---

---

---

This study aimed to produce and characterize solid lipid nanoparticles containing the essential oil (SLN-EO) of Ziziphora clinopodioides Lam. The preparation was carried out using the high shear homogenization and ultrasound method. The biological activities of the prepared nanoformulation were evaluated against Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) larvae under laboratory conditions. The particle size of SLN-EO was estimated to be under 150 nm (polydispersity index, PDI < 0.2) and zeta potential was negative. Morphology of nanoparticles was in globular form as demonstrated by transmission electron microscopy analysis. The loaded essential oil (EO) in SLN was calculated as 92% using the filtration-centrifugation method. The fumigant toxicity of EO as SLN formulation against E. kuehniella larvae was three times greater than that of pure EO. Similar results, but to a lesser extent, were obtained from comparing their contact toxicities. The fumigant durability of EO was enhanced by nanoformulation for up to two weeks. The nutritional indices of larvae, including relative growth rate (RGR), relative consumption rate (RCR), and feeding deterrence (FDI), were influenced considerably by SLN-EO compared to pure EO. The findings suggested the solid lipid nanoparticles as a suitable nanocarrier for EO in sustainable control management of Mediterranean flour moth.

---

Abstract:Self-consolidating concrete (SCC) has been used increasingly over the last two decades, especially in the pre-cast concrete industry because of its ability to consolidate without vibration even in congested areas. The development of SCC mixture design has been driven mostly by private companies who desired to utilize advantages of SCC. Consequently, there exists limited public information regarding the performance of SCC mixtures. In addition, SCC can be characterized as flowing concrete without segregation and bleeding, capable of filling spaces and dense reinforcement. Further it should be able to flow through, and completely fill the form without vibration. Due to the technical and economic advantages that can be accrued by the use of pozzolans, they play an important role when added to Portland cement by usually increasing the mechanical strength and durability of concrete structures. This paper present, an experimental study on the properties of different self-consolidating concrete mixes containing three types of pozzolanic materials in comparison with SCC mixtures without any pozzolanic materials and conventionally vibrated concrete mixtures. Silica fume, pumice powder and rice husk ash were used for both cement and filler replacements. Various experiments such as slump-flow, J-ring, L-box, V-funnel and sieve segregation resistance were investigated for fresh concrete. Further, compressive strength, water and chloride-ion permeability and capillary water absorption at various days were carried out to determine the properties of self-consolidating concretes. The test results indicated that pozzolanic materials such as RHA and VP can be used to produce SCCs. Regarding the strength properties, the test results showed that the 270-day compressive strength of ordinary SCC is about 70 MPa, while SCC mixtures containing SF, RHA and VP have strengths more than 90, 77 and 76 MPa, respectively. In addition, the results proved that artificial and natural pozzolans enhanced the durability of SCC and reduced the penetration, significantly. For instance, adding 15% pumice and 7% silica fume in the SCC specimen reduced the water depth at 90 days by 19% and 54%, respectively.

---

In recent years, many large ground motions occurred very close to modern cities and caused severe damage to buildings. Damage to modern engineering structures is beyond engineers’ expectation, because the structures are thought to have been designed according to proper ground motion-resistant design standards. In these buildings, although the distribution of strength for all stories of designed structures was considered uniform, but the distribution of overall damage of stories was non-uniform and considerable damage for some stories was observed. In this study, 8, 12 and 15-story dual steel moment-resisting frames with concrete shear wall were designed as a residential building that was located in seismic zone 4 (very high relative seismic risk region). These structures were designed with uniform strength ratio for all elements according to the modal response spectra analysis and static equivalent lateral seismic load pattern that were typically recommended by most building codes. Then six severe ground motions recorded in soil type III with magnitude greater than 6.2 on the Richter scale, without forward directivity, were selected. Finally, all structures subjected to these six severe ground motions and distribution of damage was examined by using nonlinear dynamic analysis. According to the results, despite uniform distribution of strength for all elements, element types and stories in each structure, the distribution of overall damage for element types (e.g. beams, columns and shear wall) and stories and the distribution of local damage for elements are non-uniform and among different stories, first and last stories have minimum overall damage and among different elements types, the damage of the beams is more than columns and shear wall and increasing the number of stories has not been effected on the distribution of damage of elements, and for 8, 12 and 15-story distribution of damage of elements is similar. Evaluation of distribution of damage on elements illustrate that the beams and columns near the shear wall have been damaged more than the beams and columns that are located far from the shear wall. On some stories, the beams and columns near the shear wall have been damaged considerably, but the beams and columns that are located far from the shear wall have been remained elastic. Also, these results conclude that the distribution of overall damage on stories and element types are not adequate for evaluation of seismic damage and the local damage of each element should be examined separately, because from distortion of the results caused by the temperature effect. As the complexity of equipment and speed of testing for the RCPT and RCMT tests are similar, the RCMT test can be recommended for more realistic appraisal of concrete. There was good correlation between the results of the RCMT and electrical resistance test which shows a good potential for utilization of the electrical resistivity methods for appraisal of chloride resistivity of concrete.

---

The purpose of this article is study of effects of high voltage AC stray current (380 VAC) and environmental effects on durability of concrete power poles. In Iran, annually spend large costs for replacing them with new concrete poles. In this study, the degradation effects and mechanisms of 380 VAC stray current on water saturated concrete were investigated via field and laboratory tests. They included electrical and electrochemical tests and microscopic inspections. Based on the results of tests both environment and AC stray current reduce durability of the concrete power poles. Formation of galvanic macro cell, carbonation, vibration of concrete pole due to wind force and weight of cable, diffusion of corrosive ions from soil to concrete power pole and its accumulation in near ground level are some of environmental effects on degradation of concrete power poles. In addition pollution of air can form deposit layer on insulations of concrete power pole. In raining condition, the layer absorbs water and surface resistance of insulators reduces considerably. So high voltage AC current can creep in surface of the insulator and can exchange between two other phases and ground. Generally grounding system can't act immediately or have not suitable low electrical resistance. Meanwhile if concrete of power pole has low quality then it absorbs high content of rain and its resistivity decreases considerably. Thus some parts of fault current can pass through water saturated concrete power pole. In an special location around Isfahan with polluted air condition, in raining condition current creep through the surface of some insulators occur and immediately many cracks forms on concrete cover of power pole and in some cases concrete cover start to fall without any corrosion in rebar. Based on field study, AC stray current does not occur in concrete power poles which manufactured by centrifugal method and they have very low w/c ratio in their mix design. In this method excess water of concrete mix is removed before staring curing of concrete. Microscopic study of concrete of the molded pole and centrifugal pole showed that the later had much denser structure and for this reason depth of carbonation in the later was much lower than the first. In addition the centrifugal poles have pre-stress condition and it reduce their vibration against wind force and weight of cables. Vibration has destructive effect on concrete cover of concrete poles, special in their ground level because force of vibration concentrates in this location. For study mechanism of degradation of AC stray current, some concrete samples prepared and in water saturated condition subjected to 380 VAC stray current. Based on results of tests, high voltage AC stray current can reduce the concrete pole durability by thermal and shrinkage stress and also by creating vapor pressure within water saturated concrete and transport calcium hydroxide toward cement paste-aggregate interfaces. Application of new technology for reducing water to cement ratio and proper installation and maintenance of the concrete poles considerably increases durability of them against destructive effects of AC stray current.

---

The effect of fire on the structural steel frames has been frequently studied in the recent years due to its special importance. Because steel is sensitive to the temperature and reinforcing of steel frames against fire is highly expensive it is needed that behavior of steel frames in high temperature for reduction of undesired effect of temperature increase to be studied exactly. Now, for achieving to this goal and with regard to the expensive costs laboratory test and their limitations in analyzing at various parameters in each test, employing of finite element method as a strong tool for modeling of steel frames has depicted its value under temperature conditions. With respect to the above mentioned remarks, this paper aimed is to study the effect of fire on steel structures considering the softening behavior of connections and decreasing of strength. Then by using ANSYS software the duration of structure against ignition analyzed and the tested frame is a single span with three dimension and finally different conditions on frame has been compared, which this condition include the effect of connection type, studying the effect of longitudinal expansion, the effect of temperature loading type and beam length as well as fire type. After providing computer data, this result has been compared with results of other researchers.

---

In this study, experimental study of profile geometry effect on Polycrystal Diamond Compact (PDC) drill bits performance and durability was conducted. In an extensive field study, three samples of bits was choosed among NIOC bits collection. PDC bit profile consists of apex, cone, nose, shoulder and gage, which all are effective on stability, penetration rate, aggressiveness and durability. Verification of the effect of PDC bit profile geometry needs to first determine the exact geometry. Complicated geometry of these PDC bits was obtained by 3D-scan and cloud of points. Then cutters arrangement of the profile was produced. In experimental study, field test of these bits was conducted in same condition (WOB, ROP, fluid velocity and drilling mud weight) in Ahwaz oil rig in Asmari formation. Drilling metrage and penetration rate was measured and the bits dull grading based on IADC standards was determined. Results of the bits test showed the effect of profile geometry on PDC bits performance and durability. optimization of profile geometry of PDC bits causes an increase in penetration rate, stability and durability.

