Hollow Concrete Block Research Articles

Evaluating passive PCM performance in building envelopes for semi-arid climate: Experimental and numerical insights on hysteresis, sub-cooling, and energy savings

This study evaluates the performance of macro-encapsulated Phase Change Materials (PCMs) integrated into building envelopes for semi-arid climates, focusing on typical Moroccan construction using hollow concrete blocks. The primary objective is to assess the discrepancies between experimental and numerical analyses, particularly in hysteresis, sub-cooling, and energy savings. Given the widespread reliance on numerical tools like EnergyPlus for PCM simulations, the accuracy of manufacturer-provided latent heat values is investigated. The methodology involves constructing two identical test buildings, one equipped with PCM panels and another as a reference. Experimental data were collected in June 2023, assessing temperature fluctuations and energy savings. Differential Scanning Calorimetry (DSC) tests at varying scanning rates were conducted to analyze PCM behavior, including hysteresis and sub-cooling effects. Numerical simulations were then performed to compare energy performance. Besides, the results reveal that sub-cooling significantly limits PCM efficiency, with only 43 % of the PCM's latent heat capacity utilized. At the same time, hysteresis was found to be negligible in the field test. Cooling energy consumption was reduced by 20 %, with a corresponding 2.3 °C reduction in temperature fluctuations. However, the PCM's latent heat potential is underutilized due to sub-cooling. This research underscores the need for conducting DSC measurements at specific scanning rates to reflect regional climate conditions and suggests that simulation models should adjust latent heat utilization of the PCM. The study advocates for the use of composite PCMs, which could mitigate sub-cooling and enhance overall performance. These findings contribute to improving PCM integration in passive building designs, offering practical recommendations for better energy efficiency in semi-arid climates.

Analysis of behavior and uniaxial compression failure modes in ungrouted hollow concrete block masonry and their implication in design expressions

In this study, new analytical expressions for the design and revision of ungrouted masonry of hollow concrete blocks under gravitational effects were developed. These expressions can predict the compressive strength and modulus of elasticity for full and face-shell mortar beddings. A trend chart was generated, considering various modes of failure for different strength relationships between blocks and mortar. The study revealed that the main international masonry design codes underestimate the compression resistance of masonry when using weak mortar in combination with full mortar bedding. Results obtained using the Finite Element Method indicated that the optimal compression strength ranges were: 62–70 % for weaker mortar than the block with full mortar bedding; 152 % for block weaker than the mortar with full mortar bedding; and close to 67 % with face-shell bedding mortar.

Product of Hollow Concrete Blocks Mixed with Rice Husk Ash and Cassava Fermentation Waste

Product of Hollow Concrete Blocks Mixed with Rice Husk Ash and Cassava Fermentation Waste

A unified theory for predicting the compressive stress–strain curve of concrete block masonry

I-type internal structures are commonly present in concrete hollow block masonry. A unified theory based on I-type internal structures is proposed to analyze types of masonry systematically. In this unified theory, the I-type element represents the I-type internal structure; the equivalent frame is introduced to analyze the interaction between the block and grout; and the characteristic strength of mortar is employed to measure the performance of mortar in masonry. Each subtheory of the unified theory is independent, and the application scope of this theory can be expanded by adjusting the subtheories. The predictions of the unified theory for the compressive behaviors of fully grouted, partially grouted, and ungrouted masonry are well matched with the measured data. Through targeted adjustments, the prediction of this theory for special cases is also accurate. The calculation results suggest that the unified theory can effectively analyze different types of masonry with an I-type internal structure.

A Comparative Life Cycle Assessment (LCA) of a Composite Bamboo Shear Wall System Developed for El Salvador

