On-site application of self-compacting concrete (SCC)

Self-Compacting Concrete (SCC) is a material which under its own self-weight flows to form and fill any shape, attains full compaction, without external energy input, to create a dense homogenous mass (based on Holton, 2003; The Concrete Society and BRE, 2005; Damtoft et al, 2008). It is, in respect to the history of concrete, a relatively new development, with its first UK application occurring in the late 1990s. Since then a significant amount of research has sought to understand its physical and structural properties, but there is a lack of a knowledge base on its practical application and performance in construction projects. Where it does exist, such research lacks robust and transparent data, particularly relating to the claimed attributes of the material (such as better surface finish, faster construction and lower overall costs). Using a combination of qualitative and quantitative research methods, this research investigates the construction practices employed when pouring SCC and presents new data on its practical applications. Interviews with a range of building contractors, ranging from multinationals to small UK businesses (SMEs), show that current perceptions of SCC limit its use to specific applications because practitioners see SCC as just another type of concrete . A critical examination of these attitudes led to the identification of three distinct scenarios for the use of SCC: 1. Reactive selection: in which a particular attribute of SCC provokes its use to solve a particular problem, often as a last minute substitution for conventional concrete the most common scenario. 2. Strategic change: in which the material is chosen on the basis of a balanced assessment of all its benefits and on the understanding that such benefits can only be attained if the contractor appreciates that there may be implications for the construction process a rarely experienced scenario. 3. Specification: in which there is complete acceptance of SCC as a method, not just as a material; a significant amount of early project involvement with knowledge holders, such as contractors and material suppliers, optimises the construction process. A rigorous work measurement study of live construction projects has made it possible to quantify the as-built costs of SCC for selected UK residential slab and multi-storey flat slab applications and compare this with the equivalent conventional concrete slab construction. On-site use of self-compacting concrete vi The results indicate that SCC can reduce construction times of structural topping layers of residential slabs by up to 73%, and has shown that SCC can also match, if not reduce, total as-built concrete placement costs in multi-storey applications. This new data will enable contractors, designers and specifiers to better understand the practical implications of using SCC for on-site applications, thereby leading to more potential instances of its early and planned specification, hence resulting in more of its full benefits being realised

UK contractors’ views on self-compacting concrete in construction

Self-compacting concrete (SCC) is claimed to offer faster construction, safer sites and more consistent concrete quality, but little corroborative research data exist on performance advantages, particularly in comparison with traditional construction. Industry opinions also appear to be divided. For these reasons, an extensive interview programme was undertaken with UK contractors – from large national concrete frame contractors to small, locally based housebuilders – to assess whether benefits were being achieved and to try to understand the reasons why SCC is, or is not, being used. The 48 participants reported that decisions on the suitability of SCC were inherently complex and, if selected, there were challenges in understanding ‘how’ construction should be planned and managed to accommodate the use of SCC and to fully utilise its advantages. The findings identify the need for a step change in the industry’s perception of SCC, such that it should be considered as a construction method, not simply as a material

Optimising construction with self-compacting concrete

Self-compacting concrete or self-consolidating concrete (as it is known in North America) (SCC) is used on the basis of its unique properties of flowability, passability and resistance to segregation. It requires no external energy to achieve full compaction, so is advantageous on site, but there is evidence that its higher cost is a significant barrier to greater adoption. The research entailed work measurement of 14 UK single-family home residential projects (eliciting data on construction time and labour productivity) and cost modelling of three slab scenarios (exploring the relationship between material and labour costs). The study found SCC was placed up to 73% faster than conventional concrete and, when labour and material costs are included, the supplier is able to price SCC to closely match conventional concrete, hence making SCC more viable for the contractor. This relationship between as-built costs for SCC and conventional concrete is clarified by developing Pmax, providing a new mechanism for understanding project profitability and viability of SCC

To SCC or not to SCC? UK contractors’ views

Self-Compacting Concrete (SCC) is a construction material that has yet to be fully exploited within the UK construction industry. Whilst SCC has been utilised by a large number of contractors, its overall take-up does not appear to reflect that seen in other European and International markets. Benefits to contractors have been identified in many publications but the material still remains underused in the UK. As such, it is necessary to establish the reasons for the material’s current status in the UK market and the potential for future market development. This paper presents the findings from an extensive programme of interviews with UK contractors (48 participants), ranging from large multi-nationals to small/medium regional contractors, which aimed to investigate the issues surrounding the use of SCC in the UK and to help obtain an understanding of the role that SCC plays within contracting organisations. Previous and current perceptions of the material are discussed along with the drivers and processes for material selection and how these are influenced by the structure of the individual organisations and the wider industry. This interview study has identified a number of conclusions with regard to SCC and its position and role in the industry. It has been made clear that SCC is currently viewed as a material which has a detrimental effect in considering the materials subsequent effect on the whole construction project, which can add subsequent value. It is the concept of value that is difficult to encourage due to the industries current and hereditary obsession with lowest cost

The self-compacting method, concrete that can save you time and effort

The self-compacting method, concrete that can save you time and effor