16 research outputs found
Development Of Pofa Based Geopolymer Concrete Activated With Wood Ash Lye Incorporating Timber Clinker Aggregate
Get PDFCement manufacturing has led to excessive carbon dioxide (CO₂) emission into the atmosphere, which has contributed to global sustainability challenges. Moreover, huge amount of industrial waste like palm oil fuel ash (POFA), wood ash (WA), and timber clinker aggregate (TCA) landfilled in our environments coupled with the use of naturally occurring rocks for aggregate are also a negative factor for the global sustainability. Amidst these sustainability challenges of cement production, waste management, and the use of naturally occurring rocks emerges the technology of geopolymer concrete. The development of geopolymer concrete has gained recognition in recent years as innovative and alternative construction material. However, using aggressive chemicals like sodium hydroxide (NaOH) as alkaline activator and oven curing has limited it to laboratory research only. The current study strived to answer the research questions on the effectiveness of using WA lye as alkaline activator to replace NaOH and also the utilization of TCA as coarse aggregate in geopolymer concrete at the ambient temperature. The investigation began with the optimization of liquid binder (L/B) and alkali activator ratio (AAR) using varying L/B and AAR ratio. Then specimens with GGBS as a partial replacement of POFA from 0% to 40% were produced with the view to optimize the GGBS content. TCA was optimized by producing POFA: GGBS geopolymer concrete with 0% to 100% TCA at 20% increment as partial replacement of natural aggregate
Mechanical Behaviour of Eco-Efficient Ultra-High Performance Fibre Reinforced Concrete (E-UHPFRC) and Design of E-UHPFRC Screw Piles
Get PDFUltra-High Performance Fibre Reinforced Concrete (UHPFRC) is a novel development in concrete materials that can lead to novel applications due to its excellent strength and durability potential. However, the widespread use of UHPFRC is currently limited due to its high initial cost and high carbon footprint of the cement and steel fibre constituents as well as the lack of recognised design models.
The aim of this research is to develop an Eco-Efficient Ultra-High Performance Fibre Reinforced Concrete (E-UHPFRC) by utilising alternative binders (e.g. GGBS), Recycled Tyre Steel Fibres (RTSF) and Recycled Tyre Steel Cords (RTSC). This is achieved through experimental and numerical studies, as well as the development of analytical models to aid the development of design guidelines. An extensive series of tests is carried out on twelve (12) UHPFRC mixes containing either RTSC or RTSF, or blends of the two in various ratios for total fibre volumes of 2, 3 and 4%. The fresh properties of the designed E-UHPFRC mixes are examined, followed by a comprehensive analysis of the mechanical behaviour of the hardened concrete in: flexure, compression and shear. The results show that 11 of the examined mixes can offer the desired mechanical properties and meet the requirements of workability and strength to be defined as UHPFRC. The performance of the mixes containing RTSC is comparable to what is reported in the literature for mixes containing Manufactured Steel Fibres. Design models are proposed to predict the flexural and shear strengths of E-UHPFRC mixes. The complementary material efficiency study of the mixes shows that use of RTSF and RTSC in UHPFRC provides significant cost and environmental benefits.
