Properties Of Building Materials Research Articles

Physical evidence of swelling as the cause of anomalous capillary water uptake by cementitious materials

Water uptake by capillarity is widely used for characterising the durability properties of building materials. However, cementitious materials are generally reported with an anomalous behaviour in relation to other construction materials: during capillary water uptake they show a non-linear evolution with the square root of time. Several hypotheses have been proposed to explain this anomaly, among which the most sound seems to be the hygroscopic nature of cementitious materials, since the swelling of the calcium silicate hydrates when in contact with water could limit the water flow. Using strain gauges attached to mortar and concrete samples, we monitored their deformations during capillary water uptake. This paper presents those results and their connection with water ingress. Experimental data registered during water uptake allow validating the swelling hypothesis. The idea of cementitious materials as rigid materials during capillary water uptake seems incomplete for a comprehensive description of the transport process.

Nanomechanical and Topochemical Changes in Elm Wood from Ancient Timber Constructions in Relation to Natural Aging.

Knowledge of properties of building materials affected by aging is of great importance to conserve cultural heritages or replace their biopolymer components. The objective of the study was to investigate the chemical characterization change in the biopolymer components and identify whether these changes are correlated with alterations in the nanomechanical properties of the wood cell wall bio-composites in relation to natural aging. The effects of natural aging on the elm (Ulmus) wood component (dated from 1642 to 1681) of Chenghuang Temple, an ancient timber construction in China were investigated to understand the chemical and mechanical changes in the wood cell wall. Especially, confocal Raman microscopy and nanoindentation (NI) were used to track changes in the chemical structure and nanomechanical properties. The results showed that the morphological, chemical and physical properties of cell walls changed with aging. After aging, the cell structure showed evidential alternations, and the wood components, especially hemicellulose and lignin, were degraded, leading to deterioration of mechanical properties of aged wood compared with normal wood. Morphology deterioration and micromechanical changes only occurred on the surface with the depth of about 3.6 mm of the aged element. This study would be helpful to provide practical guidance for protecting the apparent performance of ancient timber structures.

Hygric properties of porous building materials (IV): Semi-permeable membrane and psychrometer methods for measuring moisture storage curves

The moisture storage curve is an important hygric property of porous building materials. It describes the moisture storage characteristic of a material via the relation between the moisture content and the moisture potential. Current experimental protocols for measuring moisture storage curves are not satisfactory, as they often require extensive facilities while still lacking the capability to handle the adsorption process in most of the over-hygroscopic range. This paper proposes two novel and simple methods – the semi-permeable membrane method and the psychrometer method – to solve these issues. Measurements on calcium silicate, autoclaved aerated concrete and ceramic brick are performed and validated by comparing the experimental outcomes obtained from these two novel methods and from other existing protocols. It is proven that the semi-permeable membrane method and the psychrometer method are applicable for both adsorption and desorption processes, the latter both from saturated and capillary moisture content. Limited by the accuracy of the psychrometer and the condensation caused by temperature fluctuations, these two methods show their best applicable range for capillary pressures below −1·105 Pa. The semi-permeable membrane method and the psychrometer method also feature in low cost, simple handling and application efficiency.

Structural Modification of Ceramic Brick with Multi-Walled Carbon Nanotubes

The paper considers a method for improving physical and mechanical properties of ceramic bricks made from low-melting low-grade clay and quartz sand. The priority task is to develop a kind of batch based on widespread low-grade clay containing less than 13.5% of Al2O3. This provides high physical, technical and operational characteristics of brick. To improve the properties of ceramic building materials, multi-walled carbon nanotubes (MWCNTs) can be used as an effective structural modifier in an amount of 0.001-0.009% of the clay mass. Adding an aqueous dispersion of MWCNTs to the composition of ceramic batch increases the density and uniformity of the structure of ceramic matrix and influences its strength characteristics. The increase in the strength indices of ceramic has been found to occur in both cases of using freshly prepared batch and batch seasoned for a long time, up to 6 months. Nanotubes already influence the strength of the samples at the stage of air brick forming, while the compressive strength increases by 50%. After firing, the compressive strength of fired modified samples increases by 109%. Thus, using an aqueous dispersion of MWCNTs improves the structure and physical and mechanical properties of ceramic brick.

