Hollow Cement Research Articles

Performance of Geopolymer Insulation Bricks Synthesized from Industrial Waste

In the current work, aluminum dross from the aluminum industry and fired-clay brick waste (Homra) were combined with alkaline activators (Na2SiO3/NaOH) with varying molarities of NaOH to create insulating geopolymer bricks. An alkaline activator with an (S/L) ratio of 3/1 was combined with Homra to replace it partly. The mixture was then molded into 50 × 50 × 50 mm3 stainless steel molds. Water absorption, compressive strength, bulk density, and apparent porosity of the produced geopolymer were measured at various curing durations and NaOH molarities. The findings showed that adding more aluminum dross waste replacement leads to a decrease in bulk density and compressive strength and an increase in the creation of pores that improve the produced bricks’ ability to insulate against heat. Using 8 M of NaOH after 28 days, the findings revealed that 3% aluminum dross waste replacement has a compressive strength of about 8.6 MPa, water absorption of 14.6%, bulk density of 1.307 g/cm3, and thermal conductivity of 0.32 W/m·K. The Egyptian standard, ASTM C62, satisfies these outcomes. Using DesignBuilder energy simulation software version 6.1.06, the constructed insulating brick under ideal circumstances was utilized to calculate its contribution performance in energy consumption. The annual energy consumption was reduced by about 21% compared to traditional hollow cement bricks.

Evaluating Thermal Performance and Environmental Impact of Compressed Earth Blocks with Cocos and Canarium Aggregates: A Study in Douala, Cameroon

A novel low-cost earthen construction system integrating biosourced aggregates is proposed for houses’ erection of low-income households. This study is based on in-situ measurements on two representative test cells constructed in Douala, with a typical hot and humid climate. One of these buildings is made with a hollow cement block as a reference, and the other with biosourced earth bricks modified with Cocos nucifera and Canarium schweinfurthii aggregates. Dynamic thermal simulations of the two test cells were performed using the EnergyPlus building performance simulation program. The results are based on measuring air temperature and humidity, and the simulation leads to defining the discomfort hours and the annual energy consumption. The adaptive ASHRAE 55 thermal comfort model was used to evaluate the comfort conditions. The results show that air conditioning systems provide the best comfort systems with minimums of about 95% for plastered and unplastered wall construction systems. Biosourced compressed earth brick constructions offered the best thermal performance with comfort ranges of around 96% and 44% for air conditioning and natural ventilation, respectively. In terms of energy consumed, there was a gain of about 100 kWh over the year. Energy consumption is lower in the biosourced compressed earth brick building than in the hollowed cement block building: this one offered the lowest comfort range of about 40% in natural ventilation. The construction provisions were considered for the life cycle assessment, and two scenarios describing the origin of the cement raw materials were considered. It can be seen that cement accounts for more than 95% of the impacts for both construction systems, as well as for the scenarios of its origin. In all situations, the hollowed cement block construction presented the highest impact on the global warming potential: 66 KgCO2eq and 89 KgCO2eq, respectively, without plaster and with plaster. It can also be seen that the plastered layer had a carbon footprint (in terms of Green House Gas Emissions (GHG emissions)) of almost 40% on the overall functional unit. Canarium Schweinfurthii and Cocos Nucifera materials accounted for only 1% of the overall impact.

Examining Carbon Emissions in Building Materials: A Case Study of Government Buildings in Pokhara Metropolitan City

Numerous studies placed particular emphasis on reducing carbon emissions from operations, often ignoring the importance of embodied carbon emissions. To evaluate the embodied carbon emissions associated with government buildings in Pokhara Metropolitan City, a systematic process-based approach was used to estimate the total embodied carbon over the lifetime of these structures. The research findings reveal that the cumulative embodied carbon emissions stemming from these buildings contributed a total of1281.56 metric tons (Mt) and 12504540.5 MJ of embodied energy. Furthermore, the study explored the potential for reducing these emissions by adopting alternative construction materials. In particular, the inclusion of AAC (Autoclaved Aerated Concrete) blocks, hollow cement concrete blocks, and stabilized soil blocks (8% cement)in the same building demonstrated reductions in total emissions by 5.56%, 4.38%, and 5.16%, respectively. It is crucial to acknowledge that this study primarily focuses on the construction stage of the building and exclusively considers civil construction materials. It did not encompass elements such as sanitary and electrical fixtures or other stages in the building's lifecycle, including operation and maintenance and eventual demolition. Consequently, it is recommended that future research endeavors undertake a more comprehensive analysis, encompassing electrical and sanitary fixtures, as well as all phases of a building's lifecycle, to gain a more holistic understanding of embodied carbon emissions in government buildings

