جستجوی مقالات مرتبط با کلیدواژه « بتن پلیمری » در نشریات گروه « عمران »

Due to its desirable properties, polymer concrete is used for repairing or building structures that require both mechanical strength and high durability in a short period of time. On the other hand, reducing the weight of polymer concrete by using light aggregates can double the benefits of using this type of concrete in practical cases in order to make it easier to repair damaged concrete or use it in special conditions. Since the increase in concrete strength usually results in a decrease in ductility, therefore, the use of fibers in the concrete matrix can largely compensate for the problem of the decrease in ductility. The aim of this research is to investigate the mechanical properties of lightweight optimized polyester polymer concrete (with and without fibers) and compare it with the mechanical properties of lightweight concrete. To check the mechanical properties of polymer concrete, compressive strength, tensile strength, flexural strength, impact resistance and abrasion resistance tests were used. Also, electron microscope (SEM) images were used to investigate the effect of fibers on the microstructure of polymer concrete samples. The results showed that in line with the remarkable improvement of the mechanical resistance of polymer concrete compared to light concrete, the addition of fibers can improve the mechanical properties of polymer concrete. In this study, the use of 0.25 percent by volume of composite fibers in the mixing design of polymer concrete increases the compressive, tensile, flexural, and abrasion resistance by 9.1, 8.8, 6.2, and 6.3 percent, respectively, compared to polymer concrete without It is fiber. The analysis of SEM indicates the continuity and cohesion of polypropylene fibers and polymer concrete matrix, which can be considered as a good justification for improving the mechanical properties of polymer concrete containing fibers.

In this study, effect of poly vinyl alcohol (PVA) and poly propylene (PP) fiber on epoxy resin-based concrete in terms of compressive, flexural, tensile strength and deformation has been investigated. In addition, scanning electron microscope (SEM) analyses were conducted on samples. Four groups of polymer concrete with 12% epoxy resin and fiber dosage of 0.5, 1, 2 and 2,5 % were prepared for both PVA and PP fiber. The fiber length was 12 mm. Cube and prism samples with 50 mm and 50x50x300 mm dimensions were prepared and tested for compressive strength and tensile strength/ deformation at 1, 7 and 28 days. Results showed that by increase of PP dosage, compressive and tensile strength increased noticeably compared to the control sample. However, for samples containing PVA, opposite trend has been observed. Therefore, the optimum dosage of PP and PVA fiber in fiber reinforced epoxy resin-based concrete is 2.5 and 0.5% respectively. The increase in compressive and flexural strength for 0.5, 1, 2 and 2.5% PP fiber was 4.38%, 5.3%, 4.9% and 5.5% compared to the control sample, respectively. The SEM analysis showed good bonding of both PP and PVA fiber to the polymer matrix. The PP fiber had better dispersion which could be the primary factor for better physical performance.

Corin is a type of artificial stone that is produced without the use of cement and is actually a type of polymer concrete. Unsaturated polyester resin is used as an adhesive and aluminum trihydrate powder is used as a filler to produce artificial stone. This stone is usually composed of wt of unsaturated polyester resin and wt of with a low bulk density. This advantage and others such as non-porous structure result in low water absorption and anti-bacterial properties, Corian artificial stone has many applications. One of the disadvantages of this type of stone is its high price, which is due to the high price of . Another disadvantage of Corinne is its low compressive strength. In this research, in order to reduce the cost price of Corinne and increase the compressive strength, additional materials such as ceramic tile waste powder, stone powder, gypsum, and cement have been used. The study was divided into 4 phases. In each phase, one of the additives was substituted for by a certain weight. Hardener is a material that is added to the resin as a part of curing. The hardener used in this study is methyl ethyl ketone peroxide of wt resin. After mixing the resin and hardener, the powder and were added to the mixture and finally, cobalt as catalyst was added to the mixture of wt resin. After mixing and curing at ambient temperature, compressive strength of samples on Days , , , , and were measured. At each stage, one of these materials replaces part of the . Then, the compressive strength of the samples at different ages , , , , and was measured. The results showed that by replacing ceramic tile waste, rock powder, gypsum, and cement, compared to the weight of , the compressive strength of the samples increased by , , , and %.

