare autoclaved aerated concrete. The products complies with the technical requirements of GB/T11968-2006. This paper also studies the influence of the physical methods and water ratio on autoclaved aerated concrete by high calcium high sulfate ash aerated concrete. The best ratio of water and Grinding time were found in practice study.

Kinetics of Autoclave Curing Process on Autoclaved Aerated Concrete with Magnetite Tailings

Lightweight and energy saving autoclaved aerated concrete(AAC) acting as a newbuilding material were prepared by using magnetite tailings from iron ore as main rawmaterials,and the purpose of comprehensive utilization of tailings resources was to improve their utilization efficiency.The effects of curing system on AAC product performance were discussed.The autoclave curing reaction kinetics was studied as well as the generated amount of hydration product trends over autoclave curing temperature and time were analyzed.The results indicated that the properties of AAC was in accordance with Chinese national standard the A3.5 B06 class of GB/T11968-2006 by prepared from magnetite tailing as the main rawmaterials.Meanwhile,autoclave curing process was controlled by the diffusion velocity through the products ' layers of reactants,and the apparent activation energy of autoclave curing process was 19.269 k J/mol.Compressive strength of aerated concrete is improved by mutual cementation between the appropriate amount of calcium silicate hydrate and tobermorite crystal.

Utilization of Dredged River Sediment in Preparing Autoclaved Aerated Concrete Blocks

In this study,the dredged river sediment,soft texture and fine particles,is mixed with other materials and transformed into eco-friendly autoclaved aerated concrete(hereinafter referred to as AAC)blocks.The results indicated the bricks produced under the conditions of 30%–34%dredged river sediment,24%cement,10%quick lime,30%fly ash,2%gypsum and 0.09%aluminum powder with 0.5 water to material ratio,2.2 MPa autoclave pressure and 6 h autoclave time,the average compressive strength of 4.5 MPa and average dry density of 716.56 kg/m³were obtained,the two parameters(strength&density)both met the requirement of national industry standard.At the same time,the contents of dredged river sediment,cement,lime,fly ash,gypsum and aluminum powder were 15%,48%,20%,15%,2%and 0.09%,respectively,and the non-AAC block made of 0.5 water to material ratio,the average compressive strength of 3.1 MPa and average dry density of 924.19 kg/m³were obtained,the two parameters(strength&density)also met the requirement of national industry standard.In addition,the AAC block’s phase composition and morphology were micro-analyzed by SEM and XRD,the main substances in AAC block were found to be tobermorite and CSH,Among them,the chemical bond between Si-O-Si and Al-O-Al is broken,Al-O-Si is regenerated,Al substituted tobermorite with better strength is formed,and the compressive strength of AAC is further improved.

Nano-treatment of Autoclaved Aerated Concrete Waste and Its Usage in Cleaner Building Materials

Autoclaved aerated concrete waste(AACW)was used as a raw material to prepare nucleation seed for acceleration of Portland cement.Nano AACW seed with median particle size of 324 nm was prepared by wet grinding method.Both the electrical conductivity and pH value of nano AACW suspension were obviously improved.Both the setting times and intensity of the main hydration heat peak were promoted by nano AACW,indicating the possibility of AACW suspension as nucleation seed.The early age compressive strength before 3 days was also clearly improved by nano AACW,with no negative effect on the late age strength.Furthermore,the reduced CH content with dosage of nano AACW indicates that nano AACW not only plays a role of nucleation seed in cement hydration,but also has a certain pozzolanic reaction.

Influence of Polycarboxylic-type Admixture on the Strength of Autoclaved Aerated Concrete

The influence of polycarboxylic-type admixture on the strength of autoclaved aerated concrete（AAC） was investigated. The flexural strength and compressive strength of AAC with polycarboxylic admixture（PA） were tested. The microstructure of AAC reinforced by PA was analyzed using scanning electron microscopic（SEM） methods. The crystal structure analysis of AAC with PA was also carried out using X-ray diffraction（XRD）. The results showed that the compressive strength and flexural strength of AAC were increased by 43.9% and 42.8%, respectively, when 1.5wt% of PA was mixed. In addition, the dosage of admixture influenced the reinforcing effect. Admixture affected pore structure and surface characteristic of the products in autoclaved curing process and improved the formation of high crystallite tobermorite which led to the enhancement of the compressive and flexural strength of AAC.