An investigation of South African low-income housing roof anchor systems

The current roof anchoring methods for houses in South Africa are described in the standard SANS 10400. The adequacy of these prescribed roof anchoring methods for low-income houses (LIHs) is questionable, due to several recently reported failures caused by strong winds. This study quantitively investigates the performance of the prescribed roof anchoring methods through numerical methods, and focuses on LIHs with light-weight roofs supported on single-leaf masonry walls. The masonry walls comprise either solid bricks or hollow cement blocks. The peak wind reaction forces that are expected to occur at the roof anchor systems were determined through a series of static analyses. Finite element analysis techniques were performed to predict the capacity of the roof anchor systems. The predicted resistance of the roof anchor systems was compared to the calculated peak wind reaction forces at the roof anchors to determine the adequacy of the roof anchor systems. The results of the research suggest that, for LIHs constructed from solid bricks, the prescribed roof anchor systems perform poorly under the expected South African strong wind climate. The results indicated that the roof anchors will pull out at peak basic wind speeds of between 27 m/s and 32 m/s, and cracks will develop in the masonry prior to anchor pull-out. This study suggests that further research is required to develop adequate roof anchoring methods for LIHs with light-weight roofs, supported on solid brick walls, and that the relevant codes should be amended accordingly. Furthermore, the results showed that the prescribed roof anchor systems for LIHs constructed from hollow blocks performed well and were able to withstand the expected wind loads under the South African strong wind climate.

Bidirectional convection mechanism and cooling performance of road embankment with a new duct-ventilated slope in permafrost regions

Embankment with duct-ventilated slope (EDVS) is a new kind of proactive roadbed cooling measure in permafrost regions, which is composed of multiple hollow cement ventilation ducts assembled side by side, and the ducts are laid down on embankment slope. To investigate its cooling mechanism and performance, a prototype field test was carried out on the Qinghai-Tibet Plateau. The in-situ flow visualization test revealed that EDVS can conduct the convection process of airflow upward parallel to the embankment slope at the windward slope and downward parallel to the slope at the leeward slope. Thus, the bidirectional airflow in the ducts is available, which is termed as “bidirectional convection mechanism” and first discovered in embankment slope cooling measures. The numerical simulation results indicated that the wind pressure gradient is the primary reason for the bidirectional convection mechanism. The bidirectional convection mechanism can effectively utilize the low-temperature air to reduce the subgrade temperature in cold seasons. The monitored data showed that EDVS reduced the annual average slope temperature by 3.8°C compared to the traditional no-covered embankment. EDVS provides new research for roadbed cooling measures in permafrost regions.

A model for thermal comfort assessment of naturally ventilated housing in the hot and dry tropical climate

PurposeA major challenge faced by West Africa is to find comfortable housing as a result of climate change and population growth. The climatic adaptation of buildings and their indoor environment become an essential condition for maintaining the health and productivity of the occupants. This paper proposes a model to assess the thermal comfort of naturally ventilated buildings in hot and dry climates in Burkina Faso.Design/methodology/approachThe proposed method is an adaptive model which relies on a combination of parameters such as the operative temperature, the new effective temperature and the basic parameters of thermal comfort. It consists in proposing the zones of thermal comfort on the diagram of the humid air for each climatic region.FindingsA decision-making tool is set up for evaluating the comfort of buildings to better consider the bio-climatic concept through a long-term comfort index. This comfort index is defined and is used to assess the degree of thermal discomfort for various types of housing. Two natural ventilation pilot buildings located in Ouagadougou were considered. The results show that the pilot building whose wall are is made of Earth blocks achieves 26.4% of thermal comfort while the building made of hollow cement block achieves 25.8% of thermal comfort.Originality/valueThe decision-making tool proposed in the present study allow building stakeholders to better and easily design, assess and improve the thermal environment of buildings.

