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Dr. Jonathan Oti
University of South Wales

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Cement
Bricks
compressive strength
Construction
Mortar
Freeze and Thaw
microstructural analysis
Permeability
Composite
Thermogravimetric Analysis
swelling

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Journal article
Published: 20 August 2021 in Sustainability
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The current study investigated the development of a sustainable thermo-chemical approach to effectively optimize MgO-waste activated GGBS formulations, using four types of magnesium oxide (MgO) waste materials with ground granulated blast-furnace slag (GGBS) to develop binary cementitious systems (MgO-GGBS). This stems from the expected complexity of cementitious binder optimization outcomes into a simpler analytic form, enhancing the rapid delivery of optimization results and contributing to the global awareness of sustainable approaches and use of industrial wastes. Three levels of Portland cement by weight (90, 80, and 70 wt.%) was replaced with MgO wastes including an industrial by-product (GGBS) to develop an experimental regime. Investigation was carried out by employing an experiment-based optimisation technique (thermo-chemical approach), which involved the design of an experimental regime and application of experimental tests (pH measurements, thermogravimetric and derivative thermogravimetric analysis—TG/DTG and isothermal calorimetry), establishment of design variable/parameters, measurement of the design performance of the identified design parameters, and review of the relationship between the independent (control) and dependent variables (MgO wastes and their compositions). The experimental test results successfully optimised the binder compositions, established the best performing binder system (MG1), and provided an in-depth insight into the thermal stability and hydration kinetics of the investigated binder systems.

ACS Style

Blessing Adeleke; John Kinuthia; Jonathan Oti. Optimization of MgO-GGBS Cementitious Systems Using Thermo-Chemical Approaches. Sustainability 2021, 13, 9378 .

AMA Style

Blessing Adeleke, John Kinuthia, Jonathan Oti. Optimization of MgO-GGBS Cementitious Systems Using Thermo-Chemical Approaches. Sustainability. 2021; 13 (16):9378.

Chicago/Turabian Style

Blessing Adeleke; John Kinuthia; Jonathan Oti. 2021. "Optimization of MgO-GGBS Cementitious Systems Using Thermo-Chemical Approaches." Sustainability 13, no. 16: 9378.

Journal article
Published: 03 February 2021 in Sustainability
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Treated bentonite-rich soils used as liner materials in landfills may provide an effective solution to the problems of increased void ratios upon swelling at reduced suction as well as desiccation cracking when suction is increased during desaturation. Accordingly, this study provides an understanding of the evolution of void ratio of the mixed materials during swelling at three different suction levels upon saturation as well as the soil water retention (SWR) during desaturation. For the treatment process, low quantity of cement binder whose production leverages raw material resources with efficient dry-process kilns and the benefit of lower energy consumption were used. Results indicated increased mixed soils’ strength irrespective of increased fines content due to thixotropy. The mixed soils exhibited almost equal values of void ratios at different hydration stages, suggesting that slightly reduced expansion mostly affects the subsequent phases of moisture ingress at full saturation compared to the natural soils. Lower values of void ratio obtained at full saturation also suggests possible reduced infiltration of water into landfills. The observed increased moisture retention within the osmotic suction zone and a decrease in the same as the fines content increased in the mixed soils can aid contaminant encapsulation while also reducing desiccation cracking. The findings of this research are intended to serve as a benchmark for further studies using other sustainable materials for treatment of mixed soils.

ACS Style

Eyo Eyo; Samuel Abbey; Jonathan Oti; Samson Ng’Ambi; Eshmaiel Ganjian; Eoin Coakley. Microstructure and Physical-Mechanical Characteristics of Treated Kaolin-Bentonite Mixture for Application in Compacted Liner Systems. Sustainability 2021, 13, 1617 .

AMA Style

Eyo Eyo, Samuel Abbey, Jonathan Oti, Samson Ng’Ambi, Eshmaiel Ganjian, Eoin Coakley. Microstructure and Physical-Mechanical Characteristics of Treated Kaolin-Bentonite Mixture for Application in Compacted Liner Systems. Sustainability. 2021; 13 (4):1617.

Chicago/Turabian Style

Eyo Eyo; Samuel Abbey; Jonathan Oti; Samson Ng’Ambi; Eshmaiel Ganjian; Eoin Coakley. 2021. "Microstructure and Physical-Mechanical Characteristics of Treated Kaolin-Bentonite Mixture for Application in Compacted Liner Systems." Sustainability 13, no. 4: 1617.

