Hollow Clay Block Research Articles

Assessing the Impact of Vertical Greenery Systems on the Thermal Performance of Walls in Mediterranean Climates

This study investigates the impact of vertical greenery systems (VGSs) applied to several typical wall configurations on indoor thermal conditions in a building module situated in the Mediterranean climate of Catania, Italy. By means of dynamic simulations in TRNSYS vers.18, the research compares the thermal behavior of walls made of either hollow clay blocks (Poroton) or lava stone blocks against a lightweight wall setup already in place at the University of Catania. The primary focus is on evaluating the VGSs’ capability of reducing peak inner surface temperatures and moderating heat flux fluctuations entering the building. The findings indicate that adding an outer vertical greenery layer to heavyweight walls can decrease the peak inner surface temperature by up to 1.0 °C compared to the same bare wall. However, the greenery’s positive impact is less pronounced than in the case of the lightweight wall. This research underscores the potential of green facades in enhancing the indoor thermal environment in buildings in regions with climates like the Mediterranean one, providing valuable insights for sustainable building design and urban planning.

Experimental and Numerical Characterization of the In-Plane Shear Behavior of a Load-Bearing Hollow Clay Brick Masonry System with High Thermal Performance

Modern masonry systems are generally built with hollow clay bricks with high thermal insulating properties, fulfilling the latest sustainability and environmental criteria for constructions. Despite the growing use of sustainable masonries in seismic-prone countries, there is a notable lack of experimental and numerical data on their structural behavior under lateral in-plane loads. The present study investigates the in-plane shear behavior of load-bearing masonry walls with thin bed joints and thermal insulating hollow clay blocks. Shear-compression tests were performed on three specimens to obtain information about their shear strength, displacement capacity and failure modes. The experimental characterization was supplemented by three shear tests on triplets, along with flexural and compression tests on the mortar for the thin joints. Furthermore, two Finite Element (FE) models were built to simulate the shear-compression tests, considering different constitutive laws and brick-to-brick contact types. The numerical simulations were able to describe both the shear failure modes and the shear strength values. The results showed that the experimental shear strength was 53% higher than the one obtained through Eurocode 6. The maximum shear load was found to be up to 75% greater compared to similar masonry specimens from the literature. These findings contribute to a better understanding of the potential structural applications of sustainable hollow clay block masonry in earthquake-prone areas.

Analytical prediction of the seismic resistance of masonry buildings retrofitted by Steel Fiber Reinforced Mortar coatings

An extensive experimental program has been performed in the last years at the University of Brescia to show the effectiveness of the in-plane seismic strengthening or repairing of existing masonry buildings by Steel Fiber Reinforced Mortar (SFRM) coatings. In particular, the tests on a full-scale hollow clay block masonry building showed the applicability of the retrofitting technique on the external surface of the structure only.An analytical model already developed and validated is briefly presented in this article and applied to the building experimentally tested. Particular attention is paid to the simplified schematization of the masonry piers based on the fracture lines expected before and after retrofitting. The effectiveness of the analytical model in predicting the seismic resistance of the building is assessed by comparing the analytical results with those obtained from the experimental test.Finally, the analytical model is applied to a real two-story residential building made of concrete hollow units to perform the seismic verification of the structure. The analytical prediction of the global seismic resistance of the building is compared with that obtained from a non-linear static analysis carried out with the finite element program Midas FEA. The results of the comparison will further prove the reliability of the proposed analytical model.

Experimental study on compressive strength of Interlocking Hollow Block System (IHBS) using fly ash

Interlocking Hollow Block System (IHBS) is a reasonable solution for conventional block masonry due to its structural ability and building capability. In addition, economic and ecological building of brickwork can be achieved by incorporating fly ash into IHBS. The main aim of the research is to produce interlocking compressed hollow block that satisfy the standard requirement as in Eurocode 6. The study is essentially divided into 2 phases, block production and block compression testing. This paper studies on the compressive strength of interlocking hollow clay block with various compositions including laterite soil, cement, sand and fly ash. The optimum mix design is achieved with minimum compressive strength of 7 MPa, which comply with the standard BS 5628-1:1992 Code of practice for Use of masonry – Part 1: Structural use of unreinforced masonry. Test result on addition of fly ash revealed that the optimum fly ash content was 2% with the highest compressive strength of 10 MPa. The results of this study show that the proposed block mixture meets the standard strength requirements and the structural performance of the masonry block is improved by adding fly ash into the mix design.