The application of the newly developed E-UHPFRC in the manufacturing of screw piles is proposed as a quick and more sustainable means of providing foundations for light weight structures, which given the limitations of ordinary concrete is currently only feasible with costlier steel piles. A detailed design guideline for E-UHPFRC screw piles is provided for two possible geometries
A potential environmental sustainability of wood ash in normal and geopolymer concrete – A Review
Get PDFThe production of cement for concrete has led to the emission of carbon dioxide (CO₂) into the atmosphere, which
has contributed to global warming. Moreover, the excessive amount of industrial waste from biomass energy production landfilled in our environments is continuously causing sustainability challenges. However, several studies
were carried out to ascertain the possibilities of using these waste materials in concrete production to address the
cement and waste disposal sustainable issues simultaneously. The present study reviewed multiple studies carried
out on wood ash (WA) application in both normal and geopolymer concrete with an emphasis on fresh, hardened,
and durability properties. WA can be used to replace cement in conventional mortar/concrete at up to 20% replacement level, similarly, it was revealed that WA can be effectively utilized to replace ground granulated blast furnace
slag (GGBS) or pulverized fly ash (PFA) at up to 50% replacement level in geopolymer mortar/concrete production. The sustainability impacts of WA utilization in concrete production were presented and discussed. Results
of these findings revealed its suitability as supplementary cementitious material, but still there exists a gap in its
utilization in geopolymer concrete
Influence of institutional management on collection development in Federal Colleges of Agriculture Lbraries in Northern Nigeria
No full textThis study investigated influence of institutional management on collection development in Federal Colleges of Agriculture in Northern Nigeria. The study has 3 objectives which include to: determine the types of collection available in Federal College of Agriculture libraries in Northern Nigeria; find out the influence of institutional management on collection development in Federal College of Agriculture libraries in Northern Nigeria and find out the challenges faced by the library management on collection development in Federal College of Agriculture libraries. In order to achieve the stated objectives 3 research questions were asked. The study used a descriptive research design with a population of 72 management staff of Federal College of Agriculture libraries in Northern Nigeria and the sample size drawn was 36 respondents. Out of the 36 copies of questionnaire administered, 28 copies were returned which represent 78%. Data collected was analysed using descriptive and inferential statistics at 0.05 level of significance. The findings revealed that there is availability of collection in all the libraries under study. It was revealed that the college management has a lot of influence on collection development of the college libraries. Finally, the findings revealed that funds are not sufficiently provided, which affects adequacy of collections, there is also delay in the delivery of Collections among others.Keywords: Collection, Institution, Colleges, Agriculture, Librarie
Surface Chemistry Elucidation on Effect of Fruit Garbage Effective Microorganisms Product in Enhancing Fresh and Hardened Properties of Concrete
Get PDFThis study assessed and elucidated the influence of fruit garbage effective microorganisms’ liquid product in improving the strength and other properties of concrete in terms of surface chemistry when added to concrete as partial replacement of mixing water. One control specimen was made along with four different mixes of 3, 5, 10 and 15% of the locally made liquid bio-product as replacement of the required mixing water during the concrete production. The experiments conducted on both control and liquid bio-product blended concretes were Proctor penetration test for setting time, workability and slump test for compressive strength. The results of the tests indicated that the locally made effective microorganisms’ liquid product exerted retarding effect on the setting time of the blended concretes, as well as enhanced their workability. The result further indicated that, amongst all the locally made liquid bio-product blended concretes, the concrete specimen with 3% content possessed the highest compressive strength of 29.8N/mm2 and 35.5N/mm2 at 28 and 56 curing days, respectively. All these enhanced concrete properties were influenced by changing the surface hydration behaviour of cement in the concrete mixture, which varied widely upon addition of liquid bio-product at different percentage contents. Therefore, the addition of effective microorganisms’ liquid product in the concrete mixture showed promising performance and thus, can be used as a low-cost and environmentally friendly admixture in the design of concrete. Keywords: Effective Microorganisms, concrete, Compressive strength, workability, setting time DOI: 10.7176/CER/11-6-04 Publication date:July 31st 201
From digital crafting to digital manufacturing:automated production using hybrid 3D concrete printing
Get PDF3D Concrete Printing (3DCP) has undergone a significant growth over the last 20 years and more recently, methods for improving surface finish and manufacturing accuracy have been explored by applying secondary shaping processed, post printing. These approaches are termed ‘hybrid’ manufacturing and a promising method is to use milling when the concrete is in its green state. The achievable precision and resolution of detailing is an order of magnitude greater than 3DCP alone and greater complexity than can be readily achieved in casting is possible. This step change in manufacturing capability enables a complete rethinking of design, but to date there has been no work published. This article presents the hybrid process and explores the potential for design and manufacture based around ‘The Canopy’: a full-scale demonstrator project. The article reports on the narratives around establishing the design constraints and how they influenced the achievable detail, leading to the identification of 26 features that were used to classify the material and process constraints that need to be interpreted to achieve a manufacturable assembly. An identified challenge of implementing this and other cement-based digital fabrication methods, is the tacit knowledge required by operatives to create successful outcomes. By taking the output of this work and embedding constraints in design software, this could be avoided moving such processes away from digital crafting and towards digital manufacturing