Journal article
Published: 29 December 2020 in Sustainability
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Lime stabilisation is one of the traditional methods of improving the engineering properties of lateritic soils for use as subgrade and foundation materials for the construction of road pavements and highway embankments. Understanding the mechanical performance of lime-stabilised lateritic subgrades in terms of their durability under continuous water ingress will improve environmental sustainability by conserving scarce natural resources and reducing the environmental impacts of repair and replacement of pavements. However, there are several conflicting reports on the durability of lime-stabilised soils subjected to continuous water ingress and harsh environmental conditions. Therefore, this paper evaluates the influence of leaching on the physicochemical behaviour and durability of lime-stabilised lateritic soil under continuous water ingress, simulating the typical experience in a tropical environment. Variations in the strength and durability of the lateritic soil at various lime contents (0, 2.5, 5, 7.5, 10, 15, and 20 wt.%) and soaking periods (3, 7, 14 and 28 days) were evaluated by performing the California bearing ratio tests before and after subjecting the lime-lateritic soil (LLS) samples to continuous leaching using two modified leaching cells. Furthermore, physicochemical analysis was performed to assess the variation of cation concentrations and changes in the physical properties of the pore fluid as the leaching time progressed from 3 to 28 days. The results show that the minimum strength reduction index of the soil corresponds to its lime stabilisation optimum (LSO). Electrical conductivity decreased monotonically and almost uniformly with an increase in leaching time, irrespective of lime content. So, too, was calcium concentration and to a lesser degree for pH and potassium concentration. Adverse changes in the physicochemical behaviour of the LLS samples occurred at lime contents below and slightly above the optimum lime content of the soil. Whereas permanent pozzolanic reactions occurred at lime contents above the LSO and thus resulted in a 45-fold increase in strength and durability. The results are significant for reducing the detrimental effect of the leaching-induced deterioration of flexible pavements founded on tropical floodplains.

ACS Style

Chukwueloka Okeke; Samuel Abbey; Jonathan Oti; Eyo Eyo; Abiola Johnson; Samson Ngambi; Tamunoene Abam; Mgboawaji Ujile. Appropriate Use of Lime in the Study of the Physicochemical Behaviour of Stabilised Lateritic Soil under Continuous Water Ingress. Sustainability 2020, 13, 257 .

AMA Style

Chukwueloka Okeke, Samuel Abbey, Jonathan Oti, Eyo Eyo, Abiola Johnson, Samson Ngambi, Tamunoene Abam, Mgboawaji Ujile. Appropriate Use of Lime in the Study of the Physicochemical Behaviour of Stabilised Lateritic Soil under Continuous Water Ingress. Sustainability. 2020; 13 (1):257.

Chicago/Turabian Style

Chukwueloka Okeke; Samuel Abbey; Jonathan Oti; Eyo Eyo; Abiola Johnson; Samson Ngambi; Tamunoene Abam; Mgboawaji Ujile. 2020. "Appropriate Use of Lime in the Study of the Physicochemical Behaviour of Stabilised Lateritic Soil under Continuous Water Ingress." Sustainability 13, no. 1: 257.

Journal article
Published: 08 December 2020 in Sustainability
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This study covers an in-depth investigation into the properties and practicality of the utilization of up to 40% Alumina Waste Filler (AWF) as a partial Portland Cement (PC) replacement material. AWF is a by-product from the recycling of aluminium, produced when salt slag is smelted and cleaned. Its use in concrete will lessen the landfill requirements for AWF disposal, and reduce the strain of the growing requirements and cost of PC. The results obtained from this study showed that the addition of AWF to the concrete mix caused a reduction in the compressive and tensile splitting strength values, and a less-workable concrete was achieved for every increase in the quantity of AWF added to each mix. The addition of AWF influenced the hydration reaction process and reduced the cumulative production of the heat of hydration over time, whilst the permeability of the concrete decreased.

ACS Style

Jonathan Oti; John Kinuthia; Blessing Adeleke. The Strength Characterisation of Concrete Made with Alumina Waste Filler. Sustainability 2020, 12, 10235 .

AMA Style

Jonathan Oti, John Kinuthia, Blessing Adeleke. The Strength Characterisation of Concrete Made with Alumina Waste Filler. Sustainability. 2020; 12 (24):10235.

Chicago/Turabian Style

Jonathan Oti; John Kinuthia; Blessing Adeleke. 2020. "The Strength Characterisation of Concrete Made with Alumina Waste Filler." Sustainability 12, no. 24: 10235.

