Rate Effects on the Stress-Strain Behaviour of Eps Geofoam

The rate-dependency of the stress-strain behavior of EPS (Expanded Polystyrene) geofoam with densities of 19.3 and 28.0 kg/m³ was investigated by performing unconventional unconfined compression tests. A set of monotonic loading (ML) tests were performed at different constant values of vertical (axial) strain rate, ε_v. The ε_v value was stepwise changed many times and several sustained loading (SL) tests were performed during otherwise ML at a constant ε_v in other tests. A number of SL tests were performed during global unload and reload cycles to infer the stress-strain relation when ε_v=0. The elastic properties were evaluated by applying minute unload/reload cycles during otherwise ML. The rate-dependent stress-strain behaviour observed in these tests was described by an elasto-viscoplastic model (i.e., a non-linear three-component model), for which the vertical (axial) stress, σ_v, consists of inviscid and viscous components, σ_v^f and σ_v^v, while ε_v consists of elastic and irreversible components, ε_v^e and ε_v^ir. It is shown that the viscous property of EPS geofoam is of Isotach type in that, under the loading conditions where ε_v^ir is always positive, the current σ_v^v value is a unique function of instantaneous ε_v^ir and ε_v^ir, therefore the strength increases with ε_v. This viscous property was quantified based on the test results and incorporated into the model. The rate-dependent stress-strain behaviour, including the creep behaviour, observed in the experiment is simulated very well by the proposed model. In particular, the fact that the creep strain becomes significant when the sustained σ_v value becomes larger than the inviscid yield vertical stress is well simulated.     

EPS轻质混凝土性能研究

采用类似“裹砂”工艺的预拌方法拌制发泡聚苯乙烯(EPS)轻质混凝土并测试其力学性能.结果表明:用EPS颗粒部分取代粗集料和细集料,可以制得表观密度为800-1 800 kg/m3、抗压强度达11-20 MPa的EPS轻质混凝土;微硅粉能显著改善EPS颗粒与水泥浆体的粘结性能,提高EPS轻质混凝土抗压强度,而掺入钢纤维则能显著改善其干缩性能.     

土工泡沫工程性质及其应用

综述了土工泡沫作为土工合成材料的主要工程性质 ,特别对其热绝缘性、轻质、高压缩性等传统土工合成材料产品所不具有的特点予以阐述 ,并介绍了其在岩土工程上的应用。作为热绝缘材料 ,可以防止基底及边墙受冻 ;利用轻质性能 ,作为路堤填料 ;利用高压缩性 ,产生土拱效应 ;也可用作减振材料     

Estimation of the Small-Strain Stiffness of Clean and Silty Sands using Stress-Strain Curves and CPT Cone Resistance

The initial, linear elastic range of a soil stress-strain curve is often defined by the small-strain elastic modulus E₀ or shear modulus G₀. In the present study, simpler and effective methods are proposed for the estimation of the small-strain stiffness of clean and silty sands; these are based on triaxial compression test results and the CPT cone resistance q_c. In the method based on stress-strain curves obtained from triaxial compression tests, an extrapolation technique is adopted within the small-strain range of a transformed stress-strain curve to obtain estimates of the small-strain elastic modulus. Calculated small-strain elastic modulus values were compared with the values measured using bender element tests performed on clean sands and sands containing nonplastic fines. The results showed that the method proposed produces satisfactory estimates of the small-strain elastic modulus for practical purposes. In the CPT-based method, two G₀-q_c correlations available in the literature were evaluated. For isotropic conditions, both correlations produced reasonably good estimates of G₀ for clean sands but overestimated it for silty sands. A G₀-q_c correlation which is proposed takes into account the effect of silt content of the sand and stress anisotropy.     

论膨胀聚苯乙烯颗粒保温功能砂浆

如今为了大力发展循环经济,保障我国经济的可持续发展,降低能源和资源的耗费,建筑节能已成为国家的重要政策.由此衍生出来众多节能型建筑材料,膨胀聚苯乙烯颗粒保温功能砂浆就是其中一种性价比较好的节能型砂浆.膨胀聚苯颗粒保温功能砂浆主要由膨胀聚苯乙烯颗粒、合成纤雏、化学外加剂及水泥构成,每个原材料都有其相应的技术要求,各原材料通过合理的生产改性及配制工艺,检验合格后方可出厂并应用于实际工程,在施工过程中还应严格遵守相关施工注意事项,这样才能充分发挥膨胀聚苯乙烯颗粒保温功能砂浆的保温性能,达到节能的目的.     