Evaluation of reverberation chamber relation to reverberation time and distribusion of sound pressure level with ISO 354 as standart in building physics laboratory of physics departement ITS

Many of the building materials on the market in Indonesia are not included with material properties data. In acoustic books, quite a lot of acoustic data are listed, but these data do not match the material marketed in Indonesia. Bricks that are marketed in European countries or neighboring countries, have different nature with brick in Indonesia. so that materials from abroad do not reflect the acoustic properties of building materials in Indonesia. One important data is the value of material absorption coefficient. Calculating The value of the absorption coefficient is performed in a standardized Reverberation Chamber. In this study conducted an evaluation of Reverberation Chamber in Physics Laboratory Building Department of Physics FIA ITS. The method used in the study refers to ISO 354. From the measurement results have been obtained cut-off frequency of 20 Hz while the critical frequency is 150 Hz. The measured RT value is quite high and above the minimum RT value of ISO 354 in all frequency ranges as shown in figure.1. as shown in figure.1, at a frequency of 500 Hz, Reverberation Time reaches 7.35 s. Evaluation of this Reverebration Chamber is important to know if it can be done as a test chamber.

Reinforcing Mechanism of Graphene and Graphene Oxide Sheets on Cement-Based Materials

AbstractGraphene and graphene oxide (GO) sheets have great potential to improve the properties of traditional cement-based building materials. This research studied the effects of graphene and GO s...

Influence of heavy metals on thermal conductivity of clay as a building material

ABSTRACTThermal conductivity of contaminated clay is an emerging field of interest in building construction. This study investigated the influence of some heavy metals on thermal conductivity of clay. The objective of this study is to investigate the influence of heavy metal in clay for energy-efficient in building constructions. The clay sample was collected from clay deposit and prepared. The samples were mixed (contaminated) with nitrates of Pb, Fe, Zn, Ni and Cu at different concentrations and slabs then were formed. The thermal conductivity of clay slabs were measured to determine the suitability of contaminated clay as building material for heat emitting modern equipment room. The thermal conductivity of clay slabs contaminated with nitrate of Pb, Fe, Zn, Ni and Cu ranged 0.06–0.15 Wm−1K−1; 0.06–0.18 Wm−1K−1; 0.06–0.22 Wm−1K−1; 0.06–0.19 Wm−1K−1 and 0.06–0.38 Wm−1K−1, respectively. Results showed that thermal conductivity of clay increases with increase in the concentration of heavy metal absorbed by the clay to an optimum level. Hence, heavy metals influenced the thermal properties of clay building material.

A round robin campaign on the hygric properties of porous building materials

The reliable determination of the hygric properties of porous building materials is important. In earlier round robin campaigns large discrepancies of measured hygric properties were found among different labs. Later studies indicated that differences in lab conditions and more importantly, personnel’s operation procedures and data processing methods, might have the greatest impact. To gain further insight, a new round robin campaign has been launched by KU Leuven (Belgium), to which another eight institutes contributed. A relatively stable and homogeneous ceramic brick is tested, and 3 standard tests are performed: the vacuum saturation test, the capillary absorption test and the cup test. During the campaign, two rounds of measurements are performed. In the 1st round, tests are performed according to participants’ respective experimental protocols. Next, a strict and detailed common protocol is prescribed. This paper reports on the results obtained in the 1st round of measurements. Results show that not much progress has been made since the EC HAMSTAD project: the vacuum saturation test leads to the most consistent results, while the cup test produces the largest discrepancies, most probably originating from sample sealing and humidity control.