Journal article
Published: 05 December 2020 in Sustainability
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Expansion of soils has been found to produce significant negative economic and environmental impact on various civil engineering infrastructure. This impact is more deleterious in soils containing sulphates, when treated with calcium-based stabilizers such as Lime and/or Portland cement (PC). The reported study investigated the strength and swell characteristics of Kaolinite clay artificially induced with high levels of Gypsum (sulphate) contents after stabilization with CEM I (PC), which is a calcium-based stabilizer. An optimum stabilizer content/Gypsum dosage, aimed at investigating the maximum magnitude of expansion possible using high levels of 10, 15 and 20% Gypsum contents (4.7, 7 and 9.3 wt.% sulphate) stabilized with calcium-based content of 7, 8, 9 and 10 wt.%. This was expected to provide further understanding on the mechanisms behind high sulphate-bearing clay soils, and the impact of sulphate and calcium content on strength and swell characteristics. The research outcomes showed that the introduction of sulphate to a Kaolinite clay soil reduces the compressive strength of the stabilised product by a factor range of 6–47% at 28 days curing age, while the swell behaviour is mainly dependent on both the sulphate content and curing age. Furthermore, the observed result suggests an 8 wt.% binder content to produce maximum magnitude of expansion (swell) with a high Gypsum content of 10% by weight. This finding is of economic importance, as it is expected to serve as a benchmark for further research on the stabilized clay systems, at high sulphate levels using sustainable binder materials.

ACS Style

Blessing Adeleke; John Kinuthia; Jonathan Oti. Strength and Swell Performance of High-Sulphate Kaolinite Clay Soil. Sustainability 2020, 12, 10164 .

AMA Style

Blessing Adeleke, John Kinuthia, Jonathan Oti. Strength and Swell Performance of High-Sulphate Kaolinite Clay Soil. Sustainability. 2020; 12 (23):10164.

Chicago/Turabian Style

Blessing Adeleke; John Kinuthia; Jonathan Oti. 2020. "Strength and Swell Performance of High-Sulphate Kaolinite Clay Soil." Sustainability 12, no. 23: 10164.

Journal article
Published: 21 June 2020 in Geosciences
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Clayey soils endure adverse changes in strength and volume due to seasonal changes in moisture content and temperature. It has been well recognised that high cement content has been successfully employed in improving the mechanical properties of clayey soils for geotechnical infrastructural purposes. However, the environmental setbacks regarding the use of high cement content in soil reinforcement have necessitated the need for a greener soil reinforcement technique by incorporating industrial by-product materials and synthetic fibres with a reduced amount of cement content in soil-cement mixtures. Therefore, this study presents an experimental study to investigate the mechanical performance of polypropylene and glass fibre-reinforced cement-clay mixtures blended with ground granulated blast slag (GGBS), lime and micro silica for different mix compositions and curing conditions. The unconfined compressive strength, linear expansion and microstructural analysis of the reinforced soils have been studied. The results show that an increase in polypropylene and glass fibre contents caused an increase in unconfined compressive strength but brought on the reduction of linear expansion of the investigated clay from 7.92% to 0.2% at fibre content up to 0.8% for cement-clay mixture reinforced with 5% Portland cement (PC). The use of 0.4–0.8% polypropylene and glass fibre contents in reinforcing cement-clay mixture at 5% cement content causes an increase in unconfined compressive strength (UCS) values above the minimum UCS target value according to American Society for Testing and Materials (ASTM) 4609 after 7 and 14 days curing at 20 °C to 50 °C temperature. Therefore, this new clean production of fibre-reinforced cement-clay mixture blended with industrial by-product materials has great potential for a wide range of applications in subgrade reinforcement.

ACS Style

Samuel J. Abbey; Eyo U. Eyo; Jonathan Oti; Samuel Y. Amakye; Samson Ngambi. Mechanical Properties and Microstructure of Fibre-Reinforced Clay Blended with By-Product Cementitious Materials. Geosciences 2020, 10, 241 .

AMA Style

Samuel J. Abbey, Eyo U. Eyo, Jonathan Oti, Samuel Y. Amakye, Samson Ngambi. Mechanical Properties and Microstructure of Fibre-Reinforced Clay Blended with By-Product Cementitious Materials. Geosciences. 2020; 10 (6):241.

Chicago/Turabian Style

Samuel J. Abbey; Eyo U. Eyo; Jonathan Oti; Samuel Y. Amakye; Samson Ngambi. 2020. "Mechanical Properties and Microstructure of Fibre-Reinforced Clay Blended with By-Product Cementitious Materials." Geosciences 10, no. 6: 241.

Conference paper
Published: 29 March 2018 in Proceedings of EECE 2020
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The establishment of sustainability credentials of emergent construction materials is very subjective, and most available tools such as BREEAM, CEQUAL, ARUP SpeAR among others are not fully quipped or equipped at all to deal with individual material systems. The main problem emanates from the challenges of the audit of each aspect of the material processing, and especially the quantification of the relevant transport, energy, environmental and other inputs into the composite product. Incorporation of materials with long and complex recycling processes further exacerbate the challenge. This paper reports on a simplified approach towards full Life Cycle Assessment (LCA) of seven clay-based brick products developed in UK and in Spain, based on known material data and estimated energy inputs in the manufacturing processes. In order to test the robustness of the proposed approach, results on UK-based bricks are compared with a parallel LCA on clay-based product developed in Spain. Finally, the clay-based products are compared with a typical Portland cement-based concrete block and fired clay brick. In the LCA, boundary conditions include fixed transport, thus attempting to factor only the (i) material ingredients, (ii) their known atmospheric emissions, and (iii) estimated energy inputs during processing. Results suggest that the most challenging aspect in the undertaking of LCA is the availability of reliable input data. Results also show that there are numerous parameters that can reliably and corroboratively facilitate the comparison of performance, besides carbon dioxide emissions.