Case study of prototype and small-scale model behavior of clay blocks masonry under compression

The small-scale models have been used for decades to reproduce the strength and failure behaviour in Engineering problems. The main goal of this study was to analyse the scale factor between masonry components prototypes and models to preview the mechanical properties of hollow clay blocks masonry under compression. For this purpose, it was tested full and small-scale of hollow clay blocks, wallettes and two-blocks-high stackbond prisms with a reduction proportion of 1:5. The sand of the bedding mortar on small-scale model was graduated according to the sand maximum diameter. Compressive, splitting tensile strength and elastic modulus of the blocks, prisms and wallettes were determined during experimental tests. It was also determined the vertical and horizontal strain of masonry wallettes. From experimental results it was possible to conclude that the strength ratio between full and small-scale models were 1.27, 2.05 and 2.75 for blocks, prisms and wallettes, respectively. When it was compared the elastic modulus ratio between full and small-scale, the results were 1.16, 1.32 and 1.28 for blocks, prisms and wallettes, respectively. The failure mode of masonry specimens was too similar between full and small-scales, indicating that for blocks, prisms and wallettes components could be used to represent strength and strain behavior of masonry under compression.

Cyclic Test on a Full-Scale Unreinforced Masonry Building Repaired with Steel Fiber-Reinforced Mortar Coating

The present work reports the results of two quasi-static reverse cyclic tests performed on an unreinforced hollow clay block masonry building before and after repairing with a single 30-mm thick layer of mortar applied on the façades. Unlike traditional coating-based retrofitting techniques, the one proposed herein adopts a cement-based mortar reinforced with short high-strength steel fibers randomly diffused in the mortar matrix. In order to assess the effectiveness of the strengthening intervention, a preliminary cyclic test was carried out on the unstrengthened building in order to predamage masonry. The experimental results showed that the repaired structure exhibited a significant improvement of seismic behavior both at the serviceability and ultimate limit state conditions. Moreover, based on the observed ultimate ductility of the retrofitted building, some considerations on the behavior factor are reported.

Numerical investigation of optimal wall materials for effective thermal performance in warm and hot climatic regions

Purpose Heat gain in buildings occurs due to heat transfer through the building fabric or envelope, especially the walls and roof. The purpose of this paper is to identify and recommend the suitable wall materials for better thermal performance in buildings in warm and hot climatic zones of India. As India lies between the tropic of cancer and the equator, the solar radiation from the sun falls more on the walls than the roofs of the buildings. Thus, it is imperative to protect the walls from heat gain to promote thermal comfort in naturally ventilated buildings and reduce the energy loads due to artificial cooling systems in air-conditioned buildings. Design/methodology/approach In this paper, an investigation of heat flow characteristics in steady-state and the transient state for five different uninsulated wall structures using computational fluid dynamics (CFD) software has been carried out. The climate conditions at Madurai, India have been considered for this study. Findings The findings of the study revealed that aerated autoclaved concrete (AAC) and hollow clay blocks (HCB) for external walls in naturally ventilated buildings in warm climatic regions could improve the building’s thermal performance index and reduce peak indoor operative temperature by about 6°C–7°C. The results of steady-state and transient state analysis were found to be in good agreement with the results of the reviewed literature. Research limitations/implications Over the past few decades, only very few architects and builders have been successful in influencing their clients to accept alternate materials such as AAC blocks, HCB, stabilized earth blocks, adobe blocks, fly-ash bricks as an alternate to conventional bricks in an attempt of highlighting their benefits, such as; materials that are easily available, more energy-efficient, can withstand the extreme weather conditions, promote thermal comfort and cost-effective. This paper provides strong evidence that AAC and HCB blocks are the most appropriate materials for improving the thermal performance of envelope walls in regions where the outdoor temperatures are above 40°C. Originality/value This paper has made an attempt to identify the appropriate wall materials for effective thermal performance in warm and hot climates. A comparative analysis between five different wall types under the existing solar conditions has been analyzed using CFD simulation study in steady-state and transient conditions under summer conditions and the appropriate wall materials have been suggested. There has been no attempt carried out so far to analyze the thermal performance of different walls using 24 h transient approach in CFD.

