Clay Masonry Research Articles

Using Blends of Construction & Demolition Waste Materials and Recycled Clay Masonry Brick in Pavement

In Egypt and many developing countries, the use of Construction & Demolition (C&D) waste and Recycled Clay Masonry (RCM) brick materials as Unbound Granular Materials (UGMs) in pavement construction is generally very limited. There has been reluctance to adopt recycled materials in pavement construction. Despite the fact that there are allocated land fill areas for dumping this kind of waste, in Egypt C&D waste is usually dumped on the sides of canals, minor roads and at the entrance of the cities and towns. This causes environmental problems and affects the daily lives of people. Therefore, blends of C&D waste materials with RCM were evaluated for use as UGMs. The C&D waste and RCM materials were obtained from some dumps on the sides of roads and canals around Mansoura City, Egypt. The collected materials were crushed and mixed in the laboratory. The proportions of the C&D/RCM blends were 100/0, 90/10, 80/20, 70/30, 55/45, 40/60, 20/80, and 0/100% of the total aggregate mass. The characterization of C&D/RCM blends as well as the response to cyclic loading by Repeated Load Triaxial Testing (RLTT) was covered in this research paper. Static triaxial shear tests and RLTT were conducted using a Universal Testing Machine. RLTT and static triaxial shear test specimens were prepared at the optimum moisture content and compacted according to modified Proctor. RLTT were performed in accordance with the AASHTO T307 on triplicate specimens. RCM materials (100%) as UGMs failed to meet the requirements of Los Angeles Abrasion (LAA) test of 50% maximum as specified by the Egyptian Code of Practice (ECP). RLTT data showed that all C&D/RCM blends yielded high resilient moduli however, no significant variation in resilient moduli values were observed between the different C&D/RCM blends.

Use of bottom ash from olive pomace combustion in the production of eco-friendly fired clay bricks

Olive pomace bottom ash was used to replace different amounts (10–50wt%) of clay in brick manufacturing. The aim of this study is both studying bricks properties and showing a new way of olive pomace bottom ash recycling. Properties of waste bricks were compared to conventional products following standard procedures in order to determine the maximum waste percentage. The amount of olive pomace bottom ash is limited to 20wt%, obtaining bricks with superior engineering properties when 10wt% of waste is added. Adding higher amount of waste (30–50wt%) resulted in bricks with water absorption and compressive strength values on the edge of meeting those established by standards. Therefore, the addition of 10 and 20wt% of olive pomace bottom ash produced bricks with a bulk density of 1635 and 1527kg/m3 and a compressive strength of 33.9MPa and 14.2MPa, respectively. Fired bricks fulfil standards requirements for clay masonry units, offering, at the same time, better thermal insulation of buildings due to a reduction in thermal conductivity of 14.4% and 16.8% respectively, compared to control bricks (only clay).

Structural performance of confined masonry walls retrofitted using ferrocement and GFRP under in-plane cyclic loading

This paper presents the results of in-plane cyclic loading tests conducted on confined masonry walls retrofitted using low-cost ferrocement and GFRP systems. Ten wall assemblies with a 0.80-scale were built, consisting of a clay masonry panel, two confining columns and a tie beam. The assemblies were tested under a combination of a vertical load and lateral reversed cyclic loading with a displacement controlled loading protocol up to failure. Wall panels had various configurations, namely, solid walls, perforated walls with window and door openings. Two composite materials (ferrocement and GFRP) and three retrofitting configurations (diagonal “X”, corner, and full coverage) were investigated. Key experimental results showed that the proposed upgrading techniques improved the lateral resistance of the confined walls by a factor ranging from 25% to 32%with a significant increase in the ductility and energy absorption of the panel ranging from 33% to 85%; however, the improvement in lateral drifts was less significant. Regarding the upgrading configurations, the diagonal “X” and full coverage can help prevent diagonal shear failure especially in tie columns and convert the failure mode to a panel-rocking mode. Additionally, in all retrofitting cases, collapse was significantly delayed by maintaining the wall integrity under large lateral deformations. A good agreement was found by comparing deformed shapes, crack patterns and capacity curves of finite element models included in this study.