ACS Style

John Kinuthia; Sara Marcelino; Jonathan Oti; Andres Seco. Problems Encountered in the Life Cycle Assessment (LCA) of Recycled Materials in Construction. Proceedings of EECE 2020 2018, 48 -64.

AMA Style

John Kinuthia, Sara Marcelino, Jonathan Oti, Andres Seco. Problems Encountered in the Life Cycle Assessment (LCA) of Recycled Materials in Construction. Proceedings of EECE 2020. 2018; ():48-64.

Chicago/Turabian Style

John Kinuthia; Sara Marcelino; Jonathan Oti; Andres Seco. 2018. "Problems Encountered in the Life Cycle Assessment (LCA) of Recycled Materials in Construction." Proceedings of EECE 2020 , no. : 48-64.

Journal article
Published: 01 August 2017 in Applied Clay Science
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ACS Style

Sara Marcelino-Sádaba; John Kinuthia; Jonathan Oti; Andres Seco Meneses. Challenges in Life Cycle Assessment (LCA) of stabilised clay-based construction materials. Applied Clay Science 2017, 144, 121 -130.

AMA Style

Sara Marcelino-Sádaba, John Kinuthia, Jonathan Oti, Andres Seco Meneses. Challenges in Life Cycle Assessment (LCA) of stabilised clay-based construction materials. Applied Clay Science. 2017; 144 ():121-130.

Chicago/Turabian Style

Sara Marcelino-Sádaba; John Kinuthia; Jonathan Oti; Andres Seco Meneses. 2017. "Challenges in Life Cycle Assessment (LCA) of stabilised clay-based construction materials." Applied Clay Science 144, no. : 121-130.

Conference paper
Published: 01 October 2015 in Proceedings of the Institution of Civil Engineers - Construction Materials
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ACS Style

Jonathan E. Oti; John M. Kinuthia. Development of stabilised brick and mortar using biomass waste. Proceedings of the Institution of Civil Engineers - Construction Materials 2015, 168, 241 -250.

AMA Style

Jonathan E. Oti, John M. Kinuthia. Development of stabilised brick and mortar using biomass waste. Proceedings of the Institution of Civil Engineers - Construction Materials. 2015; 168 (5):241-250.

Chicago/Turabian Style

Jonathan E. Oti; John M. Kinuthia. 2015. "Development of stabilised brick and mortar using biomass waste." Proceedings of the Institution of Civil Engineers - Construction Materials 168, no. 5: 241-250.

Conference paper
Published: 01 October 2015 in Proceedings of the Institution of Civil Engineers - Construction Materials
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This paper reports the potential of using cereal ash and bottom ash waste generated from biomass combustion plants for the manufacture of stabilised bricks and sustainable masonry mortar for brick joints and plaster. For the stabilised brick production, the cereal ash waste and bottom ash waste were used as full substitutes for primary clay, while magnesium oxide ash was used as a partial substitute for conventional stabilisers. The blending for the production of the masonry mortar was accomplished by the partial replacement of Portland cement, quicklime or hydraulic lime with large volumes (up to 70%) of cereal ash waste. The properties investigated under this study include material characterisation and compressive strength and durability using freeze–thaw tests. The results obtained suggest that there is potential for the manufacture of sustainable construction materials such as bricks and mortar from cereal ash, bottom ash and magnesium oxide ash waste streams.

ACS Style

Jonathan E. Oti; John M. Kinuthia. Development of stabilised brick and mortar using biomass waste. Proceedings of the Institution of Civil Engineers - Construction Materials 2015, 168, 1 -10.

AMA Style

Jonathan E. Oti, John M. Kinuthia. Development of stabilised brick and mortar using biomass waste. Proceedings of the Institution of Civil Engineers - Construction Materials. 2015; 168 (5):1-10.

Chicago/Turabian Style

Jonathan E. Oti; John M. Kinuthia. 2015. "Development of stabilised brick and mortar using biomass waste." Proceedings of the Institution of Civil Engineers - Construction Materials 168, no. 5: 1-10.