掺EPS颗粒水泥浆体的吸波性能

研究了发泡聚苯乙烯(EPS)填充率和试样厚度对EPS填充水泥浆体吸波性能的影响,发现:当EPS填充率为60%(体积分数)、试样厚度为20 mm时,EPS填充水泥浆体在8.0~18.0 GHz频率内对电磁波的反射率都在8 dB以上,反射率大于10 dB的带宽达到了6.2 GHz.同时指出了水泥基复合材料向高技术化和高功能化方向发展的前景.     

超长循环荷载下轻质混凝土疲劳特性

采用MTS万能试验机对外掺30%体积分数聚苯乙烯颗粒的轻质混凝土试件施加不同频率(5,10Hz)及荷载幅值(30,35,40kN)的超长循环荷载,进行累计2 000×104振次的疲劳试验,研究其动应力-应变滞回曲线形态随振次的变化规律,并计算了对应的阻尼比、动弹性模量等动力学性能.结果发现:与同强度等级的混凝土相比,轻质混凝土阻尼比较大,动弹性模量稍低,表明其吸能效果更好,韧性与抗裂性能也更为优异;轻质混凝土试件在1 570×104振次左右出现了细微裂缝,根据其附近的应力应变关系发现,该试件的阻尼比与动弹性模量在疲劳损伤前后基本保持稳定;提出和验证了轻质混凝土疲劳寿命预测公式,并对其应用于道床的可行性进行了研究.     

膨胀聚苯板薄抹灰外墙外保温系统防火构造研究

该研究采用大尺寸墙角火试验,对比研究了防火隔离带对聚苯板外墙外保温系统受到火源攻击时的防火性能及火焰传播性。试验结果证明:防火隔离带能够有效阻止火焰快速传播,延缓火灾进程,降低火苗高度,提高聚苯板外墙外保温系统的整体防火安全性。     

Temperature Dependence of Stress-Strain Properties of Freshwater Ice

Soil Mechanics and Foundation Engineering - We present the results of experimental investigation of the temperature dependences of the stress-strain properties of freshwater ice and pykrete. It is...     

Use of Compressible Expanded Polystyrene Blocks and Geogrids for Retaining Wall Structures

The use of a compressible layer such as expanded polystyrene blocks behind a rigid retaining wall and geogrid layers embedded in a dense granular backfill is examined as a reinforcement technique for retaining wall structures. The mobile model retaining walls adjacent to reinforced model specimens are subjected to different surcharge pressures, and are caused to move laterally to measure the lateral earth pressure during the wall movement. The coefficients of earth pressure at rest and active earth pressure are carefully inferred from test results. Three series of tests are conducted; one test series with expanded polystyrene blocks installed behind the wall, another with geogrid layers embedded within model specimens, and the last series with expanded polystyrene blocks installed behind the wall and geogrid layers fixed between two adjacent expanded polystyrene blocks and embedded within model specimens. The reductions in the earth pressure at rest and the active earth pressure due to various patterns of reinforcement are interpreted in relation to the concept of controlled yielding of compressible expanded polystyrene blocks, tensile strains induced along geogrid layers, fixity between expanded polystyrene blocks and geogrid layers, and a facing unit consisting of expanded polystyrene blocks.     

EPS纤维轻质土导热系数测定

文章对新型填土材料EPS纤维轻质土,利用导热系数仪,对养护龄期28 d、不同配比条件下的轻质土的导热系数λ进行了试验探讨。试验结果表明：在其它条件相同的条件下,试样的导热系数λ随EPS含量的增加而减小;纤维含量的增加对导热系数λ没有大的影响。     

废聚苯乙烯泡沫塑料作保温砂浆轻骨料的研究

研究了聚苯乙烯泡沫塑料（EPS）的表面改性技术效果；研究了EPS颗粒形貌、粒径、级配对砂浆性能的影响；对比分析了EPS保温砂浆与膨胀珍珠岩保温砂浆的性能；进行了EPS保温砂浆的工程实践，结果表明：以废弃EPS为轻骨料，采用适宜技术路线，可配制出施工性、抗裂性、保温隔热性良好的新型外保温砂浆。     

EPS泡沫冲击压缩和吸能特性试验研究

采用小直径霍普金森压杆(SHPB),对3种密度的聚苯乙烯(expanded polystyrene,EPS)泡沫进行冲击测试,得到了5种应变率下的应力-应变全曲线.为了比较EPS泡沫在冲击荷载和准静态加载下的不同响应,对EPS泡沫试样进行3种应变率下的准静态单轴压缩试验.探讨了泡沫密度、加载应变率对EPS泡沫应力-应变行为、能量吸收性能和破坏特征的影响,应用能量吸收能力、吸能效率曲线和能量吸收图评价了其在冲击荷载下的能量吸收性能.结果表明:泡沫初始密度和加载应变率对EPS泡沫的吸能与冲压特性具有较大影响.     

