Improving Cementitious Properties of Blended Pozzolan Based Materials for Construction of Low Cost Buildings in Mbeya Region, Tanzania PDF Download

Author: Duwa Hamisi Chengula
Publisher: kassel university press GmbH
ISBN: 3737604428
Category :
Languages : en
Pages : 226

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Book Description
This study therefore investigated and improved cementitious properties of pozzolan blended with calcium hydroxide, gypsum and cement in order to extend its use from low strength mortars to concrete works which can be used for low to medium rise structural applications. Characterization, strength tests and durability tests were performed on pozzolan mixtures under laboratory conditions and the effects of adding gypsum to pozzolan and calcium hydroxide mixtures on the compressive strength and durability of cured concrete specimens were investigated.

Author: Ekkehard Fehling
Publisher: BoD – Books on Demand
ISBN: 3737611599
Category : Technology & Engineering
Languages : en
Pages : 310

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Book Description
Sustainable construction, with the overarching goal of reducing the environmental footprint of everything we build is becoming increasingly important and urgent in the light of the climate change the world is facing. The use of innovative and sustainable building materials, especially concrete as the worldwide most commonly used building material, offers a great opportunity to significantly reduce climate-relevant emissions in the construction sector. Due to their performance and reliable durability, the use of innovative high-performance concretes will help to reduce the need for new constructions and to sustainably repair existing infrastructure. In new buildings in particular, the use of high-performance materials can help to save energy and natural resources, which reduces climate-relevant emissions and thus global warming. With the current HiPerMat 6, we are responding to the growing understanding of the impact of our construction activities on the environment by placing greater emphasis on sustainability issues.

Author: Bernhard Middendorf
Publisher: BoD – Books on Demand
ISBN: 3737608288
Category : Technology & Engineering
Languages : en
Pages : 206

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Book Description
With HiPerMat 5 on March 11-13, 2020 the 5th International Symposium on Ultra-High Performance Concrete and High Performance Construction Materials documents the actual state of development of application in the fields of: Material Science and Development, Composite Concrete Materials, Strength and Deformation behaviour of UHPC, Durability and Sustainability of UHPC, Design and Construction with UHPC, Structural Modelling and Optimisation, Lightweight Concrete Structures, High-Precision Manufacturing for Pre-Fabrication, Nanotechnology for Construction Materials, Innovative Applications, Smart Construction Materials, This volume contains the short versions (two pages) of all contributions that have been accepted for publication at HiPerMat 5.

Author: V.M. Malhotra
Publisher: CRC Press
ISBN: 1482296764
Category : Architecture
Languages : en
Pages : 204

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Book Description
This volume provides an overview of the mineral admixtures used in concrete, including silica fume, slag, rice-husk ash, fly ash and natural pozzolans. It also includes the mineral/chemical composition of the admixtures, their chemical reactions with cement and as a method of recycling.