Journal article
Published: 11 October 2014 in Applied Clay Science
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This work reports the potential of using Brick Dust Waste (BDW) as a partial substitute for clay in the development of unfired clay building materials (brick, block and mortar). BDW is a waste material from the cutting of fired clay bricks. There are various reasons necessitating the cutting of bricks — corner bricks, construction of chimneys, and other uses needing bricks of various shapes and sizes. This results in the disposal of BDW as an environmental problem of concern. In order to investigate the clay replacement potential of BDW, four types of mixes were designed at varying BDW replacement levels — 5%, 10%, 15% and 20%. Ground Granulated Blastfurnace Slag, an industrial by-product from steel manufacture was activated using quick lime and the mixture was used to stabilise Mercia mudstone clay for unfired clay production. The 56 day compressive results using cylinder test specimens showed a significant strength gain (up to 2.1 N/mm2). Overall, the results suggest that it is possible to develop unfired clay building material using up to 20% BDW as partial substitutes for primary clay.

ACS Style

J.E. Oti; John Kinuthia; R.B. Robinson. The development of unfired clay building material using Brick Dust Waste and Mercia mudstone clay. Applied Clay Science 2014, 102, 148 -154.

AMA Style

J.E. Oti, John Kinuthia, R.B. Robinson. The development of unfired clay building material using Brick Dust Waste and Mercia mudstone clay. Applied Clay Science. 2014; 102 ():148-154.

Chicago/Turabian Style

J.E. Oti; John Kinuthia; R.B. Robinson. 2014. "The development of unfired clay building material using Brick Dust Waste and Mercia mudstone clay." Applied Clay Science 102, no. : 148-154.

Journal article
Published: 06 June 2013 in Engineering Geology
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This paper presents the results of an investigation for the application of alumina filler wastes and coal ash waste for unfired brick production. Mechanical test and durability assessment were carried out on unfired brick test specimens made using marl clay soil and alumina filler waste as a target material, and 70% mix of coal ash waste were used as commercials additive (Portland cement and Lime) replacement. The laboratory results demonstrate that the compressive strength resistance of the unfired bricks reduced as the clay replacement level increased. The unfired brick test specimens made with the blended mixtures containing coal ash waste and lime tended to achieve higher strength values when compared with the coal ash waste and Portland cement blends. The unfired brick test specimens were able to withstand the repeated 48-hour freezing/thawing cycles. The results obtained suggest that there is potential to manufacture unfired bricks from alumina filler waste and coal ash waste.

ACS Style

L. Miqueleiz; F. Ramirez; J.E. Oti; Andres Seco; John Kinuthia; I. Oreja; P. Urmeneta. Alumina filler waste as clay replacement material for unfired brick production. Engineering Geology 2013, 163, 68 -74.

AMA Style

L. Miqueleiz, F. Ramirez, J.E. Oti, Andres Seco, John Kinuthia, I. Oreja, P. Urmeneta. Alumina filler waste as clay replacement material for unfired brick production. Engineering Geology. 2013; 163 ():68-74.

Chicago/Turabian Style

L. Miqueleiz; F. Ramirez; J.E. Oti; Andres Seco; John Kinuthia; I. Oreja; P. Urmeneta. 2013. "Alumina filler waste as clay replacement material for unfired brick production." Engineering Geology 163, no. : 68-74.

Journal article
Published: 31 May 2012 in Applied Clay Science
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This paper reports on designed non-fired clay mixes for sustainability and low carbon use. Ground Granulated Blastfurnace Slag (GGBS), an industrial by-product, was used as a partial substitute for conventional stabiliser (Lime or Portland cement) to stabilise Kaolinite Clay (KC) and Lower Oxford Clay (LOC), for sustainable and low carbon non-fired clay building material production. Although GGBS has been used extensively in concretes to reduce the carbon footprint, there is an unexplored potential for its use as a cement replacement for stabilised soil production. The benefits of using GGBS in non-fired clay building material development include lower emissions of greenhouse gases and improved durability. The parameters considered under this study are: (1) material characterisation, (2) unconfined compressive and (3) durability. For the assessment of durability, a MX 2000VJ Tech multi-channel data logger equipped with a digital displacement transducer and computer device was employed to monitor the linear expansion behaviour of the stabilised test specimens. The 90-day unconfined compressive results for the test specimens showed that there is significant strength gain (up to 5 N/mm2) for all the stabilised mixtures. The lime-activated GGBS stabiliser has significantly higher influence in the strength gain compared to the equivalent PC-based system. These results suggest that there is potential in using Lime or Portland cement activated GGBS blend for the stabilisation of natural clay soil for sustainable and low carbon building materials production.

ACS Style

J.M. Kinuthia; J.E. Oti. Designed non-fired clay mixes for sustainable and low carbon use. Applied Clay Science 2012, 59-60, 131 -139.

AMA Style

J.M. Kinuthia, J.E. Oti. Designed non-fired clay mixes for sustainable and low carbon use. Applied Clay Science. 2012; 59-60 ():131-139.

