废水泥浆对水泥胶砂性能的影响研究

研究了废水泥浆澄清液、浆体以及干燥后的粉体对水泥胶砂流动度以及抗压强度的影响,为废水泥浆在预拌混凝土生产中的的回收利用提供技术基础,解决废水泥浆的环境污染和资源化利用问题。     

回收碳纤维混凝土导电性

碳纤维增强树脂复合材料从生产、服役到退役的整个生命周期都会产生巨量废弃物,带来了严重的环境污染与资源浪费问题。本文将生产过程中产生的废弃碳纤维掺加到混凝土中,研究其对混凝土强度及导电性的影响规律与机制。结果表明,回收碳纤维对混凝土强度改善效果不明显,这是由于工业碳纤维表面的涂层使其在混凝土拌合过程中更易聚集成束,不易分散。回收碳纤维的掺入可明显提升混凝土导电性,掺量为0wt%～0.3wt%时,干燥/吸水过程改变混凝土孔结构且C-S-H凝胶重新排列、局部收缩与部分不可逆特性使混凝土产生新的导电路径,电阻率随含水率降低呈现先升后降的趋势;掺量为0.4wt%～1.5wt%时,混凝土内部形成了稳定的物理接触导电网络,龄期及含水率对导电率无明显影响。     

磁化水混凝土的基本特性分析

提高混凝土强度,节约水泥,降低工程造价一直是工程界所关注的问题。磁化水混凝土具有提高混凝土强度,节约水泥的特性。对磁化水的磁化机理作了深入的分析。从物理和强度两个方面深入分析了磁化水混凝土的特性。     

外加剂在提高混凝土强度上的合理使用

本文简明阐述了混凝土强度的基本理论与混凝土强度相关的主要性能参数和技术标准,以混凝土自身的各项特有性能分别叙述了混凝土外加剂在改善混凝土综合性能、提高混凝土强度等方面发挥的积极作用,也提醒在当今的外加剂复合程度越来越高的条件下应当科学审慎的使用,做到有理有据,考虑外加剂对混凝土整个周期的强度及其他性能的影响。     

浅析水利工程施工中混凝土抗裂性问题及其对策

混凝土在建筑业中被称作是人工制造的“石头”,不同类型的混凝土因其强度不同,形状相异,整体性能好,在建筑施工中得到广泛应用。但是,混凝土也有许多缺点,关键的一点就是抗裂性能差。如何在应用过程中保证混凝土强度,提高混凝土抗裂性能在施工过程中是需要迫切解决的技术难题。对混凝土在施工过程中形成裂缝的原因和如何提高混凝土抗裂性的问题进行研究和探讨。     

浅论骨料的含泥量对混凝土强度的影响

从混凝土的定义、混凝土的分类以及混凝土的主要性能来论述混凝土的一些基本概念,分别从水泥强度等级、水胶比、集料品质、外加剂、养护温度湿度和龄期等方面来讨论影响混凝土强度的因素,针对骨料中的含泥量大小对混凝土强度的影响来进行分析。本文重点讨论C20混凝土、C30混凝土所用材料中泥含量不断增加,增加到多少？对混凝土强度有多大影响？我们进行了综合分析研讨。     

预制与后浇混凝土粘结后的抗折性能分析

为保证装配式混凝土结构叠合面具有良好的粘结性能,对预制与后浇混凝土粘结后的抗折性能进行了研究,分析了不同后浇混凝土强度、粘结面粗糙度、温度及冷却方式对粘结后抗折性能的影响。结果表明:预制与后浇混凝土粘结后的抗折强度随着粘结面粗糙度的增加而显著增大,但随着温度的升高,粗糙度影响作用减小;提高后浇混凝土强度等级并不能有效增大预制与后浇混凝土粘结后的抗折强度,抗折强度随着温度的升高急剧下降,喷水冷却对试件的损伤要比自然冷却严重。     

基于胶浆特性的透水混凝土强度及抗冻性研究

透水混凝土的强度和抗冻性是影响其在重荷载交通道路和寒冷地区推广应用的关键性能。本工作研究了胶浆工作性能、强度、界面粘结性能及透水混凝土强度、抗冻性,并揭示了影响透水混凝土性能的主要因素。结果表明,通过最大浆集比可以评价胶浆和透水混凝土的工作性能,且当最大浆集比与设计浆集比接近时,透水混凝土的工作性能最佳。未改性胶浆界面冻融前后均发生粘结破坏。而改性胶浆未冻融时界面拉拔强度提升67%～156%,发生内聚破坏;冻融后界面拉拔强度显著降低,发生内聚、粘结混合破坏。工作性能良好的透水混凝土抗压强度为38.2～40.3 MPa,抗折强度为3.8～4.3 MPa,透水系数为2.85～2.92 mm/s。主成分分析结果表明,各因素对透水混凝土性能影响的占比依次为：界面性能、胶浆配合比、空隙特征共占44.8%,胶浆裹覆性能占27.5%,胶浆强度占20.0%。     