Concrete is the most important building material that is most used in the construction of various structures including residential buildings, infrastructure structures such as bridges, dams, roads, buildings, docks, dams and other structures. Generally, concrete is made of a mixture of cement with water and coarse aggregates, which in practice are referred to as sand. Determine the amount and weight of each of these materials to build a concrete to obtain the characteristic strength referred to as the concrete mixing scheme. In this study, we investigated the effect of silica and powder on polymeric cement concrete of styrenebutadiene (SBR) found in latex commercial market and for making samples of polymer weight percentages of 10,15 and 20 in cement with alternative 5, 10 And 15% mocrosilica and rubber powder used to replace cement. The results show that the supernatants with the addition of the samples show an increased resistance with the sample and at 42 and 28 days these samples have more than the resistance of the sample. The best resistance in the combination of microsilica and powder was between 6 and 7.5% with a 28-day increase of 15% over the control.

Selection, design and control of materials are very important for achievement of a compatible, durable and economical repair overlay. Suitable bonding of repair overlay to substrate and good resistance against fracture are basics for a durable overlay. Using Polymer Concretes (PC) and Polymer Modified Concretes (PMC) which present great performance and durability can be considered as a method of restoration in damaged structures. In this research, mechanical properties and strengths of bonding to substrate concrete of Polymer Concretes and Polymer Modified Concretes as repair overlays are investigated and compared. Strength of Bonding to substrate concrete was obtained by Pull-Off test method. Bonding strength to substrate concrete in Polymer Concretes mix designs samples was weaker than Polymer Modified Concretes mix designs samples in similar conditions. In comparison with conventional concrete repair overlays in Pull-Off test, the maximum increment of bonding strength to substrate concrete was observed in mix design containing %50 of water replacement with SBR-based polymer which was %30 of increment and after that in mix design containing %50 of water replacement with Acrylic-based polymer which was %28 of increment. In Polymer Modified Concretes, %5 replacement of cement with Silica Fume decreased the amount of shrinkage but in higher values of replacement the amounts of shrinkage were increased in samples.

In this paper, the effect of three waterborne acrylic resins on physical, mechanical, stability, and permeability of concrete was investigated. For this purpose, concrete samples were prepared with a mass ratio of water to cement and solid-resin to cement equal to 0.445 and 0.05, respectively. Compressive stress tests of 7, 28, and 56 days, tensile strength, chlorine ion accelerated migration, capillary water absorption and initial and final water absorption on the test specimens were performed. It was observed that acrylic resin could act as a superplasticizer and reduce the amount of water needed to increase the fluidity of fresh concrete. Adding a resin with a minimum film formation temperature (MFFT) above the operating temperature reduces the chlorine ion penetration depth and coefficient by 14%. As a general result, it can be said that by accepting a reduction of 20-30%reduction in compressive strength of concrete structures, the fluidity of the fresh concrete, physical and penetration properties of the concrete mix can be increased by the use of the waterborne acrylic resin with MFFT higher than ambient temperature.

Polymer concrete is kind of concrete which in its mix design cement binder is replaced with polymeric resins. Application of polymer concretes was developed due to variety and quality. Nowadays، the application of these materials is limited due to high costs in comparison with Portland cement concrete. In this work، mechanical performance (compressive and flexural strengths and abrasion resistance) and depth of water penetration of a polymer concrete made of an unsaturated orthophtalic polyester resin was investigated and results was compared to Portland cement concrete (with water to cement ratio of 0. 4). Furthermore، durability of these samples in concentrated sulfuric acid was studied for 10 months. Results showed that mechanical strengths of polymer concrete are three times and two times of normal concrete''s one at early ages and at long term curing time، respectively. Severe degradation was occurred in normal concrete specimens in sulfuric acid solution after three months of exposure while 10 and 20% decrease in mechanical performance (without apparent defects) of polymer concretes was observed after 3 and 10 months exposure to sulfuric acid.