جستجوی مقالات مرتبط با کلیدواژه "رطوبت بهینه" در نشریات گروه "عمران"

Roller-compacted concrete, a type of concrete with zero slump, is being used in road pavement construction. The use of recycled asphalt in roller-compacted concrete is an enviromental approach for reducing emissions. This study examines the impact of recycled asphalt aggregate and nano-silica on the strength behavior of roller-compacted concrete. Cylindrical samples were fabricated to determine optimal moisture content and maximum dry density. The compressive strength, along with stress and strain curves at optimal moisture, were evaluated. Additionally, the surface area under the stress-strain curve and energy absorption were measured. Results indicate that adding asphalt aggregates decreases the optimal moisture content in roller-compacted concrete. Conversely, nano-silica increases the optimal moisture content and enhances the maximum dry density of the samples. Replacing recycled asphalt with coarse aggregate revealed a decrease in compressive strength of roller-compacted concrete samples at both 7 and 90 days. Moreover, nano-silica did not improve the reduced compressive strength, with its negative impact being more pronounced at 90 days than at 7 days. The study also found that recycled asphalt increases the area under the stress-strain curve and enhances energy absorption. However, adding nano-silica to control samples and those with recycled asphalt does not improve ductility or energy absorption.

Oil contamination of soil is a significant environmental issue that various countries, including Iran, have encountered. Leakage and the spread of oil contamination in different sectors of the oil industry, such as oil production areas, refineries, and transportation lines, lead to extensive soil contamination. The physicochemical processes occurring between the pollutant and the soil alter the geotechnical behavior of soil. Nanoparticles, due to their small size and filling properties, can enhance soil density and resistance. This article investigates the impact of nano-clay as a novel additive on gasoline-contaminated soils, revealing that with increasing contamination levels, both optimum moisture content and maximum dry density decrease. Moreover, higher contamination percentages result in reduced soil plasticity limits; as gasoline content increases, the Atterberg limits decrease. Hence, Therefore, in order to achieve greater soil resistance, adding different clay nanoparticles with percentages of 0.25, 0.5, 1 to the soil contaminated with diesel oil increases the amount of leaf ether and hardens the soil.

In recent decades, using recycled asphalt materials in pavements is considered by researchers due to their economical costs. The purpose of this laboratory experiment is to introduce optimum mix design including suitable grading limits of the mixture, moisture formula for estimation of the amount of water needed for compaction and finally investigating the effect of reclaimed asphalt pavement (RAP) on unconfined compressive strength (UCS) of different cement-treated base mixtures and determination of optimum RAP content and cement with lowest construction cost. For this purpose, first, grading properties of different materials and RAP were determined and proper grading was selected. For studying the compaction characteristics and determining optimum moisture content, 12 different mixture designs, as a combination of 4 RAP percentage (0, 40, 60 and 80) and 3 cement content (3, 5 and 7 percent) were constructed. Then, 15×30 cm cylindrical samples were constructed to investigate UCS properties at optimum moisture content. Results showed that grading limits in Iran's Road Bulletin No. 101 could be the main reference for cement treated base (CTB) mixtures containing RAP materials. Also, modeling results of optimum moisture content indicated that by adding more recycled asphalt materials to the mixture would increase optimum moisture content and reduce maximum dry density. The UCS tests undertaken on 7-day cured samples at 25 0C indicated that by increasing the RAP materials to the treated mixture would decrease UCS of the samples. The pavement containing 68% of reclaimed asphalt and treated with 5% cement was the most economical mixture considering the 3.8 Mpa limit of UCS index. Finally, it could be expected that instead of compacting the samples with standard hammer, 60 seconds of vibration compression may be used

It is widely known and well emphasized that the cemented sand is one of economic and environmental topics in soil stabilization. In some instances, a blend of sand, cement and other materials such as fiber, glass, nano particle and zeolite can commercially available and effectively used in soil stabilization in road construction. In this investigation, zeolite and its effect on compaction studied as one of pozelan additive material to cement. Therefore, cilinopiolite kind of zeolite, Neka cement type II and Babolsar sand are used. Compaction poroctor tests were carried out on 24 combination type of cement and zeolite with include different cement percentages 2, 4, 6 and 8 percent of total dry weight of samples and replacement percent’s of 0, 10, 30, 50, 70 and 90 cement with zeolite. Results show that by replacement cement material by zeolite, the maximum dry density increased 2 to 2.5% in comparison with cemented samples and 14% optimum water content approximately concluded. At the end, a function fits Based on Voltra series presented to relate maximum dry density and zeolite-cement-soil parameters.