沥青混合料集料接触特性切片图像评价方法

为了评价沥青混合料集料的接触特性,提出了一种较能准确有效评价沥青混合料集料接触特性的新方法。研究中建立了表征集料接触特性的量化指标——接触对,以AC20型沥青混合料为例,对车辙板试件的72幅切片图像进行了分析,通过对所有切片的集料接触数据进行统计分析,得到了集料接触对数目的分布规律。在此基础上,还进行了集料接触特性的影响因素分析,并提出了影响集料接触特性的3个主要因子：4．75mm以上集料含量C〉4.75、细度指数FI和离析指数SI。结果表明这3个因子与集料接触对之间有较好的关联度,集料接触特性变化受3个因子共同作用的影响,单因素或双因素都不能正确反映样本的接触对数目。     

香港建筑废物再生骨料混凝土的研究进展

减少,回收和再利用各种废物是当今世界可持续发展的战略之一.香港的建筑工业每天都要产生大量的建筑废物,处理和管理这些建筑废物已经成为严重的社会问题和环境问题.随着经济的快速增长,国内的一些大城市中建筑废物的处理和管理同样成为主要的环境和社会问题之一.回收和再利用建筑废物,不仅可以节约处理建筑废物的土地,减少管理和处理建筑废物的成本,而且可以节约大量的自然资源.香港政府已经建立了回收和筛选建筑废物的设施.香港理工大学在回收和再利用建筑废物领域开展了近十年的研究工作,取得了一定的成果并向香港政府推荐了再生骨料回收再利用的规范.笔者介绍香港理工大学在研究建筑废物再生骨料混凝土方面取得的成果,包括建筑废物再生骨料环保砖、粉煤灰再生骨料混凝土、蒸汽养护再生骨料混凝土等.并介绍再生骨料混凝土在香港湿地公园的应用情况.这些技术成果将对回收和利用建筑废物起到促进作用.     

Using the scanning electron microprobe and secondary ion mass spectrometry to locate 14C- and 13C-labelled plant residues within soil aggregates

Increasing concentrations of CO2 in the atmosphere are placing emphasis on the necessity for sequestering carbon (C) into soil organic matter (SOM). By studying the interior parts of soil aggregates, a better understanding of the incorporation and sequestration of plant residue materials within these aggregates could be obtained. The location of newly added plant residues within soil aggregates may also assist in the investigation of the impact of these newly added plant materials on soil aggregation. This study investigated two different techniques for determining the location of newly added plant residues within soil aggregates by using plant materials labelled with 14C and 13C isotopes incorporated into two different soil types, Black Earth (Pellic Vertisol) and Red Clay (Chromic Vertisol). Both autoradiography combined with scanning electron microprobe analysis (14C) and secondary ion mass spectrometry (SIMS) (13C) were successfully used for detecting the presence and location of the newly added plant residues fragments within soil aggregates of both soil types. The use of labelled plant materials is essential for the study of the location of newly added plant materials within soil aggregates, and this has proven to be a useful tool for studying the impact of residue additions on soil aggregate formation. Furthermore, these methods have been shown to be useful for determining the incorporation and sequestration of C materials within soil aggregates. The development of the 13C SIMS technique could alleviate the necessity for the use of the radioactive isotope 14C in soil studies.     

细颗粒自密实钢管混凝土试验研究

研究了用于某钢管混凝土拱桥的细颗粒自密实混凝土配合比设计,对选定配合比的混凝土进行了抗压强度和弹性模量随龄期变化的测试试验.结果表明细颗粒自密实混凝土能满足钢管混凝土拱桥的施工性能和基本力学性能.     

Free mica grains in crushed rock aggregates

Enrichment of free mica (i.e. as monomineralic grains) in the fine fraction of crushed rock aggregates affects the quality of the aggregate end product. Granitoid rock from the Svecofennian Province were used as being representative of crushed rock aggregates commonly used for construction purposes. The results reveal a general trend of enrichment of mica for finer fractions. For the coarse grained rock a peak occurs at 0.25–0.5 mm followed by a decrease in the amount of free mica; for grains <0.063 mm there is an increase. The general trend and peak are correlated to the microstructural characteristics of the samples.      