Influences of local materials on the building behavior and evaluation of the cooling loads

The energy demand in buildings sector is always increasing due to the climate, the economic growth, and also the need for thermal comfort. The aim of this paper is to find a way that can significantly reduce the energy demand for a building through an improvement of the design of its thermal envelope. Within this work, we utilized the thermophysical properties of four building materials: three local materials (compressed earth block (BTC), lateritic block (BLT), and raw earth), and one modern (Hollow cement). The numerical optimization of the building design has been performed dynamically by Comsol 5.3a software: the case study is Ouagadougou and the surface is 100m2. Also, the temporal variations in the inside of the room, as well as the internal and external temperatures of the walls and the ceiling with four different materials, have been determined. The result of the simulation shows that, for BLT, the maximum of ambiante temperature is obtained 308K around 22h, for Adobe it is 308.8K around 21h, for BTC it was 309.2K at 19h30, and finally for cement block it is 310K around 17. We can safely say that BLT is the material leading to the lowest average daily indoor temperature variation, thus leading to the reduction of air conditioning load and the need for thermal comfort and around the order of 4KW of energy saving can be obtained.

Determination and Evaluation of the Cooling Load of a Building Made by Different Local Material of Construction

This paper aims to describe a passive approach to reduce the energy demand for an existing building and can be made through an improvement of the design of the thermal envelope. The essential article goal is to simulate thermal construction responses in dependence on changing different materials of the construction of the building and also with less energy usage to design a more effective cooling system. In this approach, we simulate the building with different materials: three local materials (compressed earth, lateritic, and raw material) and one modern (Hollow cement) used in Burkina Faso and an energy analysis of the building has been carried out. The numerical optimization of the building design has been performed dynamically for these four materials using the COMSOL multiphysics simulation tool. The model treated is determining the internal temperature and cooling demand concerning a tertiary building in Burkina Faso like a classroom, which is located in a hot and dry climate to improve the indoor quality of the classroom knowing the importance of the thermal comfort in the room for socio-economic performance efficiency and well-being. The analysis result of these four materials shows that energy can be saved if we use local materials instead of the modern one because around 4KW of energy can be saving with local materials. The use of local materials in the building design can be an option for reducing the heat transfer into the room and at the same time the energy consumption.

Comparative Study of Thermal Comfort Induced from Masonry Made of Stabilized Compressed Earth Block vs Conventional Cementitious Material

This paper investigates the stabilization effect on compressed earth blocks (CEB) produced from quartz-kaolinite rich earthen material stabilized with 0% - 25% calcium carbide residue (CCR). The paper evaluated various physico-thermal properties of the stabilized CEB and thermal comfort in the model building made of CEB masonry. The optical properties of CEB were evaluated from the mineral composition of the earthen material and CCR and apparent density of the CEB. A simulation was carried out on naturally ventilated model building whose masonry is made of CCR stabilized CEB comparing to the so-called conventional cementitious materials such as cement blocks and concrete. The results showed a decrease of the apparent density of the CEB from 2100 kg·m–3 for unstabilized CEB (0% CCR) to 1600 kg·m–3 for 25% CCR stabilized CEB. The thermal conductivity and depth of penetration of the heat flux on a 24 hours period of CEB respectively decreased from 1 W·m–1·K–1 and 12.7 cm for 0% CCR-CEB to 0.5 W·m–1·K–1 and 10.2 cm for 25% CCR-CEB. The emissivity, solar absorptivity and visible absorptivity of the CEB respectively decreased from 0.82, 0.82 and 0.82 for 0% CCR-CEB to 0.80, 0.64 and 0.64 for 25% CCR-CEB. The number of hours of warm and humid thermal discomfort was impacted for stabilized CEB based masonry in comparison with cement based masonry. The warm discomfort in building made of 20% CCR-CEB masonry was 400 hours lesser than that in building made of hollow cement blocks masonry. If air conditioning system is used to keep the indoor temperature below 28°C, the economy of 310,000 CFA francs (535 USD) is made every year on energy consumption for cooling in the model building made of 20% CCR-CEB masonry, corresponding to 9.6% less, with respect to that made of hollow cement blocks masonry.

Life cycle cost of different Walling material used for affordable housing in tropics

The energy consumption of affordable housing industry plays a vital role in the environmental sustainability, waste generation and energy consumption. The development of sustainable housing construction methodology helps its country’s economic development and sustainable development. Wall and roof are the most significant building component in a dwelling unit. The walling materials can determine the cost of the building as well as the total life cycle cost of a dwelling unit. In this study, the total life cycle cost of a basic dwelling unit in Sri Lanka, made of mostly available walling materials such as Brick, Hollow cement block, and Cabook, the Mud concrete blocks were calculated by using energy accounting hierarchical structure. The life cycle cost incurred due to change in above-mentioned walling materials were calculated and measured. Additionally, total LCC compared and analyzed.The results show that mud concrete block is the most suitable walling material. The brick has the highest account for the embedded energy. The hollow cement block is the worse building materials in tropics and its carbon footprint is comparatively higher. Even though the brick has higher embedded energy and construction cost, in a long run brick is less expensive than hollow cement block and Cabook walling material. Concluding, mud concrete block is comparatively most sustainable walling material for building affordable housing in tropics.