---

In this research, an intelligent method is introduced for remaining useful life prediction of an internal combustion engine timing belt based on its vibrational signals. For this goal, an accelerated durability test for timing belt was designed and performed based on high temperature and high pre tension. Then, the durability test was began and vibration signals of timing belt were captures using a vibrational displacement meter laser device. Three feature functions, namely, Energy, Standard deviation and kurtosis were extracted from vibration signals of timing belt in healthy and faulty conditions and timing belt failure threshold was determined. The Artificial Neural Network (ANN) was used for prediction and monitoring vibrational behavior of timing belt. Finally, the ANN method based on Energy, Standard deviation and kurtosis features of vibration signals was predicted timing belt remaining useful life with accuracy of 98%, 98% and 97%, respectively. The correlation factor (R2) of vibration time series prediction by ANN and based on Energy, Standard deviation and kurtosis features of vibration signals were determined as 0.87, 0.91 and 87, respectively. Also, Root Mean Square Error (RMSE) of ANN based on Energy, Standard deviation and kurtosis features of vibration signals were calculated as 3.6%, 5.4% and 5.6%, respectively.

---

Drict discharge of domestic wastewater(sewage) to the environment or into absorbing wells has caused many problems including surface and groundwater pollution. To reduce such problems, the number of wastewater treatment plants has increased significantly in Iran during the last two decades. During wastewater treatment, a significant amount of sludge, composed of organic and mineral material, is produced. This sludge, if not handled and disposed properly, can create serious environmental and health issues. One environmentally attractive way of dealing with such wastes is to use them in different types of applications. In this regard, many economical and beneficial methods have been developed to reuse sludge. Incineration of sludge for energy recovery or the use of sludge ash in cement-based construction materials are among these methods. Sludge incineration produces considerable amount of ash which should be disposed. However the ash can be used as cement substitude in procuction of cement-based material. The subject of using sludge ash as cement substitude has been investigated by a few researcher with the conclusion that the usage of ash can affect the final cement-based product quality. Based on their experimental results, the use of sludge ash tends to decrease the compressive strength of mortar or concrete. However, it should be mentioned that no research has yet been done to investigatethe the effects of sludge ash replacement on mechanical and durability properties of concrete. The main aim of this study was to investigate the effects of sludge ash usage as cement substitude on physical, mechanical and durability properties of concrete. For this purpose, the effects of three key parameters: replacement level ( 0-20%, by weight), curing times (7, 28, 91 and 180 days) and water-cementitious material ratio (0.35, 0.45 and 0.55) were investigated. The sludge used in this research was obtained from one of the local wastewater treatment plants, which subsequently was dried and then was incinerated at 800oC to produce ash, The ash was in general, made up of irregular grains which were aggregates of smaller particles. Also, the ash was composed mainly of calcium, silica and aluminium oxides. The results showed that increasing the amount of sludge ash induced higher mortar setting times as compared to the control samples, using Vicat test. The effect of ash content on mechanical properties of concrete samples was carried out by compressive strength tests. Results indicated that for 7 and 28 days curing time, concrete samples containing a mixture of sludge ash and cement yielded lower compressive strength values than those samples using only cement (without any ash content). However, for curing times greater than 28 days, the increase in ash content of concrete samples (0-15% by weight) led to an increase in compressive strength. Water absorption and electrical resistivity tests were conducted to determine the durability of concrete containing sewage sludge ash. As blending percentages of ash content increased fom 5% to 20%, electrical resistivity of concrete samples decreased for regardless of the applied curing times. This phenomenon might be the result of increased porosity and material ionization.

