Diffusion of Soluble Organic Substrates in Aerobic Granular Sludge: Effect of Molecular Weight

Aerobic granular sludge (AGS) is an advanced biofilm-based technology for wastewater treatment. Diffusion of substrates into the granules is a key aspect of this technology. Domestic wastewater contains soluble organic substrates of different sizes that could potentially diffuse into the granules. In this study, the relation between the...

Thermal aging behaviors of the waste tire rubber used in bitumen modification

Considering the application scenarios of rubber granules from waste tires in the bitumen modification process (wet or dry process), both aerobic and anaerobic aging of rubber may occur. The current study aims to investigate the thermal aging behavior of waste tire rubber samples using nanoindentation and environment scanning electron microscopy ...

The use of infrared spectroscopy to determine product quality of carbonate-rich diatomite ores

Diatomite, a rock formed by the accumulation of opaline diatom frustules, is a preferred raw material for the manufacturing of filters. Its uniqueness relies on the high porosity and inertness of the frustules. The presence of carbonates in some diatomite ores hinders these properties. The~purpose of this study was to identify the type of...

ESEM-BSE coupled with rapid nano-scratching for micro-physicochemical analysis of marine exposed concrete

Ordinary Portland cement (OPC) mortar specimens submerged in sea-water were analysed through environmental scanning electron microscopy (ESEM) in back scattered electron (BSE) mode and nano-scratching. Results from both sets of analysis show the presence of distinct phases associated with aragonite, brucite and cement paste. Phases associated...

Characterization of Portland cement paste using MIP, nanoindentation and esem techniques

Mechanical, electrical and microstructural properties of cement-based materials in conditions of stray current flow

This investigation presents a comparative study on mechanical properties, electrical resistivity and microstructure of mortar under DC current, compared to mortar in rest (no current) conditions. Monitoring was performed from 24h after casting until 84 days of cement hydration. A current density level of 10 mA/m2 was chosen as a simulation...

Microstructure Analysis of Heated Portland Cement Paste

When a concrete structure is exposed to high temperature, the mechanical damage and chemical transformation take place simultaneously, which will change the microstructure of material. On the other hand, the mechanical properties and transport properties depend on the development of microstructure of cement paste. In order to study the...

The green building envelope: Vertical greening

Planting on roofs and façades is one of the most innovative and fastest developing fields of green technologies with respect to the built environment and horticulture. This thesis is focused on vertical greening of structures and to the multi-scale benefits of vegetation. Vertical green can improve the environment in urban areas and is becoming...

ESEM drying tests: Microcracking initiation in thin cement paste due to early age drying

Scattered and discontinues microcracking as a subsequent side-effect of deformations due to early age drying, occurs in thin (approximately 1 mm thick) cement paste samples, when stepwise dried in ESEM. Microcracking of cement paste and restrains appear to be practically unavoidable. They are related to a phenomenon of interfaces (‘matrix’ and ...

Nondestructive determination of drying deformations in cement paste by means of ESEM and digital image analysis

Novel modifications of an environmental scanning electron microscope (ESEM) were made in order to measure the local deformations in drying cement paste. These nondestructively determined moisture-induced plane strains, obtained in 1 mm thick cement paste samples, are orthotropic. They vary with variations of relative humidity between 70%-80% and...

Study of ‘real’ shrinkage by ESEM observations and digital image analysis

Defining the 'real' shrinkage values of concrete is still a subject of much debate. In shrinkage experiments size effects are inherently present. Through an attempt to determine the real shrinkage of cement-based materials, these size effects have to be eliminated or at least reduced as much a possible. In this contribution drying shrinkage...

Preliminary Investigation of Drying Shrinkage Cement Paste Specimens

In order to perform drying shrinkage observations in ESEM (Environmental Scanning Electron Microscope), a preparation procedure for cement paste samples is developed. Instead of casting standard prisms (40 x 40 x 160 mm3), cement paste samples were cast in specially designed moulds of 30 x 30 x 2 mm3 and 10 x 10 x 2 mm3 in size. A special...

Quantification of shrinkage microcracking in young mortar with fluorescence light microscopy and ESEM

In this paper a method is described to quantify shrinkage microcracking in young mortar by means of crack mapping. Visualisation of the microcracks is realised with two techniques: Fluorescence Light Microscopy (FLM) and Environmental Scanning Electron Microscopy (ESEM). The preliminary results obtained with the microcrack mapping method showed...