Predicting thermal performance of fired clay bricks lightened by adding organic matter: Improvement of brick geometry

Fired clay masonry bricks adapt to a variety of constraints during use. Through their mass, these products provide thermal inertia and thus a good indoor climate. Thanks to their thermal insulation properties, they help to minimize heating and cooling costs. The brick industry allows different by-products to be added into the clay mixture at the beginning of the industrial cycle, and the incorporation of organic matter improves thermal insulation while reducing the weight of the bricks. This article presents an experimental and numerical method for determining the thermal resistance of fired clay bricks containing residue of wheat straw. As their thermal conductivity reaches a value 35% lower than that of clay without organic matter, the thermal transmittance of such bricks can be improved by more than 20% relative to existing values.

Experimental and analytical investigation of the lateral load response of confined masonry walls

This paper investigates the behavior of confined masonry walls subjected to lateral loads. Six full-scale wall assembles, consisting of a clay masonry panel, two confining columns and a tie beam, were tested under a combination of vertical load and monotonic pushover up to failure. Wall panels had various configurations, namely, solid and perforated walls with window and door openings, variable longitudinal and transverse reinforcement ratios for the confining elements and different brick types, namely, cored clay and solid concrete masonry units. Key experimental results showed that the walls in general experienced a shear failure at the end of the lightly reinforced confining elements after the failure of the diagonal struts formed in the brick wall due to transversal diagonal tension. Stepped bed joint cracks formed in the masonry panel either diagonally or around the perforations. A numerical model was built using the finite element method and was validated in light of the experimental results. The model showed acceptable correlation and was used to conduct a thorough parametric study on various design configurations. The conducted parametric study involved the assessment of the load/displacement response for walls with different aspect ratios, axial load ratios, number of confining elements as well as the size and orientation of perforations. It was found that the strength of the bricks and the number of confining elements play a significant role in increasing the walls’ ultimate resistance and displacement ductility.

Earthen masonry dwelling structures for extreme wind loads

Earthen masonry made of compressed and stabilized earth blocks (CSEBs) is emerging as a sustainable and locally appropriate construction material for affordable high-quality dwellings. Compelling features include the local availability and affordability of suitable soils, thermal insulation and humidity control properties, and small embodied energy compared with fired clay masonry. The mechanical properties of CSEBs have been the subject of several investigations. However, the research on the response and design optimization of CSEB masonry building structures is in its infancy, and a significant knowledge and technological gap exists with regard to resistance to extreme loads due to natural hazards (e.g., high winds and earthquakes). It is necessary to address this gap to understand whether engineered earth masonry can be enlisted to respond to the growing demand for hazard-resistant dwellings that are also affordable and sustainable.This paper discusses the feasibility of using earth masonry in low-rise dwelling structures to withstand extreme winds. Hurricanes and tornadoes periodically scourge vast areas in Central and North America and the Caribbean where low-income families live, and where the demand for sustainable construction meets that for structural resistance and affordability. Feasibility is studied based on the structural analysis of the main wind force resisting system (MWFRS) of a typical one-story single-family dwelling subject to wind pressures resulting from 3-s gust speeds up to 90m/s (324km/h). The output consists of parametric curves that relate wind speed with masonry compressive, tensile and shear strength demand for wall thicknesses ranging from 203 to 508mm. The structural adequacy of the MWFRS is assessed for the cases of flat and 15° gable roof. The design implications are discussed vis-à-vis strength reduction factors and design strength demands, and sustainable reinforcement options. It is concluded that it is feasible to design one-story CSEB masonry dwellings that can withstand winds loads from Category 4 hurricanes and EF3 tornadoes, provided that a rigid horizontal diaphragm is used. Grouted steel reinforcement may be used in safety shelter CSEB masonry structures to be designed for more extreme wind loads.

