Concrete Brick Walls Research Articles

Failure mode dependent shear strength of unreinforced concrete brick masonry wall panels

This study conducted diagonal compression tests to propose the failure mode dependent shear strength for unreinforced concrete brick wall panels. The test variable was the bed-joint mortar mixing ratio. Six brick wall panels were manufactured for each variable, and finally thirty specimens were tested. The test results showed five failure modes in the unreinforced masonry wall panels: diagonal tension, combined, bed-joint sliding, toe crushing, and non-diagonal failure. Furthermore, the shear strength of unreinforced brick wall panels was highly dependent on the failure mode. Based on the test results, the shear strength is suggested according to each failure mode. Additionally, the shear modulus of concrete brick wall panels was suggested as half of the value presented in the current codes for masonry structures.

A comparative analysis of compression bearing capacity in recycled concrete brick walls and composite walls incorporating coal-ash blocks.

In the face of the problem of waste disposal in the demolition of concrete structures, a composite wall composed of recycled concrete bricks and fly ash blocks was proposed, and based on the previous thermal performance research, its axial compression performance were further studied. Four types of walls were designed and constructed: (1) clay brick masonry (CBM), (2) recycled concrete brick masonry (RBM), (3) bilateral clay bricks masonry with coal-ash blocks sandwich insulation wall (CFCM), and (4) bilateral recycled concrete bricks masonry with coal-ash blocks sandwich insulation wall (RFRM). The test results showed that recycled concrete brick masonry exhibited a higher bearing capacity than clay brick masonry. The ultimate load of RBM was 15% higher than that of CBM. Moreover, the ultimate load of CFCM was 21% higher than that of CBM. Following the addition of sandwich coal-ash blocks in RBM, its ultimate load increased by over 42% than that of CBM. Following the addition of coal-ash blocks sandwich in both clay and recycled concrete bricks masonry, both the bearing capacity and strain exhibited improvement, the yielding load and compressive strength of them increased. Thus, it could be concluded that coal-ash blocks improved its bearing capacity. Based on the analysis of the axial compression tests, a theoretical computational model was developed and a computational expression to explain the compressive bearing capacity of a two-sided brick with coal-ash blocks sandwich insulation wall. Comparisons between the test ultimate loads (FT) and the estimated ultimate loads (FE) confirmed the accuracy of the theoretical calculation model for the compressive bearing capacity. Thus, theoretical computational models are highly recommended for the design of two-sided bricks with insulating walls constructed from coal-ash blocks being sandwiched together. This study provides a theoretical basis for the engineering application of recycled concrete brick wall and fly ash block composite wall.

A 0.9 - 1.5 GHz CMOS UWB Radar IC for Through the Wall Human Detection

In this paper, a UWB radar IC for the through wall radar is presented to achieve the smaller form factor of the module and low power operation. For the penetration performance enhancement, the radar IC s designed for the lower 0.9 – 1.5 GHz band. The radar IC employs the 4-channel time-interleaved equivalent time sampling receiver for 200 ps fine resolution, and the digitally synthesized impulse generator for the transmitter. The human target behind the concrete brick wall can be detected in the distance over 9.4 m with the help of signal processing part and additional amplifiers. The radar transceiver IC is fabricated in a 0.13 μm CMOS technology and the current consumption is 116.3 mA at the 1.2 V supply.

The performance optimization of concrete bricks using a sagu fiber

Sagu (sinonggi/kapurung) is a typical food of the Tolaki ethnic group. Sagu (Metroxylon sagu rottb) is an endemic plant in Southeast Sulawesi Province. So far, sagu waste in the form of fibers (sagu fiber) has not been optimally utilized. Sagu fiber waste is only left to mount; some are dumped into the river, so it is feared that it could pollute the environment. Through innovation in reducing waste in the principles of sustainable construction, sagu fiber will be used as an added material to manufacture concrete brick wall pairs. This study aimed to test the compressive strength and water absorption capacity of sagu fiber concrete bricks with variations of 0%, 50%, 60%, and 70% sagu fiber under the sand. This study uses an experimental method with stages such as preparing work tools and work materials, making test objects, and testing. Data were analyzed using mathematical formulas for the compressive strength of concrete bricks and water absorption capacity, compared with SNI 3-0349-1989 for solid concrete bricks, and analyzed comparatively. Based on the test results in this research laboratory, it is concluded that a balanced composition to get good quality is found in 70% sagu fiber and 30% sand.