To meet the UN sustainable development goal targets by 2030, it is necessary to provide adequate, resilient, and affordable housing solutions which are also low-carbon. In the context of affordable housing in El Salvador, an improved vernacular construction system, following the composite bamboo shear wall (CBSW) technology, has been developed as a feasible option to fill the current housing deficit. A life cycle assessment (LCA) has been conducted comparing a house built using the CBSW system with a reinforced concrete hollow block masonry system, considering the A1 to A5 (raw material production and manufacture) and B4 (replacement) life cycle modules. The LCA scope was limited to modules where there was sufficient confidence in the inputs. End-of-life modules were excluded as there is a large degree of uncertainty in the end-of-life scenarios for these materials in the regional context. The LCA results show that the CBSW system has approximately 64% of the global warming potential (GWP) of the reinforced masonry house, and when considering biogenic carbon, this reduces to 53%. There is additional potential to minimise impacts and maximise end-of-life opportunities (e.g., re-use, biofuel, etc.) for the biomaterials within the CBSW system, if considering modules beyond the scope of this paper, and this needs further study. Nevertheless, the results from this LCA—of limited A1 to A5 and B4 scope—show that the CBSW system has significant sustainability advantages over conventional construction systems and is considered a promising solution to alleviate the housing deficit in El Salvador.

Predicting compressive strength of hollow concrete prisms using machine learning techniques and explainable artificial intelligence (XAI)

The design of masonry structures requires accurate estimation of compressive strength (CS) of hollow concrete masonry prisms. Generally, the CS of masonry prisms is determined by destructive laboratory testing which results in time and resource wastage. Thus, this study aims to provide machine learning-based predictive models for CS of hollow concrete masonry blocks using different algorithms including Multi Expression Programming (MEP), Random Forest Regression (RFR), and Extreme Gradient Boosting (XGB) etc. A dataset of 159 experimental results was collected from published literature for this purpose. The collected dataset consisted of four input parameters including strength of masonry units (fb), height-to-thickness ratio (h/t), strength of mortar (fm), and ratio of fm/fb and only one output parameter i.e., CS. Out of all the algorithms employed in current study, only MEP and GEP expressed their output in the form of an empirical equation. The accuracy of developed models was assessed using root mean squared error (RMSE), objective function (OF), and R2 etc. Among all algorithms assessed, XGB turned out to be the most accurate having R2 = 0.99 and least OF value of 0.0063 followed by AdaBoost, RFR, and other algorithms. The developed XGB model was also used to conduct different explainable artificial intelligence (XAI) analysis including sensitivity and shapley analysis and the results showed that strength of masonry unit (fb) is the most significant variable in predicting CS. Thus, the ML-based predictive models presented in this study can be utilized practically for determining CS of hollow concrete masonry prisms without requiring expensive and time-consuming laboratory testing.

Experimental Evaluation of Compressive Properties of Early-Age Mortar and Concrete Hollow-Block Masonry Prisms within Construction Stages.

Early-age masonry structures require temporary support until they achieve full strength. Nevertheless, there is a limited understanding of the properties of freshly laid masonry and the design of newly constructed, unsupported masonry walls. This situation has led to numerous instances of structural damage and injuries to workers, prompting conservative construction bracing techniques. This paper presents comprehensive experimental studies on early-age mortar cubes and masonry prisms to assess the effects of curing time on the compressive properties of masonry assemblies, which is necessary for the design of temporary bracing. The change in modulus of elasticity and compressive strength of masonry prisms and mortar with curing time has been experimentally assessed. The results indicate that the compressive strength of freshly cast mortar cubes is relatively insignificant until approximately 24 h after construction, when it was observed to increase logarithmically. Regarding the performance perspective, the compressive strength of early-age masonry prisms is inconsiderable, less than 15% of full strength during the first day after construction. By contrast, regarding the life safety perspective, the compressive properties of a mortar joint within a masonry assembly (which is of more practical interest) appear to have no effect on the failure strength of concrete masonry prisms over the range of ages tested. The failure modes of the early-age mortar cubes and early-age masonry prism samples depend on the curing time, and different failure modes occurred before and after the start of the primary hydration phase, which is 20.8 h after construction. It is anticipated that the proposed research will provide valuable material properties leading to efficient design of control devices (e.g., temporary bracing) and improved guidelines for concrete-block masonry construction.

