Mechanical properties characterization of different types of masonry infill walls

It is remarkable, the recent advances concerning the development of numerical modeling frameworks to simulate the infill panels’ seismic behavior. However, there is a lack of experimental data of their mechanical properties, which are of full importance to calibrate the numerical models. The primary objective of this paper is to present an extensive experimental campaign of mechanical characterization tests of infill masonry walls made with three different types of masonry units: lightweight vertical hollow concrete blocks and hollow clay bricks. Four different types of experimental tests were carried out, namely: compression strength tests, diagonal tensile strength tests, and flexural strength tests parallel and perpendicular to the horizontal bed joints. A total amount of 80 tests were carried out and are reported in the present paper. The second objective of this study was to compare the mechanical properties of as-built and existing infill walls. The results presented and discussed herein, will be in terms of strain-stress curves and damages observed within the tests. It was observed a fragile behavior in the panels made with hollow clay horizontal bricks, without propagation of cracks. The plaster increased the flexural strength by 57%.     

页岩空心砖抗压强度分布特征统计分析

对四川地区常用的3种页岩空心砖分别进行不同受压面的抗压强度试验,取四、五、六孔3种孔洞形式的空心砖各90块,每种空心砖大面、条面和顶面抗压强度试验试件各为30块。计算了不同孔洞形式空心砖不同受压面的抗压强度变异系数,对比分析了不同空心砖同一受压面和同种空心砖不同受压面的强度离散性。比较正态分布和Weibull分布对页岩空心砖抗压强度分布特征的反映情况。通过Weibull分布对不同空心砖相同受压面及同种空心砖不同受压面的9组试验的抗压强度进行可靠度分析。结果表明:Weibull分布比正态分布更能反映空心砖抗压强度的分布特征规律; 空心砖的抗压强度离散性及其可靠度受孔洞形式影响,相同受压面的3种页岩空心砖中,四孔空心砖离散性较大,而六孔空心砖的抗压强度离散性最小,可靠度最好; 同种空心砖的不同受压面也影响空心砖的抗压强度离散性和可靠度,同种空心砖的3个受压面中,顶面抗压强度明显高于条面和大面的抗压强度,且顶面抗压强度分布更集中,离散性最小,可靠度最好。     

Utilization of phosphogypsum as raw and calcined material in manufacturing of building products

The main objective of this research was to investigate the utilization potential of phosphogypsum with fly ash and lime in construction industry. Phosphogypsum was used as raw and calcined material for making the cementitous binder. A series of the tests were conducted to determine the compressive and flexural strength, water absorption and unit weight after 28 days of the specimen preparation. On the basis of the test results, it was concluded that the curing conditions have an important influence on the compressive and flexural strength of the binder specimens. It was also concluded that the cementitous binder obtained can be used for the production of interior wall materials such as bricks and blocks.     

Energy savings potential by integrating Phase Change Material into hollow bricks: The case of Moroccan buildings

The building sector in Morocco represents 25% of the country’s total energy consumption. The poor thermal performance of the building envelopes is one of the principal reasons for this consumption rate. In this study, the efficiency of integrating Phase Change Materials (PCM) into hollow bricks used in three typical housing types in the six climate zones in Morocco is investigated. The numerical model is based on the heat transfer equation and the apparent heat capacity formulation to model the phase change. A heat flux analysis is performed at the internal surface of the wall, giving a good understanding of the thermal behavior of hollow bricks with PCMs compared with hollow bricks with air. The results show that the heat flux density at the internal face of the wall is constant when the PCM is partially solid/liquid, and follows the outdoor conditions when the PCM is fully solid or fully liquid. Irrespective of the climate zone, the PCM with a 32 °C median melting temperature reduces the heat flux peak value in the hotel housing while the PCM with a 37 °C median melting temperature is better for the individual and collective housing. On the other hand, the PCM with a 27 °C median melting temperature is able to save up to 25% and 40% of energy consumption in the Saharan climate and oceanic climate, respectively.     

