Contribution of composite cements in reducing embodied CO[sub]2

Over the last decades, there is a growing demand to reduce the Portland Cement (PC) content and increase the amount of various supplementary cementitious materials (SCMs) used in concrete mixture to help reduce the embodied CO2 (ECO2) of concrete and more generally, the environmental impacts of concrete industry. The main objective of this paper is to assess the CO2 emissions associated with concrete production using various combinations of SCMs as per EN197-1 and further to develop concrete mixes with reduced ECO2 and enhanced durability. The results indicate that the ECO2 reduction in the composite cements is proportional to the substituted amount of PC by the SCMs in the concrete mix. In addition to the environmental benefits generated by the use of high content of SCMs as substitute of PC, the obtained results reveal a significant long-term improvement in strength properties and durability performance of composite cement concretes. Keywords. Supplementary cementitious materials, Initial surface absorption, Mechanical properties, Sustainable concrete, Embodied CO

Cost and safety optimisation in 'Berlin' type retaining walls

Studies for earth retaining wall structures provide engineers with the values for the response of design characteristics which represents the stability and the required budget for the completion of a project. Fundamental theories guide engineers to combinations of design variables values. These values have a direct relation to the responses of the earth retaining wall structure. The requirement of this analysis is that there is no proven technique which ensures the best combination of design variables for the simultaneous optimisation of safety factor and overall cost of a project. This paper presents an integration of the desirability analysis which provides the multivariate optimisation with the performance of few experimental runs based on statistical tools and finite elements methodology. The methodology provides a 24% higher safety factor and 50% lower overall cost comparing to the results of an experienced foundation engineering company

Integrated Advance Data Storage Technology for Effective Construction Logistics Management

Abstract This paper presents a study on applying an integrated application of RFID, GPS and GSM technology for mobile, pervasive and ubiquitous tracking and locating of any objects in construction supply chain and logistics. Accurate and timely identification and tracking of resource are vital to operating a well managed and cost efficient construction project. RFID integrated with the GPS provides an opportunity to uniquely identify materials and to locate and track them in a real time basis using minimal or no worker input where transmission of data from the system to the central database will be carried out with the help of standard cellular phone communications networks technology such as GPRS and SMS. In this research GIS will be used for analyzing and representing collected data. The authors believe that full automation of the construction supply chain and logistics can increase the efficiency and productively and lead to reductions in project costs and time

Pretensioned BFRP reinforced concrete beams : flexural behaviour and estimation of initial prestress losses

Fibre Reinforced Polymers (FRP) are becoming a popular reinforcement option for RC elements mainly due to good strength to weight ratio and resistance to corrosion. The main limitation for their wider application is their relatively low Young’s modulus, which results in unfavourable serviceability performance, in terms of early development of deflections and cracks. Among others, prestressing has been suggested as one of the possible approaches to addressing this issue, with encouraging results from research conducted so far. This experimental study aimed to explore prestress losses of basalt fibre reinforced polymer (BFRP) reinforced pretensioned concrete beams. Five beams were produced, three of them internally reinforced with 6mm diameter BFRP bars, pretensioned to 20%, 30% and 40% of the ultimate load level of prestress. Additionally, two beams, acting as control samples, were reinforced with unprestressed BFRP and steel bars of same cross-sectional area, respectively. The dimensions of all samples were 125x200x1900 mm. Prestress losses were monitored with the aid of strain gauges attached to the reinforcing bars, as well as load cells. The strain readings were continuously taken during the pretensioning process, from initial application of the prestressing force, during casting and curing of concrete, until releasing of the beams from prestressing devices after curing. Ultimately, all samples were subjected to a quasi-static, load-controlled, four-point bending test until destruction. The results provide the information about the flexural behaviour of pretensioned BFRP reinforced beams, along with insight into some of the initial prestress losses of these elements