An Investigation of the Mechanical and Durability Properties of Hollow Concrete Blocks Made with Copper Mine Tailings as a Partial Cement Replacement

The increase in copper productivity in Zambia has resulted in the expansion of disposal areas occupied by mineral wastes and tailings. This not only consumes land but also, due to insufficient management, poses negative environmental impacts and health risks to people. Therefore, efficient and sustainable approaches for the proper management of these waste materials must be developed. In this study, the potential utilization of copper mine tailings was assessed. After analyzing the physical and chemical properties of copper mine tailings from Kitwe Tailings Dam (TD25), hollow concrete block specimens were prepared. Copper mine tailings were used as a partial replacement for cement in the mix design, with replacement ratios as follows: 0% for CBCMT O% (control specimen), 10% for CBCMT1O%, 20% for CBCMT2O%, 30% for CBCMT3O%, 40% for CBCMT4O%, and 50% for CBCMT5O%, all aimed at achieving a target strength of 5 MPa. Specimen compressive strength was evaluated, and it was found that CBCMT1O% and CBCMT2O% achieved the target compressive strength at 28 days of age. Water absorption rates and resistance to acid attack were also assessed. Findings revealed that all specimens outperformed the control specimen in terms of these properties. Furthermore, the environmental feasibility of the hollow concrete blocks specimens was examined, and the results showed limited leaching of heavy metals from the specimens, with concentrations within permissible thresholds. Additionally, a statistical analysis was conducted to study the influence cell shape has on the specimens’ compressive strength. Aimed at identifying the optimal specimen type for achieving compressive strength at an early age, results indicated that cell shape had a significant impact on the 28-day age of hollow concrete blocks. The study proposes a novel copper mine tailings (waste) management approach, by utilizing the potential it has to replace cement in the production of hollow concrete blocks, evident from the observed enhancement of the mechanical and durability properties.

Environmental Cost of Locally Manufactured Hollow Concrete Block in Jordan Using the Life Cycle Assessment Approach

Environmental Cost of Locally Manufactured Hollow Concrete Block in Jordan Using the Life Cycle Assessment Approach

Manufacturing Environmentally Friendly Hollow Blocks using Different Aggregates: Effect on Mechanical Properties

Hollow concrete block (HCB) is one of the most fundamental materials in building and construction worldwide. Therefore, HCB has emerged as a viable alternative to traditional building materials likebrick. It is an excellent choice for constructing walls, pavements, and other masonry work construct a long-lasting structure. Today's new world requires a green, eco-friendly, and sustainable world, and HCB can play a significant role in achieving that goal. HCB has superior thermal and fire resistance properties, greater strength, cost-effectiveness, and eco-friendliness. Only a small amount of construction in Bangladesh is done using HCBs. However, as sustainable structural technology advances, more frequent use of HCBs will be required. As a result, this article will provide a brief overview of the various applications of HCBs in Bangladesh, including the manufacturing process and its benefits and drawbacks. Specifically, this work investigates and compares the effect of different natural fine aggregates collected from different areas of Bangladesh on the mechanical properties of HCB. The fine aggregates used in this study came from the Dharala, Patgram, Lalmonirhat, and Someshwari rivers in Durgapur, Netrokona, Bangladesh. HCBs were manufactured using a hydraulic press machine and were constructed using mix design ratios of 1: 5: 1: 3 (Cement: Gravel Sand: Sylhet Sand: Crushed Stone), 1: 4.17: 1.67: 1.5 (Cement: Gravel Sand: Sylhet Sand: Crushed Stone), 1: 2.33: 2: 1.33 (Cement: Gravel Sand: Stone Dust: Crushed Stone), 1: 3.33: 2.33 (Cement: Gravel Sand: Stone Dust) and 1: 2.5: 1: 0.50 (Cement: Gravel Sand: Stone Dust: Crushed Stone) with water cement (W/C) ratio of 0.37. The specimens' dimensions were chosen to be 390 mm x 190 mm x 100 mm. The specimens were tested for unit weight, water absorption, compressive strength, and tensile strength after 28 days of water curing. The results showed that HCBs made with different fine aggregates from the Dharala, Patgram, Lalmonirhat, and Someshwari rivers in Durgapur, Netrokona, Bangladesh, have different compressive strengths at 28 days, namely 978 PSI, 1604 PSI, 1267 PSI, 1162 PSI, and 2128 PSI. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 12(2), 2023, P 153-158

Biomimicry in construction: Glycoprotein-stabilised adobe bricks for enhanced compressive strength inspired by termites mounds

