A survey on problems encountered in current concrete construction and the potential benefits of self-healing cementitious materials.

The annual costs for repair, maintenance and replacement of civil engineering infrastructure attracts significant expenditure in the UK. Anecdotal evidence suggests that a significant number of existing and new concrete structures suffer from repair and maintenance problems, but a lack of objective construction industry supported data concerning these problems makes it difficult to establish, with any certainty, the actual problems encountered in current concrete construction in the UK. To address this lack of data, a market research exercise was commissioned by the Materials for Life (M4L) EPSRC funded research project. The market research has shown that damage in the form of cracking in concrete structures was experienced by more clients, design team members and civil engineering contractors than any other problem. Structures requiring articulation and subject to dynamic loads such as bridges were noted as being the most vulnerable to damage, with this damage mostly occurring in the joints and half joints, bearings and the deck of such structures. The main consequential effects of damage in concrete structures were the need for the contractor to return for repairs as well as the need for regular monitoring. The current approaches taken to enhance a structure’s longevity mainly involve the use of additional cementitious material to improve the barrier between the environment and the steel reinforcement. However, an alternative could be to use the self-healing cementitious materials that have been proposed by the M4L research team. Until now there has been insufficient evidence regarding how these materials may be deployed in the construction industry, and the applications to which they may be best suited in terms of added-value. The market research results show that highways and infrastructure generally and water retaining structures would benefit most from self-healing cementitious materials, with reduced maintenance costs over a structure’s lifetime justifying a premium in the capital material cost. Reduced whole-life costs and fewer repair and maintenance interventions will have a significant influence on the economic, environmental and social impact of repair and maintenance events, which will be of benefit to the UK as a whole

An investigation into the use of manufactured sand as a 100% replacement for fine aggregate in concrete

Manufactured sand differs from natural sea and river dredged sand in its physical and mineralogical properties. These can be both beneficial and detrimental to the fresh and hardened properties of concrete. This paper presents the results of a laboratory study in which manufactured sand produced in an industry sized crushing plant was characterised with respect to its physical and mineralogical properties. The influence of these characteristics on concrete workability and strength, when manufactured sand completely replaced natural sand in concrete, was investigated and modelled using artificial neural networks (ANN). The results show that the manufactured sand concrete made in this study generally requires a higher water/cement (w/c) ratio for workability equal to that of natural sand concrete due to the higher angularity of the manufactured sand particles. Water reducing admixtures can be used to compensate for this if the manufactured sand does not contain clay particles. At the same w/c ratio, the compressive and flexural strength of manufactured sand concrete exceeds that of natural sand concrete. ANN proved a valuable and reliable method of predicting concrete strength and workability based on the properties of the fine aggregate (FA) and the concrete mix composition

Underslung cable structures – a feasible alternative?

This paper examines the behaviour and feasibility of under-slung cable structures. Consideration is given to their structural behaviour, their dynamics, their cost-effectiveness and the practicality of adopting such structures. The parameters that govern the behaviour and response of these structures are investigated and structural arrangements and details are proposed, which it is suggested would make the construction of such structures feasible. The aim of the paper is to generate discussion of this novel form of construction and to identify opportunities for the exploitation and development of such a concept. This paper discusses how underslung structures, when combined with a radical trussed stiffening girder, can provide an innovative but more sympathetic structure, which is stiff, stable and economically viable for both medium and long-span structures. It is shown that when there is a need to minimise the number or limit the location of the foundations required, such structures provide a means of adopting relatively large spans, while restricting the height of the cable supports and hence minimising the impact of the structure. The paper concludes by summarising the benefits that can be obtained from such structures both during construction and in use, and seeks to identify the opportunities and challenges that must still be met to facilitate the exploitation and development of such a concept

BIM for infrastructure: An overall review and constructor perspective

The subject of building information modelling (BIM) has become a central topic to the improvement of the AECOO (Architecture, Engineering, Construction, Owner and Operator) industry around the world, to the point where the concept is being expanded into domains it was not originally conceived to address. Transitioning BIMinto the domain of infrastructure projects has provided challenges and emphasized the constructor perspective of BIM. Therefore, this study aims to collect the relevant literature regarding BIM within the Infrastructure domain and its use from the constructor perspective to review and analyse the current industry positioning and research state of the art, with regards to the set criteria. The review highlighted a developing base of BIM for infrastructure. Fromthe analysis, the related research gapswere identified regarding information integration, alignment of BIM processes to constructor business processes & the effective governance and value of information. From this a unique research strategy utilising a framework for information governance coupled with a graph based distributed data environment is outlined to further progress the integration and efficiency of AECOO Infrastructure projects

A collaborative unified computing platform for building information modelling (BIM)

The current dominant computing mode in the AEC (Architecture, Engineering and Construction) domain is standalone based, causing fragmentation and fundamental interoperability problems. This makes the collaboration required to deal with the interconnected and complex tasks associated with a sustainable and resilient built environment extremely difficult. This article aims to discuss how the latest computing technologies can be leveraged for the AEC domain and Building Information Modelling (BIM) in particular. These technologies include Cloud Computing, the Internet of Things and Big Data Analytics. The data rich BIM domain will be analysed to identify relevant characteristics, opportunities and the likely challenges. A clear case will be established detailing why BIM needs these technologies and how they can be brought together to bring about a paradigm shift in the industry. Having identified the potential application of new technologies, a future platform will be proposed. It will carry out large scale, real-time processing of data from all stakeholders. The platform will facilitate the collaborative interpretation, manipulation and analysis of data for the whole lifecycle of building projects. It will be flexible, intelligent and able to autonomously execute analysis and choose the relevant tools. This will form a base for a step-change for computing tools in the AEC domain

Experimental Everglades Virus Infection of Cotton Rats (Sigmodon hispidus)

We characterized Everglades virus infection of cotton rats from South Florida to validate their role as reservoir hosts in the enzootic transmission cycle