scholarly journals Grain Density-Based Approaches to Predict the Mechanical, Thermal and Hygric Properties of Carbon-Negative Aggregate Concretes

2021 ◽  
Vol 13 (15) ◽  
pp. 8194
Author(s):  
Imen Rahmouni ◽  
Geoffrey Promis ◽  
Omar Douzane ◽  
Frédéric Rosquoet
Keyword(s):  
Waste Recycling ◽  
International Standards ◽  
Analytical Models ◽  
Engineering Properties ◽  
Thermal Mass ◽  
Concrete Mixtures ◽  
Experimental Campaign ◽  
Hygric Properties ◽  
Predictive Approaches ◽  
Mineral Aggregates

The suitability of replacing mineral aggregate with carbon-negative ones mainly depends on the properties of the aggregates produced from waste recycling, reducing CO2 emissions. This study aimed to investigate the predictive approaches adapted to concrete mixtures where mineral aggregates are replaced by carbonated aggregates (at different substitution rates from 25 to 100% with aggregates of various origins). A large experimental campaign of aggregates and carbonated aggregate concretes highlighted their physical, mechanical, thermal and hygric properties and the influence of density and porosity of aggregates on these properties. Thanks to these results, predictive approaches were formulated to establish the main engineering properties: mechanical compressive strength, elasticity modulus, thermal conductivity, thermal mass capacity and hygric diffusivity. These empirical and analytical models were based on the density of aggregates. Maximum deviations of around 15% were obtained with the experimental data, highlighting the influence of grain density on carbonated aggregate concretes. These models could then be used to optimize the formulation of concrete mixtures with carbonated aggregates, replacing international standards adapted to mineral aggregates.

scholarly journals Effect of Burn Joss Paper Ash on Properties of Ground-Granulated Blast Furnace-Based Slag Geopolymer

2020 ◽  
Vol 10 (14) ◽  
pp. 4877
Author(s):  
Wen-Ten Kuo ◽  
Chuen-Ul Juang ◽  
Zhi-Rong Chen
Keyword(s):  
Blast Furnace ◽  
Setting Time ◽  
Microscopic Analysis ◽  
Waste Recycling ◽  
Engineering Properties ◽  
X Ray Diffraction ◽  
Granulated Blast Furnace Slag ◽  
Substitution Ratio ◽  
Dry Shrinkage ◽  
Peak Value

The purpose of this study is to make geopolymers using burned joss paper ash (BJPA)—which is used in traditional Chinese festivals—and ground-granulated blast-furnace slag (GGBFS). GGBFS-based geopolymers were replaced by BJPA, by mass, at levels of 0%, 20%, 40%, 60%, 80% and 100% and the liquid-to-solid ratios (L/Ss) were 0.3, 0.4 and 0.5. The properties of fresh, hardening, durability and microscopic analysis were examined to determine the effect of BJPA-substitution ratios and L/S on the engineering properties of composite geopolymers. The results show that among the fresh properties, as the amount of BJPA replacement increases, the setting time tended to increase, but the fluidity slowed down. The maximum compressive strength reached 81.1 MPa. As the amount of BJPA replacement increased, the elastic modulus of the geopolymer increased and the brittleness decreased. However, in the dry shrinkage test, it was found that an increase in BJPA helped reduce the dry shrinkage of the geopolymer. X-ray diffraction analysis revealed that a rise in the BJPA-substitution ratio increased the peak value of calcium carbonate. Scanning electron microscope images showed that microcrack size decreased with an increase in the BJPA-substitution ratio, with maximum and minimum crack sizes of 5.80 μm and 176.8 nm, respectively. This was because BJPA was unable to undergo complete polymerization and therefore was able to fill the cracks produced during the polymerization. In conclusion, BJPA may be used for waste recycling in the production of geopolymers.