Earth is a green building material with very low embodied energy and almost zero greenhouse gas emissions. However, it lacks strength and durability when used without stabilisation. By incorporating responsibly sourced stabilisers, it is possible to enhance the strength of this material. In this study, adobe bricks stabilised using bio-inspired stabilisers were investigated. This research was inspired by the high strength and durability of termite mounds, exploring the stabiliser behind such robust natural constructions. Termites build their mounds by incorporating a glycoprotein from their saliva to cement the sub-soil particles together. Biomimicry has been employed to investigate the potential use of the termites' construction stabiliser in adobe bricks. Three glycoproteins from meat and fish industry waste were identified as potential stabilisers in adobe bricks. Bovine serum albumin (BSA) from cows' blood, mucin from the porcine stomach, and gelatine from cold-water fish skin were the three stabilisers used in this study. Two soils were used to prepare adobe bricks for testing. The primary soil used in this study was from Devon in the United Kingdom (UK). The second soil was obtained from the Mayo neighbourhood in Khartoum, Sudan, and used only in key tests. Adobe bricks were made and stabilised with different concentrations of these bio-inspired stabilisers. Controlled unstabilised adobe bricks were used for comparison. The bricks were tested for their unconfined compressive strength. The main conclusion of this study is that BSA has proven its potential to be used as a stabiliser in earth construction. Using 0.5 % BSA resulted in a 17 % and 41 % increase in the unconfined compressive strength of the British and Sudanese adobe bricks, respectively. In addition, using 5 % BSA resulted in a 203 % and 97 % increase in the unconfined compressive strength of the British and Sudanese adobe bricks, respectively. The compressive strength of BSA-stabilised adobe bricks is higher than that of earth bricks stabilised using 5 % cement and 5 % lime reported in the literature. Furthermore, the compressive strength of the 5 % BSA-stabilised adobe bricks is higher than the lower recommended compressive strength for the hollow concrete blocks in the UK. Hence, these BSA-stabilised adobe bricks could substitute hollow concrete blocks to construct internal walls. The other stabilisers tested did not significantly improve the unconfined compressive strength of the adobe bricks. The study underscores the value of biomimicry and proposes glycoproteins as viable natural stabilisers in earth construction, with further recommendations for in-depth research to optimise application methods and formulations.

Optimising of thermal insulation thickness based on wall orientations and solar radiation using heating-degree hour method

Buildings consume more than a third of the world's energy demand, and painstaking adjusting the insulation thickness of external walls is an effective way to save energy. Thermal insulation plays an important role by reducing the heat transfer rate to save energy, and it is important to determine the thickness of the appropriate insulation material in the walls. In this research, considering only the heating factor, four different building materials (Pumice, Hollow concrete block - HCB, Hollow red clay block - HRCB and Reinforced concrete - RC) and eight different insulation materials (Extruded polystyrene - XPS, Expanded polystyrene - EPS, Expanded polyurethane - PUR, Wood fiber - WF, Hemp fiber - HF, Linen fiber - LF, Fiber glass - FG and Sheep wool - SW) are investigated on the exterior of a building in Sivas province of Türkiye. To reach more accurate results, life cycle cost analysis is taken as a basis, and the optimal insulation thicknesses, payback periods and energy savings of 32 different wall + insulation combinations with solar radiation (SR) are estimated using heating degree-hours. The heating requirement of a building covers more than three quarters of the year in Sivas, depending on different facing walls. These rates are calculated as 85 % (without SR), 80 % (North), 78 % (West), 77 % (East) and 75 % (South). Results also showed that the total minimum heating cost, the total maximum energy saving cost and the shorthest payback period are obtained HRCB + FG + South with 14.19 €/m2, RC + FG + solar radiation free with 72.76 €/m2 and RC + LF + solar radiation free with 1.60 year.

