Experimental Investigation on the Effect of Specimen Size in Determining Fracture Parameters of Concrete

his paper presents the experimental results in investigating the effect of specimen size (ratio of beam width to aggregate size) on the value of stress intensity factor (KIC) and fracture energy (GF) using three-point bend (TPB). A test method recommended by RILEM was chosen to measure the KIC and the GF as fracture parameters. Three different specimen sizes of concrete beam with water/binder ratio of 0.2 and 0.30 were engaged in the experiments. Both qualitative and quantitative analyses based on the normalized stress against deflection curve, and the KIC and the GF were employed. Statistical analysis was carried out based on coefficient of variation of the measured value of fracture parameters in order to investigate the variability of corresponding results. It was found that specimen size have a relatively insensitive influence on the value of KIC, however, have a significant effect on the value of GF

Experimental investigation of the effects of aggregate size distribution on the fracture behaviour of high strength concrete

This paper examines the influence of different aggregate size distributions on the fracture behaviour of high strength concrete. Three-point bend test was performed on 63 notched beams casted using three aggregate size distributions and two water to binder ratios. The total fracture energy, GF, and critical stress intensity factor, KIC, were used to determine the fracture characteristic of concrete. The results show that the values of GF decrease substantially with increasing coarseness of aggregate grain structure, λ. Values of KIC also decreased but demonstrated only limited dependence on λ. In contrast, reducing the total w/b ratio substantially increases the value of KIC but had no measurable effect on GF

Optimization of preventative maintenance strategies for bridges

The use of preventative maintenance (PM) has been acknowledged as an effective way of reducing the whole life cost of maintaining bridges in good, safe and functional condition. However, there are many uncertainties associated with the need and effectiveness of PM. Such uncertainties if not addressed can lead to incorrect decisions and wastage of resources. In addition optimization procedures are necessary to produce strategies with minimum cost while maintaining the reliability of the bridge at an acceptable level. This paper examines the issue of effectiveness of different PM on reinforced concrete bridges deteriorating due to the corrosion of reinforcement from chloride ions. It investigates the applicability of an optimization methodology, using the principles of genetic algorithm (GA) to identify optimum PM strategies based on their effectiveness and cost

Building Sustainability Impacts from the Bottom Up: Identifying Sustainability Impacts throughout a Geotechnical Company

Geotechnical contractors install and repair foundations for buildings and large infrastructure projects. Previously, geotechnical companies have typically focused on sustainability improvements on individual construction projects, with a primary focus on improving the environmental sustainability of site operations. However, the activities of geotechnical companies have sustainability impacts far beyond what they do on site. In the context of the UN Sustainable Development Goals (SDGs), whole company sustainability must also address social and economic sustainability. This paper therefore explores all the processes carried out across a geotechnical company, from human resources through to site operations, assessing their impact against the SDGs using a pedigree matrix approach. Through this investigation, we see that geotechnical companies impact every SDG in some way. There is a strong focus on health and well-being (SDG 4) and economic sustainability (SDG 8) throughout a geotechnical company. Some functions, such as procurement, impact a broad range of SDGs, whilst others, such as HR, mostly only impact social or environmental sustainability. Overall, this approach highlights which processes in each function have the greatest impact on the overall sustainability of the company. It also reveals more sustainability impacts than previous top-down approaches. This means geotechnical contractors can better target sustainability improvements in specific parts of their business, making sustainability relevant to each department. It also aims to empower employees to improve the sustainability of their own day-to-day processes

FEA on Grey Cast Iron Assets: A Case Study on Penstocks in the Waste Water System

Penstocks have been used in the water industry for flow control since the Victorian expansion and consolidation of clean and waste water networks. However, the Victorians were the first to use grey cast iron (GCI) castings to manufacture large scale penstocks. Most of these ageing assets are still in operation, however engineering assessments are necessary to determine a structure’s fitness-for-service. Even today, penstocks in the sewer system tend to be made from GCI, due to ease of manufacturing, resistance to corrosion and cost. One characteristic property of grey cast iron is the graphite flake structure in the material, contributing to its low toughness, inconsistency in material strength and brittle behaviour, despite exhibiting slight hardening properties. Finite element analysis (FEA), is a numerical method which allows the analysis of complex structures by splitting it into finite parts and solving them with a computer processor. Despite the versatility of FEA, appropriate considerations and assumptions are necessary due to the difficulty to obtain data from inspection and unique material behaviour of GCI. The article shows concerns for an analysis of GCI penstocks using FEA, which extends into the application of fracture mechanics approaches for defect assessments