Performance Enhancement of Polycondensate‐Based Superplasticizers by Encapsulation

A cost‐effective and robust encapsulation system for chemical admixtures with delayed release mechanisms for construction materials like dry mix mortars is presented. Based on supplementary cementitious materials, a superplasticizer was encapsulated in matrix‐based encapsulations. Subsequently, the particle characteristics of the agglomerates and the release behavior of the superplasticizer were examined. The main objective of this research was to prove the functionality of such encapsulations for the future use in construction materials. The results obtained indicate that the performance of construction chemicals could be improved by encapsulation and controlled release for the future development of new construction materials. Furthermore, material characteristics of the supplementary cementitious material like the incline to excessive dusting or the materials density were improved by encapsulation.     

沥青胶浆流变性能指标影响因素的灰色关联分析

针对沥青胶浆流变性能评价指标的影响因素,采用灰色关联度分析方法,分析了不同剪切应力水平、不同角速度、不同温度和粉胶比对沥青胶浆流变性能指标的影响程度,为沥青混合料的优化设计提供理论依据。     

KB憎水膨珠保温砂浆及其应用

KB憎水膨珠保温砂浆由水泥、KB憎水膨珠、SF憎水粉及少量胶粘剂按一定比例干混而成,保温、防水、防火、容重轻,且集保温与找坡为一体,便于施工。本文结合工程实例说明了该砂浆在平面、立面以及节点处的施工方法。     

散装预拌砂浆与传统自拌砂浆优缺点对比分析以及使用过程中需改进的几点意见

预拌砂浆作为一项绿色建材得到政府和社会的认同,预拌砂浆采用密闭容器进行运输和现场存储,以往施工现场砂浆搅拌过程中的扬尘满天飞情况可以基本杜绝,符合北京市地方标准绿色施工管理规程(DB11/513-2008)中"施工现场易飞扬细颗粒散体材料,应密闭存放"的规定。密封运输、密封储存,减少浪费,减少扬尘,真正做到文明施工;精确搅拌使用,施工质量容易控制;加快施工速度,节约成本。但是使用过程中还存在一些需改进的地方,文中详细介绍。     

Laboratory investigation of carbonated BOF slag used as partial replacement of natural aggregate in cement mortars

Direct mineral carbonation produces a material rich in carbonates and with reduced quantities of free oxides. The aim of this work was to show that such materials can be used in the construction domain. Basic Oxygen Furnace (BOF) slag from the steelmaking process has been traditionally seen as unfit for bounded applications due to its propensity to swelling, resulting from hydration of its high free lime content. Here, BOF slag was crushed to suitable particle sizes, carbonated in an aqueous solution of carbonic acid, and utilized to replace 50% of natural sand aggregate in cement mortars. The mechanical and chemical properties of these mortars were compared to mortars containing non-carbonated slags, and a standard cement mortar as a reference. Tests were conducted to determine mortar paste consistency and soundness, and cured mortar compressive strength and leaching tendencies. The results showed a satisfactory performance for all considered aspects (comparable with the reference) of the mortar sample containing 37.5 wt% (1.5 in 4 parts solids) carbonated BOF slag of <0.5 mm particle size.     

麻布纤维对水泥砂浆裂纹扩展影响分析

为研究麻布纤维对水泥砂浆裂缝扩展的控制效果及实用性,通过试验并结合ANSYS软件模拟,研究了麻布纤维对水泥砂浆裂纹扩展与强度的影响。结果表明:适量麻布纤维对提高水泥浆体的强度及控制裂缝的发展效果显著,具有实际应用价值;不同的麻布纤维掺量对水泥砂浆强度和裂缝的影响效果不同。     

A mechanism based on finger-sliding behavior for designing radial menus

Human behavior about sliding their fingers on touch screens needs to be understood for the design of radial menus. For this purpose, data about the angles of finger sliding in performing radial pointing to eight predefined directions were collected. The optimal angle ranges and boundaries for these directions were then determined by the proposed mechanism. Consistent with previous research, results showed that the deviations of slide angles for the four diagonal directions were larger than that for the four orthogonal directions. Therefore, to reduce overall pointing errors, the angle ranges for the diagonal directions should be wider than that for the orthogonal directions. Based on the proposed mechanism, the total probability of pointing errors could be limited to 0.05%, compared to the error of 2.00% if the eight angle ranges were evenly divided by the radii of a regular octagon. Besides the angles, the lengths and starting points of the slides were reported and discussed along with the oblique effect, judder effect, and screen orientation. Possible applications of the proposed mechanism for dynamic and personalized radial menus are addressed. Further research would be worthwhile to examine the effects of screen orientation and the number of predefined directions on pointing performances. Moreover, extending the research to mid-air sliding gestures would be of interest and value in designing three-dimensional radial menus.Relevance to industryThe proposed mechanism could effectively enhance the accuracy of the selections through radial menus, and could be applied to the remote controls via smart handheld devices.     

用于迷宫屏蔽计算的蒙特卡罗减方差方法研究

本文应用多种减方差技巧提出了强迫指向自动重要抽样（FPAIS）方法，并在MCNP5程序平台实现了该方法。采用该方法对1个多折迷宫算例进行了模拟计算，计算结果与MCNP5程序的直接模拟、DXTRAN球、点通量3种方法的结果进行了比对。基于此算例对FPAIS方法进行了引导面设置和粒子数敏感性分析。结果表明，FPAIS方法在保证一定计算精度的前提下，比其他3种方法的FOM提高2~3个量级，且该方法对引导面设置不敏感、可用性强，对于迷宫屏蔽计算是一种准确、高效的解决方案。     

鉴定和防治混凝土泌水性的砂浆试验方法

混凝土产生泌水会影响混凝土结构的外观和质量,其产生原因有多种,施工现场需要迅速确定产生原因并及时解决。本文提出一种快速鉴定和防治混凝土泌水性的新方法—砂浆泌水检验法,对施工现场混凝土泌水的主要原因提供了一种简单易行的确定方法。文中还对采用掺加一定量的蔗糖减少混凝土泌水性进行了研究,并取得良好的工程应用效果。     

Effect of self-healing on strength and durability of zeolite-immobilized bacterial cementitious mortar composites

There is a compelling economic incentive to develop concrete materials that can repair its own damage, increase durability and prevent structural failure. This research investigated the potential of adding two different mineral producing bacteria into two types of cementitious mortar matrix to enhance self-healing ability for autonomous crack repair. In this study, zeolite was used as a carrier material to protect bacteria in high pH environment normally exists in concrete. The spore forming ability and ureolytic activity of zeolite-immobilized bacteria were investigated in order to examine potential for producing healing compounds. The self-healing ability of bacteria incorporated normal and fiber reinforced mortars was judged based on the development of compressive strength and permeation properties of cracked specimens with age as well as micro-structural characterization of crack healing compounds using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction.