The use of various additives (admixtures) in concrete and cement products has been considered by various researchers in recent years. Microsilica (Silica fume) can also be considered as one of the most widely used additives (admixtures) in this section. In this study, 120 concrete specimens were constructed using a mix design based on ACI in the laboratory with an overview of records and advantages of using microsilica in concrete. The microsilica used in concrete specimens has been considered 2%, 5.5% and 7.5% by weight of cement. Finally impact permeability, tension and uniaxial compressive strength tests were done on concrete specimens and their mechanical properties were evaluated. The results show that microsilica improves the mechanical properties of concrete. The results also show that the use of microsilica in ordinary concrete has a very positive effect in controlling the surface cracks and increasing some strength parameters such as tensile and compressive strength of concrete.
P. Kapalo, F. Domniţa, C. Bacoţiu and Nadija Spodyniuk
From various other studies, it is known that the maximum carbon dioxide concentration in different countries is between 1,000 ppm up to 1,500 ppm. Therefore, the research is focused on indoor environment, namely the production of pollutants from the persons inside office rooms. The article presents the trend of the carbon dioxide concentration from the occupants inside an office. It is examined the carbon dioxide production separately for men and women, for persons of different mass and for persons of different ages. It is also analyzed the carbon dioxide production during a sedentary and physical activities. In parallel with the production of carbon dioxide is presented the monitoring of the human pulse and blood pressure. All these parameters are monitored together with relative humidity and indoor air temperature. The aims of this paper is to describe the partial results of human respiration impact on indoor air quality in closed spaces and to research the connection between carbon dioxide concentration and human health.
Today, advanced countries compete enormously for further exploitation in the offshore area, for its enormous fresh resources and space. Therefore, these competitions will double the importance of these types of structures. As it is known, the most important part in the design of the offshore structures is the design of the piles on which the structure will be placed. Engineers have always been trying to build these types of structures with the least cost and the highest safety factor. In this research, the effect of distance and the ratio of the elliptical pile diameters on the strength of the pile group was evaluated using numerical modeling. Five different states of diameter ratios including: 1.2, 1.4, 2, 2.5, 3 and five different distance ratios were investigated. The results demonstrate that with the increase in the diameter ratio, the amount of force decreases while it increases as the distance ratio rises.
Ana Diana Ancas, M. Profire, I. L. Cirstolovean, M. Hornet and G. Cojocaru
The lifetime of glass reinforced plastic pipes is 50 years. Extensive use of this type of pipe in its various applications, led to investigate their behavior in land that anthropogenic or natural causes, shows the different values of pH to neutral. The paper presents experimental results conducted on three samples of a PN SN10000 DN150 PN10 pipe buried in three different types of terrain: neutral, acidic, basic. They were subjected to axial load, measuring the force applied deformation force function. On the basis of the calculation formulas determined rigidity of the pipeline, the deformation speed of 50 mm / min. This concludes the type of land affects the rigidity of the pipe so its length of life decreases to that provided by suppliers in order to be taken compensatory measures in this regard such as choosing a higher class of pressure and stiffness pipeline than those arising discounted. This will allow for long-term value (50 years) in the mechanical characteristics sufficient for safe operation.
Sara Mirzabagheri, F. Vatankhah, Zeynab Ziaee, Ghazaleh Derhamjani, Sahar Maharati and H. Aslani
In ancient structures such as Jabalieh dome at Kerman and Dokhtar Bridge at Mianeh in Iran, it was said that egg and in some cases egg and camel milk were used in the mortar. Thus, it was imagined that the stability of these structures were based on these traditional materials. Therefore egg parts and also camel milk were used as a portion of water in the concrete to evaluate this traditional theory. For this purpose, 16 concrete mix designs included 144 cubes, 16 cylinders and 16 prisms were casted. Various percentages of albumen, yolk or camel milk were used. Results showed that by substituting 0.5% of water content with albumen, compressive strength was similar to control specimen. But splitting tensile strength and three-point flexural strength were 7.2% and 18.9% higher than control specimen, respectively. Moreover, because of camel milk’s fat, usage of this material was not suggested.
K. Ullah, M. S. Khan, M. T. Lakhiar, A. A. Vighio and S. Sohu
The problem of delay is a regular phenomenon in construction projects all around the world and the Malaysian building projects has no exclusion. The aim of this paper is to determine and rank the effects of delay in Malaysian building projects with respect to their Relative Importance Index. Literature review and questionnaire survey were used to gather data for this study. A thorough literature review was performed to identify the common effects of delays in building construction projects. A questionnaire was distributed among key project participants; contractors, clients and consultants, to rank the effects of delay in Malaysian building projects based on the perception of survey respondents. In total 300 questionnaires were distributed, as a result of 240 questionnaires were received. The collected data of questionnaire survey was analysed using statistical software SPSS. In total, 17 effects of the delays have been determined and findings from the survey revealed that time overrun, cost overrun, dispute, loss of profit, arbitration, claims, contract termination, litigation, poor quality of work, and total project abandonment were the main effects of delay in Malaysian building projects. The findings of this study might encourage construction stakeholders to focus on the issue of delays in building projects.