Acoustic and Thermal Correlation for a Building’s Envelope in a Mediterranean Climate in Morocco

The aim of this paper is to present a comparative analysis of the thermal and acoustic insulations of four different buildings' envelopes: Single layer clay brick wall (Wall(a)), Single layer concrete brick wall (Wall(b)), double layer hollow brick wall with a medium of polystyrene (Wall(c)) and double layer hollow brick wall with a medium of air (Wall(d)), which are all modelled and simulated by using finite element method (FEM) under different climatic conditions. Moreover, the study of noise transmission through these walls was released by placing a linear nonmonochromatic source of sound 1m away from the exterior side of each wall and it is emitted sound waves with a velocity of 200 m/s with low frequencies, while an acoustical comparative analysis was investigated under the same thermal conditions as the two previous steady states study. The analysis of the heat transfer and sound pressure level (SPL) variations through the walls (a), (b), (c) and (d) shows that the wall (d) is a good thermal and sound insulator compared to the walls (a), (b) and (c) due to the insulation by air gap with a thickness of 0.06 m, it provides a high rate of sound pressure level attenuation compared to the other walls under study. Finally, the insulation by air-gap gives is good enough to ensure simultaneously energy savings and acoustic comfort.

The utilization of plastic waste in a mixed pair of concrete brick walls

Plastic is a daily consumable material due to its easy accessibility and affordability. The high production of plastic waste contributes to the increase risk of hazardous environment which is difficult to be processed and decomposed. One of the solutions is to recycle plastic waste. In this study, the types of High Density of Polyethylene (HDPE) and Polypropylene (PP) were utilized as substation material with 10% of ratio to be mixed in pair with concrete brick walls. The sample study was concrete bricks characterized with dimensions of 40x20x10 cm3 and 15x15x15 cm3. The addition of admixture SikaPayer HC-1ID and silica fume as additive was carried out to improve the performance of testing samples. Samples of concrete bricks were then attached on the wall as a mixed pair with dimension 105x95 cm2, and compression properties were performed. The results showed that visual appearances, content weight, and adsorption ability of two samples were classified as concrete brick type I, and the addition of HDPE and PP to the concrete bricks walls contributed into type II which were able to with-stand load around 2200 and 2800 Psi respectively. The other eminence that was observed from the addition of HDPE and PP was milder weight compared to neat concrete bricks.

Experimental investigation of hysteretic behaviour of non-structural dry gypsum infill walls

Studies carried out concerning the non-bearing partition wall systems used in buildings have increased in recent years. A very limited number of studies about the behaviour of gypsum wallboard systems under cyclic repeated loads have been found in the literature. An experimental study was carried out under earthquake loads to investigate the properties of gypsum wallboard systems, such as general load–displacement behaviour, stiffness, displacement ductility ratios and energy dissipation capacities. Ten different non-bearing wall specimens were produced. Four of these wall specimens consisted of different gypsum wallboard infill walls and the remaining six consisted of plastered and non-plastered infill wall specimens built with clay bricks, light concrete briquettes and aerated concrete blocks. As a result of this study, the performance levels and general behaviours of dry gypsum infill wall systems under the effect of horizontal cyclic reversible loading were determined by comparing with other infill wall systems. Although the initial stiffness and ultimate load capacity values of the dry gypsum infill wall systems were lower compared to a masonry infill wall and lightweight concrete brick walls, it was determined that they performed very successfully in terms of displacement ductility ratio and energy dissipation capacity.

Selective demolition of masonry unit walls with a soundless chemical demolition agent

A soundless chemical demolition agent was applied for selective demolition to unit masonry [2 full-scale concrete brick walls in Type N mortar and 2 wallettes in lime mortar – 1 historic brick and 1 concrete brick]. Typically, cracking began shortly after 9 h and ultimately produced an average crack length of 418 mm per hole and an average maximum 5.22 mm crack width. Samples in Type-N mortar exhibited slower but significantly more cracks and wider cracking. Ninety-three percent of cracking occurred within 4 days. No masonry units were damaged and partial demolition was successful, although selective unit removal was not due to confinement.

The impact of thermal mass on building energy consumption: A case study in Al Mafraq city in Jordan

This research discusses the usage of thermal mass of construction materials to produce comfortable thermal indoor environment and to reduce energy consumption used for cooling and heating. What motivated this research is the disappearance of traditional construction methods and materials, such as thick stone and clay walls. Stone is used as a coating material in new buildings, but little attention is given to its significant thermal properties. These construction methods which are ideal to perform as thermal masses are becoming extinct in modern buildings. To achieve this aim a test of thermal mass efficiency is conducted on a case study building which consists two parts of different thermal mass under same climate condition in Jordan. Indoor temperatures of two rooms; one with clay walls; and a second room with concrete brick walls are measured at day and night times in summer and winter. Findings indicate that in hot and cold climates, the temperature inside the room of clay walls are kept within the human comfort zone, unlike the temperature in the room with concrete walls, which was not in the human comfort zone by 5°C. Results are recorded and analyzed to draw useful insights and recommendations. This research concludes that construction materials of high thermal mass, such as clay-bricks, significantly keep the indoor environment within the human thermal comfort zone. Thus, the energy required for maintaining the thermal comfort of the room is greatly reduced.