浅析水利工程施工中混凝土抗裂性问题及其对策

混凝土在建筑业中被称作是人工制造的“石头”，不同类型的混凝土因其强度不同，形状相异，整体性能好，在建筑施工中得到广泛应用。但是，混凝士也有许多缺点，关键的一点就是抗裂性能差。如何在应用过程中保证混凝土强度，提高混凝土抗裂性能在施工过程中是需要迫切解决的技术难题。对混凝土在施工过程中形成裂缝的原因和如何提高混凝土抗裂性的问题进行研究和探讨。     

水玻璃的磁化改性对水玻璃砂性能的影响

研究了水玻璃流速和流量对水玻璃的磁化改性效果及磁化改性对水玻璃砂表面强度的影响。     

Production of sustainable fibre-reinforced concrete incorporating waste chopped metallic film fibres and palm oil fuel ash

The consumption of waste materials is one of the essential concerns of waste management strategies in many parts of the world. With the advances in concrete technology, the utilisation of waste materials in the sustainable construction has developed increasingly widespread because of technological, economic and ecological advantages. This paper presents the workability and mechanical properties of concrete incorporating waste chopped metallic film (WCMF) fibres and palm oil fuel ash (POFA). Waste plastic results in waste discarding disaster and consequently causes significant harms to the environment. WCMF fibres were prepared by recycling metallic–plastic films used for food packaging. Six concrete mixes containing 0–1.25% WCMF fibres with a length of 20 mm were made of ordinary Portland cement (OPC). Further, six concrete mixes with the same fibre content were made, where 20% POFA substituted OPC. The combination of WCMF fibres and POFA decreased the workability of concrete mixes. The inclusion of WCMF fibres to OPC and POFA concrete mixes decreased the compressive strength. However, at the curing period of 91 days, the POFA-based mixes obtained higher compressive strength values than those of OPC-based mixtures. The positive interaction between WCMF fibres and POFA consequently enhanced the flexural and tensile strengths, impact resistance, thereby increasing energy absorption capacity and ductility of concrete composites. It revealed that WCMF fibres acted as a bridge arrester and improved the load-transfer capacity of the concrete specimens. The study showed that the utilisation of WCMF fibres in the production of sustainable concrete is a beneficial, affordable and feasible solution.     

Dynamic compressive and splitting tensile properties of concrete containing recycled tyre rubber under high strain rates

In order to raise the efficiency of resource utilization, recycling waste rubber particles into concrete as aggregate has been widely accepted. When the size and content of the rubber particles are appropriate, rubberized concrete can achieve many excellent properties. This study investigated the impact of rubber replacement on dynamic compressive and splitting tensile properties of concrete. The split Hopkinson pressure bar tests of rubberized concrete containing 5%, 10%, 15% and 20% volume replacement for sand were completed. The failure modes, stress curves and dynamic strength values of rubberized concrete under high strain rates were recorded. The results reveal that the dynamic compressive and splitting tensile strength of rubberized concrete decrease with increasing rubber content. Meanwhile, peak strain increases with increasing rubber content. Dynamic increase factors (DIFs) of compressive and splitting tensile strength also were calculated, where rubberized concrete shows a stronger strain rate sensitivity. The analysis of specific energy absorption illustrates that rubberized concrete with 15% rubber replacement has the best impact toughness. In addition, ratios of dynamic compressive–tensile strength of rubberized concrete were calculated, which are between 3.82 and 5.39.     

废弃混凝土再生利用技术的研究进展

废弃混凝土再生利用对于保护环境、减少资源与能源浪费以及实现可持续发展具有重要意义。从混凝土再生骨料对混凝土性能的影响、混凝土再生骨料的应用、提高再生混凝土性能的方法3个方面介绍了目前国内外废弃混凝土再生利用技术的研究现状。指出除了进一步加大相关试验及基础理论研究外,国家以及相关机构还应在政策、资金等方面进行支持,并建立废弃混凝土再利用的具体实施标准、规范等,最终实现废弃混凝土"零排放"。     

Immobilization of copper indium selenide solar module waste in concrete constructions

The aim of this study was to investigate the properties of concrete containing various quantities of copper indium selenide (CIS) solar module waste by replacing a certain part (up to 40%) of sand. The obtained results have shown that an increase in the content of solar module waste resulted in an increase of the density of fresh and hardened concrete. The compressive strength of the specimens compared to the control specimens has been higher, when sand aggregate was replaced by CIS solar module waste particles from 5 to 20%. Also, a decrease in the water absorption and porosity of concrete specimens containing immobilized waste compared to those with no waste has been observed. The leaching behaviour of the concrete containing immobilized waste was also studied. The results showed that the concrete with sand aggregate replacement by waste particles between 5 and 10% has the best leaching properties. That replacement can be used for CIS solar module waste recycling in concrete production.     

