Grout rheological properties for preplaced aggregate concrete production

yesThis paper investigates the effect of cement based grout rheology on the injection process through coarse aggregate for producing preplaced aggregate concrete. Four different sands were used in the grout production at different water-cement ratios and cement-sand ratios. Superplasticiers and pulverised fuel ash were also employed in the grout production. Coarse aggregate of known weight was compacted into 150 mm cubic forms, and then the grout was injected through a plastic pipe under self weight into the stone ‘skeleton’. It has been found that there are threshold values of the rheological parameters beyond which full injection is not possible. In particular, all grout mixes with and without additives and admixtures exhibited the same yield stress threshold value for full injection, whereas the threshold values for other rheological properties including the grout plastic viscosity, flow time and speed were different according to the materials added to the mix

Analysing the technical and behavioural shifts of social housing tenants following the retrofitting of external wall insulation

Environmental, economic and social issues present local housing associations with many challenges in terms of management of their existing housing stock. Multiple problems arise from poorly insulated properties, and the twin foci of this research regards the performance of residential external wall insulation, and identifying the additional benefits that External Wall Insulation (EWI) provides to social housing tenants, which are uncovered through means of behavioural and technical monitoring. The research process generated two sets of data points per household relating to the start and the end of the study and comparative analysis techniques are used to identify changes in user behaviours. Qualitative and quantitative data were collected using survey methods that explored environmental knowledge, attitudes, beliefs, and everyday behaviours with regard to energy consumption and use. Additional data capture involved temperature logging, meter reading, thermal imaging, and the analysis of energy meter readings to monitor changes in usage in the pre and post stages of retrofitting external wall insulation. The results of this study identify changes in the technical performance of the properties, and benefits in the well-being and behaviour of the tenants

Rheology, fiber dispersion, and robust properties of Engineered Cementitious Composites

The capability of processing robust Engineered Cementitious Composites (ECC) materials with consistent mechanical properties is crucial for gaining acceptance of this new construction material in various structural applications. ECC's tensile strain-hardening behavior and magnitude of tensile strain capacity are closely associated with fiber dispersion uniformity, which determines the fiber bridging strength, complementary energy, critical flaw size and degree of multiple-crack saturation. This study investigates the correlation between the rheological parameters of ECC mortar before adding PVA fibers, dispersion of PVA fibers, and ECC composite tensile properties. The correlation between Marsh cone flow rate and plastic viscosity was established for ECC mortar, justifying the use of the Marsh cone as a simple rheology measurement and control method before fibers are added. An optimal range of Marsh cone flow rate was found that led to improved fiber dispersion uniformity and more consistent tensile strain capacity in the composite. When coupled with the micromechanics based ingredient-tailoring methodology, this rheological control approach serves as an effective ECC fresh property design guide for achieving robust ECC composite hardening properties.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94214/1/Mo-Rheology-2012.pd