The moisture buffering capacity of unfired clay masonry

In this paper, the results of static and dynamic hygric tests on 114 unfired clay masonry samples are presented. Samples were prepared as Compressed Earth Blocks (CEB) or plasters. The variability of soils, the soil density and the preparation methods were investigated to determine their influence on the moisture buffering capacity, water vapour permeability and sorption isotherms. The Moisture buffering Value (MBV) was measured according to the Nordtest protocol and the results could therefore be compared to conventional materials. The results indicate unfired clay masonry has a much higher potential to regulate the indoor humidity than conventional construction materials previously reported in the literature. Because of the benefits of humidity buffering, using unfired clay masonry could reduce health risk for inhabitants, reduce mould growth, reduce energy consumption of air conditioning and ventilation systems and increase the durability of building materials. The presented results show that the soil selection (mineralogy and particle size distribution) is more important for humidity buffering than changes than can be made to a particular soil (density, preparation methods or stabilisation) and the information presented will therefore allow designers to maximise the buffering capacity of buildings.

On the compressive strength of Botswana masonry units

This paper presents results and discussion on research to investigate the compressive strength of masonry units in Botswana against the standard requirements. It was limited to concrete masonry bricks and burnt clay masonry bricks from large-scale manufacturers who either had their products certified by the Botswana Bureau of Standards or indicated the strength of their products. Nine sets of different products (six concrete masonry units and three clay masonry units) were tested. It was found that only three products complied with the Botswana Bureau of Standards requirements. Four of the six products that did not meet the Botswana Bureau of Standards requirements were two classes below the levels claimed by the manufacturers. For example, some units supplied as 14 MPa only fulfilled requirements of units with strength below 7 MPa. Users of masonry units in Botswana are therefore supplied with low strength products. This may greatly compromise the safety of the public.

Temperature Control Responses of Structural Clay Masonry Blocks

The compressive strength as well as other technical properties of structural clay masonry blocks are usually significantly affected by the firing temperature. The present work studied the temperature control response of structural clay masonry blocks when changing the firing condition from 700 to 800°C. Structural clay blocks fired at 700°C in an industrial furnace were compared with those fired in a laboratory electrical muffle furnace at 800°C. Both water absorption and compressive strength tests were carried out for the different brick samples. The block sample fired at 700°C failed to attend both the water absorption and the compressive strength requirements for structural elements. By contrast, after 800°C firing, the laboratory sample attended the water absorption specifications and showed higher compressive strength within the Brazilian standards.

Seismic performance of masonry strengthened with steel strips

Strengthening of unreinforced masonry structures to improve their seismic performance is getting attention of civil engineers across the world. In this study, laboratory tests were carried out to investigate the seismic performance of unreinforced burnt clay masonry wall panels strengthened with externally anchored steel strips. Six masonry panels having an aspect ratio of 0.7 were constructed. First masonry panel was unreinforced reference specimen and remaining specimens were strengthened with steel strips using different steel ratios and mesh patterns. Three specimens were strengthened with steel strips on one face and two specimens were strengthened with steel strips on both sides. All the specimens were tested under lateral cyclic loading at constant axial pressure to determine seismic performance. The test results revealed a significant improvement in energy dissipation, ductility and lateral strength of strengthened masonry wall panels. The main contributing factors in performance improvement were 1) amount of steel reinforcement, 2) mesh pattern and 3) single or double side application of steel strips. The proposed steel strips strengthening technique is quite simple and economical which involves external application of steel strips and does not alter the mass significantly. The simplicity, cost effectiveness and efficacy of the technique can help the local designers and engineers to enhance seismic performance of existing masonry structures.

Permanent Strain of Unsaturated Unbound Granular Materials from Construction and Demolition Waste

AbstractThis paper presents a new equation for estimating the permanent strain of different combinations of recycled clay masonry and recycled concrete aggregate using the concept of matric suction. The aim of this paper was to develop a new equation with a single set of constants for all the materials. The unbound granular material (UGM) was prepared at moisture contents ranging between 70 and 90% of optimum moisture content (OMC) and tested in a repeated-load triaxial test (RLTT) apparatus under a single-stress state. Soil water characteristic curves (SWCC) were established for each material by preparing samples at various moisture contents and measuring matric suction with filter papers. In order to obtain the wet end of the SWCC, further samples were conditioned on a tension plate at suctions controlled by the hanging water column method. Permanent strain was influenced by moisture content or suction and was found to provide a better correlation with suction than with moisture content. Permanent defor...