A Study of Compressive, Flexural, Heat Humidity and Heat Transfer of Autoclaved Aerated Concrete Mixed Polypropylene Fiber under Climate of Bangkok

This paper presents the experimental results of study on mechanical properties, heat and humidity transfer through AAC （autoclaved aerated concrete） mixed with PP （polypropylene fiber）. The performance of AAC-PP is investigated in terms of compressive strength, flexural strength, splitting tensile strength, porosity, heat and humidity capacity. The results are compared with control specimen made of autoclaved aerated concrete only （Non-AAC-PP）. Results showed that ultimate compressive strength, flexural strength and splitting tensile strength can be obtained when the content of polypropylene fiber added at 0.75% by volume while porosity of specimens rapidly decreased when content of fiber addition increased above 1% of its volume. Additional, a comparison study of heat and humidity transfer properties on AAC-PP walls showed that the AAC-PP house had lower indoor air and moisture content than （Non-AAC-PP） house. Therefore, addition PP fiber on AAC increased mechanical properties, enhanced hygrothermal performance and reducing moisture content under tropical climate of Bangkok.

Autoclaved Aerated Concrete Block Prefabricated Multi-Storey Building Technology

In active response to the national requirements of promoting green building materials and developing prefabricated buildings,it is necessary to continuously optimize and reasonably employ relevant technologies.Autoclaved aerated concrete block prefabricated multi-storey building technology is a new technology,which will not only effectively realize green environmental protection in construction engineering,but also promote the further development of prefabricated buildings.Therefore,this paper analyzes the autoclaved aerated concrete block prefabricated multi-storey building technology for future references.

Flexural behavior of textile reinforced mortar-autoclaved lightweight aerated concrete composite panels

To improve the deficiencies of prefabricated autoclaved lightweight aerated concrete(ALC)panel such as susceptibility to cracking and low load-bearing capacity,a textile-reinforced mortar-autoclaved lightweight aerated concrete(TRM-ALC)composite panel was developed in this study.One group of reference ALC panels and five groups of TRM-ALC panels were fabricated and subjected to four-point flexural tests.TRM was applied on the tensile side of the ALC panels to create TRM-ALC.The variable parameters were the plies of textile(one or two),type of textile(basalt or carbon),and whether the matrix(without textile)was applied on the compression side of panel.The results showed that a bonding only 8-mm-thick TRM layer on the surface of the ALC panel could increase the cracking load by 180%−520%.The flexural capacity of the TRM-ALC panel increased as the number of textile layers increased.Additional reinforcement of the matrix on the compressive side could further enhance the stiffness and ultimate loadbearing capacity of the TRM-ALC panel.Such panels with basalt textile failed in flexural mode,with the rupture of fabric mesh.Those with carbon textile failed in shear mode due to the ultra-high tensile strength of carbon.In addition,analytical models related to the different failure modes were presented to estimate the ultimate load-carrying capacity of the TRM-ALC panels.

Kinetics and capacities of non-reactive phosphorus (NRP) sorption to crushed autoclaved aerated concrete (CAAC)

With growing interest in resource recovery and/or reuse,wastematerials have been considered a promising alternative for phosphorus(P)adsorption because they are low-cost and easily accessible.Crushed autoclaved aerated concrete(CAAC),as representative construction waste,has been extensively studied for P removal in ecological technologies such as treatment wetlands.However,most of the previous studies focused on the adsorption of orthophosphate,namely reactive phosphorus,and lacked attention to non-reactive phosphorus(NRP)which is widely present in sewage.This study presents the first investigation on the potential and mechanism of CAAC removing four model NRP compounds.Adsorption isotherm and kinetics of NRP onto CAAC indicate that the removal of NRP was a chemisorption process and also involved a two-step pore diffusion process.The desorption experiment shows that different NRP species showed varying degrees of desorption.Most NRP was irreversibly adsorbed on CAAC.Among the model compounds considered in this study,the adsorption capacity and hydrolysis rate of organophosphorus were much less than that of inorganic phosphorus.Moreover,the adsorption of different NRP species by CAAC in the mesocosm study was different from the results of laboratory adsorption experiments,and the possible biodegradation was essential for the conversion and removal of NRP.The findings confirmed the validity of CAAC for NRP removal and the potential advantages of CAAC in terms of costs and environmental impact.This study will contribute to a better understanding of NRP conversion and environmental fate and that can be the basis for a refined risk assessment.