The levels of radioactive materials in some common UK building materials

Measurements have been made of the radon exhalation rates and radionuclide contents of some common UK building materials. These include concrete blocks incorporating pulverised fuel ash from coal-fired power stations as well as more traditional materials such as clay bricks and concrete blocks. Simple models are applied to the results to calculate the radiation exposure of people living in houses constructed with these materials. It is estimated that building materials make only a small contribution to the total radon concentration in most houses. A similarly small contribution to the effective dose equivalent received by people arises from the gamma-ray emission from building materials, and in most cases will exceed the contribution to the effective dose equivalent from the radon exhalation of those materials.     

Properties of EPS RHA lightweight concrete bricks under different curing conditions

The depletion of non-renewable resources has become an alarming issue nowadays. Many environmentalists and researchers have been investigating the use of waste materials as a renewable resource for use especially as raw materials in construction. This paper reports on the potential use of waste rice husk ash (RHA) and expanded polystyrene (EPS) beads in producing lightweight concrete bricks. The RHA was used as a cementitious material since it is a lightweight reactive pozzolanic material. RHA was used as partial cement replacement, while the EPS was used as partial aggregate replacement in the mixes. Bricks of 215 mm × 102.5 mm × 65 mm in size were prepared in this study. The engineering properties of the bricks were investigated. Among the properties studied were hardened concrete density, compressive strength and water absorption of the EPS RHA concrete bricks. Scanning electron microscopy (SEM) analysis was also performed on the brick samples. Four types of curing conditions were employed in this study. These include full water curing, air dry curing, 3-day curing and 7-day curing. It was found that the properties of the bricks are mainly influenced by the content of EPS and RHA in the mix and also the curing condition used.     

空心砖瞬态传热数值研究

利用自然对流和热传导的物理耦合模型,控制方程采用有限容积法,求解算法使用SIMPLE算法,研究了空心砖在外界环境变化条件下的瞬态传热规律。通过计算得到空心砖内外壁温的变化情况及延迟特性,同时也研究了通过空心砖的热流变化规律,并与实心砖的传热过程比较,发现实心砖和空心砖的内壁面温度的延迟相差不大。而空心砖与实心砖热流量相差很大,实心砖的平均热流约比空心砖平均热流大41.5%,说明空心砖节能效果显著。     

环境相容的砌筑材料

环境相容材料是应最大限度地减轻环境污染，而材料本身也应是耐久的。因此要求大量利用工业废料。文章仅涉及砌筑材料，即在此将仅简单介绍烧制工业废料砖和垫心砌块、胶凝粉煤灰垫心砌块及蒸压粉煤灰砖和空心砌块等。     

The compressive strength of cement blocks permeated with an organic phase change material

The authors investigate the feasibility of constructing walls and partitions with enhanced heat storage capability from cement blocks permeated with an organic phase change material (pressed stearic acid). The blocks are lightweight, easy to produce and are cured in the same way as cement or concrete.The ratio of components (cement, stearic acid (SA) and water) was optimized with respect to compressive strength. With normal portland cement, the best compressive strength 2.2 MPa was obtained with a ratio C:SA:W of 1:0.8:0.65 (i.e. 32% stearic acid) after 28 days of curing. This was increased to 4.4 MPa when high early strength cement was used, about as strong as Sipporex, lightweight concrete or lightweight clay bricks.As expected, the compressive strength decreased linearly with temperature between 25°C and 100°C, at a rate of 15 kPa/°C. The drying shrinkage of the modules was found to be 50% greater than for cement mortars. The addition of fibreglass gave only a 15% increase in the compressive strength. Samples containing 35% fatty acid showed surface deterioration after 200 thermal cycles (between ?5°C and 6 °C) while none was observed with those containing 32%. The dynamic modulus of elasticity did not change after 200 cycles.     

