Journal of Civil Engineering and Materials Application
Volume:5 Issue: 2, Spring 2021

Predicting the current consumption of cutting machine in the process of cutting building stones can be one of the most important and fundamental steps to achieve optimal conditions from the perspective of energy consumption in the building stone cutting industry. Therefore, it is necessary to study the relationship between the operational characteristics of the machine and the workpiece with the amount of consumed energy by the machine. In this paper, an attempt has been made to provide a precise model for predicting the current consumption of cutting machines using statistical studies. For this purpose, laboratory studies were performed under different operational conditions such as different depth of cut (15, 22, 30 and 35 mm) and different feed rates (100, 200, 300 and 400 cm/min). During sawing process, 12 samples of soft and hard rock were studied by using a cutting machine on a laboratory scale (with the ability to change machining parameters and equipped with measuring current consumption). Following laboratory studies, rock samples were transferred to the rock mechanics laboratory to determine the Schimazek's F-abrasiveness factor, and after determining the abrasion of the samples, statistical studies were performed by using the SPSS software. Thus, the new statistical models were presented to predict the current consumption of the cutting machine based on the abrasion of the building stone sample, cutting depth and the progress rate of the workpiece as an independent variable. The proposed statistical models can be used with high reliability to estimate the current consumption in the cutting process.

In recent years, geopolymers, as a new class of green cement binders, have been considered as an environmental-friendly alternative to Ordinary Portland Cement (OPC) which can potentially reduce negative environmental impacts of OPC including carbon footprint and energy consumption. In this experimental research, effects of different alkaline activator solutions on the compressive, indirect tensile and flexural strengths, water absorption and resistance to acidic condition of metakaolin-based Geopolymer Concrete (GPC) were investigated. Furthermore, a novel type of alkaline activator for GPC was introduced. In this regard, GPC specimens based on metakaolin were manufactured and cured in 90 ˚C. The results showed that addition of NaOH to the mix after 3 min of mixing KOH and Na2SiO3 with dry components (1/3 of the total mixing duration) resulted in the highest compressive, tensile and flexural strengths as well as, the lowest water absorption capacity and weight loss under acidic condition, amongst other cases.

Today, in most parts of the world, there has been a tremendous development in the technology of concrete to achieve high strength concrete. The use of metakaolin (MK) in concrete to achieve high-strength and durable concrete has been in the concrete industry for several years. Due to its significant pozzolanic activity and reaction with calcium hydroxide in the cement, this material has reduced porosity and permeability and increased durability and strength in concrete. In the present study, the role of (MK) and its effect on the mechanical properties to achieve the optimum percentage of MK use for high strength and durability have been investigated. In this study, laboratory tests at early and hardened state including temperature change, slump, liquidity examination, water absorption, specific gravity of concrete, electrical strength test (indicating permeability and corrosion rate) and compressive strength test on samples with 0, 10, 15 and 20 percent cement-substituted MK at 7 and 28 days of age were tested on 15cm cube specimens. The results showed that the addition of 10% cement substitute MK in slump test, 15% cement substitute MK in compressive strength test and 20% cement substituent MK in electrical resistance test had the highest values and 15% cement substitute MK in concrete weight density test. 20% of cement-substituted MK in the experiment showed the lowest water absorption percentage compared to other mixes designs. Microscopic analysis shows the more durable MK replacement in comparison with normal concrete.

Seismic analysis of earth and rockfill dams is generally done in two ways: quasi-static and dynamic. However, a quasi-static method with easy application and simple assumptions may lead to unsafe and uneconomical results. In the present study, two static and dynamic analyzes have been used nonlinearly using the Rayleigh Damping rule to calculate the stress and strain of Azadi Dam in the stages of the end of construction and steady-state seepage. Also, in numerical analysis, Abaqus software and simple elastoplastic behavior model based on the Mohr-Coulomb criterion have been used. The results show that in both quasi-static and dynamic seismic analysis, the highest strain of the Azadi Dam core occurred at the upper levels of the core and the highest stress occurred at the level of the core floor. The stress in the dynamic state is higher than the quasi-static one in the directions σxx 49%, σxy 30%, respectively.and σyy 28%. Also, the maximum shell stress at 1255 m, 1275 m and 1300 m levels is 29%, 68%, and 72% higher than the core,

In this study, improvement of the Hemmae Exp-east, between the Haqhani Exp and Sayad Shirazi Exp, was investigated using the smartization implementation and geometric designing. The traffic volumes of passing vehicles through light and heavy detachments were collected, and traffic information involved the PHF and the peak hour were extracted from them. The speed of the vehicles, the number of transmission lanes, and the width of the lanes were taken and the improvement of delay indices, speed, travel time and distance traveled, fuel consumption, and pollutant emissions, were investigated by providing solutions in three scenarios. The first scenario was implemented on-ramp metering. In the second scenario, two lanes were added to the Hemmat Exp, and both of the scenarios were implemented in the third scenario. The Delay index was decreased by 22% in scenario 1. In the third scenario, the speed indicator increased by 77%. Compared to different scenarios, the improvement rate for delay indices, speed, travel time, fuel consumption, and pollutant emissions in scenario 3 had more improvement than the other two scenarios. After the software calibration, in which the results are more reliable, scenario 3 showed better results than the first and second solutions.