Author: Zhenhua Wei
Publisher:
ISBN:
Category :
Languages : en
Pages : 150

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Book Description
Ordinary portland cement (OPC) has been used as the primary binding material in concrete for construction of buildings and other infrastructure over the last century due to its low-cost and the widespread geographical abundance of its raw materials. The manufacture of OPC accounts for approximately 3% of primary energy use and 9% of anthropogenic CO2 emissions globally. Such energy consumption and CO2 release is mainly attributed to the calcination and clinkering of raw materials (i.e., limestone and clay) in the cement kiln at high temperatures. Therefore, there is great need to reduce the CO2 footprint of cement, and secure alternative solutions for cementation as required for building and infrastructure construction. On the other hand, space conditioning consumes nearly 20% of annual energy consumption in the United States, which is still increasing with the increasing demand for thermal comfort in the context of climate change. The embedment of phase change materials (PCMs) in concrete is an effective means to improve its thermal inertia for building envelope applications, and can thus improve the energy efficiency of buildings. However, the viability of employing PCMs to enhance thermal performance of concrete depends on the stability and durability of PCMs in the highly caustic cementitious environment, and the durability of the PCM-added concrete. To address these limitations on sustainability and energy efficiency of current cement-based building materials, this dissertation mainly examines: [TM] PCM survivability during fabrication of PCM-mortar composites with respect to damage and/or rupture of the PCM microcapsules that may occur during mechanical mixing, as well as chemical durability of PCM within cementitious matrices, and the potential interactions between the PCM and the pore-fluid that result in enthalpy alteration, [TM] Cementitious matrix durability, with emphasis on assessing how dosage of PCMs alters water absorption, drying shrinkage, and restrained shrinkage cracking behaviors of cementitious composites containing PCMs, and [TM] The feasibility of developing sustainable building material through clinkering-free cementation by fly ash carbonation, with emphasis on the effects of CO2 concentration and processing temperature on the progress of carbonation reaction, the development of microstructure, and the strength evolution of the material. The results of research on PCM embedded cementitious composites show that a reduction of around 25% in the phase change enthalpy is observed, irrespective of PCM dosage and aging. Such reduction in enthalpy is mainly caused by chemical interactions with dissolved sulfate ions. Examination of the influence of PCM additions on water absorption and drying shrinkage of PCM-mortar composites reveals that PCM microcapsules reduce the rate and extent of water sorption due to their non-sorptive nature and diluting effect. PCM inclusions do not influence the drying shrinkage of cementitious composites due to their inability to restrain the shrinkage of the cement paste. Assessments of free and restrained shrinkage, elastic modulus, and tensile strength also show that the addition of PCMs enhances the cracking resistance of cement paste because PCMs as soft inclusions offer crack blunting and deflection, and improved stress relaxation. In an effort to synergize the utilization of fly ash and CO2 in fly ash, the study shows that Ca-rich fly ash paste can readily react with dilute concentrations of CO2 in moist environments to produce cemented solids with sufficient strength (35 MPa) for use in structural construction. Detailed results from thermodynamic modeling, XRD analyses, and SEM observations suggest that fly ash carbonation results in the formation of reaction products including calcite, hydrous silica, and C-S-H, which collectively bond proximate particles into a cemented solid.

Author: Thomas B. Kennedy
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 156

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Author: A.R. Pourkhorshidi
Publisher: Elsevier Inc. Chapters
ISBN: 0128088966
Category : Technology & Engineering
Languages : en
Pages : 21

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Book Description
This chapter discusses various methods available for evaluating pozzolans as cement replacement materials. The merits and disadvantages of the methods are elaborated, and some existing anomalies are highlighted. Guides on applying a combination of these methods are presented in order to evaluate pozzolans in a way that complies with pozzolan performance in concrete.

Author: T. E Stanton
Publisher:
ISBN: 9780803156395
Category : Cement
Languages : en
Pages : 0

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Author: James Sarfo-Ansah
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659544798
Category :
Languages : en
Pages : 156

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Book Description
The causes and effects of inadequate shelter provision in a developing country such as Ghana are explored. Calcined clay pozzolana is introduced as a cost-effective partial substitute to Portland cement for housing construction. In this research mechanical activation of clay pozzolana to enhance reactivity was investigated. Properties of the mechanically activated pozzolanas were studied and reported. Mechanically activated were found to have improved properties such as enhanced compressive strength compared to reference Portland cements.

Author: GS. Barger
Publisher:
ISBN:
Category : Alkali-silica reaction
Languages : en
Pages : 8

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Book Description
The goal of producing concrete that provides longterm durability with regard to properties such as improved sulfate resistance and reduced susceptibility to alkali-silica reactions (ASR) has led to the development of several high-performance materials. While the use of fly ashes and ground granulated blast-furnace slags (GGBFS) in concrete is gaining acceptance in various applications, the mineralogical composition of such byproduct materials cannot be as easily controlled as a manufactured pozzolan. Since 1993, Ash Grove has developed and directed the manufacture of pozzolans to improve concrete durability, while avoiding the potential problems of byproduct pozzolan availability and uniformity. Processing of these performance-enhancing pozzolans is accomplished by thermally treating and converting crystalline clay materials to amorphous alumino silicates. These pozzolans can be interground with portland cement clinker and gypsum to produce a Type IP blended cement or they can be ground separately as mineral admixtures for concrete. These two products are produced under the specification requirements of ASTM C 1157 or ASTM C 595 for hydraulic cements and ASTM C 618 for mineral admixtures, respectively. In ASTM C 618, the classification for raw or calcined natural pozzolans is Class N. The data contained in this paper describe some of the choices that are available to manufacturers of blended hydraulic cements to "engineer" into the cementitious system the desired properties for concrete such as improved sulfate resistance, reduced permeability, and the ability to strongly mitigate ASR.