Chicago/Turabian Style

J.M. Kinuthia; J.E. Oti. 2012. "Designed non-fired clay mixes for sustainable and low carbon use." Applied Clay Science 59-60, no. : 131-139.

Journal article
Published: 30 April 2012 in Applied Clay Science
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Currently there is a growing pressure on energy efficiency for new buildings in the UK and worldwide. This has arisen partly due to the increasing awareness of the public for sustainable building construction. In addition, there is pressure on building materials manufacturers, due to new government regulations and legislations that are targeting energy usage and carbon dioxide emissions in new buildings. This paper reports on unfired clay bricks for environmental and sustainable use. Lime or Portland cement was used as an activator to an industrial by-product (Ground Granulated Blastfurnace Slag) to stabilise Lower Oxford Clay for unfired clay brick production. Portland cement was used in the formulation of the unfired clay brick test specimens predominantly as a control. Industrial scale brick specimens were produced during two separate industrial trials. The first trial was at Hanson Brick Company Ltd, Bedfordshire, UK, while the second was carried out at PD Edenhall Ltd, Bridgend, South Wales, UK. From the environmental and sustainability analysis results, the unfired clay material has shown energy-efficiency and suggests a formidable economical alternative to the firing of clay building components. This study is one of the earliest attempts to compare fired and unfired clay technologies, and also to combine energy use and CO2 emission for the evaluation of unfired clay bricks relative to those bricks used in mainstream construction. This is an attempt to come up with one parameter rating. The overall results suggest that the spinoff from this technology is an invaluable resource for civil engineers and other built environment professionals who need quick access to up-to-date and accurate information about the qualities of various building and construction materials.

ACS Style

J.E. Oti; John Kinuthia. Stabilised unfired clay bricks for environmental and sustainable use. Applied Clay Science 2012, 58, 52 -59.

AMA Style

J.E. Oti, John Kinuthia. Stabilised unfired clay bricks for environmental and sustainable use. Applied Clay Science. 2012; 58 ():52-59.

Chicago/Turabian Style

J.E. Oti; John Kinuthia. 2012. "Stabilised unfired clay bricks for environmental and sustainable use." Applied Clay Science 58, no. : 52-59.

Conference paper
Published: 01 August 2010 in Proceedings of the Institution of Civil Engineers - Construction Materials
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This paper reports on the engineering properties and microstructure of concrete incorporating slate waste aggregates generated from roofing slate production in the UK. Various concrete mixtures were designed using different sizes of slate waste as aggregate replacement. Concrete produced with limestone aggregate was used as control. The results showed that concrete produced with limestone aggregate tended to fail predominantly through the interfacial zone between the aggregate surface and the cement paste and mortar, without any observed aggregate fragmentation. In contrast, the concrete made with slate waste aggregate showed signs of failure emanating from both the interfacial zone as well as from the cracking and subsequent fragmentation of the aggregates. The findings show that the concrete made with slate waste aggregates attained compressive strength of 25–30 N/mm2, splitting strength of 2–3 N/mm2 and elastic modulus of 25–32 kN/mm2 thus indicating potential for using slate waste as a replacement for limestone aggregate in most low- to medium-strength engineering applications.

ACS Style

Jonathan Oti; J. M. Kinuthia; J. Bai; R. Delpak; D. G. Snelson. Engineering properties of concrete made with slate waste. Proceedings of the Institution of Civil Engineers - Construction Materials 2010, 163, 131 -142.

AMA Style

Jonathan Oti, J. M. Kinuthia, J. Bai, R. Delpak, D. G. Snelson. Engineering properties of concrete made with slate waste. Proceedings of the Institution of Civil Engineers - Construction Materials. 2010; 163 (3):131-142.

Chicago/Turabian Style

Jonathan Oti; J. M. Kinuthia; J. Bai; R. Delpak; D. G. Snelson. 2010. "Engineering properties of concrete made with slate waste." Proceedings of the Institution of Civil Engineers - Construction Materials 163, no. 3: 131-142.