Recycling of washed olive pomace ash for fired clay brick manufacturing

Milled or micronized washed olive pomace ash was used to replace different amounts (5 and 10wt%) of clay in brick manufacture. The properties of these bricks were compared to conventional products following standard procedures. Bricks formed with ash showed a decrease of 0.13–0.16W/mK in thermal conductivity. With a minimum bulk density and bending strength of 1790–1810kgm−3, and 10–12Nmm−2, respectively, fired bricks fulfil standard requirements for clay masonry units. Milled ash performs better than micronized ash. The ash leachate is a valuable source of potassium for the manufacture of fertilizers.

Conditions affecting the moisture buffering measurement performed on compressed earth blocks

Unfired clay masonry has a high potential to regulate indoor humidity and therefore create healthier living environments. The measurement of such potential on various building materials has received increasing attention and has generated the Moisture Buffering Value (MBV) concept. This work experimentally explored various conditions affecting the measurement and calculation of the buffering potential. Measurements of MBV and steady state properties (water vapour permeability and sorption isotherms) were performed on 18 samples, Compressed Earth Blocks (CEB) and Stabilised Compressed Earth Blocks (SCEB). It is quantitatively shown how the variability of experimental conditions in the dynamic measurement can change the obtained MBV (MBVpractical). The calculated buffering potential (MBVideal) is equally affected by the variability of the steady state properties measurements. A good agreement between calculated and measured MBV was observed for most samples when reducing this variability which was shown by using a DVS (Dynamic Vapour System) system to obtain the sorption isotherms of the material.

Characterization of materials formed by rice husk for construction

This review article delves into the use of agro-industrial wastes, which in construction field provides alternatives for environmental problems with the use of them. This fact enables development and lower costs for new options in the brick, cluster, mortar and concrete industry, what represents benefits for environment, housing and generally everything related to construction, looking for sustainability. For that reason a literature review is made to support the theme focusing on the use of rice husk in its natural, ground or ash state for manufacturing elements with clay masonry, precast and optimization of concrete and mortars. The technique used is based on scientific articles and researches found in reliable databases that were analyzed and integrated into a synthesized structure, which summarized the objectives, analysis processes, the physical and mechanical properties and finally the results. The conclusions are focused on potentiality of elements production in the construction development based on the high effectiveness like thermal insulation, low density and various benefits offered by high silica content pozzolanic properties, etc.

Laboratory Evaluation of Recycled Concrete Aggregate and Recycled Clay Masonry Blends in Pavement Applications

Abstract This paper presents the assessment of blends of recycled clay masonry (RCM) with recycled concrete aggregate (RCA) for applications in pavements. The study reviewed materials from two South Australian suppliers with the proportion by dry mass of RCM being up to 30 % of the total aggregate mass. Testing included drying shrinkage, static undrained triaxial shear strength and multi-stage repeated loading triaxial testing (RLTT). Although the target dry density ratio was set at 98 % of maximum dry density (MDD) for all compacted specimens, moulding moisture content was varied to investigate the influence of moisture on strength and stiffness of the materials. Static shear strength decreased almost linearly as the initial moisture content increased. The importance of shear strength was demonstrated on RLTT testing and the applied stress states in later stages of the test. A review of the RLTT data showed that both resilient modulus and permanent strain were sensitive to molding moisture content, as well as the applied stresses. Recommendations based on the permanent strain behavior and resilient modulus of the tested specimens, were made regarding the general applications of the various blends in road construction. Potential applications ranged from upper or lower sub-base and base for various traffic levels, depending on percentage of crushed masonry, or RCM, initial moisture content, and product supplier.

