Evaluation of Thermal Properties and Air Void Characteristics of Porous Concrete PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Evaluation of Thermal Properties and Air Void Characteristics of Porous Concrete PDF full book. Access full book title Evaluation of Thermal Properties and Air Void Characteristics of Porous Concrete by Pengyu Xie. Download full books in PDF and EPUB format.
Author: Pengyu Xie Publisher: ISBN: Category : Lightweight concrete Languages : en Pages : 61
Book Description
Porous concrete is becoming an attractive pavement solution due to its great performances in mitigating urban heat island (UHI) effect and managing storm water. As a heterogeneous material, the properties of cement-based porous concrete are complicated to quantify and hard to predict. This thesis focused on the evaluation of thermal properties and air void characteristics of porous concrete. The thermal properties of aggregates, cement pastes, and porous concretes were measured by transient plate method (TPS) and steady-state heat flow meter method, respectively. X-ray computed tomography (CT) technique was utilized and three-dimensional (3-D) pictures were treated to analyze the microscopic structure of air voids in porous concrete. The existing analytical models were employed to estimate thermal conductivity of pervious concretes and compared to experimental measurements. The tests results show that thermal conductivity and heat capacity of cement paste increases as water cement ratio increases. Meanwhile, for the same mix design, the thermal properties of different cement paste samples had few variations. However, the porous concrete is very heterogeneous and the same mix design cannot ensure the similar porosity; instead, significant variations of porosity were observed. The existing analytical results did not show satisfactory prediction results of thermal conductivity as compared to testing results. This indicates the existing models are not suitable to estimate the thermal conductivity of porous concrete. This is because the models ignore the complex microscopic structures of porous concrete. Based on the CT-scanned images, within the horizontal plane of cylindrical sample, slight differences of normalized projected lengths of air voids were observed in the orthogonal horizontal directions; while the normalized projected length of connected voids in vertical direction was found smaller than those in horizontal directions. The smaller aggregates tend to form the longer air void length in porous concrete. The curvatures of air voids for smaller aggregates are greater than that of larger aggregates. Meanwhile, within the same mix design, the curvature of air voids increases with the increasing of porosity. The porosity and aggregate size do not have significant influences on the ellipticity and tortuosity of air voids within porous concrete. However, with the increase of porosity, the air voids tend to have the greater equivalent diameter.
Author: Pengyu Xie Publisher: ISBN: Category : Lightweight concrete Languages : en Pages : 61
Book Description
Porous concrete is becoming an attractive pavement solution due to its great performances in mitigating urban heat island (UHI) effect and managing storm water. As a heterogeneous material, the properties of cement-based porous concrete are complicated to quantify and hard to predict. This thesis focused on the evaluation of thermal properties and air void characteristics of porous concrete. The thermal properties of aggregates, cement pastes, and porous concretes were measured by transient plate method (TPS) and steady-state heat flow meter method, respectively. X-ray computed tomography (CT) technique was utilized and three-dimensional (3-D) pictures were treated to analyze the microscopic structure of air voids in porous concrete. The existing analytical models were employed to estimate thermal conductivity of pervious concretes and compared to experimental measurements. The tests results show that thermal conductivity and heat capacity of cement paste increases as water cement ratio increases. Meanwhile, for the same mix design, the thermal properties of different cement paste samples had few variations. However, the porous concrete is very heterogeneous and the same mix design cannot ensure the similar porosity; instead, significant variations of porosity were observed. The existing analytical results did not show satisfactory prediction results of thermal conductivity as compared to testing results. This indicates the existing models are not suitable to estimate the thermal conductivity of porous concrete. This is because the models ignore the complex microscopic structures of porous concrete. Based on the CT-scanned images, within the horizontal plane of cylindrical sample, slight differences of normalized projected lengths of air voids were observed in the orthogonal horizontal directions; while the normalized projected length of connected voids in vertical direction was found smaller than those in horizontal directions. The smaller aggregates tend to form the longer air void length in porous concrete. The curvatures of air voids for smaller aggregates are greater than that of larger aggregates. Meanwhile, within the same mix design, the curvature of air voids increases with the increasing of porosity. The porosity and aggregate size do not have significant influences on the ellipticity and tortuosity of air voids within porous concrete. However, with the increase of porosity, the air voids tend to have the greater equivalent diameter.
Author: ACI Committee 522 Publisher: ISBN: 9780870313646 Category : Lightweight concrete Languages : en Pages : 38
Book Description
"This report provides technical information on pervious concrete's application, design methods, materials, properties, mixture proportioning, construction methods, testing, and inspection. The term 'pervious concrete' typically describes a near-zero-slump, open-graded material consisting of portland cement, coarse aggregate, little or no fine aggregate, admixtures, and water." [p. 1]
Author: Pierre Pimienta Publisher: Springer ISBN: 3319954326 Category : Technology & Engineering Languages : en Pages : 152
Book Description
This book presents the work done by the RILEM Technical Committee 227-HPB (Physical properties and behaviour of High-Performance Concrete at high temperature). It contains the latest research results on the behaviour of high-performance concretes at high temperature. The book presents the state of the art of experimental data on High-Performance concretes and it collects and synthesizes useful data about concrete behaviour at high temperatures. The book is divided into independent chapters dealing with degradation reactions in concrete exposed to high temperatures; mass transport properties; thermal properties; and mechanical properties. The results presented especially target a group of users composed by universities and testing laboratories, building material companies and industries, material scientists and experts, building and infrastructure authorities, designers and civil engineers.