Effect of Void Area on Hollow Cement Masonry Mechanical Performance

Originally, brick/block was formed by placing moist clay/cement mortar in a mold by hand. As modern industrial methods were implemented in the cement block manufacturing process, the majority of production was changed from a molded process to an extrusion process. Extrusion more easily accommodates the inclusion of hollow (void area) in a block unit, which in turn can make the manufacture and use of block more cost-effective and material efficient. Although void area in block varies from place to place, hollow masonry unit standards are defined by ASTM C90-11b, and specifications are related to the minimum face shells and a web requirement. This paper examines the effect of the void area on aspects of the performance of hollow cement block masonry. The performance of five comparison sets of hollow cement masonry was evaluated for different range of void area. Water absorption, compressive strength of cement block, compressive, shear, and flexural tensile strength of masonry prism were measured on each type of hollow block and used as indicators of potential performance in a masonry wall.

An Experimental Investigation of the Passive Cooling of a Building Using Nighttime Radiant Cooling

An experimental study to determine the feasibility of using nocturnally cooled water for space cooling is presented. The experimental test rig consist of a room, flat plate sky radiator, a heat exchanger unit, a storage tank, pump, interconnecting pipes, and a control room. The test room has a dimension of 3.0 m × 3.0 m × 2.5 m and is made from 6 inch (0.15 m) hollow cement blocks. It has two windows and an access door while the roof is pitched at 12°. The cooling process occurs in two parts: the nocturnal part when water is cooled by night sky radiation and the diurnal part when the water cooled during the nocturnal part is circulated through a heat exchanger for space cooling. Series of tests were conducted under the meteorological condition the Federal University of Technology, Owerri, for the period of November, 2010 to March, 2011. Results obtained showed that with the facility in place, a room temperature of 26 to 28°C could be maintained on a day when the maximum ambient temperature is 34°C. This corresponds to a temperature depression of up to 2.5°C below the average room temperature, representing about 101 kJ of cooling. Thus, passive cooling using nocturnally cooled water has a great potential in space cooling in the tropics.

Effect of construction materials on embodied energy and cost of buildings—A case study of residential houses in India up to 60 m2 of plinth area

Worldwide buildings consume annually about 30–40% of primary energy in construction, operation and maintenance. An enormous part of this energy is consumed in construction activities alone. Nearly two million residential buildings for economic weaker section alone, are required to be built annually in India, apart from offices, commercial, public and industrial buildings. Use of low embodied energy and cost effective building materials, in the building construction, can significantly reduce the overall energy consumption and thus eventually minimize energy footprint of buildings. In this paper, the embodied energy and construction cost have been estimated for the residential houses (up to four storied) of a chosen typology. The calculation has been done for total 122 nos of houses, having plinth area varying between 20m2 and 60m2. The embodied energy and construction cost have been compared and analyzed for various building materials (i.e. burnt clay bricks, hollow cement concrete blocks, aerated autoclaved blocks, fly ash lime gypsum blocks, solid cement concrete blocks etc.). It is estimated, that the embodied energy (EBE) is least (2.092GJ/m2) for two storied houses, constructed with hollow cement concrete block based masonry, however cost of building materials is found to be lowest (US$ 62/m2) for four storied houses constructed with AAC block based masonry.

Coupled heat transfer modes for calculation of cooling load through hollow concrete building walls

A CFD model was developed to study thermal performance of hollow cement wall constructions of buildings under hot summer conditions. The approach employed couples conjugate, laminar natural convective flow of a viscous fluid in hollow building blocks with long-wave radiation between the cavity sides. Realistic boundary conditions were employed at the outdoor and indoor surfaces of the wall. A state-of-art building energy simulation program, ESP-r, was used to determine the outdoor thermal environment that included solar radiation, equivalent temperature of the surroundings and convective heat transfer coefficient. The CFD problem is put into dimensionless formulation and solved numerically by means of the control-volume approach. The study yielded comprehensive, detailed quantitative estimates of temperature, stream function and heat flux throughout the wall domain. A detailed parametric study showed that using a wider cavity within a building block does not necessarily reduce heat flux through the block. Radiation heat transfer between cavity sides may account for a significant fraction of heat flux through the block and neglecting its effect can lead to errors that could be as large as 46%. The geometry of the hollow blocks was demonstrated to affect the heat flux by as much as 30%.