Recycling of Waste Limestone as Fine Aggregate for Conventional and Green Concretes

2018 ◽  
Vol 928 ◽  
pp. 257-262 ◽  
Author(s):  
Trong Phuoc Huynh ◽  
Chao Lung Hwang ◽  
Si Huy Ngo
Keyword(s):  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Concrete Mixture ◽  
Engineering Properties ◽  
Fine Aggregate ◽  
Normal Concrete ◽  
Design Algorithm ◽  
Green Concrete ◽  
Concrete Mixtures

This paper presents the results of the experimental works to investigate the use of waste limestone from water treatment industry as fine aggregate in green concrete. Two concrete mixtures with a constant water-to-binder ratio of 0.3 were prepared for this investigation, in which, the normal concrete mixture was designed following the guidelines of ACI 211 standard, while the green concrete mixture was designed using densified mixture design algorithm (DMDA) technology. For comparison, both types of concrete samples were subjected to the same test program, including fresh properties, compressive strength, strength efficiency of cement, drying shrinkage, electrical surface resistivity, ultrasonic pulse velocity, and thermal conductivity. Test results indicate that both concrete mixtures showed the excellent workability due to the round-shape of waste limestone aggregate and the use of superplasticizer. In addition, the green concrete mixture exhibited a better performance in terms of engineering properties and durability in comparison with the normal concrete mixture. The results of the present study further support the recycling and reuse of waste limestone as fine aggregate in the production of green concrete.

scholarly journals Thermal mass and the effects on heating and cooling demands – an experimental study of an exposed concrete floor

2020 ◽  
Vol 172 ◽  
pp. 03004
Author(s):  
Alessandro Nocente ◽  
Steinar Grynning
Keyword(s):  
Energy Demand ◽  
Energy Use ◽  
Positive Impact ◽  
Thermal Mass ◽  
Wooden Floor ◽  
Heating Systems ◽  
Heating And Cooling ◽  
Experimental Campaign ◽  
Office Rooms ◽  
Positive Effect

The increase of thermal mass in buildings is discussed as a useful measure for reducing the energy demand for heating and cooling while contributing to improve the internal comfort. Several studies confirmed its positive effect, but few conducted a solid comparative measurement campaign and rarely in comparative conditions. The present work reports the results of an extensive comparative campaign in a test cell facility, where the internal conditions are measured in two identical rooms. One of the rooms was equipped with a large concrete mass while the other was constructed with a thin wooden floor. Measurements were conducted for circa a month, divided in four phases. The internal temperature of the two rooms was kept within typical boundaries of actual office rooms by a water-based cooling and heating systems. The energy demand of both heating and cooling was measured. Occupancy was simulated by a mannequin and by the lighting, both active only in office hours. The results demonstrated a positive impact of the thermal mass on the energy use. Since the test rooms are highly insulated, the energy use associated to cooling was dominant. During the experimental campaign, a reduction of up to 44% of the energy demand due to cooling was registered.

scholarly journals Towards a New Analytical Creep Model for Cement-Based Concrete Using Design Standards Approach

Buildings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 155
Author(s):  
Pablo Peña Torres ◽  
Elhem Ghorbel ◽  
George Wardeh
Keyword(s):  
International Standards ◽  
Analytical Models ◽  
Recycled Aggregates ◽  
Creep Model ◽  
Design Standards ◽  
Replacement Ratio ◽  
Creep Coefficient ◽  
Eurocode 2 ◽  
Natural Aggregates ◽  
Predicted Values

Creep properties are determined in design standards by measuring the creep coefficient, noted φ, as a function of time, t, and the age of the concrete at loading, t0. The work aims to study the validity of the analytical models proposed in the most used international standards and to check the possibility of their extension to estimate the creep of recycled aggregates concrete (RAC). A database was built from experimental results available in bibliographic references including 121 creep curves divided into 73 curves for natural aggregates concrete (NAC) and 48 curves for RAC. The comparison between the experimental and predicted values showed a significant dispersion for NAC and RAC. For the remediation of this dispersion, a new analytical model was developed for NAC. The parameters being the conventional creep coefficient, φ0, the power of the ageing function, named α, and βh, which accounts for the relative humidity and the compressive strength in the ageing function, were identified by inverse analysis. It was found that the power of the ageing function is 0.44 and not 0.3, as fixed by Eurocode 2 (EC2). Moreover, new expressions were proposed for φ0 and βh. The presence of recycled aggregates was considered through the equivalent replacement ratio.

