A mortar for rising damp studies

A mortar for rising damp studies has been developed and used in the construction of test walls.

One chemical injection technique used in some test walls failed to provide an effective damp-proof course although a degree of water repellency was created in some of the injected bricks. The walls however were virtually saturated throughout when injected and it is concluded that a realistic performance test for treatments against rising damp should use walls with lower moisture contents at the treatment level combined with a substantial moisture gradient up the wall.

A test wall with a substantial moisture gradient was constructed using a graded washed sand for the mortar mix. On injection, an effective damp-proof course was formed.     

Treatment of rising damp in historical buildings: wall base ventilation

Intervention in older buildings increasingly requires extensive and objective knowledge of what one will be working with. The multifaceted aspect of work carried out on buildings tends to encompass a growing number of specialities, with marked emphasis on learning the causes of many of the problems that affect these buildings and the possible treatments that can solve them. Moisture transfer in walls of old buildings, which are in direct contact with the ground, leads to a migration of soluble salts responsible for many building pathologies.     

Rising damp in masonry walls and the importance of mortar properties

This paper briefly reviews the rising damp phenomenon with a discussion of the controlling mechanisms and contributing factors such as capillary effect, water absorption, evaporation and salt formation. It also presents the results of a study on rising damp based upon a practical year-long test. Measurements were made on rising damp on walls made from different mortars and the observations were compared with theoretical models. It was found that mortar characteristics would significantly affect the height of rising damp. It was also observed that there was a strong correlation between rising damp and the Sharp Front Model, and the rate of absorption of water into the mortar was a key factor in determining the height of the rising damp front. In addition, walls with rising damp treatment are warmer than their control counterparts due to a reduction in surface moisture evaporative cooling.     

Mathematical analysis of the evaporative process of a new technological treatment of rising damp in historic buildings

The treatment of rising damp in historic buildings walls is very complex, due to the thickness and heterogeneity of those walls. The traditionally techniques used to deal with this kind of problem (such as watertight barriers, injection of hydrofuge products, etc.) show, sometimes, to be ineffective, justifying the need to find a new approach.     

The influence of the thickness of the walls and their properties on the treatment of rising damp in historic buildings

Intervention in older buildings increasingly requires extensive and objective knowledge of what one will be working with. In old buildings, rising damp in walls that are in direct contact with the ground leads to the migration of soluble salts that are responsible for many of the pathologies observed. Our research allows us to conclude that the most efficient way of treating rising damp is by ventilating the wall base [2], [4]. This technique was experimentally validated to limestone walls 20 cm thick. As it experimental validation of different thicknesses and different compositions has not been possible, numerical investigation has been carried out in order to analyse their influence.In this paper we will present the results of the work developed in the Department of Civil Engineering of the University of Coimbra in collaboration with the Department of Civil Engineering in the Faculty of Engineering of the University of Porto. The main purpose is to analyse the influence of the thickness and composition of walls on the new treatment for rising damp in historic walls: the ventilation of the wall base.     

Infectivity of Giardia lamblia cysts obtained from wastewater treated with ultraviolet light

Several waterborne outbreaks of giardiasis have been linked to discharge of wastewater effluents into surface water. Little is known about the infectivity of Giardia lamblia cysts present in UV treated wastewater effluents. In this study, the infectivity of G. lamblia cysts, recovered from primary effluent and secondary effluent, both upstream and downstream of operating full-scale UV reactors at four wastewater treatment plants, was assessed using the Mongolian gerbil model. Infectivity of cysts obtained from the primary effluents was scored as either strong or moderate for induction of infection in gerbils at three out of four wastewater treatment plants. G. lamblia recovered from secondary effluent both upstream and downstream of the UV reactors caused weak infections in the gerbils. The probability of weak infections caused by inoculums of 50-1400 cysts per gerbil was, on the average, reduced by approximately 10% at the four wastewater UV installations with coliform reduction equivalent doses ranging from 6 to 18 mJ/cm². The UV systems provided considerably less inactivation of the parasite than expected based on the UV dose response of Giardia reported in the literature.     

等离子体改性纤维布在水泥砂浆中的应用研究

应用大气下介质阻挡放电等离子体处理铺展在水泥砂浆内的纤维布，研究处理后的纤维布对砂浆抗压和抗冲击性能的影响。结果表明，在砂浆中加入等离子体处理的纤维布，其抗压和抗冲击性能比加未处理纤维布的试样分别提高了7％和108．3％。     

Core size and time effects on water absorption values of rock and cement mortar samples

There is no standard size for samples used to establish water absorption (WA) by weight and volume. A total of 150 samples with five different diameters (54, 48, 42, 30 and 21 mm) were cored from sandstone, limestone and cement mortar with a length:diameter ratio between 2.0 and 2.5. The laboratory experiments were continued for 90 days, although some samples reached their maximum absorption at 43 and 60 days. The study has shown that WA values vary significantly with sample dimension and time. NX (54 mm) cores had the lowest WA values while 21 and 30 mm diameter cores gave the highest WA values. The difference between 24-h and 90-day WA values was greatest for the 21 mm cores.     