Deformable Polyurethane Joints and Fibre Grids for Resilient Seismic Performance of Reinforced Concrete Frames with Orthoblock Brick Infills.

The behaviour of reinforced concrete frames with masonry wall infills is influenced a lot by the stiffness and strength difference between the frame and the infill, causing early detrimental damage to the infill or to the critical concrete columns. The paper reports the results from shake table seismic tests on a full-scale reinforced concrete (RC) frame building with modified hollow clay block (orthoblock brick) infill walls, within INMASPOL SERA Horizon 2020 project. The building received innovative resilient protection using Polyurethane Flexible Joints (PUFJs) made of polyurethane resin (PU), applied at the frame-infill interface in different schemes. Further, PUs were used for bonding of glass fibre grids to the weak masonry substrate to form Fibre Reinforced Polyurethanes (FRPUs) as an emergency repair intervention. The test results showed enhancement in the in-plane and out-of-plane infill performance under seismic excitations. The results confirmed remarkable delay of significant infill damages at very high RC frame inter-story drifts as a consequence of the use of PUFJs. Further, the PUFJ protection enabled the resilient repair of the infill even after very high inter-story drift of the structure up to 3.7%. The applied glass FRPU system efficiently protected the damaged infills against collapse under out-of-plane excitation while they restored large part of their in-plane stiffness.

Performance of Different Glass Fibre-reinforced Polymer Strengthening Schemes on Masonry Infilled RC Frames under Seismic Loading

ABSTRACT In this study is investigated the performance of different glass fibre-reinforced polymer strengthening schemes on infilled reinforced concrete (RC) frames. The main objective was to limit the damage to beam–column joints and inter-storey drift ratios and to protect RC frames against the negative effects caused by infill-RC frame interaction. Five specimens were tested: one without infill and four infilled with full-scale hollow clay block masonry unit, three of which were strengthened with different schemes. Results showed that the beam–column joints could remain undamaged, lateral strength and stiffness were enhanced, inter-storey drift was limited, and new load carrying systems are generated.

Optimal insulation thickness of common classic and modern exterior walls in different climate zones of Iran

Insulation thickness optimization has become a prominent factor in building design for energy saving. This study aims to determine ideal insulation thickness of the external wall, energy saving, and payback period of investment in all climate zones of Iran. A classic gray brick wall and three modern walls (Hollow clay block, LECA block, and AAC block) were selected by considering four cardinal orientations. Eight cities were chosen as representatives of all climate zones. Optimization was performed using life-cycle cost analysis method along with a numerical solution to determine the transmission load. Results revealed that the use of thermal insulation in the AAC block wall, which is one of the common modern walls in Iran, is not economical in some cities. The maximum insulation thickness in Iran is not more than 4 cm which is much lower than the reported values for other countries. Also, the figures for energy saving and payback period in Iran are very different. This is due to the economic structure and low energy costs in this country. This study confirms the requirements in reforming regional energy policy and pricing mechanisms as a roadmap for insulation application in building envelope.

Seismic strengthening of clay block masonry buildings with composites: an experimental study of a full scale three-storey building model

The efficiency of strengthening of unreinforced hollow clay block masonry buildings with fibre reinforced mortar coatings has been investigated. A full scale three-storey building model and a series of accompanying walls have been built and tested. Reference unstrengthened, and strengthened specimens of each type have been tested by subjecting them to cyclic shear at constant compressive load. First, the three-storey model was tested in its original state until the maximum resistance was attained and major, but still repairable damage, developed in the walls. Then, the damaged model was strengthened with fabric reinforced cementitious mortar coating and re-tested up to near collapse limit state. Typical storey mechanism was observed in original and strengthened state, with the majority of damage concentrated in the walls of the bottom storey. Diagonally oriented shear cracks prevailed in the elements in the direction of loading. The behaviour of single walls in cyclic shear tests was similar to that observed in the piers of the building models. The analysis of test results indicated that the resistance and displacement capacity of unreinforced masonry structures of the particular type tested can be significantly improved if delamination and separation of coating is prevented. Finally, a calculation model for the assessment of seismic resistance of reference and strengthened building model is presented and the comparison between calculated and experimental results discussed.