Reuse of Hollow Concrete Blocks Waste in the Formulation of an Eco-Mortar Reinforced with Natural Fibers for Use in Filling Materials

Reuse of Hollow Concrete Blocks Waste in the Formulation of an Eco-Mortar Reinforced with Natural Fibers for Use in Filling Materials

Thermo-mechanical Stability Analysis of Hollow Cellular Concrete Block Air Convection Embankments for Cold Regions

Crushed-rock air convection embankment (ACE), as a highly open-graded porous medium, has been used to mitigate the thaw settlement of pavement structures in permafrost regions. Previous studies have revealed that cellular concrete has significant potential as a cost-effective material for ACE to solve the problem of crushed rock shortage in interior Alaska and improved the thermal stability of pavement structures in cold climates. The design configurations of the hollow cellular concrete block ACE were further designed to maximize the performance benefits and facilitate future implementation and field construction. However, the mechanical behaviors of the proposed structures and ice-rich subgrade were still unknown. In this study, a thermo-mechanical coupling model was developed to evaluate the thermal effect on the long-term mechanical stability of the selected pavement structures and subgrade soils. The results indicated that the thermal stability of the proposed hollow cellular concrete block ACEs was superior to that of the conventional crushed-rock ACE. The maximum thaw settlement of the proposed hollow cellular concrete block ACE was only 13.4% that of the conventional crushed-rock ACE. Thermal and mechanical analyses showed that the proposed cellular concrete ACEs have a significant advantage over conventional crushed-rock ACE.

The strength of complex compressed reinforced concrete structures utilising hollow concrete blocks

Structures in which elements from different materials work together are successfully used in various combinations. Recently, new, effective construction materials and products have appeared. In complex or multi-component structures, elements made of materials with different physico-chemical or strain-strength characteristics should be sensibly combined for joint work. The more fully the properties of the components’ materials are utilised, the more efficient the design itself is. By analysing global practice, it can be seen that small concrete blocks have become widespread. The use of masonry made of hollow concrete blocks in modern construction differs from traditional ones in that the void area (up to 70%) makes it possible to create complex high-strength load-bearing structures by filling them with monolithic reinforced concrete. This also enables speeding up the construction process itself and reducing the cost of work on the construction site. The purpose of the study was to examine the strength of centrally compressed columns composed of hollow blocks and concrete filling with different transverse and longitudinal reinforcements, as well as to improve their calculation methodology. Experimental studies of centrally compressed columns, with different percentages of reinforcement using hollow concrete blocks as permanent formwork, have been carried out. The article presents the results of the research on strength, but the results of the strain studies were not included in this work. The proposed method of calculating complex constructions can be applied in design practice. A good correlation was observed between the experimental results and the results of the analytical model.

Shaking table tests of a one-quarter scale model of concrete hollow block masonry houses retrofitted with fiber-reinforced paint

Unreinforced masonry (URM) buildings are prone to significant damage when subjected to ground motion. Some strengthening methods have been proposed to increase the seismic capacity. However, the widespread adoption of these methods faces various challenges, including economic constraints experienced by common people in developing countries, the complexity of implementation, efficiency, and seismic safety of each technique. This paper introduces a new retrofitting method of fiber-reinforced paint using fiberglass as the primary reinforcing material. The advantage of this technique lies in its simplicity and ease of application, with the added benefit of using the paint to improve the appearance of the house. Two 1:4 scale concrete hollow block (CHB) masonry houses were constructed to represent unreinforced masonry and retrofitted masonry structures using fiber-reinforced paint (FR-Paint). The shaking table test results indicate that the retrofitted house model showed improvements of up to 18 times in deformation capacity and up to 13 times in energy dissipation compared to the non-retrofitted house model. FR-Paint has a robust performance even in high input motion at a seismic intensity JMA of 7 (Japan Meteorological Agency). This confirms that this retrofitting method has a high earthquake-resistant performance.