基于废弃印刷线路板中非金属的复合板材制备

随着废弃电子电器产品的快速增长带来的环境问题日趋严重,废弃印刷线路板的资源化问题一直成为关注的焦点。着重研究了气流分选后得到的废弃印刷线路板非金属粉碎料的资源化再生制板材的可行性,探讨了不同填料粒径、投加量和改性剂下所得复合材料拉伸强度、弯曲和冲击强度的变化。研究表明以马来酸酐接枝聚丙烯（MAH-g-PP）作为改性剂,聚丙烯S700为基体树脂,在粒径范围为0.125～0.3mm的非金属粉碎料添加量为20%的条件下,板材力学性能较优,具有广泛的应用前景。     

激发剂对废弃加气混凝土活性的影响及其机理研究

以磨细的废弃加气混凝土替代部分水泥,并掺入Ca(OH)2、CaSO4、激发剂T对其进行活化,采用力学性能测试、XRD、SEM等对活性激发效果进行评价。结果表明,在不掺入激发剂的情况下,增加废弃加气混凝土微粉量会显著降低砂浆的强度。当废弃加气混凝土粉料掺量为40%时,掺2.5%~4%CaSO4对试样强度的影响很小;当Ca(OH)2掺量为3%时效果最好,试样的28d抗压强度提高了60%;掺入0.02%激发剂T可使试样的28d抗压强度提高约80%,效果最好。XRD、SEM和TG-DSC的测试结果较好地印证了力学性能测试结果。     

Influence of recycled aggregate on slump and bleeding of fresh concrete

The recycling of construction and demolition (C&;D) waste as a source of aggregates for the production of new concrete has attracted increasing interests from the construction industry. While the environmental benefits of using recycled aggregates are well accepted, some unsolved problems prevent this type of material from wide application in structural concrete. One of the major problems with the use of recycled aggregates in structural concrete is their high water absorption capacity which leads to difficulties in controlling the properties of fresh concrete and consequently influences the strength and durability of hardened concrete. This paper presents an experimental study on the properties of fresh concrete prepared with recycled aggregates. Concrete mixes with a target compressive strength of 35 MPa are prepared with the use of recycled aggregates at the levels from 0 to 100% of the total coarse aggregate. The influence of recycled aggregate on the slump and bleeding are investigated. The effect of delaying the starting time of bleeding tests and the effect of using fly ash on the bleeding of concrete are explored.     

Strength and durability properties of polyester concrete using pet and fly ash wastes

Recycled poly(ethylene terephthalate), PET, mainly recovered from plastic beverage bottles, can be used to produce unsaturated polyester resins. In turn, these resins can be mixed with inorganic aggregates (sand and gravel and fly ash waste), to produce polyester concrete (PC). The strength and durability properties of plain and steel-reinforced polyester concrete (PC) using unsaturated polyester resins based on recycled PET and fly ash fillers are discussed in this paper. The recycling of PET and fly ash in PC helps in reducing the cost of the material and alleviating an environmental problem posed by waste materials. The material may effectively be used in many construction applications such as utility, transportation and building components, and the repair and overlay of pavements, bridges and dams.     

骨料种类与品质对透水混凝土性能影响的研究进展

骨料作为支撑透水材料空间骨架结构的原料,其形状、粒径范围及分布、种类与品质都对材料强度、透水性及耐久性产生重要的影响。文章从透水混凝土的骨料种类与品质要求为切入点,介绍了应用于透水混凝土中的天然骨料,建筑垃圾、工业固废、人造骨料及生活垃圾底渣等再生骨料与砂基细骨料的基本物理化学特性,重点综述了各类骨料对透水混凝土强度、透水性、耐久性及水质净化等性能影响的研究进展,并进行了简要分析与总结。最后,提出了透水混凝土可以通过对骨料的质量控制来提升其透水时效性与耐久性,指出未来需扩大透水混凝土行业协同处置废弃物的范围与能力。     

建筑废弃物再生利用的相关性能及应用前景分析

近年来,我国城市化进程的推进和新农村建设的发展,不但使得国家能源负担日益加重,而且还随之产生了大量的建筑废弃物需进行处理,这些建筑废弃物已在城市固体垃圾中占有了一个相当大的比例,并且还在不断增长当中。对此,我国政府越来越重视节能和资源的回收利用问题,大力提倡和发展建筑废弃物的再利用。再生混凝土和再生砂浆作为新型的节约型建筑材料,对于保护环境、节约资源、发展生态建筑具有重要意义,近年来国内外学者开展了相关研究,并取得一定成果。本文通过分析再生混凝土、再生砂浆等主要再生建筑废弃物的力学性能及其破坏机理,以期为再生废弃物的进一步深入研究和应用提供更完善的科学依据。