Thermal properties of local Sardinian masonry and insulation materials: experimental assessment on full-scale models

The demand on reducing energy consumption of buildings, recently became tighter and tighter, as well as the need of shortening the building materials’ supply chain. It is generating a growing attention to natural and local construction materials and opening new and interesting research scenarios. The use of novel materials makes necessary reaching a deeper and appropriate understanding of their thermal performances by means of an accurate thermal characterization. The present research has been addressed at testing and verifying the thermal performance of Sardinian local masonry materials (hollow clay blocks and adobe bricks) and three different natural insulations: cork, sheep-wool and reeds. By the use of a dedicated hot box apparatus, working on full-scale wall models, the thermal resistance of eight different samples has been measured and then compared with the theoretical values calculated according to current standards. The results show that the measured values are by far higher than the calculated ones and that the use of local natural materials, if not accompanied by a rigorous standardization of production and installation procedures, can lead to overestimate their thermal performances.

Structural condition assessment of a reinforced concrete driveway

The reinforced concrete structure of a driveway built in the eighties of the 20th century is under consideration. It is a single-storey structure with a length of approx. 66.00 m, made in the form of a reinforced concrete skeletal structure, consisting of 7 frames with cantilevers, spaced at 9.00 m: 3 frames in the horizontal part of the driveway are three-span ones, and 4 in the sloping part are single-span frames. The driveway frame main beams have a rectangular cross-section and are based on pillars that have been placed on the spread footing these elements form a monolithic structure. Prefabricated reinforced concrete hollow floor plates were laid on them in the central part of the driveway, and in the outer parts the driveway floor was made of hollow clay slab blocks (Ackerman type). At the time of investigation, the upper layers of the driveway consisted of a surface waterproofing layer, a concrete slab of approx. 10 cm thickness made on a 1 cm sand layer. However, no internal waterproofing layer was found as was in the original design. The paper describes the process of determining the current technical condition of the reinforced concrete driveway structure, paying attention to the design and construction of the object, its operation (including the issues of durability of concrete under the conditions of possible impacts of the marine environment). Static and strength calculations were also performed (supported by concrete and reinforcement tests) and the conditions for further operation of the driveway were analyzed as well as concepts of rehabilitation.

Testing and analysis of masonry hollow clay block prisms filled with mortar

In some design situations, in construction systems with structural masonry, an increase in the capacity of the walls is required, which can be achieved with the filling of empty cells of masonry blocks with grout. The Brazilian technical standard for clay masonry blocks aiming at attaining greater agility and flexibility in the construction process allows the use of bedding mortar instead of grout to fill the cells of the blocks. In this context, the objective of this study was to evaluate the mechanical behaviour of prisms filled with bedding mortar. Six classes of mortar and one type of clay block with nominal resistance of 6 MPa were studied. The results of the compressive strength of the prisms indicate the viability of using bedding mortar with the same structural function as grout. This article presents also an analytical study to evaluate the mechanical behaviour of clay block prisms filled with mortar. Analyses were conducted using general-purpose, nonlinear finite element software that simulates structural behaviour under different loading scenarios. A three-dimensional model of the prisms was developed using eight-node brick elements for both block and mortar with nonlinear properties assigned to each material.