---

Over the course of time into the 21th century, concrete has been known as one of the most high usage materials in the construction industry. As a consequence, trying to produce light concrete is an active and developing area within the new field of construction science. This technology consists of lowering the whole weight of structure by using new bulding techniques, new materials and optimizing ways of manufacture. Lowering the weight not only economizes on the expenses, time and energy but also decreases the damages of earthquakes. Furthermore, it keeps the constructions safe and minimizes the damages resulting from the overweight of the structure during different waves of shocks and aftershocks. In spite of considerable amount of compressive strength, low tensility strength and relatively high fragility of the concrete, there are limitations in using it in some parts which are partially or fully under forces of tention in different parts of structures. This fundamental defect of concrete in practice can be eliminated by reinforcing it through using steel tabs in the direction of traction forces. Having in mind that the armature just constitues a small part of the whole cross section of the structure, it will not be correct to conceive of the cross section of concrete as an isotropic and homogeneous surface. In recent decades, in order to come up with the isotopic condition and decrease the fragility, weakness and retrogression of concrete new techniques and trends of applying slender fibers running through the internal section of the bulk of concrete has become prevalent and common practice. The concrete containing nano materials compared with the normal concrete affected by nono chemical materials with cement particles and clcium hydroxide crystals which exist in cement, has a severe effect on the performance of concrete composites while such mixtures come into each others’ contact.
In this study,we examined the effect of Nano-silica and polypropylene fibres on mechanical properties and durability of normal and light weight concretes. In the design of light weight concrete, lecalight weight aggregates were used. More than 384 cubic and cylindrical samples were made based on ASTM standards and compressive strenght, indirect tensile strength, ultrasonic and electrical resistance experiments were done.
The results of the experiments showed considerable increase in mechanical characteristics and durability of normal and light weight concretes. Nano-silica contributes to the proper spread of the fibers. Compressive strength, indirect tensile strength, and the dynamic elasticity module of the ordinary concrete were higher than those of the light weight concrete, while the electrical resistance of the light weight concrete was higher compared to the corresponding samples.
Compressive strength and indirect tensile strength increased to 71 and 55 percent in normal concrete and to 43 and 47 percent in light weight concrete respectively. Considerable increase in electrical resistance indicates high durability of these kinds of concretes. Of course, economic considerations of using nano-silica and polypropylene fibers require special attention. Finally, the right amount of utilization of the polypropylene fibers and nano silica were determined in order to achieve normal concrete and light weight concrete with optimal properties.

---

One major weakness of concrete is the brittle fracture behaviour in tension, with low tensile strength and ductility. This brittleness has been recognized as a bottleneck hindering structural performances in terms of safety, durability and sustainability. The lack of structural ductility is due to brittle nature of concrete in tension which may lead to loss of structural integrity. Many infrastructure deterioration problems and failures can be traced back to the cracking and brittle nature of concrete. Many attempts have been made in the recent years to overcome these problems. To effectively solve these severe problems, a new type of composite, called as Engineered Cementitious Composites (ECC), reducing the brittle behaviour of concrete has been developed in recent decades. ECC with its flexible processing has emerged from laboratory testing to field applications leading to speedy construction, reduced maintenance and a longer life span for the Structures. Micromechanical design allows optimization of ECC for high performance, resulting in extreme tensile strain capacity while minimizing the amount of reinforcing fibers, typically less than 2% by volume. Tensile strain capacity exceeding 5% has been demonstrated on ECC reinforced with polyethylene and polyvinyl alcohol (PVA) fibers. Unlike ordinary cement-based materials, ECC strain hardens after first cracking, similar to a ductile metal, and demonstrates a strain capacity 350 to 550 times greater than normal concrete. Even at large imposed deformation, crack widths of ECC remain small, less than 80 μm. With intrinsically tight crack width and high tensile ductility, ECC represents a new generation of high performance concrete (HPC) material that offers significant potential to naturally resolving the durability problem of reinforced concrete structures. In the past few decades, substitution of mineral admixtures, such as fly ash (FA) and Ground Blast-Furnace Slag (GBFS), has been of great interest and gradually applied to practical applications of ECC. It has been found that incorporating high amount of FA can reduce the matrix toughness and improve the robustness of ECC in terms of tensile ductility. Additionally, unhydrated FA particles with small particle size and smooth spherical shape serve as filler particles resulting in higher compactness of the fiber/matrix interface transition zone that leads to a higher frictional bonding. This aids in reducing the steady-state crack width beneficial for long-term durability of the structure. In this study, the workability, mechanical properties and durability of ECC different mixtures contains two mineral materials (slag / fly ash) as to replace part of the cement weight and two types aggregate (Silica/ River sand) were evaluated. The results showed that mixtures containing fly ash despite lower mechanical strength to compared with mixtures containing slag, significantly have higher performance in strain- hardening behavior at post- cracking portion. ECC mixtures performance against the durability testing (Rapid chloride penetration, Electrical Specific Resistivity, Drying Shrinkage and Accelerated Reinforcement Corrosion) were appropriate and quantitatively was to form of slag> fly ash. In this study, in order to calculate the direct tensile strength of ECC mixtures, a new model (different geometry) compared to other models (used by prior researchers) proposed and tested. The its results showed that the tensile strength measured by the new model compared to the previous models, was higher 10% to 17%.