Fish responses to manipulated microhabitat complexity in urbanised shorelines

Abstract The diversity‐habitat complexity relationship has been utilised widely in conservation and biodiversity enhancement interventions, but few studies have attempted to tease apart the components of complexity that drive this relationship. The ecological engineering of seawalls is one area where this topic has advanced, albeit not often at scales relevant to fish. We constructed habitat enhancement units (Simple, Complex and Freestyle ‘fish houses’) out of hollow concrete blocks and installed them at the base of tropical rip‐rap seawalls. Simple and Complex fish houses were cuboid, had the same surface area and volume and included 100 holes (microhabitats). The holes in Simple fish houses were all the same size, whereas 25 size variations were used in the Complex design (volume‐independent manipulation of a single complexity element). The Freestyle fish house was non‐cuboid and had more overall volume, microhabitat types and sizes. We examined the volume‐independent (Simple vs. Complex fish houses) and volume‐dependent (Freestyle fish house) effects of microhabitat complexity on fish taxonomic and functional assemblage metrics at two spatial scales and across diel cycles. We also investigated diurnal and nocturnal fish‐microhabitat size relationships. There was a modest, but not significant, volume‐independent effect of complexity on fish assemblages. The Freestyle design, however, supported significantly greater abundance, species richness, and distinct taxonomic and functional compositions. These results were dependent on spatial scales and diel cycles. Diel variation in fish activity patterns resulted in stronger size‐matching relationships between fish and microhabitats at night than during the day. Synthesis and applications. Our study shows that, to enhance fish diversity, it is important to provide three‐dimensional habitat architecture that incorporates a wide range of microhabitat sizes and types. Our findings also highlight some key considerations when assessing the performance of intervention designs, including spatial‐scale dependent effects of structural complexity, diel variation in fish‐microhabitat relationships, and choice of intervention assessment metric (i.e. taxonomic vs. functional diversity).

Thermal behavior of dry-cast concrete blocks masonry walls at elevated temperatures

This study aims to contribute to a better understanding of the behavior of masonry structures in the event of a fire, addressing a critical gap in both local and international standards and design guidance. Particularly in Brazil, the widespread adoption of structural masonry contrasts with the absence of national standards for evaluations at high temperatures, mainly due to the scarcity of research on the subject, potentially leading to severe consequences for life safety and property losses. This paper addresses a comprehensive study on the thermal behavior of dry-cast hollow concrete blocks masonry at high temperatures. The study combines both experimental and numerical analyses and involves underexplored topics, including characterization of thermal properties at elevated temperatures of commonly used blocks, post-fire condition of masonry's components, and determination of isotherms in the masonry cross-section in scenarios with one or both faces of the wall exposed to fire (separating and non-separating walls). Despite differences in the physical characteristics of the concrete used in block production, the temperature dependency of thermal properties obtained during experiments showed similar to that in Eurocode 2. Numerical and experimental results also indicate a low influence of block strength and mortar joints on the temperature evolution within the masonry. A key finding refers to a relatively fast temperature increase during heating due to the small thickness of the shells and webs of the blocks, thus impacting the performance of masonry structures in fire.

Engineering experimental study on mechanical and durability properties of banana leaves ash as partial cement replacement in hollow concrete blocks

This engineering study investigates the mechanical properties and durability of Hollow Concrete Blocks (HCBs) made with banana leave-ash-replaced cement. This study focused on analyzing the physiochemical composition of banana leaf ashes (BLAs) and their impact on the mechanical and durability properties of these blocks. HCB production requires binding materials such as cement, and BLAs, a byproduct of agricultural waste containing Pozzolana, serve as an alternative. This study experimented with alternative mixtures to evaluate the influence of BLAs on the strength and durability of blocks, particularly their resistance to acid and sulfate attacks. The test was conducted by partial replacement of Dangote Ordinary Portland cement 42.5R with 0%, 5%, 10%, 15%, and 20% BLAs for Class “A,” “B” and “C” HCBs. The test results indicated that HCBs produced by BLAs can replace cement HCBs to achieve better strength and durability properties with respect to standards. Statistical results show that BLAs have a significant effect on the compressive strength of HCBs. Chemically acidic and sulfate-attack-resistant HCBs were examined, and the results showed that HCBs with BLAs had good resistance. The results of an experimental study on the mechanical and durability properties of BLAs blended with cement HCBs showed that replacing BLAs by up to 20% improves the durability and strength of blocks, resulting in better performance than the standards. The optimum percentage of partial replacement of BLAs with cement to produce HCBs is 20%.

Sustainability Analysis of Hollow Concrete Blocks Manufactured Using Recycled Concrete Aggregate and Fly Ash as an Eco-Friendly Construction Component

Sustainability Analysis of Hollow Concrete Blocks Manufactured Using Recycled Concrete Aggregate and Fly Ash as an Eco-Friendly Construction Component