Testing and analysis of masonry hollow clay block prisms filled with mortar

Testing and analysis of masonry hollow clay block prisms filled with mortar

Assess of hollow clay block masonry wallets under high temperature

The main goal of this study was the behavioral assessment at high temperatures of masonry wallets built with different geometries of hollow clay blocks. In total, four type of structural wallets were erected; blocks of 15 x 20 x 30 cm nominal dimensions (width x height x length) and compressive strength of 7, 10, 15 and 18 MPa were built, employing laying mortar with compression resistance of 6, 8 ,10 and 12 MPa, respectively. The wallets were submitted to a constant temperature of 900°C, up to 4 hours, while heated gases permeability, thermal insulation and mechanical resistance were assessed. As conclusions, it was possible to observe that some wallets demonstrated the best thermal insulation performance, above 4 hours. Regarding the mechanical resistance and the gas permeability, none of the wallets analyzed reached the flexural criteria established for the work. Keywords: high temperature performance; clay blocks; masonry wallet.

In-Plane Strengthening of Clay Brick and Block Masonry Walls Using Textile-Reinforced Mortar

This study evaluates the use of a composite material composed of multiaxial hybrid glass-fibers and polypropylene fabric coated in a hydraulic lime-based mortar (referred to as textile-reinforced mortar) to improve the in-plane shear strength and displacement capacity of solid clay-brick and hollow clay-block masonry walls with the aim of defining a comprehensive test protocol. Design parameters of the adopted strengthening system are investigated, and both single-sided and double-sided configurations for application on wall surfaces are considered. The influence of the presence of an external thermal insulation layer on walls’ in-plane performance is also considered. The first stage characterizes the materials, their bonding properties, and the initial shear strength of the masonry bed-joints. The second stage investigates the in-plane behavior of strengthened masonry wall panels using diagonal compression testing. No premature debonding is observed, even with no mechanical anchorage between the masonry substrate and the strengthening layer. Out-of-plane deformation due to structural asymmetry is observed in the single-sided strengthening configuration.

Experimental study on the contribution of masonry infill in the behavior of RC frame under seismic loading

An experimental investigation is conducted to study the behaviour of masonry-infilled reinforced concrete (RC) frames with various lateral strengths. In addition, we study the behaviour of masonry units when the masonry walls are erected after the RC frame is cast. This construction technique is widespread in Kosovo. Eight 2/3 scale, single-bay, single-story RC frame specimens were tested. Six were infilled with hollow clay block masonry units and combined with RC frames with various strengths, one was infilled with solid clay bricks, and one was without infill (bare frame). The test results showed that the type of masonry unit influenced the failure mechanism of the masonry-infilled RC frames. Further, the results show that the main failure modes of the masonry-infilled RC frames, infilled with hollow clay blocks was the shear failure of the masonry infill, beam column joint failure, and the formation of flexural hinges in the part of RC frame. Whereas, the main failure mode of the masonry-infilled RC frames infilled with solid clay bricks was shear failure of the column and the masonry infill. Based on the experimental results, minimum lateral design strength criteria for RC frames infilled with hollow clay blocks is proposed in order to ensure the controlled ultimate failure mechanism.

Evaluation of the Thermal Performance of the External Walls of Buildings with Hollow Clay Blocks in Temperate and Humid Climate

Evaluation of the Thermal Performance of the External Walls of Buildings with Hollow Clay Blocks in Temperate and Humid Climate

Seismic Response of URM Walls Strengthened with FRP Reinforced Coating

A set of individual URM walls as well as an assemblage of a three-storey URM hollow clay block masonry structure composed of two shear- and two cross-walls have been tested in original and strengthened state. As a method of strengthening, the coating of the walls, consisting of glass fiber reinforced polymer (GFRP) grid laid in fiber reinforced cementitious mortar matrix (sometimes called textile reinforced mortar), anchored to the walls with glass fiber anchors, has been used. All specimens were subjected to constant vertical load simulating the effect of gravity loads and cyclic horizontal displacements with step-wise increased amplitudes, induced either at the top of the walls or at the floor levels of the assemblage, simulating the effect of seismic loads.The observed behaviour and failure mechanisms were of the shear type. The results show that by the application of FRP reinforced coatings, the seismic performance of URM structures can be significantly improved. As the results of experiments indicate, the energy dissipation, displacement capacity and shear resistance of URM increase substantially. In this regard, adequate anchoring of coating to the masonry and into the r.c. floor structures is essential.