Cultivation of Gelidiella acerosa in the open sea on the southeastern coast of India

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 382:49-57 (2009) - DOI: https://doi.org/10.3354/meps07891 Cultivation of Gelidiella acerosa in the open sea on the southeastern coast of India M. Ganesan1,*, S. Thiruppathi1, K. Eswaran1, C. R. K. Reddy2, B. Jha2 1Marine Algal Research Station, Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, Mandapam Camp - 623 519, Tamilnadu, India 2Discipline of Marine Biotechnology & Ecology, Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, Bhavnagar - 364 002, Gujarat, India *Email: ganesandr@yahoo.com ABSTRACT: Four cultivation methods: raft, bottom net, coral block and cement block were evaluated for the propagation of Gelidiella acerosa in the open sea. Of the 4 methods, the raft method resulted in significantly (p < 0.001) highest daily growth rate (DGR) of 1.11 to 1.31% and biomass of 973 to 1288 g fresh weight (wt) m–2. Biomass values showed direct correlation with initial seedling densities. Initial seedling densities ≥500 g fresh wt m–2 registered maximum yields of 1425 ± 90 g fresh wt m–2, while lower initial seedling density (200 g fresh wt m–2) showed higher DGR values (0.71 ± 0.07 and 0.48 ± 0.06% during the 1st and 2nd harvests respectively). The 180 d cultivation period registered the highest yield of 367 ± 45 g fresh wt m–2, which significantly differed (p < 0.001) from values obtained for the 30, 60 and 90 d cultivation periods. The germplasm collected from Sethukarai (subtidal reef) showed the highest yield (525 ± 34.6 g fresh wt m–2, p < 0.001) and DGR (0.54 ± 0.04%) compared with those collected from Pudumadam (intertidal rock), Ervadi (intertidal reef) and Rameswaram (subtidal rock). The findings of this study indicate that the raft method of cultivation using germplasm from Sethukarai, an initial seedling density of ≥500 g fresh wt m–2 and a 180 d cultivation period are important criteria for the successful cultivation of G. acerosa. The augmentation of exploited seaweeds through cultivation practices will help preserve natural biodiversity and ecosystem functioning. KEY WORDS: Bamboo raft · Coral block · Daily growth rate · Gelidiella acerosa · Cultivation · Gulf of Mannar · Hollow cement block · Open sea · Seedling density Full text in pdf format PreviousNextCite this article as: Ganesan M, Thiruppathi S, Eswaran K, Reddy CRK, Jha B (2009) Cultivation of Gelidiella acerosa in the open sea on the southeastern coast of India. Mar Ecol Prog Ser 382:49-57. https://doi.org/10.3354/meps07891 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 382. Online publication date: April 30, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

FINITE ELEMENT PREDICTION OF UNSTEADY HEAT TRANSFER IN HOLLOW BLOCKS

This paper presents a numerical method for describing the transient heat transfer through hollow cement blocks via the employment of finite element technique. The block under consideration is assumed to be of rectangular cross-section and composed of two parts, a solid inside which an enclosure (space) is located. The outer surface of the block is exposed to the solar flux. The temperature distribution inside the block as function of space coordinates and its variation with time are the unknown variables of the problem. This leads to a parial differenial equation in the temperature. Finite element technique is used to obtain the solution of the problem for different boundary conditions. The effect of the presence of the enclosure is investigated by comparing homogeneous and hollow blocks results.

Cement tubules — another look

The existence of previously reported hollow cement tubules has been confirmed for realistic water: cement ratios by utilising multiple electron microscope viewings (TEM, SEM, STEM) of the hydration products and noting their behaviour (damage etc) under a concentrated electron beam. However, microanalysis of these tubes along with selective phase hydration experiments show unambiguously that the “reverse-silica garden” mechanism cannot be solely responsible. A reinvestigation of the original silica garden experiment coupled with the microanalysis results indicate that a more complex chemical multi-phase system is operating in which rheological factors are also important.