节能型烧结空心砖(砌块)强度检测与砌筑的探讨

为降低烧结砖墙体的"使用耗能",烧结空心砖采用薄壁多孔洞单向错位排列结构设计。比对试验证明,单向错位排列的孔洞结构导致烧结空心砖的不同受压面的抗压强度相差悬殊。因此,烧结空心砖必须按产品说明书规定的砌筑面施工和检测。节能型烧结空心砖(砌块)是烧结空心砖(砌块)的一种,也属于"烧结保温砖和烧结保温砌块"。目前尚无国家、行业、地方"节能型烧结空心砖和空心砌块"专用标准,该文建议将《烧结保温砖和保温砌块》(GB26538-2011)作为"节能型烧结空心砖"产品标准执行。砖厂应在产品说明书中标明"砌筑面"及强度等级,施工必须按规定面砌筑。     

Mechanical properties of adobe bricks in ancient constructions

A study of the mechanical properties of adobe bricks collected from houses and land dividing walls in Aveiro district, Portugal, representative of existing traditional constructions, was conducted. Cylindrical adobe specimens were subjected to simple compression and splitting tests. From these tests it was possible to evaluate the strength capacity, stiffness and deformation evolution for increasing loading. Correlations between the evaluated properties were determined, and the results obtained for houses and land dividing walls were compared. This study contributes for the characterization of adobes traditionally used in Aveiro district, and provides reference values that can be considered in rehabilitation processes.     

碳化养护制备高强钢渣砖的研究

以水泥、钢渣、标准砂为原材料,通过碳化养护制备钢渣砖。研究了钢渣掺量、水灰比、碳化强度和碳化时间对钢渣砖抗折、抗压强度的影响,并利用XRD和SEM对钢渣砖的矿物组成和微观结构进行了分析。结果表明:随着钢渣掺量的增加,钢渣砖的力学性能先提高后降低,钢渣掺量为40%时,钢渣砖的力学性能最佳,7 d抗折、抗压强度分别为6.9、47.7 MPa;钢渣砖的力学性能随着水灰比的升高而降低,水灰比为0.5时,钢渣砖的抗折和抗压强度最高;碳化压强为3 MPa、碳化时间为3 h时钢渣砖力学性能最好。     

Use of recycled aggregates in molded concrete bricks and blocks

This study aimed to develop a technique for producing concrete bricks and paving blocks using recycled aggregates obtained from construction and demolition waste. Laboratory trials were conducted to investigate the possibility of using recycled aggregates from different sources in Hong Kong, as the replacement of both coarse and fine natural aggregates in molded bricks and blocks. A series of tests were carried out to determine the properties of the bricks and blocks prepared with and without recycled aggregates. The test results showed that the replacement of coarse and fine natural aggregates by recycled aggregates at the levels of 25 and 50% had little effect on the compressive strength of the brick and block specimens, but higher levels of replacement reduced the compressive strength. However, the transverse strength of the specimens increased as the percentage of replacement increased. Using recycled aggregates as the replacement of natural aggregates at the level of up to 100%, concrete paving blocks with a 28-day compressive strength of not less than 49 MPa can be produced without the incorporation of fly ash, while paving blocks for footway uses with a lower compressive strength of 30 MPa and masonry bricks can be produced with the incorporation of fly ash.     

巴西拉机械厂住宅 竞赛项目，赫尔辛基，2004（建造中）

住宅区位于赫尔辛基中心区的前铁路机械设备厂附近。红砖是住宅区周围旧建筑的主要材料,新建筑也将采用红砖作为主要的立面材料。在芬兰的特殊环境下,深色砖立面通常会使住宅区显得过于灰暗。为了丰富环境并使建筑显得更加轻盈。除了砖墙以外，这些住宅还使用了白色和其他多种色彩。钢材也在住宅区的细部处理上加以应用，     

Towards a participatory loan – supported housing scheme: Helwan New Community, Egypt

Most of the developing countries, including Egypt, face problems of providing affordable housing for low-income strata. The evolution of these problems and their nature differ from one country to another, according to the political, social and economic contexts. This paper represents an attempt to provide an insight into the development of a housing scheme which offers a way of reducing costs without completely losing control of appearance. This case study, of low-income housing projects in Egypt’s Helwan new community, provides an example which serves to present the major common problems in such housing projects. The paper will shed light on the obstacles that were encountered when implementing the project and the recommended actions that should be taken in order to apply this policy. It is argued that the participatory loan-supported housing scheme is a means of creating low income and affordable housing in many developing countries.     