Conference paper
Published: 01 August 2010 in Proceedings of the Institution of Civil Engineers - Waste and Resource Management
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This paper reports on freezing and thawing of stabilised clay brick incorporating a latent hydraulic binder. The latent hydraulic binder used for the stabilised clay bricks is an industrial by-product (slag) arising as an inherent consequence of iron production. Laboratory and industrial-scale masonry bricks were produced. In order to improve on the cementitious properties of the latent hydraulic binder, between 1·4 to 2·6% of lime was used as an activator. The brick specimens were moist cured at a room temperature of about 20°C for between 3 and 90 days before testing for compressive strength. Since the major factor influencing the durability of clay masonry units is the degree to which the clay masonry unit becomes saturated with water, the durability assessment of the unfired bricks was carried out by means of 24 h repeated freezing/thawing cycles. The results showed that the compressive strength values of the industrial-scale bricks were higher than those of the laboratory bricks. The results of the freeze–thaw suggest that both the laboratory and industrial unfired clay bricks were able to withstand 100 (24 h) repeated freeze–thaw cycles. These results gave an indication of the feasibility of a durable stabilised clay brick incorporating a lime-activated latent hydraulic binder. This paper reports on freezing and thawing of stabilised clay brick incorporating a latent hydraulic binder. The latent hydraulic binder used for the stabilised clay bricks is an industrial by-product (slag) arising as an inherent consequence of iron production. Laboratory and industrial-scale masonry bricks were produced. In order to improve on the cementitious properties of the latent hydraulic binder, between 1·4 to 2·6% of lime was used as an activator. The brick specimens were moist cured at a room temperature of about 20°C for between 3 and 90 days before testing for compressive strength. Since the major factor influencing the durability of clay masonry units is the degree to which the clay masonry unit becomes saturated with water, the durability assessment of the unfired bricks was carried out by means of 24 h repeated freezing/thawing cycles. The results showed that the compressive strength values of the industrial-scale bricks were higher than those of the laboratory bricks. The results of the freeze–thaw suggest that both the laboratory and industrial unfired clay bricks were able to withstand 100 (24 h) repeated freeze–thaw cycles. These results gave an indication of the feasibility of a durable stabilised clay brick incorporating a lime-activated latent hydraulic binder.

ACS Style

Jonathan Oti; John Kinuthia; Jiping Bai. Freeze–thaw of stabilised clay brick. Proceedings of the Institution of Civil Engineers - Waste and Resource Management 2010, 163, 129 -135.

AMA Style

Jonathan Oti, John Kinuthia, Jiping Bai. Freeze–thaw of stabilised clay brick. Proceedings of the Institution of Civil Engineers - Waste and Resource Management. 2010; 163 (3):129-135.

Chicago/Turabian Style

Jonathan Oti; John Kinuthia; Jiping Bai. 2010. "Freeze–thaw of stabilised clay brick." Proceedings of the Institution of Civil Engineers - Waste and Resource Management 163, no. 3: 129-135.

Conference paper
Published: 01 May 2010 in Proceedings of the Institution of Civil Engineers - Construction Materials
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Blended mixtures of ground granulated blastfurnace slag and Portland cement were used in making sustainable masonry mortars suitable for brick joints and for plastering, with Portland cement mortar as control. The testing programme included the determination of a relationship between the mortar flow value and mortar water demand for a wide range of mix compositions. The mortar tensile strength is not a very critical property due to the fact that brickwork mortar is not usually under tension when in service; however, this parameter was determined in the laboratory using a standard briquet towing/testing machine. Chemical durability of the control and blended mortar in aggressive sulfate-bearing exposure conditions was investigated. The relationship between compressive strength of the mortar cured in water and in sodium sulfate solution at room temperature (20 ± 2°C) for from 3 to 120 days was established. The results demonstrated that after a prolonged period of exposure, significant strength and weight loss in the control mortar was observed. This phenomenon is explained, due to calcium hydroxide production as a consequence of Portland cement hydration, change in mortar morphology, inhibition of reaction species and the final disruption of the mortar matrix, resulting in loss of strength and weight at late age. The results obtained suggest that ground granulated blastfurnace slag can be incorporated into Portland cement for the development of sustainable and durable mortars in the UK.

ACS Style

Jonathan E Oti; J. K. Kinuthia; J. Bai. Sustainable masonry mortar for brick joint and plaster in the UK. Proceedings of the Institution of Civil Engineers - Construction Materials 2010, 163, 87 -96.

AMA Style

Jonathan E Oti, J. K. Kinuthia, J. Bai. Sustainable masonry mortar for brick joint and plaster in the UK. Proceedings of the Institution of Civil Engineers - Construction Materials. 2010; 163 (2):87-96.

Chicago/Turabian Style

Jonathan E Oti; J. K. Kinuthia; J. Bai. 2010. "Sustainable masonry mortar for brick joint and plaster in the UK." Proceedings of the Institution of Civil Engineers - Construction Materials 163, no. 2: 87-96.

Conference paper
Published: 01 February 2010 in Proceedings of the Institution of Civil Engineers - Waste and Resource Management
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The potential of using slate waste generated from roofing slate production in the UK in various applications is reviewed and the environmental impact of the stockpile of slate waste is also assessed. The findings suggest that there is potential for using slate waste in many situations, including engineering applications. In order to reduce the environmental impact arising from the quarrying of conventional construction materials, the abundance of slate waste in Wales in particular and the UK in general could be exploited. With associated economic advantages despite reported transportation difficulties, utilisation of this waste stream for most practical and low- to medium-strength engineering applications is feasible and would maximise the use of surplus regional and national industrial wastes and minimise the environmental impact of their disposal.

