Materials and technology solutions to tackle the challenges in daily concrete construction for housing and infrastructure in sub-Saharan Africa

Schmidt, Wolfram; Msinjili, Nsesheye Susan; Kühne, Hans‐Carsten

doi:10.1080/20421338.2017.1380582

Cited by 18 publications

(18 citation statements)

References 7 publications

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“…After combustion ideally all organic components are removed, by weight 17–18% of ash remain from the husks [ 36 ]. The dominating remaining chemical components are silica (typically more than 85%, up to 98% [ 37 ]) and trace elements like potassium, calcium, aluminum, iron and magnesium. Even though the variation of trace elements can affect the final performance of RHA, pozzolanic activity is always given, due to these high amounts of reactive silica.…”

Section: Previous Studies On the Use Of Rha As Scmmentioning

confidence: 99%

Performance of Rice Husk Ash as Supplementary Cementitious Material after Production in the Field and in the Lab

et al. 2020

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Supplementary cementitious materials (SCM) can reduce the total amount of Portland cement clinker in concrete production. Rice husk ashes (RHA) can be converted from an agricultural by-product to a high-performance concrete constituent due to a high amount of reactive silica with pozzolanic properties if they are burnt under controlled conditions. The way and duration of combustion, the cooling process as well as the temperature have an effect on the silica form and thus, the chemical and physical performance of the RHA. Various studies on the best combustion technique have been published to investigate the ideal combustion techniques. Yet, the process mostly took place under laboratory conditions. Investigating the difference between the performance of RHA produced in a rural environment and laboratory conditions is useful for the assessment and future enhancement of RHA production, and its application both as building material, for example in rural areas where it is sourced in large quantities, and as additive for high performance concrete. Thus, the paper presents a comparison between RHA produced under rudimentary conditions in a self-made furnace in the rural Bagamoyo, Tanzania and under controlled laboratory conditions at the Technical University of Munich, Germany, with different combustion methods and temperatures. In a second step, RHA was ground to reach particle size distributions comparable to cement. In a third step, cement pastes were prepared with 10%, 20% and 40% of cement replacement, and compared to the performance of plain and fly ash blended cement pastes. The results show that controlled burning conditions around 650 °C lead to high reactivity of silica and, therefore, to good performance as SCM. However, also the RHA burnt under less controlled conditions in the field provided reasonably good properties, if the process took place with proper burning parameters and adequate grinding. The knowledge can be implemented in the field to improve the final RHA performance as SCM in concrete.

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Section: Previous Studies On the Use Of Rha As Scmmentioning

confidence: 99%

Performance of Rice Husk Ash as Supplementary Cementitious Material after Production in the Field and in the Lab

et al. 2020

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“…Another relevant source of binder alternative comes from agriculture such as the ashes of many by-products from food processing such as cassava peels, rice husks, sugar cane bagasse, palm kernel or maize cobs [23][24][25][26][27][28][29]. A major limiting factor for the large-scale use of these wastes, which are often produced by smallholders or cooperatives, is the relatively small amount as well as the lack of infrastructure to collect, monitor, control and homogenise the residues for further industrial use.…”

Section: Mineral Bindersmentioning

confidence: 99%

“…Besides agents such as starch and cellulose that are largely known products to modify the viscosity of concrete and grout, other polysaccharides than can be derived from by-products of food production or directly harvested from nature have shown great potentials to modify the rheological properties of cementitious systems.  The starch of cassava has pointed out to have moderate plasticizing effect [23]. Since chemical admixtures are typically added at low dosages to concrete, the starch residues adhered to the peels can be used to derive construction chemicals, so that the full tuber can be used for food processing.…”

Section: Chemical Admixtures For Concretementioning

confidence: 99%

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Innovation potentials for construction materials with specific focus on the challenges in Africa

et al. 2020

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Africa is urgently in need of adequate basic infrastructure and housing, and it is one of the continents where massive construction activities are on the rise. There is a vast variety of potentially viable resources for sustainable construction on the continents, and consequently, the continent can bring innovative, greener technologies based on local sources effectively into practice. However, unlike established concrete constituents from industrialised countries in the global North, most of the innovation potentials from the African continent have not yet been the focus of intensive fundamental and applied research. This clearly limits the implementation of more sustainable local technologies. This paper presents a case for the need to first appreciate the rich diversity and versatility of the African continent which is often not realistically perceived and appreciated. It discusses specific innovation potentials and challenges for cementitious materials and concrete technology based on local materials derived from sources on the African continent. The unique African materials solutions are presented and discussed, from mineral binders over chemical admixtures and fibres to reinforcement and aggregates. Due to the pressing challenges faced by Africa, with regards to population growth and urbanisation, the focus is not only put on the technological (durability, robustness and safety) and environmental sustainability, but also strongly on socio-economic applicability, adaptability and scalability. This includes a review of alternative, traditional and vernacular construction technologies such as materials-saving structures that help reducing cementitious materials. Eventually, a strategic research roadmap is hypothesised that points out the most relevant potentials and research needs for quick implementation of more localised construction materials.

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“…They can, thus, replace Portland cement clinker [12][13][14][15][16].  Eventually, plant-based components can be used as aggregates or fibres to enhance the physical properties or the ductile behaviour of concrete components [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Plant based chemical admixtures – potentials and effects on the performance of cementitious materials

et al. 2019

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While today, engineers can choose from a wide range of rheology modifying admixtures, in some parts of the world, these are difficult to access, due to their complex processing. However, alternatives can be bio-based polymers such as polysaccharides from various sources. These are easily accessible all over the world, do not demand for complicated processing, and typically they are more sustainable than many established materials, which are crude oil-based. The paper presents the effects of acacia gum, cassava starch and the gum of triumfetta pendrata A. Rich on the rheological performance of cementitious systems. It is shown that acacia gum can be as efficient as polycarboxylate based superplasticisers, cassava starch can reduce the yield stress slightly with little effect on the plastic viscosity, and the gum of triumfetta pendrata A. Rich increases the thixotropy of cement pastes with plasticizing polymers significantly.

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Materials and technology solutions to tackle the challenges in daily concrete construction for housing and infrastructure in sub-Saharan Africa

Cited by 18 publications

References 7 publications

Performance of Rice Husk Ash as Supplementary Cementitious Material after Production in the Field and in the Lab

Performance of Rice Husk Ash as Supplementary Cementitious Material after Production in the Field and in the Lab

Innovation potentials for construction materials with specific focus on the challenges in Africa

Plant based chemical admixtures – potentials and effects on the performance of cementitious materials

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