Advance Researches in Civil Engineering
Volume:4 Issue: 2, Spring 2022

In this study 11 different combinations of micro fly ash and calcium oxide were replaced instead of cement. Fly ash with 5%, 10%, 15% and 20% of cement and calcium oxide with 5%, 10%, 15% and 20% of cement and then a combination with fixed 15% fly ash and 5%, 10% and 15% of calcium oxide are replaced instead of cement. Then 108 sample of cubic concrete have been prepared and samples at the ages of 7, 28 and 56 days were applied compression strength and ultra sound tests and results were recorded and compared. According to the results, the samples had the best results at 56 days. The reason for the good results at 56 days was the entry of pozzolan into the system and its reaction with calcium hydroxide resulting from the hydration reaction.

During the non-stop construction, risk analysis is essential to ensure airport safety. This study aims to perform risk evaluation of airport safety during the non-stop construction using both Fuzzy Analytical Hierarchy Process (F-AHP) and Bayesian Belief Network (BBN). Risk assessment of airport during non-stop construction involves four risk factors of personnel, equipment, environment, and management. F-AHP is utilized to rank impact of risk factors while BBN is implemented to assess probability of risk occurrence. The combination of F-AHP and BBN is implemented to identify the most significant risk. The results have revealed that environmental factor imposes the most significant influence on risk of airport safety during non-stop construction while equipment factor has the lowest impact on airport safety. The outcomes of this study allow decision makers to manage potential risk and improve airport safety during the non-stop construction.

At present, the extraction of new bio-asphalt materials from renewable energy sources has become the focus of research in the field of pavement engineering. Bio-asphalt has the characteristics of wide source, low cost, green, pollution-free and is also renewable. With the expansion of the application range of bio-asphalt, its adhesion to aggregates and the healing properties after damage have received extensive attention. In this paper, the bio-asphalt-aggregate adhesion and healing behaviors were evaluated and compared using molecular dynamics approaches. Firstly, the molecular models of vegetable oil bio-asphalt and waste edible oil were established, and the two bio-asphalt molecular models were verified according to the physical quantities such as density, viscosity, cohesive energy density (CED), glass transition temperature and solubility parameter. Then, the bio-asphalt-aggregates interlayer model was established, and the adhesion energy and the energy ratio (ER) value under water conditions were calculated and analyzed using energy theory. A bio-asphalt self-healing model was established, and concentration distribution and diffusion analysis were performed. The results show that the viscosity of bio-asphalt is significantly lower than that of base asphalt, and the shear resistance becomes lower at high temperature. In terms of adhesion, bio-asphalt has better temperature sensitivity. The two bio-asphalts have better adhesion than base asphalt and silica at different temperatures, especially at high temperature (65 °C). There was no significant difference between the adhesion energy of the two bio-asphalts. Bio-asphalt is more affected by water intrusion, and its ability to resist water damage is significantly weaker than that of base asphalt. The NPT density-time curve, concentration distribution and MSD calculation results all showed that the self-healing performance of bio-asphalt was better than that of base asphalt, while the two bio-asphalts showed little difference in healing performance.

Concrete is the second most widely used material in the construction industry after water due to its special properties. But the Portland cement production process also has major drawbacks, with one ton of Portland cement producing about a ton of carbon dioxide. Hence the need to use an alternative to Portland cement seems necessary. On the other hand, the production of new materials with environmental impacts less than the priorities will be one of the goals of sustainable development in future cities. In recent years, geopolymer has emerged as a sustainable, environmentally friendly material and an alternative to Portland cement. Geopolymers are materials such as ceramics with multidimensional three-dimensional structures that consist of the chemical activation of solids containing aluminum and silica at relatively low temperatures. Industrial waste or by-products can be used to produce geopolymer concrete and use it in construction. The present paper examines the feasibility of using geopolymer technology in sustainable materials for sustainable urban development to reduce the emission of environmental pollutants. The findings and results of this article show that geopolymer concretes have superior mechanical and chemical properties compared to conventional concrete, consume much less energy than concrete made with conventional Portland cement, and also provide significant environmental benefits.

One of the new technology that is widely used in all the world is the vacuum preloading that accelerate the process of dewatering and consolidation process along with prefabricated vertical drains (PVD)s with or without surcharge preloading. In the finite element modelling (FEM) modelling process, the reduction in conductivity due to the consolidation and increase in stress of underneath layers, plays a dramatic role in prediction of the settlement. Appling a modifier function is a good means to account for reduction in the hydraulic conductivity in FEM modelling. To illustrate the importance, the importance of applying this function in the modelling, TV2 trial embankment in Bangkok airport was appointed as a case history. After the verification of the model, the model was run in the absence of hydraulic modifier. It was observed that the predicted final settlement after 160 days is increased from 0.94 m to 1.19. Also the curve pass is unreal base on the verified model, and the quantity of the calculated settlements are 10 to 25 percent overestimated. Since the clogging of PVDs pore, is one the obstacles in modeling procedure of the vacuum preloading, the clogging effect can be applied as a modification in the resultant hydraulic modifier function derived from lab tests. By applying the proper modifier function, more realistic results can be obtained in FEM modelling in such models including PVDs and vacuum and/or surcharge preloading.