Identification of the cement type at the concrete surface with ordinary Portland cement and supplementary cementitious materials with a handheld X-ray Fluorescence analyser

This master's thesis provides knowledge on non-destructive testing of cement and supplementary cementitious materials composition in concrete with a handheld X-ray Fluorescence analyser. <br/><br/>Today, concrete production is responsible for 8\% of the world's $CO_{2}$ emissions. Recycling concrete material can directly contribute to the...

A predictive model of concrete compressive strength based on level of contamination of coarse aggregate: Experimental study and relation to the water absorption of the coarse aggregate

Recycled aggregate concrete is emphasized more and more nowadays due to its importance towards the construction industry and general welfare of our planet. Being such a significant feature with regard to universal sustainable development, every aspect of its properties should be evaluated, examined and optimized so that there is a well-known,...

Characterisation of recycled concrete aggregates from construction and demolition wastes

Construction and demolition waste form a significant problem in terms of environmental pollution and material depletion. Concrete, as part of construction and demolition waste, is already responsible for 9% of the total anthropogenic carbon dioxide emissions. Consequently, it is important to alleviate the environmental stress of concrete by...

Putting recycled concrete into practice in Belgium: From case studies over chain management to standards and quality assurance

Although there has been extensive research and several demonstration projects in Belgium and abroad, the use of recycled aggregates in concrete is still limited in practice. Several barriers were identified: lack of practical experience, limiting standards and the need for specific quality assurance. The paper describes recent developments in...

Environmental impact of concrete with recycled aggregates an evaluation through 4 case studies

The use of recycled aggregates in new structural concrete is generally considered as a measure for lowering the environmental impact of concrete. Existing literature considers transport distances and the final performance of the concrete (linked to its composition) as main influencing factors to evaluate the environmental burdens or gains when...

Impact of green public procurement on the market of recycled concrete

According to the European Commission website, construction and demolition waste (CDW - consisting of materials such as concrete, bricks, gypsum, wood, glass, metals, asbestos, excavated soil…) accounts for approximately 25% - 30% of all waste generated in the EU. To move towards a recycling society, various policies have been launched by...

The ITZ in concrete with natural and recycled aggregates: Study of microstructures based on image and SEM analysis

Aim of this work was to investigate the microstructure of the Interfacial Transition Zone (ITZ) between cement paste and aggregate in concrete utilizing Scanning Electron Microscope (SEM) in order to identify possible effects on the ITZ related to different recipes and production parameters. SEM is an important tool to carry out concrete, cement...

Packing of non-spherical aggregate particles by DEM

Loose random and dense random mono-size pacl<ing states were investigated by the discrete element modelling (DEM) for eight types of polyhedral grains, for ellipses with different aspect ratio, for cubes and for spheres. Focus was on density, sphericity of the grains and average value and frequency distribution of coordination number. The 3D...

Analogue simulation by dem of material structure for property estimation of cementitious materials

Realistic simulation of particulate materials like concrete on meso- as well as micro-level is nowadays possible by fast developments in computer technology. This would be a more economic way than by physical experiinents, which are more time-consuming, laborious and thus expensive. This concern the production of the aggregate structure or of...

Brazil Nut Effect and CONCRETE: Entering Terra Incognita

This paper presents some evidence of the impact of the Brazil nut effect (BNE) on concrete’s particulate structure on meso-level (aggregate) as well as on micro-level (cement paste). BNE is associated with long-range size segregation in particle mixtures due to vibration in slurry state of concrete, both near boundaries and in bulk. Presented...

Particulate structure and microstructure evolution of concrete investigated by DEM: Part 1: Aggregate and binder packing

Experimental approaches in concrete technology are time-consuming, laborious and thus expensive. Developments in computer facilities render possible nowadays realistically simulating the particulate structure and microstructure of cementitious materials. For that purpose, discrete element methods (DEM) are required because of more correctly...

Using particle packing technology for sustainable concrete mixture design

The annual production of Portland cement, estimated at 3.4 billion tons in 2011, is responsible for about 7% of the total worldwide CO2-emission. To reduce this environmental impact it is important to use innovative technologies for the design of concrete structures and mixtures. In this paper, it is shown how particle packing technology can be...

Determination of aggregate shapes using X-ray computed tomography and making virtual concrete

The shape of aggregates has significant effect on the concrete properties. To predict these properties with computational models the mathematically characterized shape has to be known. In the past, scientists assumed simple shapes like spheres and ellipsoids. To make models more realistic, aggregate shapes has to be also more realistic. X-ray...

An Experimental Study of Shear Fracture and Aggregate Interlock in Cementbased Composites

In the present paper the results of an exploratory study with the recently developed biaxial tension/shear apparatus of the Stevin Laboratory of Delft University of Technology are presented. The apparatus is unique in the sense that square double-edgenotched concrete plates up to a size of 200 x 200 mm can be loaded in any combination of tension...