Image Analysis Evaluation of Aggregates for Asphalt Concrete Mixtures

1998 ◽  
Vol 1615 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Chun-Yi Kuo ◽  
Reed B. Freeman
Keyword(s):  
Image Analysis ◽  
Asphalt Concrete ◽  
Morphological Characteristics ◽  
Engineering Properties ◽  
Natural Sand ◽  
Coarse Aggregates ◽  
Concrete Mixtures ◽  
Fine Aggregates ◽  
Pavement Engineering ◽  
Recent Developments

The performance of asphalt concrete mixtures is influenced by the properties of the included aggregates, such as grading, shape (angularity and elongation), and texture (roughness). Complete and accurate quantification of aggregate properties is essential for understanding their influence on asphalt concrete and for selecting aggregates to produce high-quality paving mixtures. Recent developments in the use of digital image analysis techniques for quantifying aggregate morphological characteristics in asphalt concrete are summarized. Image morphological characteristics were used to quantify flatness and elongation of coarse aggregates, to estimate the proportion of natural sand in fine aggregates, and to correlate aggregate characteristics with engineering properties of asphalt concrete mixtures. Image analysis of sections also revealed information about the grading, shape, and orientation of coarse aggregates in a mixture. An overview is presented of the broad range of useful pavement engineering applications of this relatively new approach for evaluating aggregate characteristics.

scholarly journals Mechanical and Durability Properties of Concrete Made with Used Foundry Sand as Fine Aggregate

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
G. Ganesh Prabhu ◽  
Jin Wook Bang ◽  
Byung Jae Lee ◽  
Jung Hwan Hyun ◽  
Yun Yong Kim
Keyword(s):  
Substitution Rate ◽  
International Standards ◽  
Fine Aggregate ◽  
Test Results ◽  
Natural Sand ◽  
Foundry Sand ◽  
Durability Properties ◽  
Concrete Mixtures ◽  
Concrete Production ◽  
Strength And Durability

In recent years, the construction industry has been faced with a decline in the availability of natural sand due to the growth of the industry. On the other hand, the metal casting industries are being forced to find ways to safely dispose of waste foundry sand (FS). With the aim of resolving both of these issues, an investigation was carried out on the reuse of waste FS as an alternative material to natural sand in concrete production, satisfied with relevant international standards. The physical and chemical properties of the FS were addressed. The influence of FS on the behaviour of concrete was evaluated through strength and durability properties. The test results revealed that compared to the concrete mixtures with a substitution rate of 30%, the control mixture had a strength value that was only 6.3% higher, and this enhancement is not particularly high. In a similar manner, the durability properties of the concrete mixtures containing FS up to 30% were relatively close to those of control mixture. From the test results, it is suggested that FS with a substitution rate of up to 30% can be effectively used in concrete production without affecting the strength and durability properties of the concrete.

scholarly journals Propiedades térmicas e hídricas de materiales aislantes apropiadas para fábricas históricas = Thermal and hygric properties of insulation materials suitable for historic fabrics

2016 ◽  
Vol 2 (2) ◽  
pp. 1
Author(s):  
Rosanne Walker ◽  
Sara Pavía
Keyword(s):  
Energy Savings ◽  
Thermal Inertia ◽  
Organic Content ◽  
Thermal Mass ◽  
Indoor Thermal Comfort ◽  
Operational Energy ◽  
Lime Plaster ◽  
Hygric Properties ◽  
The Impact ◽  
Solid Walls