买房之选房技巧探讨

围绕消费者买房之选房技巧，从怎样选择户型、健康住宅标准、如何看房屋设计图纸、购房如何看房屋质置、挑选房子的标准、选房要素等进行探讨，以保证购到满意住房。     

Evaluation of the FEH Rainfall-Runoff Method for Catchments in the UK

The Flood Estimation Handbook, which was published in 1999, has substantially replaced the Flood Studies Report for design flood estimation in the UK. Although there are substantial differences between the handbook and the report, the philosophy of the rainfall-runoff method has been retained in the handbook. However, there are differences in the equations that have been used to estimate parameters of the rainfall-runoff method.
This paper provides a comprehensive evaluation of the performance of the Flood Estimation Handbook rainfall-runoff method for flood-frequency estimation, using data from eighty-eight catchments in the UK. The performance is evaluated by reference to the flood quantiles obtained from single-site frequency analysis, and comparison is made with the performance of the Flood Studies Report methodology. In general terms, the handbook over-estimates flood quantiles, with respect to (a) those estimated from observed records and (b) the report's quantiles. The paper explores the causes of these over-estimations and seeks linkages with particular catchment characteristics.     

漏斗测试砂浆流变性方法的改进

简要介绍了漏斗测试砂浆流变性方法的研制过程,确认了它能测量砂浆的塑性粘度和屈服应力的相对值,试验量小,经济方便,测试效果好。     

皖南古民居对新民居生态观的传承

以皖南古民居的生态性为研究出发点,针对民居在构造、节点等生态性的做法,研究基于皖南地区新民居适宜的生态技术,以期提高对传统建筑的认识水平,更好地继承和发展传统建筑文化,促进生态民居不断发展。     

用测力延度试验评价沥青胶浆的低温性能

通过对基质沥青和SBS改性沥青两类沥青、四种粉胶比在三种温度下的沥青胶浆进行测力延度试验,分析了沥青胶浆延度、测力延度峰力值及延度拉伸柔量三个常规指标与粉胶比、温度之间的相关性,认为测力延度试验能有效的评价沥青胶浆的低温抗裂性能。     

Identification methods for Legionella from environmental samples

Laboratories responsible for Legionella diagnostics around the world use a number of different culturing methods of non-equivalent sensitivities and specificities, to detect Legionella species in environmental samples. Specific countries usually standardize and use one approved method. For example, laboratories in Australia use the Australian Standard (AS) method and those in Europe, the International Standard method (ISO). However, no standard culturing methods have been established in South Africa to date. As a result, there is uncertainty about the true prevalence and most common species of Legionella present in the South African environment. In an attempt to provide guidelines for the development of a standard method specific for South Africa, the ISO, AS and a most probable number method were evaluated and compared. In addition, the effect of sample re-incubation with autochthonous amoebae on culture outcome was studied. Samples were collected from four environments, representing industrial water, mine water and biofilm. The samples were concentrated by membrane filtration and divided into three portions and cultured without pretreatment, after acid treatment and after heat treatment, on four culture media namely alphaBCYE, BMPA, MWY and GVPC agar. A selective approach, incorporating heat treatment, but not acid treatment, combined with culture on alphaBCYE and GVPC or MWY, was most appropriate for legionellae detection in the samples evaluated. Legionellae were cultured from 82% of the environmental samples we evaluated. In 54% of the samples tested, legionellae were present in numbers equal to or exceeding 10(2) colony-forming units per milliliter (cfu/ml). Legionella pneumophila serogroups (SGs) 1-14 were the most prevalent species and were present as single, or a combination of two or more SGs in a number of samples tested. Re-incubation of sample concentrates with autochthonous amoebae improved the culturability of legionellae in 50% of cultures on alphaBCYE and 25% on GVPC.     

从保障性住房大发展看我国住房市场走向

通过对国家政策及行为、国民经济周期的分析,得出了房地产即将迎来新周期阶段这一结论,并对此阶段来临过程中的阻碍和供需变化,以及未来市场的租售结构改变进行了论述,以期指导实践。     

存放时间对预拌砂浆性能的影响

从预拌砂浆应用性能出发研究了存放时间对砂浆性能的影响.随着存放时间的延长,预拌砂浆的稠度和抗压强度经过一段时间的稳定后显著降低.预拌砂浆稠度一旦出现损失,其力学性能将不能满足设计要求.并指出砂浆专用缓凝剂可以延长预拌砂浆存放时间而保证砂浆的性能不受影响.     

Evaluation of the potential of geopolymer mortar in the rehabilitation of buried infrastructure

Concrete pipes represent the backbone of the wastewater collection systems in many cities across North America. These pipes are in various stages of deterioration, generally due to microbiological induced corrosion and/or mechanical loading. A common method of rehabilitating these structures is the use of cementitious coatings. This paper describes the development and testing of three novel geopolymer mix designs prepared using metakaolin and fly ash (class C and F) precursors. Specimens prepared using Portland cement-silica fume blend were also tested for comparison purposes. The specimens were placed in several concentrations of sulphuric acid for a period of eight weeks. The corrosion resistance and remaining compressive strength of geopolymer mortar made from class F fly ash precursor were found to be substantially higher compared with the enhanced OPC formulation. The other geopolymer mix designs were found to perform equally or better compared with the OPC binary blend.     

老年住宅细部设计

从老年人行为模式特点出发,针对老年人的特殊需要,总结了老年住宅的设计要点,落实在地面、扶手、高差、墙面、消防等建筑细部设计上,旨在为老年人提供一个安全便利、舒适舒心的居住环境。     

关于安置房景观绿化工作的思考

从经济效应、社会效益、环境效应三方面阐述了做好安置房绿化工作的重要意义,针对目前安置房小区建设局面纷乱的现象,提出应加强规划设计、重视日常养护和管理工作,从而提高小区景观绿化工作的综合绩效。