Despite the fact that self-compacting concrete has been used for many years, until now, no-one has carried out any research on the strengthening eect of the weight of concrete at any level. For this reason, employing concrete columns made out of dierent mixes of selfcompacting concrete, a research is conducted. In order to measure the concrete strength at any level, the in-situ friction-transfer method was used. Having examined over 50 mix designs, nine mixes were proved to be self-compacting concrete and, therefore, were used for this investigation. In order to see the eect of the weight of the concrete above the level considered, concrete columns were cast using self-compacting concrete without giving any form of compaction. At specied ages, the hardened concrete columns were cut at 150 mm height intervals. Using the Friction-transfer method, the strengths of concrete at dierent levels were obtained. In the friction-transfer method, a 50 mm diameter partial core is made using a diamond tipped coring drill. A metallic gripping device is xed on top of this partial core by fastening its side bolts, and torsional moment is applied to the partial core via this gripping device by hand. The applied torsional moment is gradually increased until the partial core is failed, and the maximum (failure) torsional moment is recorded. Using the existing calibration graphs, the ultimate (failure) torsion is converted to the compressive strength of the concrete tested. The results show that the weight of the concrete situated above any level has a positive eect on the strength of the concrete at that level. In addition to the comparison of the obtained results with the respective results of ordinary concrete, the eect of changes in the llers, segregation and aggregate grading, on the strength of self-compacting concrete, is also studied.

Chloride penetration into concrete and consequently corrosion of reinforcing steel is one of the main causes of concrete deterioration in Persian Gulf and Sea of Oman. Concrete deterioration exposed to tidal condition is very severe when compared to the atmospheric exposure condition. Therefore, it is necessary to accurately model the simultaneous moisture and chloride ingress into concrete for durability-based design of reinforced concrete structures. In this study, a finite element model was developed to numerically solve the governing differential equations of moisture and chloride transfer. Comparison of the model output with the ones obtained from experimental works in Bandar Abbas and Qeshm research sites showed that the proposed model can predict the chloride profile with good accuracy. By using the test results, the model output showed that the maximum chloride concentration decreased with increasing in water to cement ratio (w/c) from 0.40 to 0.45 and then slowly increased with increasing in w/c up to 0.55. Although, the total chloride concentration, which ingress into concrete, increased up to 50 %.

HPC has become popular due to its superior mechanical and durability properties.HPC significantly reduces maintenance costs and enhances service life. Internal curing of high performance concrete (HPC) by pre-saturated lightweight aggregates is a wellestablished method of counteracting self-desiccation and autogenous shrinkage. However, by introducing the internal water reservoirs strength and durability properties can be injured. Concrete is a strong and durable material that has been utilized since the beginning of civilization. It is understood that many of the early structures are deteriorating or have already deteriorated away; however, with the knowledge of the material properties of concrete that is available, it is hard to imagine that concrete structures is prematurely failing before their intended service life. There are many factors involved in these failures, some of which are due to environmental conditions and others which have arisen from human errors or lack of knowledge. Early age properties of concrete are vital to its long-term performance. Many contractors and owners are interested only on the strength of concrete in 28 days or 9 days, that they overlook the importance of other early age issue especially when the mix design has water to cementitious material ratio (w/cm) lower than ~0.42. Internal curing with LWA has been successfully used recently in large construction projects of normal density concrete structures. For example, in January 2005, about 190 000 m of internally-cured concrete was used in a large paving project in Hutchins, Texas. Although the benefits of internal curing for high-performance concrete structures have been evidenced in the laboratory and some field investigations (such as those previously mentioned), the literature does not provide any significant quantitative information regarding the additional extension of the service life that can be achieved by the use of internal curing in concrete structures. A great concern for design engineers and contractors is whether the concrete will achieve the specified compressive strength and all durability requirements in the structure during service. Cusson & Hoogeveen (2008) demonstrated that internal curing can reduce autogenous shrinkage considerably without affecting the strength and stiffness of high-performance concrete. This was achieved by reducing the amount of mix water in the concrete by an amount equal to that used in the LWA for internal curing, thus reducing the effective watercement ratio (w/c ) of the concrete when using higher quantities of pre-soaked LWA. Tests by the widely accepted methods of durability assessment, such as resistance to chloride penetration, air permeability, water absorption, autogenous and drying shrinkage and mass loss, were conducted on HPC mixes made at water to cement ratios in the range of 0.21–0.33. The effect of internal curing on the durability related properties of high-performance concretes as a function of water to cement ratio is reported.

Due to the sudden increase in the price of binder in recent years and the cracking of asphalt pavements, especially in cold areas, major problems with the implementation and operation of asphalt pavement in some parts of the country can be solved with the use of roller compacted concrete pavements. Therefore, the main objective of this research is to investigate the effect of synthetic fibers on fracture resistance of roller compacted concrete pavement in different loading modes (pure mode I, pure mode II and mixed mode). For this purpose, fracture toughness of roller compacted concretes containing 0.1, 0.2 and 0.3% of a synthetic fiber named Forta was evaluated using linear elastic fracture mechanics. The results show that the effects of the fiber percentages on the mixed mode fracture toughness is very significant and adding this fiber more than 0.3% by weight of the mixture does not lead to a significant improvement of the fracture resistance. Also, by transferring from the pure mode I to pure mode II, the resistance of roller compacted concrete pavement modified with synthetic and without fibers is reduced.

