tensile strength

In the construction industry, lightweight concrete (LWC) is a common structural and masonry element. Its low density and significant thermal and acoustic insulation properties are why it is popular. Recent studies have examined the potential benefits of adding different types of nanomaterials (NMs) to LWC to improve its characteristics. Recent decades have seen a notable increase in interest in the growing field of nanotechnology because of its innovative research and practical applications. The main objective of this review is the application of NMs to enhance both the fresh and hardened properties of LWC. The effects of NMs on the physical (thermal conductivity), mechanical (Compressive, Flexural, Splitting tensile strength), Microstructural, and Durability properties of LWC were examined. This study found that NMs improved the performance of LWC depending on the type and dosage of NMs. It showed better mechanical, microstructural, and durability properties than the samples without NMs. The addition of nanomaterials to concrete increases the pozzolanic content and surface energy of the cement composite, resulting in the durability enhancement of the cement composite. This article explored that incorporating nanoparticles into concrete enhances its strength by (12 to 58) %, (and 16 to 90) %, (16 to 55) % on the 28th day for the compressive, Flexural, and splitting tensile strength respectively, but it reduces the workability of the cement composite. However, the excessive concentration of nanoparticles causes particle agglomeration, which decreases the strength and durability of the cement composite. Thus, the review concluded that using nanomaterials in concrete is more favorable concerning the strength and durability advancement of the composite, as it improves their qualities and accelerates the hydration process. The knowledge gained from this review and the created database could be helpful to researchers and industry experts to facilitate the adoption of NMs to enhance the performance of LWC.

Due to the use of concrete structures in climatic conditions, the problem of damage to these types of structures and, as a result, their repair and maintenance is one of the main issues of experts. Nanop articles have shown unique physical and chemical properties compared to other materials. Self-Compacting Concrete (SCC) is a new technology in world construction. It fills the form without external and internal vibrators and only uses the force of weight to maintain its uniformity simultaneously. Also, in the advanced industry, nanotechnology has created tremendous changes in the concrete industry, and with the production of nanomaterials, significant changes are seen in increasing the strength and durability of concrete. This research has tried to investigate the effect of adding nanomaterials on the properties of concrete while achieving specific mixing plans for making SCC. These tests were performed on the obtained mixing designs, and the samples were examined at ages 7, 28, 90, and 180. The results showed that adding these materials increased compressive and tensile strength. Also, it was observed in other studies that with the increase of nanomaterials, water absorption by concrete decreased a lot, and it was also observed in the study of electrical resistance that these nanomaterials played a significant role in increasing the electrical resistance of concrete. The increase in electrical resistance and, as a result, the decrease in conductivity prevents the corrosion and loss of round rods and other metals used in concrete.

Today, concrete is widely used due to the use of materials with a lower price and good durability, and based on the development of common concrete technology, the construction of high-strength concrete has become popular in the design of executive structures in advanced countries of the world. According to some regulations, the minimum resistance for high-strength concrete is considered to be 55 MPa, and a resistance of this level is more attainable in laboratory conditions. Among its advantages, we can mention the increase in strength and hardness, which can reduce horizontal displacements, as well as the length of restraint and patch of rebars. Also, in order to reduce environmental pollution and increase the durability and reliability of the structure, the use of Micro Silica (MS) and Rice Husk Ash (RHA) instead of a part of all cement consumption is considered. This thesis deals with the properties of concrete containing MS and RHA. In total, two mixing plans were made with two water-to-cement ratios of 0.37 and ratios at the age of 7 and 28 days. The durability performance of high-strength concrete containing RHA and MS was measured using compressive strength, tensile strength, and elastic modulus tests. The results of the tests show that the compressive strength of concrete containing MS is higher than that of concrete containing RHA, and the tensile strength of concrete containing RHA is higher than the compressive strength of concrete containing microsilica.

Recycled glass waste is one of the most attractive waste materials that can be used to create a concrete mix.Therefore, researchers focus on the production of concrete using recycled glass as an abrasive or as a pozzolanic material, but the use of recycled glass in the form of coarser particles to replace sand in concrete increases the alkali-silica reaction and this causes Unfavorable performance in the mechanical properties of concrete.To prevent this, microsilica is used to improve the strength and mechanical properties of concrete.In this research, after building the control mixing design, recycled glass was replaced with sand and silica foam as microsilica in four designs with a fixed ratio of 5% by weight of cement.The compressive strength test was performed at the ages of 7 and 28 days, and three samples were taken in each test, and a total of 24 cubic samples were tested.Tensile test, like compressive strength test, were tested at the ages of 7 and 28 days, which included two cylindrical samples in each test, and a total of 16 cylindrical samples were tested.The presence of silica foam in concrete causes adhesion and reduction of slump fluidity, and the highest slump fluidity was observed at 5% ratio.The result of testing the compressive strength and tensile strength of the concrete containing glass shards and silica foam had decreased in quality compared to the control mixing plan, which shows the unfavorable performance of coarse glass particles in the concrete structure.

One of the disadvantages of concrete is low tensile strength and poor crack resistance. The use of fibers in the concrete mixing design is an effective and practical method to increase ductility and energy absorption capacity, reduce cracking and enhance the tensile strength of concrete. Using natural fibers in concrete is always recommended with the aim of saving non-renewable resources and using sustainable materials. In this research, the effect of using goat hair as an example of natural fibers on the mechanical properties of concrete was investigated. To achieve this goal, concrete samples were made with different percentages of 0, 0.25, 0.5, 0.75 and 1% goat hair with a length of 13-22cm and diameter of 50-60 microns. To assess the effectiveness of this fiber, plain concrete properties were used. The results indicated that the addition of goat hair fibers increases the compressive and tensile strength of concrete samples at ages 7 and 28-day. This fact was more evident in the samples containing 0.5% goat hair with respect to the weight of cement. For example, at the age of 28-day the improvements in compressive and tensile strength was 18.2% and 83.4%, respectively. Also, by adding goat hair fibers to concrete, workability was reduced and concrete samples containing 0.75% or less fibers had acceptable workability. In general, the use of 0.5% of goat hair fibers is recommended as the optimal percentage in reinforced concrete due to its effect on the mechanical properties of concrete and economic efficiency.