Numerical investigation of thermal insulation options for non-insulated buildings in Saudi Arabia

ABSTRACT Residential electricity prices in Saudi Arabia sharply increased by more than 250% in early 2018. In this study, to improve the thermal insulation efficiency of non-insulated houses, the respective effects of internal and external insulation on heat transfer through different types of brick walls with reinforced concrete floor slab were predicted by implementing a multi-scale finite-element modelling method. The results demonstrated that the efficiency of external insulation is 50% higher than that of internal insulation, and insulating a concrete brick wall is more economical than insulating a red clay brick wall. Furthermore, although external insulation saves approximately 16% more energy per year than internal insulation, the time required for the amount of energy saved to offset the cost of installation is longer.

Through-Wall Multiple Targets Vital Signs Tracking Based on VMD Algorithm.

Targets located at the same distance are easily neglected in most through-wall multiple targets detecting applications which use the single-input single-output (SISO) ultra-wideband (UWB) radar system. In this paper, a novel multiple targets vital signs tracking algorithm for through-wall detection using SISO UWB radar has been proposed. Taking advantage of the high-resolution decomposition of the Variational Mode Decomposition (VMD) based algorithm, the respiration signals of different targets can be decomposed into different sub-signals, and then, we can track the time-varying respiration signals accurately when human targets located in the same distance. Intensive evaluation has been conducted to show the effectiveness of our scheme with a 0.15 m thick concrete brick wall. Constant, piecewise-constant and time-varying vital signs could be separated and tracked successfully with the proposed VMD based algorithm for two targets, even up to three targets. For the multiple targets’ vital signs tracking issues like urban search and rescue missions, our algorithm has superior capability in most detection applications.

Comparative study on the construction cost including carbon emission cost for masonry walls

Abstract Carbon dioxide (CO2) emissions resulting from construction are one of the main factors causing global warming. It is therefore necessary to make efforts to reduce CO2 emissions in the construction industry. Although some researchers have studied CO2 emissions in the industry, there has been a lack of study on the cost of CO2 emissions. Therefore, this study examines and compares the construction costs, including the cost of CO2 emissions, of masonry wall types – including common brick, concrete brick, and fired brick walls. The study found that CO2 emission cost was the highest for brick walls, followed by concrete brick walls. The findings provide information that can be used in engineering methods to determine the cost of CO2 emissions.

The Heat Transfer Coefficient of Recycled Concrete Bricks Combination with EPS Insulation Board Wall

Four tectonic forms samples were conducted to test their heat transfer coefficients. By analyzing and comparing the test values and theoretical values of the heat transfer coefficient, a corrected-value calculation method for determining the heat transfer coefficient was proposed; the proposed method was proved to be reasonably correct. The results indicated that the recycled concrete brick wall heat transfer coefficient is higher than that of the clay brick wall, the heat transfer coefficient of recycled concrete brick wall could be effectively reduced when combined with the EPS insulation board, and the sandwich insulation type was better than that of external thermal insulation type.

Experimental Study on the Seismic Performance of Recycled Concrete Brick Walls Embedded with Vertical Reinforcement.

Recycled concrete brick (RCB) is manufactured by recycled aggregate processed from discarded concrete blocks arising from the demolishing of existing buildings. This paper presents research on the seismic performance of RCB masonry walls to assess the applicability of RCB for use in rural low-rise constructions. The seismic performance of a masonry wall is closely related to the vertical load applied to the wall. Thus, the compressive performance of RCB masonry was investigated firstly by constructing and testing eighteen RCB masonry compressive specimens with different mortar strengths. The load-bearing capacity, deformation and failure characteristic were analyzed, as well. Then, a quasi-static test was carried out to study the seismic behavior of RCB walls by eight RCB masonry walls subjected to an axial compressive load and a reversed cyclic lateral load. Based on the test results, equations for predicting the compressive strength of RCB masonry and the lateral ultimate strength of an RCB masonry wall were proposed. Experimental values were found to be in good agreement with the predicted values. Meanwhile, finite element analysis (FEA) and parametric analysis of the RCB walls were carried out using ABAQUS software. The elastic-plastic deformation characteristics and the lateral load-displacement relations were studied.