Ammar S. Dawood, Mushtak T. Jabbar, Mudhar H. Gatea and Hayfaa J. Al-Tameemi
The present work evaluated the groundwater quality index (GWQI) depending on some physicochemical analyses of thirteen groundwater samples in the Zubair district in Basra Province, Iraq. The collected groundwater samples were subjected to an extensive physicochemical analysis to evaluate the characteristics of water for drinking purpose according to Iraqi standard. For calculating the (GWQI), twelve water quality parameters were considered; turbidity, pH, chloride, total dissolved solids, total hardness (TH), electrical conductivity (EC), sodium, sulphate, phosphate, calcium, nitrate, and magnesium. The analysis of the results reveals that all the samples surpassed the portability of drinking water limits. High values of the (GWQI) in the obtained groundwater samples could possibly be caused by the higher values of electrical conductivity, total hardness, chloride, total dissolved solids and sodium within the groundwater. The calculated GWQI values ranged from 73.36 to 595.92. The pollution index (PI) was calculated for the study area with values ranged from 2.97 to 8.26. Correlation coefficients amongst the chosen water parameters exhibited some strong relationships. Finally, the analysis shows that the groundwater in this particular area needs to be treated before its consumption, and in addition, it usually needs to avoid the hazard of contamination. Principal component analysis (PCA) and cluster analysis (CA) indicate that the acquiring-data from groundwater samples are explained 90.5 % of the variance in the data with a four-component system that explains a large portion of the total variance of collected data.
Office buildings are responsible for a great portion of total energy consumption. In this study, solar system based retrofitting measures such as daylighting control system (DCS), Trombe wall (TW) and photovoltaic (PV) systems are modeled to an office building located in Dayton, Ohio, United States. An energy modeling tool, eQuest is utilized to analyze the economic and environmental impacts of the proposed single retrofitting measures along with the combined measure to identify the optimized building energy reduction opportunity. Compared to the baseline energy consumption, adopting single energy efficiency measures such as PV, DCS, TW, and overhangs/fins to windows results in about 25, 10, 9, 1 percentages of energy reduction respectively. In terms of economic perspectives, overhang and fins provide the best simply payback time around 1 year. Other solar system based retrofitting measures such as TW, DCS and PV can provide economic simple payback with 1.5, 2.5, and 12 years respectively. PV turned out to be the most costly options although it provides the largest energy savings which lead to the largest CO2 reductions. Adopting the combined system along with 50 kW photovoltaic array to the rooftop results in 45 percent office building energy reduction.
M. Horneț, I.L. Cîrstolovean, D.C. Năstac, Ana Diana Ancaș and M. Profire
It is known the fact that buildings become one of the major energy consumers. In order to ensure thermal comfort in buildings, more and more complex heating, ventilation and air conditioning systems have been used over time, which are currently large primary energy consumers. At the same time, today, the main source of energy production is still the burning of fossil fuels, which is the process leading to significant emissions of greenhouse gases. That is why the current European Union directives enforce both reducing buildings energy consumption with 20% before 2020 and using an amount of 20% of renewable energy. One of the heating systems that best respond to the need to reduce the energy consumption of buildings is the low-temperature radiant heating system., This is the reason why the present paper presents a research project that concerns the use of TABS heating/cooling systems that harness the renewable geothermal energy of the ground provided by a ground-air heat pump in Romania. The experimental research building is one of the research laboratories of the Research, Development, Innovation Institut of Transilvania University of Brasov-Romania In the first cold season of activity for heating the experimental building (2017-2018), the system provided a thermal enegy of 48 MWh, covering 48 % from the amount of the heating load. During the monitored period, the average COP for heating of the heat pump was 4,6. The research will continue to take place, results regarding the economy for cooling the building in the warm season and for the year’s transition periods being expected to follow.
This paper presents sustainable architecture as a function of sensory experience through time. Entitled sitesynthesis, this proposed approach forms the foundation of a holistic design methodology grounded physically in the geographical location of a given community and metaphysically in the spirit of place derived from sense experience. Sitesynthesis is made up of sitescapes which range from natural to cultural to social landscapes, themselves the product of the sensescapes through timescapes. The site is the place in geological, archaeological and historical time. The symbiotic relationship between the natural, cultural and social environs which sitesynthesis endeavours to attain is mutualistic rather than parasitic, a relationship from which society and the site both benefit rather than the former benefiting at the expense of the latter.