Analysis of coupled natural convection–conduction effects on the heat transport through hollow building blocks

In the present study, the coupled convective and conduction heat transport mode in a common hollow building brick is studied. Heat transfer rate through building bricks is examined in order to asses the suitable brick insulation configuration. Three different configurations for building bricks are considered. The first is a typical brick of three identical hollow cells (air cavities), the second is obtained by filling these cells with ordinary polystyrene bars and the third is obtained by using hollow polystyrene bars. The geometry of the first and third configurations considered in this study is simply a solid closed frame surrounding square cavities filled with air. The second configuration is a solid composite slab. Solving Navier–Stocks equations assuming Boussinesq approximation, using the commercial Fluent software, showed that the cellular air motion inside blocks’ cavities contributes significantly to the heat loads. Insertion of polystyrene bars reduced the heat rate by a maximum of 36%. Using a hollow polystyrene bars reduces the heat rate by 6% only due to the air motion inside cells. In order to estimate the heat rate during a day, the air temperature and solar insolation data of a typical summer day for the city of Jeddah, Saudi Arab, are used. A quazi-steady state approach is implemented to estimate an equivalent facade surface temperature, which is then used as boundary for solving the simulation model. Such an approach showed that the effective overall daily heat rate reduction using polystyrene filled bricks to be 25%.     

秸秆石膏渣空心砌块墙体轻质节能

目前,我国的建筑内外墙体仍以粘土砖为主,混凝土空心砌块为辅。混凝土空心砌块属非粘土质新型墙材产品,用于建筑围护结构热工性能差,容重大是较突出的问题。秸杆石膏渣墙体空心砌块容重450-1000kg/m3,导热系数为0.12-0.135W/m·k,作为建筑围护结构不仅容重轻,节约基础用材,且单一材料即可满足建筑节能50%的要求。为小城镇绿色住宅建设就近提供了环保墙材,既可降低生产成本,又能保护耕地,节约能源。其技术、经济、社会效益均十分显著。     

甘肃省墙体材料放射性水平安全调研报告

针对利用工业固体废弃物生产墙体材料的放射性问题,甘肃省墙改领导小组办公室委托兰州大学核科学与技术学院开展《甘肃省部分地区新型墙体材料放射性水平检测评价研究》市场调研项目,选取有代表性的甘肃省某市墙体材料产品(烧结煤矸石砖、粉煤灰砖、加气混凝土砌块、烧结空心砌块、纤维水泥板)进行了抽样测试.经检测,墙体材料产品全部符合国...     

Cementless pressed blocks from waste products of coal-firing power station

The effect of altering composition of cementless building materials on basis of waste products of power station including hydrophobic additive and the molding compaction on the compressive strength, water uptake and water absorption was examined. A possibility to get water-stable materials at curing in the ambient air was established. It was shown that water uptake might be reduced by different methods, the best of which is short-term impregnation by a hydrophobic liquid of the siloxane group. Results from experiments with small specimens and full size pressed blocks were compared. It is noted that blocks answered to the requirements of Israeli Standard to cement concrete blocks.     

高凝胶强度吸水树脂的性能及在雨水处理中的应用

利用杭锦土合成了一种凝胶强度较大的吸水树脂,并将其用来处理雨水,考察了树脂添加量、处理时间、雨水的pH等因素对处理效果的影响;此外还利用该吸水树脂制成了强度较高的保水砖,研究了吸水树脂的添加量对保水砖失水的影响。试验结果表明:杭锦土能成功地接枝吸水树脂;加入杭锦土的吸水树脂,其凝胶强度明显提高;高凝胶强度吸水树脂能较好去除雨水中的主要污染物,100 mL雨水在pH值为7~8、树脂投加量为1 g左右、吸附时间为10 min左右时的处理效果较好;含10%吸水树脂的生态砖,其保水性能较好,所制保水砖的其他性能达到JC 943—2004标准。