Acoustic and thermal properties of hemp-cement building materials

Abstract The present research aims to analyze the sound absorption coefficient and the thermal conductivity of the building materials based on hemp. Nowadays, two main problems affect the characteristics of the space where people live and work: the unwanted sounds and the thermal insulation. On the materials building market there are products which can reach these parameters, but separately. For this reason this study looks at more in-depth constructive solutions of the hemp-based composite materials, which can respond at the same time to the acoustic and thermal properties of the space where people are. The experimental program was based on the study of hemp based building materials divided in two categories: monolayer and multilayer samples. For obtaining the building materials the hemp elements used were the fiber and shiv, produced in Romania. The binder which connected the hemp elements was the white cement. The sound absorption coefficients were analyzed using the impedance tube and for the thermal conductivity the Fox200 device was used. It was noticed, in the first situation, that the recipe which was made only from one layer of fiber had better acoustic and thermal properties than the shiv monolayer recipe. In the second situation the samples with triple layer compositions presented a difference of 25% for the sound absorption coefficient and 20% for the thermal conductivity coefficient depending of the layer composition of the samples.

Towards stochastic generation of 3D pore network models of building materials

Pore-scale-based prediction of the hygric properties of porous building materials is on the rise as an attractive alternative for the current experimental procedure. Pore-scale simulations do however require a complete pore network model for the building material. With the currently available characterization techniques, such complete pore network model cannot be established, instead typically fragmented direct (pores sizes, shapes, positions, connections, …) or indirect (pore size distribution, pore surface area, …) information is obtained. The aim of this paper is to present stochastic pore network generation, wherein the fragmented pore structure information is used to generate a complete pore network for the building material involved. The novelty of our approach lies in the generation of a PNM by matching the distributions of direct parameters as well as indirect parameters of the input data and the model. Additionally, the position of the pores are no longer bound to a cubic lattice. This workflow will first be tested on a single scale material with a relatively straightforward pore space such as sintered glass. Finally, the hygric properties of the generated network will be compared to the measured properties of the real material as a validation step.

Calculation method to determine capillary properties of building materials with automatic free water intake test

The water absorption coefficient and capillary saturation water content are common building physical material properties. This paper presents a calculation method to determine these values with an automated free water intake test arrangement. Buoyancy affects weighing results in the automatic measurement and it is recommended to take these factors into account when deriving the real water intake of a specimen. A new mathematical method is presented and trial experiments have been conducted. The method is proven to work with the polymer modified plaster, concrete, autoclaved aerated concrete and lightweight aggregate concrete, which represent materials from both extremes of capillary activity. The functionality and advantages of the test arrangement for both low and high suction materials are presented.

Centrifuge experiments for the determination of the moisture storage and transport properties in the overhygroscopic range

This study explores the potential of a centrifuge experiment for hygric property determination. In this method, a core sample is placed in a tube which is spun at different rotational speeds to create a distribution of moisture contents and capillary pressures. This way, a simultaneous determination of the moisture retention curve and moisture permeability curve is possible. Measurements performed in the petroleum industry and in soil science already showed the technique to be an appropriate substitute for the pressure plate method. In building physics, the potential of the centrifuge method is currently still unexplored. Therefore, in this study, preliminary desorption measurements on brick samples are performed. To infer the moisture retention curve, an approximate data analysis method is applied. This approach is compared to a more sophisticated parameter estimation technique, which is also used to infer the moisture permeability curve. From a theoretical point of view, the centrifuge method allows a simultaneous determination of the moisture storage and transport properties of building materials. In practice, however, experimental inaccuracies make the experimental results unusable for a reliable determination of the moisture transport properties.

Methods for determination of acoustic properties of building materials

Experimental determination of acoustic properties of building materials is an important task gaining higher importance due to demand for materials suitable for constructions located in places with high level of noise, typically in urban areas and places close to the areas with heavy traffic. In this paper, two types of experimental setups are arranged, and tested on steel prism and brick block. Transmitter-receiver method is based on exciting the tested material by one period of harmonic signal and analysis of response on two accelerometers placed on the excited and the opposite side of the sample. The second method is based on measurement of the sound pressure level in a system of two reverberation chambers by precise microphones and vibration analyzer. Transmitter-receiver measurement conducted on steel sample revealed the fact that further adjustment of the measurement setup and successive analysis is necessary. Measurement in reverberation chambers is convenient for comparison of acoustic insulation ability of heterogeneous building materials.