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

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(CEFRPs).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.

AAC环保新型砌块施工技术应用

中国人寿研发中心F-05地块(数据中心)工程外墙采用了AAC蒸压轻质砂加气混凝土砌块。施工中,通过对墙体放线、砌块排列就位、砂浆灌缝等步骤进行处理,保证了保温效果。在高层框架等结构中,采用蒸压轻质砂加气混凝土砌块代替传统加气混凝土砌块,效益可观。

钢框架内嵌角部圆弧缺口AAC砌体填充墙滞回性能研究

基于在填充墙的角部设置缺口可弱化拉(压)力带的原理,设计了一系列钢框架内嵌角部圆弧缺口填充墙试件,包括1个纯钢框架、1个无缺口蒸压轻质加气混凝土(AAC)砌体填充墙钢框架和9个带不同尺寸圆弧缺口的AAC砌体填充墙钢框架,采用ABAQUS软件对各试件进行了有限元模拟分析。研究了填充墙角部设置的圆弧缺口构造对钢框架滞回性能、承载能力、延性、刚度退化、强度退化及耗能能力的影响。结果表明:填充墙角部设置的圆弧缺口构造可以削弱AAC砌体填充墙对钢框架承载能力的贡献,有效延缓墙体破坏,降低墙体对钢框架的附加刚度,延缓AAC砌体填充墙钢框架的刚度退化速率;填充墙角部设置的圆弧缺口构造还能改变AAC砌体填充墙的破坏模式;根据有限元分析结果,建议圆弧缺口的弧长为πl/2,圆弧半径l为AAC砌体填充墙高度的1/10~1/7。

AAC砌块承重墙体滞回特性试验研究

通过6片AAC砌块承重墙体在低周反复荷载作用下的抗震试验,得出各墙体的滞回曲线和骨架曲线,主要研究了不同高宽比和不同竖向压应力对墙体滞回特性的影响。研究表明,高宽比可以影响墙体破坏的弹塑性阶段和破坏阶段,竖向压应力只能影响弹塑性阶段;高宽比较小和竖向压应力较大的墙体抗剪强度高,抗震性能好。

装配式AAC砌体填充墙平面外抗震性能分析

为了适应国家绿色建筑和装配式建筑的发展,减少地震中填充墙的平面外破坏,采用ABAQUS有限元程序研究了装配式AAC砌体填充墙的平面外抗震性能。进行了不同工况下足尺有限元模型的模拟,分析了填充墙高厚比、配筋率及填充墙与框架间连接方式对其平面外抗震性能的影响,以峰值、极限状态下的荷载与跨中位移评定其平面外抗震性能。分析结果表明:采用ABAQUS进行填充墙平面外抗震性能数值模拟与试验结果吻合较好;填充墙高厚比越小,平面外承载力越大,当高厚比小于10时,墙体延性大幅下降;填充墙配筋率和承载力近似呈正比关系,但当配筋率大于0.2%时,墙体延性也会下降;高厚比在15~20和配筋率在0.1%~0.2%范围内,填充墙呈适筋延性破坏模式;填充墙与框架之间布置双向柔性连接约束,墙体具备一定延性,墙体平面外承载力较单向连接件布置有所提升。

混凝土结构中AAC内墙板安装连接构造节点优化加固技术

轻质蒸压砂加气混凝土墙板(AAC)是一种轻质、防火、节能、环保的新型墙材,是中国建筑节能和墙体材料改革的中坚力量。本文参照06CG01图集以及砂加气混凝土板材的生产工艺、性能,结合工程实例和实践经验,根据不同的工况,优化完善了AAC内墙板在混凝土结构中的连接构造节点,为轻质蒸压砂加气混凝土墙板能更好的在建筑工业化中推广应用,向同类工程中的施工技术人员提供参考依据。