Journal of Civil Engineering and Materials Application
Volume:3 Issue: 2, Spring 2019

With the rapid development of nanotechnology multi-disciplinary cross applications as well as the limitations of traditional materials, nanomaterials have been introduced to improve the soil. This paper investigates the potential advantages of nanotechnology for innovative solutions in the area of soil improvement. Studies on applied nanomaterials in geotechnical engineering show the way these nanoparticles are applied to improve soil engineering parameters. In the present study, we aimed to investigate the effect of adding Nano clay on the geotechnical properties of clay and silt soil and improve their engineering properties. For this purpose, a series of tests were conducted including granulation, uniaxial, direct shear, Atterberg limits, compaction and triaxial tests on clay and silty soils. The results show that the liquid and plastic limits of soil will increase with increasing nanoparticles in soil composition. Also, according to the results of compaction test, by increasing in Nano clay the unit weight of clay soil will increase and optimum moisture content will decrease. According to the results from direct shear tests, by increasing in nanoparticles, the adhesion of clay and silt soils also increase. However, the internal friction angle of both clay and silt soil is reduced.

Steel shear walls are far cleaner and are considered more rapid replacements for the concrete shear walls in terms of execution and more reliable in terms of strength and behavior.  Also, the system takes advantage of all good characteristics of concentrically braced frames (CBF) like V and X-shaped bracings, etc. and also those of eccentrically braced frames (EBF). They are also efficient in terms of execution and good behavior and in many cases, act better. In this research, the effect of opening location in the corrugated plate is investigated using the pushover analysis. For the analysis and investigation of the model, use has been made of ABAQUS software and the two available methods for analysis and design of steel shear walls are incorporated. The obtained results showed that the opening in the corrugated steel shear wall causes reduced safety and lateral resistance of the wall, so that where the openings are located at the corners, the effect of reduction is more severe. On this basis, the minimum reduction in stiffness and strength of the steel shear wall with opening is where it is located at the middle of the wall and the worst case is where the opening is located at the corners and close to the columns.

Slab on grade, also called floors on ground, are different from other structural members. First, they are supported directly by soil, and their success or failure may depend more on the soil qualities than on the slab construction. Second, they carry equipment and floor finishes, and any defect in the slab's integrity or moisture resistance affects those elements. A floor slab undergoing drying shrinkage may not only crack, but also break the brittle ceramic tile it carries. Failure may also occur due to overloading. For reducing cracks propagation, control or contraction joints are used. In this research, 225 specimens by fifteen mix design with different dosage of polypropylene and steel fibers were prepared for evaluating compressive, impact and flexural testing at the ages of 7 and 28 days. As a result, optimum dosage of polypropylene fibers was 1.6 kg/m3 and at this dosage, impact resistance enhanced about 460% and flexural strength enhanced about 70% in comparison with control specimens. Steel fibers improved impact resistance and flexural strength about 312% and 58% respectively at the dosage of 30 kg/m3. Results also showed that compressive strengths of specimens are not significantly increased by using fibers.

A solution for synthesizing environmentally friendly concrete is to reduce the conventional Portland cement (OPC) content and utilize activated pozzolanic binders. Geopolymers are a sort of mineral polymers, so that their chemical composition resembles zeolites and their microscopic structure is not crystalline, but rather amorphous. In this study, it is attempted to address the behavior of synthetic geopolymers through the investigation of their base materials, e.g. blast furnace slag, metakaolin, fly ash and other curing agents such as potassium hydroxide or sodium hydroxide solutions. It is tried to study the behavior of geopolymer concrete (GPC) at different contents of curing agents and base materials using the literature review and, eventually, make an SVM model to find out whether the results of compressive strength and consistency of GPCs can be estimated using support vector machine or not. The research results suggest that it is possible to estimate the compressive strength and consistency of GPCs using SVM and also there is a significant relationship between molarity and compressive strength of concrete at different ages, molarity and consistency of concrete, ratio of sodium hydroxide to sodium silicate, compressive strength and liquid limit (LL) of concrete.

Lightweight concrete has been used in the construction industry for many years, and by introduction of modern technologies in the construction industry, this type of concrete has been accounted as one of the powerful and reliable materials in the construction industry. The density of lightweight concrete is about 0.56 that of the ordinary concrete. This type of concrete is commonly used as a flooring material in buildings. Thus there is possibility of its corrosion   in different climatic conditions. In the present research, we would investigate the compressive strength and durability of the lightweight concrete in the acid environment, so that by specifying the corrosion rate one could have a better understanding of the behavior of these concretes. For making the lightweight concrete in the present research use has been made of pumice aggregate in the mix design, and the acid used is 1M sulfuric acid. Also, the effect of adding two types of Nanomaterials i.e., Nano-silica and Nano clay on the concrete behavior is assessed. The results have shown that in case of keeping the specimens of lightweight concrete in the acid environment for 90 days, their weight reaches 0.56 that of the ordinary specimens. The results of the current research have shown that the use of Nano-silica and Nano lime per 10 wt% of cement could result in the increased compressive strength of the lightweight concrete. So that the concrete compressive strength per 10 wt% of Nano lime increases by 1.43%. On the other hand, the concrete durability in the acid solutions reaches the maximum value per addition of 5% Nano-silica and 5% Nano lime, and has lost a lower percentage of its weight.