Engineering Application of New Wall Materials Anti-Cracking and Anti-Leakage Performance Summary of Several Experiments and Analysis

New wall materials are widely used in the construction industry, which have green environmental protection. But the cracking and leakage wall causes the building function decline, heat preservation and insulation failure, which hinder its comprehensive promotion. Some regularities and conclusions had been got through several researches on the engineering application of new walls anti-cracking and anti-leakage performance. Researches are based on many aspects, such as design calculations, structural measures and detecting techniques. The summary in this paper includes: material crack propagation mechanism, experimental investigation of shrinkage of concrete brick walls at different ages, new walls in-field test of surface permeability, image processing of wall crack etc.

The Energy Saving Effect Evaluation for Outside Wall with Different Material in Island District

In order to evaluate the energy saving effect for building outside wall under the damp island environment, the heat insulation performance of brick wall, MU10 concrete brick wall and aerated concrete are tested. The testing method is combined of infrared photos and heat flow meter. The results showed that the insulation performance of clay brick is worst, its heat transfer coefficient is 60% more than that required by energy saving standard. Although the concrete brick has painted 25mm polystyrene granule outside, the heat transfer coefficient is still smaller than energy saving standard required. The economic thickness of polystyrene granule is 79mm , which makes the both heating cost and insulating layer minimum during the life cycle of heat insulating layer. Among the three types of outside wall, only the aerated concrete can satisfy the energy saving standard for hot summer and cold winter district, it constitutes the self-insulating system.

Seismic Performance Study of Concrete Porous Brick Wall

Four constructional columns with concrete porous brick walls were constructed for low cyclic loading test. The damage on the characteristics and strength of the wall, hysteresis curve, ductility and other seismic performance were analyzed. Setting constructional columns in the wall at both ends increase the ultimate strength and improve its deformation, ductility and other properties. Meanwhile the height-wide-ratio of wall, axial pressure and other factors on the shear bearing capacity on the wall have been studied. Based on the shear capacity formula of wall in the Structural Seismic Design Code, considering the contribution of the constructional columns on the shear strength, according to the results, the shear capacity formula of constructional columns with concrete brick walls is presented.

조적벽의 CO2배출비용을 포함한 건설원가 비교에 관한 연구

The carbon dioxide() emissions that result from construction are one of the main factors causing a global warming problem. It is therefore necessary to make efforts to reduce emissions in the construction industry. Some researchers have studied emissions in the industry ; however, there has been a lack of study on emissions cost. Therefore, in this study, the construction costs, including the emission cost, of masonry wall type, which is a common brick wall, concrete brick wall, and fired brick wall, were examined. The purpose of this study is to compare the construction costs of masonry wall types, including emission costs. The study found that the emission costs were highest for the fired brick wall, followed by the concrete brick wall. This research could provide basic information that can be used in other engineering methods to convert emissions to emission cost.

Parametric study of the sound insulation performance of a ventilation window.

The sound insulation performance of a specifically designed facade device, which allows natural ventilation but can provide relatively high-sound insulation, is studied experimentally in the present study. The experiment was carried out in two coupled rooms with one of them very reverberant and the other made semi-anechoic. The former acted as the receiver room and the latter contained a linear loudspeaker array (25 loudspeakers) as the noise source. The full scale facade device was installed on the concrete brick wall between the coupled rooms. Nine microphones were used to measure the average sound intensity inside the reverberant room. The effect of the size of the device opening (for ventilation) on the sound insertion loss was then determined by the difference between the average intensities with and without the device (an opened window). The present results show that the present facade device can offer additional acoustical protection of ∼12–13 dB(A) compared to that resulted from the conventional openable window design when exposed to traffic noise. The introduction of sound absorption materials at the top internal surface of the window cavity in general can result in a maximum of 2 dB extra benefit.

Blast Response of Walls Retrofitted with Elastomer Coatings

Abstract : Recent tests at Tyndall Air Force Research Laboratory show that an elastomer-coated to the inside wall of a building can offer significant protection for occupants by keeping wall fragments together and shielding out blast debris. In this paper, we develop an equivalent single degree-of-freedom model that can be used to predict dynamic response of a polymer-retrofitted concrete brick wall subjected to a stand-off explosion. As an example, we consider the blast response of a l 0 ft-square, 8 in-thick concrete brick wall coated with a 0.083 in thick layer of polyurea. Explosive field tests with a uniformly-distributed pressure pulse of 40 psi peak value and 20 ms pulse duration indicate that the retrofitted wall reaches a maximum deflection of about 7 in. Our analytical model suggested that the blast response of this wall could be simulated assuming the concrete modulus was reduced to about 5% of its original value. The proposed single degree-of-freedom model, which is based on coupling of the bending/membrane resistance of the wall, compared very well with the ABAQUS results when the maximum deflections of the wall were between 1-2 times the wall thickness.