Supplementary information files for "On the origins of anisotropy of extrusion-based 3D printed concrete: the roles of filament skin and agglomeration"
No full textSupplementary files for article "On the origins of anisotropy of extrusion-based 3D printed concrete: the roles of filament skin and agglomeration"One of the most significant challenges facing extrusion-based 3D concrete printing (3DCP) is the anisotropy present in the printed material: under load, the observed performance is typically lower than a cast equivalent and significantly so in certain directions. In addition, the performance is also more variable than cast material. These observations are, in part, due to surface moisture evaporation and air entrapment. Here, we investigate the hypothesis that the printed concrete comprises of agglomerated filament core and skin having distinct properties as a necessary consequence of the printing process. Through novel X-ray computed tomography measurements, we show that printed concrete comprises the core and Filament Interfacial Zone Network (FIZN) and that, in contrast to the cores, the FIZN is found to be free from pores except at boundaries where there is incomplete bonding. Through morphological, chemical and mechanical analysis, the FIZN is also found to contain 20% less sand and 60% more anhydrous cement than the filament cores, while the FIZ material was inferred to have 11% higher compressive strength, 28% lower flexural strength and 22% lower elastic modulus than the core. The findings from this work suggest that anisotropy will always exist and that care should be devoted to the material rheology, printing system and the filaments arrangement in order to produce consistent and predictable hardened material properties.© The Author(s), CC BY 4.0</p
On the origins of anisotropy of extrusion-based 3D printed concrete: the roles of filament skin and agglomeration
No full textOne of the most significant challenges facing extrusion-based 3D concrete printing (3DCP) is the anisotropy present in the printed material: under load, the observed performance is typically lower than a cast equivalent and significantly so in certain directions. In addition, the performance is also more variable than cast material. These observations are, in part, due to surface moisture evaporation and air entrapment. Here, we investigate the hypothesis that the printed concrete comprises of agglomerated filament core and skin having distinct properties as a necessary consequence of the printing process. Through novel X-ray computed tomography measurements, we show that printed concrete comprises the core and Filament Interfacial Zone Network (FIZN) and that, in contrast to the cores, the FIZN is found to be free from pores except at boundaries where there is incomplete bonding. Through morphological, chemical and mechanical analysis, the FIZN is also found to contain 20% less sand and 60% more anhydrous cement than the filament cores, while the FIZ material was inferred to have 11% higher compressive strength, 28% lower flexural strength and 22% lower elastic modulus than the core. The findings from this work suggest that anisotropy will always exist and that care should be devoted to the material rheology, printing system and the filaments arrangement in order to produce consistent and predictable hardened material properties.</p
From digital crafting to digital manufacturing: Automated production using hybrid 3D concrete printing
No full text3D Concrete Printing (3DCP) has undergone a significant growth over the last 20 years and more recently, methods for improving surface finish and manufacturing accuracy have been explored by applying secondary shaping processed, post printing. These approaches are termed ‘hybrid’ manufacturing and a promising method is to use milling when the concrete is in its green state. The achievable precision and resolution of detailing is an order of magnitude greater than 3DCP alone and greater complexity than can be readily achieved in casting is possible. This step change in manufacturing capability enables a complete rethinking of design, but to date there has been no work published. This article presents the hybrid process and explores the potential for design and manufacture based around ‘The Canopy’: a full-scale demonstrator project. The article reports on the narratives around establishing the design constraints and how they influenced the achievable detail, leading to the identification of 26 features that were used to classify the material and process constraints that need to be interpreted to achieve a manufacturable assembly. An identified challenge of implementing this and other cement-based digital fabrication methods, is the tacit knowledge required by operatives to create successful outcomes. By taking the output of this work and embedding constraints in design software, this could be avoided moving such processes away from digital crafting and towards digital manufacturing.</p
On the origins of anisotropy of extrusion-based 3D printed concrete: The roles of filament skin and agglomeration
Get PDFOne of the most significant challenges facing extrusion-based 3D concrete printing (3DCP) is the anisotropy present in the printed material: under load, the observed performance is typically lower than a cast equivalent and significantly so in certain directions. In addition, the performance is also more variable than cast material. These observations are, in part, due to surface moisture evaporation and air entrapment. Here, we investigate the hypothesis that the printed concrete comprises of agglomerated filament core and skin having distinct properties as a necessary consequence of the printing process. Through novel X-ray computed tomography measurements, we show that printed concrete comprises the core and Filament Interfacial Zone Network (FIZN) and that, in contrast to the cores, the FIZN is found to be free from pores except at boundaries where there is incomplete bonding. Through morphological, chemical and mechanical analysis, the FIZN is also found to contain 20% less sand and 60% more anhydrous cement than the filament cores, while the FIZ material was inferred to have 11% higher compressive strength, 28% lower flexural strength and 22% lower elastic modulus than the core. The findings from this work suggest that anisotropy will always exist and that care should be devoted to the material rheology, printing system and the filaments arrangement in order to produce consistent and predictable hardened material properties