Assessment of the effects of temperature and moisture content on the hygrothermal transport and storage properties of porous building materials

Heat and moisture transfer models are increasingly used in building thermal and energy simulation tools. These phenomenological transfer models are based on experimentally evaluated input data. Therefore, to ensure a better prediction of the hygrothermal behavior of the building envelope, a correct and reliable experimental evaluation of these parameters is required. Indeed, these input data are the thermal and hygric properties of the materials constituting the wall. However, the hygrothermal properties available in the databases are far from complete, particularly regarding the evolution of these properties with changes in the water content and temperature of the material. In this paper, an experimental characterization campaign of the main transfer and storage hygrothermal properties is conducted, with particular interest in the variation of these properties as a function of the temperature and the water content of the material. In this work, different materials are analyzed: cinderblock, plaster, chipboard and red brick. This study includes analysis of the thermal conductivity, the specific heat capacity, the water vapor permeability, and the moisture storage capacity. The obtained results confirmed that the water content and the temperature of the material have considerable effects on the values of its hygric and thermophysical properties. Indeed, the thermal conductivity and the specific heat capacity of a hygroscopic material as plaster can reach an increase of 2 times between dry and saturated states. Concerning water vapor permeability, a relative gap of 30% is observed between the values obtained at 20 °C and 30 °C. Therefore, enriching existing databases with this type of information is essential to ensure a reliable prediction of the hygrothermal behavior of the whole building.

Efficient complex activation of Portland cement through processing it in the vortex layer machine

Today, more and more studies are devoted to activation of primary components of building materials. This paper is concerned with the viability of activating mineral bonding materials, Portland cement in particular, in the Vortex Layer Machine (VLM) with a purpose of physical modification. By applying modern methods for studying the specific surface, pH change, X‐ray phase and differential‐thermal analysis, and IR spectroscopy, it was found that activation of Portland cement in the VLM constitutes an efficient method for enhancing physical and chemical activity. It was also found that, depending on the content of mineral additives in the VLM, activation of Portland cement leads to significant extension of its specific surface, decrease of particle size, and also to prevalence of processes related to activation of an agent in the surface layer. During activating Portland cement, mineral crystal structure is being destructed, with the most significant changes observed for C3S. Besides, processing Portland cement in the VLM results in polycondensation of SiO4‐tetrahedral units, which reduces the basicity of hydrated calcium silicates during hydration; in the cement stone, ettringite content increases, and so does content of low‐basic hydrated calcium silicates and aluminates, which reinforces strength and chemical resistance of concrete. The acquired results speak for benefits of activating mineral bonding materials in the VLM with the purpose of enhancing physical‐mechanical properties of building materials.

The Protection of Masonry Blocks with Using Hydrophobization Before Load Due to Increased Moisture

The Faculty of Civil Engineering (Brno University of Technology) has for several years been developing and researching the properties of modern building materials. One area of research is the development and modification of the properties of masonry elements, particularly masonry blocks that are able to withstand increased moisture loads. These masonry blocks can be used as protection in buildings in flood areas or buildings that may be prone to damage from natural disasters. Increased moisture is one of the most common problems encountered in building structures. Most problems concern moisture in liquid form, which can have significant effects on changing the properties of materials and structures. If the structure of brick blocks is changed by moisture in liquid form due to porosity and water absorption, thereby affecting load, it can reduce the service life of masonry blocks. This paper investigates the use of special silicone products on the surface layer of ceramic masonry elements. The application of these silicone agents forms a protective surface layer on masonry blocks, protecting them via hydrophobisation and the effects of increased humidity. Hydrophobisation reduces water absorption into masonry blocks and eliminates the negative effects of moisture on the properties of masonry blocks. Through hydrophobisation, masonry blocks can be extremely effective for use as preventive protection in case of failure or damage on the part of conventional waterproofing measures.

