Microproportioning with crushed sand

The PhD student completed the micro proportioning model and submitted two new manuscripts for journal articles in 2021 (PhD student first author on both) on this topic. The first article is a compact and quite user-friendly description of a regression based micro proportioning model for rheology of filler modified cement paste based on crushed aggregate. The other article is a comprehensive comparison of the same measured rheological properties with a new Artificial Intelligence (AI) model developed in cooperation with DTU for such prediction based on Matlabs Multilayer Perceptron module. The results show that AI gives better prediction than several different suspension models that are investigated and their predicting capabilities compared to that of AI. Suspension models and empirical relations between composition and rheology have been investigated based on material modelling and laboratory measurements of different material parameters. The material parameters include particle properties (size, distribution, shape, surface, particle packing, type of crushed aggregate etc) and suspension- and fluid properties (industrial rheological methods, advanced rheometry, viscosity of suspending fluid) for concrete, filler modified paste and fluid separated from paste. An important lack of suspension models is, however, that they do not account for the effect of SP. This we have included in the AI model and in the empirical model. Still, some of the investigated suspension models give very good prediction for certain selections of parameter variations as SP-dosage varies. A fundamental multi-effect model (YODEL) has been reviewed but not investigated experimentally. That would be too demanding (experimentally, modelling) for the resources of this project to study percolation, adsorption of SP, the surface physics, effect on rheology of interstitial fluid etc. We leave this to future research. Our modelling has been limited to a bilinear function where dosage of polymer-based plasticizer reaches saturation at a knee-point at the end of the linear part of the adsorption isotherm. After that the concentration of polymer in the suspending fluid increases much more at increasing dosage while the effect on rheology gets weaker. In addition, the PhD-student has investigated the further development of an existing industrial measurement method for rheology of filler modified cement paste by numerical simulation using CFD ? computational fluid dynamics. The existing method measures only plastic viscosity and hence is not giving a complete rheological characterization. The results of the new numerical simulations, however, show that a modified geometry can give very good information on both plastic viscosity and yield stress of filler modified cement paste. An abstract has been submitted to international conference to be held in Oslo in 2022. The PhD-work has been central in the project including model-input to the laboratory experiments at Sintef and full-scale testing in the industry, supervision of master students at NTNU, cooperation internationally etc. Fundamental competence has hence been developed with new insights and understanding for the PhD and the Post Doc for application of crushed aggregate as replacement of natural aggregate on an industrial scale. SINTEFs work has consisted of review, development of measurement methods and studies of material parameters in several larger laboratory scale experiments. The experiments have included particle packing measurements, proportioning og concrete and rheological properties of concrete to verify modelling of fresh concrete. The work is based on thorough review of methods for measurements of particle packing, own measurements and use of the matrix results of the PhD-student. A paper has been published based on literature review and a comprehensive measurement series of different methods for measuring packing. The results form the basis for and verification of a concrete proportioning model in a digital tool. NTNU, Skanska and Heidelberg Norcem Norbetong (including the former Post Doc swhich is now working with the industry) has developed a beta-version of the digital tool. The tool can optimize proportions of concrete with reduced environmental impact including use of manufactured aggregate and predict the fresh properties of the concrete. The user interface of the tool makes it applicable both for industry, research laboratories and education with user friendly entering of data of the constituent materials, choice of desired matrix- and concrete properties and calculation and presentation of results. Feiring Bruk AS and one of their customers are exploiting the tool in a series of full-scale experiments in the autumn of 2001 in cooperation with Norcem/Norbetong, Skanska and NTNU. The project will be closed with presentations at the Norwegian Concrete Day 21st of October 2021 and in a separate workshop 9th of November emphasizing transfer of competence to industry.

Proporsjoneringsverktøyet utviklet optimaliserer betongsammensetningen uten prøvestøp via input om delmaterialene og modeller for flytegenskaper. Materialparametre brukes til å beregne sammensetning og flyteegenskaper av betong med industrielt produsert tilslag. Resultatene fra full skala demonstrerer bruk av verktøy for valg av delmaterialer, proporsjonering og egenskaper for bygg (M60) og anleggsbetong (M40) med 100 % industrielt fremstilt tilslag. Fullskala utprøving gjøres med kombinasjon av kubisator, syklon mm i for kontroll og styring av fillerinnhold og pakning. For industrien anvendes resultatene i produktutvikling for redusert miljøpåvirkning. For universitetene brukes resultatene i undervisning og veiledning av master og PhD studenter. Resultatene av prosjektet brukes og til analyse, modellering og forskningspublisering, samt til undervisning.

Future concrete industry will use crushed (manufactured) aggregate because use of natural sand and gravel is depleting natural aggregate resources. Environmental impact of transport is reduced by production from local bedrock. The properties of crushed aggregate differ from those of natural ones: angular shape/rougher surfaces and high fines content affecting fresh concrete rheology, -stability, - pumpability and also surface aestethics. Advanced production of fines and tailoring of particle properties (size, surface, shape) can reduce the need for expensive chemicals, making concrete production more sustainable and economical. The project will perform scientific research in the fields of particle production and characterisation, rheology and application of fresh concrete and develop a new microproportioning method to make sustainable concrete with crushed aggregate, particularly aplying the fines. Knowledge to transform concrete industry into user of crushed aggregate is done in 6 research areas: 1. Full-scale aggregate production. 2. Mapping of material parameters. 3.Material models. 4.Upscaling to concrete rheology. 5.Full scale testing. 6.Result dissemination and publishing. The industrial need for this research is corroborated by Norcem AS with aggregate, cement and concrete value chain, Feiring Bruk, a local producer and Skanska as end user. The research will be carried out in close collaboration with international partners lead by the Norwegian University of Science and Technology: The Technical University of Denmark (DTU), Sintef, National Institute of Standards and Technology (NIST) and Princeton University, USA. Numerical simulations of rheology will be combined with verification experiments on a wide range of crushed aggregate particles produced and combined with state of the art binder powders and chemical admixtures giving basic understanding of how to produce powder particles as well as microproportioning rules.