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With respect to the studies conducted so far and lack of researches on the post-heat behavior of cement mortars containing pozzolanic materials, the purpose of this paper is to investigate the post-heat mechanical characteristics (i.e. compressive, tensile and flexural strength) of cement mortars containing granulated blast-furnace slag (GBFS) and silica fume (SF). In doing so, selected temperatures include 25, 100, 250, 500, 700 and 9000c. Last, the X-ray diffraction test was conducted to study the microstructure of mixtures and subsequently, the results were presented as power-one mathematical relations.

Totally, 378 specimens were built to conduct flexural, compressive and tensile strength tests. Accordingly, these specimens include cubic and prismatic specimens with dimensions of 5 × 5 × 5 cm and 16 × 4 × 4 cm, respectively, to conduct compressive and flexural strength tests together with briquette specimen used for tensile strength test in which cement was replaced by 7, 14 and 21 per cent of SF and GBFS. To study the effect of temperature, the specimens were heated. In this respect, they were heated with a rate of 5°C/min and exposed to temperatures of 25 (ordinary temperature), 100, 250, 500, 700 and 900°C.

On the basis of the results, the most profound effect of using GBFS and SF, respectively, takes place in low (up to 250°C) and high (500°C and greater degrees) temperatures. Quantitatively, the compressive, tensile and flexural strengths were enhanced by 73 and 180 per cent, 45 and 100 per cent, 106 and 112 per cent, respectively, in low and high temperatures. In addition, as the temperature elevates, the particles of specimens containing SF and GBFS shrink less in size compared to the reference specimen.

The specimens were cured according to ASTMC192 after 28 days placement in the water basin. First, in compliance with what has been specified by the mix design, the mortar, including pozzolanic materials and superplasticizer, was prepared and then, the sampling procedure was conducted on cubic specimens with dimension of 5 × 5 × 5 mm for compressive strength test, prismatic specimens with dimensions of 16 × 4 × 4 mm for flexural strength test and last, briquette specimens were provided to conduct tensile strength tests (for each temperature and every test, three specimens were built).

The purpose of this paper is to identify the main reworks and their causes in a case study of the ongoing mass housing project in Iran. Using the real data captured from the project, the most important causes for reworks have been computed and prioritized.

More than 900 non-conformance forms filled in the construction site have been used to categorize reworks. Then, the frequency and cost of each rework group in the project have been estimated. Finally, using these data, the primary classification and sorting of the main causes of reworks have been specified.

Results show “Poor site supervision and inspection” with 24 percent of costs had the most impact and “unclear project management process” with about 6 percent of costs had the least impact on the formation of non-conformances. “Cost of each incidence” (COI) ranged from 0.67 for “The need to categorize the complicated operations” to 1.86 for “Unclear project management process.”

The causes of rework which are not in contractor’s hand (like change orders from the client) have not been considered in this study.

Although some works have been done in rework causes, the key elements and causes of reworks in mass housing projects in developing countries have not been yet fully specified through the real data. Knowing the root causes of reworks can help project managers to remove them and reduce reworks costs in future projects. COI which is defined here for the first time and computed in a relative concept could be a good criterion to compare rework causes between two or more similar projects.

Claim formation is a fact and a regular occurrence in construction industry projects and often leads to a waste of money and time for organizations. Organizations can, however, reduce and control claims by promoting an integrated claim management system and improving productivity in the results of the claims. Establishing a claim management office is one of the ways to help organizations achieve this.

Based on library research, expert opinion and analysis of organizations' contracts as case studies and identifying the root causes of the claim, this paper proposes a claim management office maturity model and determines its levels.

This paper proposes a claim management office maturity model and also determines its levels. The general structure of this model is based on three parameters: “characteristics of each level,” “requirements of each level” and “transition period of each level” in five levels, where the first level is the most basic level and level five is the highest level of the implementation of a claim management office in the organization.

It can be clearly emphasized that this research is one of the first research studies that has dealt with the issue of claim management office in the construction industry and has proposed the model of maturity and development of claim management office in the organization. The use of numerous and experienced experts in achieving the results and case organizations to develop this research has increased the value and credibility of this research. This study also helps to improve the level of claim management in construction industry organizations so that these organizations can implement each level of claim management maturity model in the organization according to their competence and need for claim management. And by implementing it correctly, solve or reduce the problems of claim management in the organization and their projects.