聚合物纤维对聚苯乙烯颗粒保温砂浆性能的影响

主要研究纤维种类、掺量和长度对EPS保温砂浆抗裂性的影响。结果表明,掺入纤维对EPS保温砂浆有显著的增强作用,其中以聚丙烯纤维增强效果最佳。聚丙烯纤维使EPS保温砂浆收缩率降低,断裂能增大,裂缝指数显著降低,表明EPS保温砂浆抗裂性得到显著改善。聚丙烯纤维的适宜掺量为0.1%,最佳长度范围为12~15 mm。     

建筑工业行业产品标准《膨胀聚苯板薄抹灰外墙外保温系统》主要特点简介

随着我国各项节能技术的发展和对节能重视程度的不断提高,近年来,我国在建筑节能方面已取得了长足的进展,其中外墙外保温技术的发展尤为迅速。国内有关企业通过直接引进国外先进技术,或结合我国国情进行研制开发,涌现出多种外墙外保温技术,在许多省、市、地区的工程中取得了成功的应用。膨胀聚苯板薄抹灰外墙外保温系统(以下简称薄抹灰外保温系统)作为其中一种有代表性的类型,也得到了广泛的应用和推广,取得了十分可喜的成绩。目前,《膨胀聚苯板薄抹灰外墙外保温系统》产品行业标准(以下简称本标准)的编制工作已经完成,并由建设部正式批准为…     

EPS材料在桥头软基处理中的技术经济分析

采用EPS超轻质材料填筑路堤,通过与其他处理方式比较,结果表明,EPS材料在深厚软土地基低填方路堤中具有良好经济性和处理效果。     

EPS板外墙外保温+氟碳平面金属漆系统施工质量控制

文章概述了外墙外保温及氟碳平面金属漆系统的应用,着重介绍了外墙外保温及氟碳平面金属漆系统施工时的质量控制。     

高强页岩陶粒混凝土的基本力学性能

在高强页岩陶粒性能测定的基础上，配制了10种不同配合比的混凝土拌和物，其设计强度为20～60MPa．根据试验结果，将混凝土的轴心抗拉强度、轴心抗压强度、弹性模量与混凝土的抗压强度以及干表观密度的关系进行了回归分析，并将得到的回归公式与有关规程确定设计标准值时采用的回归公式进行了比较．结果表明，高强页岩陶粒混凝土的轴心抗压强度、抗拉强度和弹性模量等基本力学性能都符合相应规范的要求，其力学性能的标准值和设计值可按相应规程的规定取用．     

废弃聚苯乙烯泡沫(EPS)外墙外保温砂浆研究

通过改性,EPS表面由憎水性变为亲水性,能被新拌硅酸盐水泥浆体所润湿。以改性EPS为轻骨料,水泥为胶结材,辅以纤维和聚合物改性,可配制施工性、热工性、耐候性、抗裂性良好的保温砂浆。这种新型保温砂浆可用于外墙外保温,突破了传统保温砂浆只能作内保温的局限,已在建筑工程中大规模应用。     

可发性聚苯乙烯无卤阻燃泡沫材料制备及性能

采用包覆法,将含有无卤阻燃剂的热固性酚醛树脂胶包覆在预发泡的可发性聚苯乙烯(EPS)珠粒表面,再通过水蒸气发泡、模压成型工艺制备出无卤阻燃EPS泡沫材料.研究了3种无卤阻燃剂(三聚氰胺磷酸盐、三聚氰胺氰尿酸盐和聚磷酸铵)在EPS泡沫材料中的阻燃作用,探讨了聚磷酸铵用量对EPS泡沫材料阻燃性能、力学性能和隔热性能的影响.结果表明,在3种无卤阻燃EPS泡沫材料中,采用聚磷酸铵与酚醛树脂包覆制备的无卤阻燃EPS泡沫材料综合性能最好.当EPS、酚醛树脂和聚磷酸铵质量比为100∶100∶40时,无卤阻燃EPS泡沫材料的综合性能较好,其压缩强度为0.42MPa,弯曲强度为0.70MPa,氧指数(体积分数)为30.5%,导热系数为0.025 6W·m-1·K-1.