New Mortar for Clay Masonry Structures

Construction system using timber frame with earth brick infill shows the formation of cracks at their interface with the fluctuation of temperature and humidity. Geopolymer binder has been identified to create good adhesion between these two materials. The aim of the study is to characterize the pullout and shear mechanical behavior of laboratory masonry assemblies of wood, geomaterial binder and extruded earth brick. Compression test on the brick were also performed. Full-field deformation of double shear test sample werecarried-out by digital image correlation (DIC) in order to better describe and understand the mechanical behavior. The geopolymer binder show good adhesion properties with mean shear test results around 1.5 MPa and pullout test result around 0.82MPa.

Development of a novel mortar for use with unfired clay bricks

Interest in traditional unfired clay building materials, including cob, earth brick, and rammed earth, has grown in the UK in recent years. Although the use of vernacular techniques, such as cob and rammed earth, has raised the profile of earthen architecture, a wider impact on modern construction is more likely to come from modern innovations such as unfired extruded clay masonry units and premixed plasters. Traditional unfired clay walls often have basal widths of 300 mm or more, providing an inherent stability and resistance to toppling through self-weight. Masonry units extracted from UK brick production lines before the firing process are typically 100 mm wide, which requires good mortar-brick bond strength to meet structural robustness requirements in a typical 2.4 m high wall. In testing, traditional mortars based on clay, cement or lime, have not provided sufficient strength. This paper examines the bonding of unfired clay units with unconventional mortars based on novel binders. It reports on the development of a mortar which appears to be suitable for a wide range of clay types. This mortar can be readily recycled and has a carbon footprint lower than many alternative binders. Results of long-term bond strengths and the structural performance of masonry walls are given, which demonstrate the suitability of this mortar for use with unfired clay masonry units.

Geotechnical Properties of Blends of Recycled Clay Masonry and Recycled Concrete Aggregates in Unbound Pavement Construction

AbstractThis paper presents the engineering characteristics of blends of recycled clay masonry (RCM) with recycled concrete aggregate (RCA) from two material producers from South Australia. The pro...

Behavior of clay hollow-brick masonry walls during fire. Part 1: Experimental analysis

Understanding the behavior of masonry structures when exposed to fire and predicting their fire-resistance is a major need that has been expressed by brick manufacturers. Whereas clay brick masonry is widely used because of its thermal and sound insulation performance; fire-resistance is certainly its weakness if improper design methods are used.These design methods require prior exhaustive experimental tests, which should not be limited to evaluating standard fire-resistance as a global standard criterion but should also permit a detailed analysis of the thermo-mechanical behavior of masonry walls.In this paper, four wall-tests are presented to illustrate the behavior of clay masonry walls during fire. Selected wall-tests are generically representative of the overall results obtained during a more extended experimental campaign.The experimental results are presented and analyzed with regard to the risk of spalling on the fire-resistance of masonry. The analysis contains a detailed investigation of temperature, deformation and local mechanical degradation phenomena in the tested walls.Finally, the study is concluded by summarizing end-point parameters that significantly control the fire-resistance of clay masonry walls and deserve consideration in any modeling approach.

Seismic Performance of Low-Rise Wood-Framed and Reinforced Masonry Buildings with Clay Masonry Veneer

AbstractThis paper describes a coordinated experimental and analytical study that investigated the seismic performance of wood-stud construction with clay masonry veneer and of RC masonry construction with clay masonry veneer designed according to current U.S. building codes. As part of this study, two 1-story buildings were tested on a shaking table. Both had clay veneer on the outside. One had wood-frame walls for the backing and load-resisting system, whereas the other had RC masonry walls. With one exception, the behavior of the veneer in the wood-framed building was satisfactory up to levels of shaking consistent with the design level earthquake. That exception was related to the relatively low pullout strength in wet wood of the conventional nails used to attach the veneer connectors to the wood-stud wall. On the basis of this study, code changes have been implemented to require the use of higher-capacity fasteners for such applications. The wood-frame building specimen itself did not collapse under...