Time and price of contracted construction as well as their overrun are among highly pronounced issues in the construction practice. Numerous studies indicate that there is a dependency between these parameters at various construction markets. The paper shows the results of a research conducted on a group of 40 projects related to water supply systems carried out in the Federation of Bosnia and Herzegovina from 2001 to 2012. Collected data, obtained through interviewing chief engineers of construction companies, have been used as input parameters for implementation of single linear regression by applying the BTC (Bromilow time-cost) algorithm. The final result is a model in the form of an exponential equation. Whereas it was obtained based on effectuated values, it can be considered appropriate for assessing and testing the construction time in the early planning stage, as well as at work contracting. Since the parameter values in the model depend on circumstances of the specific area under consideration, the application of the model is recommended primarily in the area where the research was conducted. Results of the price overrun and construction overrun interdependence have not resulted in determining the exponential model. The paper also proposes application recommendations and guidelines for further research.

Results obtained by studying the possibility of replacing cement in mortars with local industrial by-products, i.e. with silica fume and red mud, are provided in the paper. The results of fresh and hardened mortar properties tests conducted on five mixtures in two series are presented. 10% of cement was replaced with silica fume, and 0%, 5%, 10%, 15% and 20% of cement weight was replaced with red mud. The first series was tested after 28 days of curing, and the second series was subjected to freezing and thawing cycles after proper curing, and then submitted to testing. The results point to satisfactory behaviour of mixtures with a low red mud content.

In recent years, various studies have been conducted on the utilisation of bauxite residue from alumina production (known as red mud) in the construction industry. It is particularly noteworthy as a partial replacement for cement in concrete because of its favourable chemical composition. In this study, red mud and silica fume were investigated as partial replacements for cement in concrete. Five mixtures were tested. Herein, cement was replaced with red mud at 0, 5, 10, 15 and 20 % by cement mass. Furthermore, cement was replaced by silica fume at 10 % by cement mass in all the mixtures. The workability, bulk density, and air content were tested to evaluate the properties of the fresh concrete. The bulk density, water absorption, compressive strength, splitting tensile strength, water penetration, and freeze–thaw resistance were tested to evaluate the properties of the hardened concrete. The results indicated that for a low red mud content, reasonable fresh and hardened concrete properties were achieved.