ResumenMejorar el rendimiento térmico de los edificios mediante la adaptación del aislamiento puede reducir la pérdida innecesaria de calor y energía minimizando el impacto ambiental. El aislamiento térmico interior es a menudo el elegido en los edificios históricos para preservar sus características. Sin embargo, el aislamiento interior puede aumentar la acumulación de humedad en paredes que socavan su durabilidad. Hay una falta de conocimiento sobre la eficacia de sólidos muros históricos y el impacto del aislamiento interno en su comportamiento higrotérmico. Este artículo investiga las propiedades térmicas e hídricas de siete opciones de aislamiento internos, incluyendo la pintura térmica, aerogel (AG), corcho-cal (CL), cal-cáñamo (HL), silicato de calcio bordo (CSB), tablero de fibra de madera (TFB) y placa de polisocianurato (PIR). Sus propiedades se comparan con un enlucido de cal tradicional. El PIR y el aerogel AG muestran extraordinarias propiedades térmicas que contribuyen a la comodidad y ahorro de energía, y la CL y HL son permeables al vapor y a la capilaridad. Estos tienen aproximadamente el doble de la masa térmica de los otros aislantes. Además, la CL tiene una buena inercia térmica (segunda difusividad más baja) y, a pesar de su contenido orgánico, una adsorción de baja a alta RH.AbstractImproving the thermal performance of buildings by retrofitting insulation can reduce unnecessary heat loss and building operational energy minimising environmental impact. Internal thermal insulation is often favoured for historic buildings to preserve their features. However, internal insulation may increase moisture accumulation in walls undermining their durability. There is a lack of knowledge on the performance of historic solid walls and the impact of internal insulation in their hygrothermal behaviour. This paper investigates the thermal and hygric properties of seven internal insulation options including thermal paint, aerogel (AG), cork lime (CL), hemp lime (HL), calcium silicate board (CSB), timber fibre board (TFB) and polyisocyanurate (PIR) board. Their properties are compared with a traditional lime plaster. The PIR and aerogel AG show outstanding thermal properties that contribute towards indoor thermal comfort and energy savings and the CL and HL are vapour permeable and capillary active. They have approximately double the thermal mass of the other insulations. In addition, the CL has a good thermal inertia (2nd lowest diffusivity) and, in spite of its organic content, a low adsorption at high RH.

scholarly journals Recycling and reuse of solid wastes; a hub for ecofriendly, ecoefficient and sustainable soil, concrete, wastewater and pavement reengineering

2019 ◽  
Vol 14 (3) ◽  
pp. 440-451 ◽  
Author(s):  
Kennedy Chibuzor Onyelowe ◽  
Duc Bui Van ◽  
Obiekwe Ubachukwu ◽  
Charles Ezugwu ◽  
Bunyamin Salahudeen ◽  
...  
Keyword(s):  
Solid Waste ◽  
Co2 Emissions ◽  
Civil Engineering ◽  
Waste Recycling ◽  
Solid Wastes ◽  
Engineering Properties ◽  
Waste Incinerator ◽  
Supplementary Cementing Materials ◽  
Zero Carbon ◽  
Solid Waste Recycling

Abstract Ecofriendly, ecoefficient and sustainable civil engineering work has been research with emphasis on adapting the byproducts of solid waste recycling and reuse to achieving infrastructural activities with low or zero carbon emission. The direction combustion model, the solid waste incinerator caustic soda oxides of carbon entrapment model (SWI-NaOH-OCEM) developed by this research has achieved a zero carbon release. This research adopted the literature search method to put together research results of previous works relevant to the aim of this present work. It has been shown that CO and CO2 emissions can be contained during the derivation of alternative or supplementary cementing materials used in the replacement of ordinary Portland cement in civil engineering works. In the overall assessment of the present review work has left the environment free of the hazards of CO and CO2 emissions. It was shown that these supplementary cementing materials derived from solid wastes improve the engineering properties of treated soft clay and expansive soils, concrete, and asphalt. Bio-peels, another form solid waste has been established as a good detoxificant used in treating wastewater. It has been shown that solid waste recycling and reuse is a hub to achieving ecofriendly, ecoefficient and sustainable infrastructural development on the global scale.

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