ACS Style

Jonathan Oti; J. M. Kinuthia; D. G. Snelson; J. Bai. Applications of slate waste material in the UK. Proceedings of the Institution of Civil Engineers - Waste and Resource Management 2010, 163, 9 -15.

AMA Style

Jonathan Oti, J. M. Kinuthia, D. G. Snelson, J. Bai. Applications of slate waste material in the UK. Proceedings of the Institution of Civil Engineers - Waste and Resource Management. 2010; 163 (1):9-15.

Chicago/Turabian Style

Jonathan Oti; J. M. Kinuthia; D. G. Snelson; J. Bai. 2010. "Applications of slate waste material in the UK." Proceedings of the Institution of Civil Engineers - Waste and Resource Management 163, no. 1: 9-15.

Conference paper
Published: 01 February 2010 in Proceedings of the Institution of Civil Engineers - Waste and Resource Management
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This paper discusses the potential of using slate waste generated from roofing slate production in the UK in the manufacture of unfired clay masonry bricks. Ground granulated blast-furnace slag activated by lime and Portland cement were used to stabilise Lower Oxford Clay incorporating slate waste in the preparation of laboratory cylindrical test specimens. The specimens were moist cured at room temperature (20±2°C) for between 3 and 90 days before testing for compressive strength. The drying and linear expansion behaviours of the test samples were assessed by means of moisture content measurement (at the age of testing) and linear expansion measurement after soaking the samples in deionised water. The strength of the cement-activated blended mixture was lower than that of the lime-activated mixtures. An environmental comparison of the unfired clay masonry bricks with mainstream construction (fired) bricks shows that the unfired clay bricks have good environmental characteristics over a range of important criteria. These results suggest that there is potential for using activated slag mixtures in the manufacture of bricks for low-cost environmentally friendly housing and energy-efficient masonry wall construction within the UK.

ACS Style

Jonathan Oti; J. M. Kinuthia; J. Bai. Unfired clay masonry bricks incorporating slate waste. Proceedings of the Institution of Civil Engineers - Waste and Resource Management 2010, 163, 17 -27.

AMA Style

Jonathan Oti, J. M. Kinuthia, J. Bai. Unfired clay masonry bricks incorporating slate waste. Proceedings of the Institution of Civil Engineers - Waste and Resource Management. 2010; 163 (1):17-27.

Chicago/Turabian Style

Jonathan Oti; J. M. Kinuthia; J. Bai. 2010. "Unfired clay masonry bricks incorporating slate waste." Proceedings of the Institution of Civil Engineers - Waste and Resource Management 163, no. 1: 17-27.

Journal article
Published: 31 January 2010 in Materials & Design
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This paper reports on a laboratory and theoretical method for determining the design values for thermal conductivity and thermal resistance of unfired clay masonry bricks from both experimental and theoretical design point of view. The paper describes the methodology of obtaining these values using the measured lower and upper lambda limits. In order to determine the basic design thermal value and the design thermal resistance, a Laser-comp FOX 200 thermal conductivity meter equipped with WinTherm32an software package was employed for the laboratory data collection and analysis. Lime or Portland cement (PC)-activated Ground Granulated Blastfurnace Slag (GGBS) binder was used to stabilise Lower Oxford Clay (LOC) for unfired masonry brick specimen production. The major influence of the design values on the thermal conductivity and thermal resistance are illustrated in this study, using two different types of unfired clay bricks (LG and PG) at 2% moisture content prior to test. This paper covers conductivity test for each unfired clay bricks within the temperature range 2.5–17.5 °C. The measured thermal properties of the unfired clay bricks were compared to the design thermal properties of fired bricks. The results were used to predict the design thermal values of unfired clay masonry bricks at varied density and moisture contents prior to testing. A comparison of the measured thermal values for the unfired bricks to the design thermal values of fired clay bricks can also be seen. The results demonstrate that the unfired clay bricks were able to comply with the design thermal requirements for clay masonry units, suggesting that the unfired clay bricks can be used for low-medium cost housing and energy efficient masonry structures.

ACS Style

J.E. Oti; John Kinuthia; J. Bai. Design thermal values for unfired clay bricks. Materials & Design 2010, 31, 104 -112.

AMA Style

J.E. Oti, John Kinuthia, J. Bai. Design thermal values for unfired clay bricks. Materials & Design. 2010; 31 (1):104-112.

Chicago/Turabian Style

J.E. Oti; John Kinuthia; J. Bai. 2010. "Design thermal values for unfired clay bricks." Materials & Design 31, no. 1: 104-112.