Climatic influences on the building materials properties based on wood-polymer compositions

The work is devoted to the assessment of the influence of climatic influences on wood-polymer composites (DPC), which are actively used for the production of building materials. In particular, terraced boards and other construction materials are made from them. Since terraced boards are often used outdoors, it is necessary to study in detail the effect of moisture on the change in color of products, their water permeability, the ability to withstand UV radiation, etc. In the work, terraced boards produced by the domestic company Savewood are investigated. The matrix polymer was polyvinyl chloride (PVC). The studies were accompanied by theoretic studies of water permeability. The relationships describing water permeability of polymers are given. These ratios include the parameters of the chemical structure of polymers. Experiments on the influence of climatic effects are performed with the help of modern instruments at positive and negative temperatures

New Method for Historic Rammed-earth Wall Characterization: The Almohade Ramparts of Malaga and Seville

ABSTRACTThe goal of this research is to propose a new method of characterizing rammed-earth walls. Based on their historic building materials properties, five broad test groups were established for the characterization: chemical and mineralogical composition, physical properties, mechanical properties, particle size distribution, and dating. These determinations can, in turn, be grouped into two different types: instrumental techniques such as XRF, XRD, and SEM-EDX, as well as adaptations of standard methods (mainly UNE-EN standards) for application to these materials. As case studies where the proposed method is applied, we present our research on the rammed-earth walls in the ramparts of Seville and Malaga (Spain), clearly showing the method’s capacity for comparing and differentiating different rammed-earth walls.

Automated and Optimized Sensor Deployment using Building Models and Electromagnetic Simulation

With the advent of wireless sensing technology and interest in tracking resources, researchers have developed advanced tracking algorithms by using one or more sensor systems for improved accuracy and reliability of tracking. The objective of this research lies in another aspect−deployment−of tracking that has received only little attention until now. The research explores a method for sensor deployment particularly designed for the building in which the sensors are used. To tailor our solution to a specific building, we integrate a building information model with an electromagnetic energy analysis. By using such a model, the system extracts the properties of building materials, which are used as parameters of sensor deployment optimization. Then, we find a method of optimizing the deployment of a Received Signal Strength Indication (RSSI)-based tracking sensors for reducing wireless energy dissipation during the operation of the tracking system. For the numerical validation of the proposed method, the High-Frequency Structural Simulator (HFSS) runs an electromagnetic simulation to generate comparison data of electromagnetic energy flow from optimized sensor deployment and random sensor deployment. The results indicate that the proposed method could produce results that are correlated to the HFSS results. In addition, the method shows clear evidence of a reduction in signal power loss. Finally, optimized sensor deployment through the proposed framework can use signals of electromagnetic energy more effectively and potentially improve the efficiency of the RSSI-based tracking system.

دراسة تأثیر تقنیات النانو على مواد البناء وانعکاسها على العمارة أحمد حنفى محمود أحمد

Nanotechnology has dominated various aspects of life in this age, especially architecture , It is the most promising technology in the field of architecture, It offers a variety of trends in the manufacture of new materials and modified materials after improving their properties, whether in construction materials or non-structural or coating materials, insulation and lighting, It also provides architecture with new systems that narrow the gap between the evolution of modern design methodologies resulting in complex forms and the methods available in the implementation of these forms and complex configurations, Which means that the design process is affected by nanotechnology, It also gave architecture multiple possibilities to form an architectural product that is interacting with the environment through the use of improved building materials such as glass, concrete, etc. - Therefore, the study of the integration of nanotechnology and architecture increases the level of building performance, Development in this area can lead to the removal of the boundary between the building and the external environment, The casing of the building serves as a data-gathering interface that responds to the stimulus and external influences and adapts them through interaction with different levels of intelligence and responsiveness, The building envelope can also be transformed from one shape to another, from a fixed system to a dynamic one. - The research deals with the development of nanotechnology and its impact on architecture, and its advanced properties of construction systems and various construction materials, whether concrete, steel, wood derivatives, or various cladding materials, Using digital processing, a new approach to the design and manufacture of building casings can be introduced by controlling the mechanical and physical properties of building materials at the scale of their nanoscale structures and their atomic composition To obtain new materials that are more efficient and effective than the less effective original materials. These new technologies allow buildings to create a dynamic relationship between the building and surrounding environmental factors such as heat, humidity, light, sound and wind, by modifying the performance and behavior of materials and even their form to ensure environmental control and energy saving strategies.