高品质再生骨料的生产工艺

分离附着在废弃混凝土块上的废旧水泥砂浆和去除混杂在再生骨料内的微细粉末（如泥土等）是提高再生骨料品质的两个有效措施。当前国内的再生骨料生产工艺未能很好地解决这两个问题，生产出的再生骨料一般含有大量的水泥砂浆同时含泥较多，品质较低。文章介绍并分析了国外两种高品质再生骨料生产工艺，即加热磨损法和湿处理法。由这两种生产工艺生产出的再生骨料可满足用于结构混凝土的要求。最后，提出了我国借鉴该生产工艺需要进一步解决的问题。     

热处理温度对低硅含量SiO2微粉固废性能的影响

对回收的w（SiO₂）<85%的低硅含量SiO₂微粉固废进行了不同温度（400、500、600、700、800、900和1 000℃）保温5 h的热处理，并对热处理后的粉体进行了分析。结果表明：随着热处理温度升高，试样逐渐烧结。热处理温度低于800℃时，SiO₂微粉保持原有粒状、球状SiO₂颗粒团聚体结构。但热处理温度为500℃及以下时，团聚体强度较低。热处理温度800℃以上结块严重，并析出方石英相。热处理温度控制在600～800℃可制得具有一定强度，体积密度在0.73～0.95 g·cm^-3的球壳结构的球状粉体，该粉体可以作为轻质原料用在低温保温浇注料，也可以作为其他行业填料。     

Development of morphological properties of road surfacing aggregates during the polishing process

This study investigated the morphological properties of different road surfacing aggregates. Eleven types of aggregates with great variances in their mineralogical properties were chosen for the study. For each type, 500-gram test samples were prepared and subjected to polishing using the Micro-Deval (MD) apparatus. Before and after polishing, 48 particles from each type of aggregate were selected and run through the aggregate imaging system and X-ray computed tomography equipment to capture the change of morphological characteristics, including sphericity, angularity and texture. The results showed that log-normal functions are ideally suited to describe distributions of the analysed morphological characteristics before and after MD. The mass loss of each aggregate can be well described with a function using the expected value of morphological parameters with the aid of a multiple regression analysis. The change of angularity is the main cause for the mass loss whilst the changes of both the sphericity and texture only have an ancillary influence.     

NMR relaxometry during internal curing of Portland cements by lightweight aggregates

The hydration of an ordinary Portland cement of low water-to-cement ratio under the influence of internal curing by addition of water-saturated lightweight aggregates (LWA) is investigated by non-destructive low-field NMR relaxometry. The methodology, which was recently developed to investigate internal curing by addition of a water-saturated polyelectrolyte gel, is applied to follow the transition of water from the mineral aggregates into hydrating cement paste and to detect the time dependence of the water consumption by the hydration reaction. By the changes of the transverse relaxation times of the physically bound water, the compaction of the pore space of the hardening cement is estimated qualitatively. The water retention potential of two types of LWA and the temporal moisture requirement of the cement during internal curing are determined without and with superplasticizer.     

Presence of indigestible peptide aggregates of soybean meal in pig ileal digesta residue

With the purpose of analysing the molecular size and composition, proteinaceous material was extracted from the insoluble components of a digesta sample obtained from pigs fed a feed consisting of only soybean meal. Gel permeation chromatography indicated that the alkali‐extractable fraction of the proteinaceous material from the residue was of relatively high apparent molecular weight. However, the combined results from gel electrophoresis, RPLC‐MS, and MALDI‐ToF MS showed that the extracted protein material was in fact, to a high extent, composed of aggregated peptides. To our knowledge this has not previously been described. Aggregates extracted by dilute alkali were fully degraded upon subsequent proteolytic treatment. N‐terminal sequencing of selected protein bands from SDS‐PAGE gels indicated the presence of partly degraded β‐conglycinin alpha subunits in the residue. Copyright © 2007 Society of Chemical Industry