Lowering the weight of concrete used in buildings and other structures has been one of the main priorities of the specialists. This will reduce the dead load and the forces involved in the structure during the earthquake. A wide range of research has been done around the world.In this work, a research on the construction of lightweight aggregates of Scoria has been used to increase the flexural strength of the beams tested in the glass fiber, as well as to reduce the use of cement, reduce the amount of pollutants in Iran, as well as increase the efficiency of concrete from zeolite and ash powder The wind has been used and the mechanical characteristics of these lightweight concrete structures, in particular the flexural behavior of lightweight structural beams, have been investigated in the laboratory environment, and the results indicate that light concrete was constructed and pressurized in Due to the presence of a network of fibers up to 3% by weight of cement and the resulting flexibility, the strain is very crisp And preventing it from breaking down and increasing the compressive strength by up to 20% and 10% of the flexural strength compared to the control sample. Addition of powdered zeolite along with ash to 15% by weight of cement has the same adhesion properties as cement to light concrete Data has increased the flexural strength by up to 15%.

Self-compacting concrete or SCC can be considered as the concrete of the future. The most important feature of self-compacting concrete is flowing under its own weight to fill the mould or framework completely, and also to create a dense and sufficiently homogeneous mix between the bars, without any need for vibration. But the excessive Liquidity of this concrete increases the hydrostatic pressure on the frameworks. So, decrease in the weight of self-compacting concrete could be lead to reducing the pressure on frameworks. It is also clear that decreasing the density of concrete has a significant effect on the reduction of the structure’s weight and will lead to decrease in the size of structural elements. On the other hand, there are general concerns about the segregation of lightweight aggregates during transportation or placing. In this research, the ability of maintaining the homogeneity of the mixture and the mechanical properties of lightweight self-compacting concrete (LWSCC) made with common lightweight aggregates in the country including Scoria, Leca and Pumice, has been investigated on concrete columns, using the Semi-destructive and non-destructive methods. To do this, reinforced concrete columns made by self-compacting concrete were investigated using a semi-destructive core test to determine the compressive strength and impermeability. Non-destructive ultrasonic test at different heights of the columns was also conducted. The results showed that Scoria aggregate had generally better performance in self-compacting concrete compared to other lightweight aggregates.

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.

The potential use of leca and scoria aggregates available in Iran to produce high strength lightweight concrete has been studied. As a result of various concrete mixes with different lightweight aggregate amount, and using normal techniques, it was possible to obtain high quality lightweight concrete which is suitable for application in reinforced and prestressed concrete structures.In order to investigate the mechanical short term properties of this type of high strength concrete, different tests had done. The properties obtained include unit weight, compressive strength, static modulus of elasticity and poisson's ratio.Among the 28 day aged tested specimens, we could produce HSLWC containing scoria with 55 MPa compressive strength and 2070 kg/m3 weight.In LWC containing leca, a cube compressive strength of about 41 MPa with a unit weight of 1865 kg/m3 was reported.Static modulus of elasticity in concretes containingleca was between 15 to 19 GPa. It was between 17 to 19.5 GPa forconcretescontainingscoria. Some equations were offered to estimate static modulus of elasticity of these concretes based on their compressive strength and unit weight. The mechanical properties were improved by reducing the amount of lightweight aggregate. The results show that both scoria and leca were effective in improving the mechanical properties, but scoria could reach superior limits.Stress- strain curves of investigated concretes were studied and some recommendations are presented for estimating the curves.Stress-strain curves of investigated concretes are almost linear in ascending and descending branch.According to the observed coefficients, withincrease in concrete strength, the slope of the curve is reducedin comparison with modulus of elasticity. For scoria, the slope of curve is lower than modulus in all three mix designs, because of the higher modulus of elasticity of scoria aggregates, in comparison with leca.

Aggregates constitute the largest proportion of material in pavement projects, which includes concrete pavements or asphalt pavements (about 70 to 80 % by weight of concrete, and 90 to 95% by weight of asphalt mixes).Therefore, the quality of aggregates in the mixes is crucial for forming the behavior and the performance of pavement, and studies have shown it has the most influence on pavement properties. In addition, at present the most important issue for a pavement is its durability. Pavement durability is affected by various factors, such as type of aggregate, mix design method, environmental conditions and its implementation techniques. The use of aggregates of suitable quality and high durability can reduce most of the common pavement failures. Therefore, the durability and quality of aggregate materials should be tested before they are used in pavements. This paper reviews and investigates a variety of available experimental methods for determining the durability of aggregates. It also specifies the advantages and disadvantages of each of these methods. Finally, the most appropriate method is presented with regards to the limitations and availability of laboratory equipment in Iran.