Author: J. T. Kevern Publisher: ISBN: Category : Air content testing Languages : en Pages : 10
Book Description
The current pervious concrete placed in cold climates generally contains air entrainment but, unlike traditional concrete, the evaluation of entrained air is not performed. This paper presents results from a study that characterized the entrained air voids in pervious concrete using a RapidAir system. The RapidAir system is an automatic device that determines the air void properties of hardened concrete according to ASTM C457, "Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete." Two types of aggregates, i.e., crushed limestone and rounded river gravel (pea gravel), and two types of air entraining agents, i.e., natural and synthetic, were used. The air entrainment dosage rates varied from zero to double the manufacturer's recommended dosage. Compressive strength, tensile strength, and freeze-thaw durability (ASTM C666A) of the pervious concrete were tested. The results show that use of air entrainment improves workability of pervious concrete, thus reducing the overall porosity and increasing unit weight of the pervious concrete. The strength and freeze-thaw durability also increases with the level of entrained air in pervious concrete.
Author: Publisher: ISBN: Category : Concrete Languages : en Pages : 19
Book Description
Observations at the Research Council, coupled with the national interest in possible changes in the air void characteristics of air-entrained concretes because of the wide use of admixtures and changes in cement properties, raised a question as to whether or not there was a progressive increase over the years in the size of air voids being incorporated in concrete. Thus, the main objective of the study reported here was to evaluate the changes in air void characteristics of hardened concrete as determined by ASTM C457 and by other means for concrete produced in Virginia from 1945 to 1980. Air void parameters including the air content, specific surface, and spacing factor --were determined on 630 concretes. The results did not indicate an overall significant increase in the size of air voids; however, it was observed that, in general, they did show that the average size and the distribution of the voids were marginal compared to generally accepted values. While this finding indicates that air voids may not be as small as optimum, the freeze-thaw performance of air-entrained concretes in Virginia supplied under the present specifications generally has been satisfactory.
Author: Lijun Sun Publisher: Butterworth-Heinemann ISBN: 0128028939 Category : Technology & Engineering Languages : en Pages : 1072
Book Description
Structural Behavior of Asphalt Pavements provides engineers and researchers with a detailed guide to the structural behavioral dynamics of asphalt pavement including: pavement temperature distribution, mechanistic response of pavement structure under the application of heavy vehicles, distress mechanism of pavement, and pavement deterioration performance and dynamic equations. An authoritative guide for understanding the key mechanisms for creating longer lasting pavements, Structural Behavior of Asphalt Pavements describes the intrinsic consistency between macroscopic performance and microscopic response, structure and material, as well as global and local performances, and demonstrates the process of pavement analyses and designs, approaching science from empirical analyses. - Analyzes the external and internal factors influencing pavement temperature field, and provide a review of existing pavement temperature prediction models - Introduces a "Bridge Principle through which pavement performance and fatigue properties are consolidated - Defines the intrinsic consistency between macroscopic performance and microscopic response, structure and material, as well as global and local performance - Summaries the mechanistic response of pavement structure under the application of heavy vehicle, distress mechanism of pavement, pavement deterioration performance and dynamic equations, and life cycle analysis of pavement
Author: D. M. Roy Publisher: Strategic Highway Research Program (Shrp) ISBN: Category : Technology & Engineering Languages : en Pages : 204
Book Description
Durability of concrete in highway systems is a problem of national concern. In order to better understand the mechanisms which intrinsically control durability in highway concrete, it is necessary to define and understand those factors which impact concrete microstructure which is a consequence of both its formulation and the processes taking place during mixing, placing and curing. This report documents an investigation of those variables which control cement hydration and consequent microstructural development.
Author: Peter Hewlett Publisher: Butterworth-Heinemann ISBN: 0081007957 Category : Technology & Engineering Languages : en Pages : 898
Book Description
Lea's Chemistry of Cement and Concrete, Fifth Edition, examines the suitability and durability of different types of cements and concretes, their manufacturing techniques and the role that aggregates and additives play in achieving concrete's full potential of delivering a high-quality, long-lasting, competitive and sustainable product. - Provides a 60% revision over the fourth edition last published in 2004 - Includes updated chapters that represent the latest technological advances in the industry, including, but not exclusive to the production of low-energy cements, cement admixtures and concrete aggregates - Presents expanded coverage of the suitability and durability of materials aggregates and additives
Author: F. Pacheco-Torgal Publisher: Elsevier ISBN: 1782422889 Category : Technology & Engineering Languages : en Pages : 855
Book Description
This book provides an updated state-of-the-art review on new developments in alkali-activation. The main binder of concrete, Portland cement, represents almost 80% of the total CO2 emissions of concrete which are about 6 to 7% of the Planet's total CO2 emissions. This is particularly serious in the current context of climate change and it could get even worse because the demand for Portland cement is expected to increase by almost 200% by 2050 from 2010 levels, reaching 6000 million tons/year. Alkali-activated binders represent an alternative to Portland cement having higher durability and a lower CO2 footprint. - Reviews the chemistry, mix design, manufacture and properties of alkali-activated cement-based concrete binders - Considers performance in adverse environmental conditions. - Offers equal emphasis on the science behind the technology and its use in civil engineering.
Author: Pengyu Xie
Author: Pengyu Xie
Author: ACI Committee 522
Author: Pierre Pimienta
Author: J. T. Kevern
Author: 
Author: Lijun Sun
Author: D. M. Roy
Author: Peter Hewlett
Author: ACI Committee 122
Author: F. Pacheco-Torgal