---

The surface protection materials have effective results to prevent concretes from corrosion. Reinforced concrete structures have the potential to be very durable and capable of withstanding a variety of adverse environmental conditions. However, failure in the structures does still occur as a result of premature reinforcement corrosion. There are corrosion protection systems and methods to extend the long-term durability of steel reinforced concrete. For example, application of zinc rich or cement based protective primers to reinforcement, surface protection systems of concrete, Cathodic protection using sacrificial zinc anodes, and conductive anode overlays within an impressed current cathodic protection system. In general, the main duty of surface protection is controlling both physical and chemical damages to concrete in order of preventing or reducing from steel bar corrosion and creating a coat of safekeeping against penetration of chloride ion, carbon dioxide, oxygen, and most importantly water. According to European Norm, three types of protection materials are existed based on function mechanism. Coating, hydrophobic impregnation, and impregnation materials are these systems, and two types of them used in this study. In this study, two materials of surface protection have used on the surface of three types of concrete. Two types of self compacting concrete with different w/c ratio and one ordinary concrete with similar mixture design to one of those SCC were used for estimating of durability of concrete. Epoxy resin and silane-siloxane were two types of surface treatment materials used in this study. SEM analysis and water contact angle test were done to study the function mechanism of surface protection material. The other tests are water vapor permeability, corrosion potential, and corrosion intensity. Some of the results of this study is that using this materials have effective impact on declining of corrosion potential, decreasing of corrosion intensity, and after all increasing durability of concrete. As shown in this paper, all of the protected samples except one, until 49th week did not have a sign of corrosion active phase. Increasing in ratio of W/C in the substrate makes weakness in function of this materials. In the other hand, results of half-cell potential of unprotected samples show SCC2 with 0.55 w/c ratio and NC with 0.45 w/c ratio shift from passive to active state in first days and SCC1 with 0.45 w/c ratio attained its active state in 5 weeks. However once corrosion has started in SCC2-EP in 8 weeks, corrosion rate was lower than unprotected samples. In the presence of surface protection systems, due to their ability to reduce water ingress in concrete, the corrosion intensity in all samples were lower than 0.23 µA/ cm^2. The results of water vapor permeability test showed that epoxy can decrease the water vapor permeability up to 65% instead of unprotected concrete. In the meantime, silane-siloxane doesn't have effective results in concrete breathability and have a similar performance to unprotected concrete. The results show using SCC don't have much different effect on quality of the materials function instead of ordinary concrete. Another important result is that protection materials which don't let to enough evaporate, are cause of much corrosion in compare of those that let concrete to breath.

---

Persian Shallot is a vegetable and at the same time a rare medicinal plant with a short shelf life. Edible coatings increased shelf life and maintain the quantitative and qualitative characteristics of some vegetable crops in the post-harvest stage. In this study, the effect of different amounts of chitosan (0.5, 1 and 2%), gelatin (0.25, 0.5 and 1%) and aloe gel (50, 75 and 100%) as edible coatings on fresh-cut persian shallot during 14 days of storage under refrigerated conditions (4±1 °C and 75-80% relative humidity) were investigated. The weight loss, pH, flavor index and total soluble solids during storage in coating treatments compared to control samples showed significantly less increase and amount of ascorbic acid, titratable acidity, pyruvic acid, total antioxidant capacity, total phenol, and soluble carbohydrates, showed significantly less decline. In this study, it was observed that edible coatings of chitosan (2%), gelatin (1%) and aloe gel (100%) had the greatest effect on maintaining the shelf life and quality properties of fresh-cut Persian shallot, respectively. According to the results obtained of this study, chitosan coating (2%) is recommended as a more suitable coating for fresh-cut Persian shallot.

---

---

Maintenance and repair of structures during the life of the structure is inevitable. Therefore, using a repair material that have the ability to re-service in a longer time is necessary. Today, produce a repair material that has a complete bond with the damaged element and makes it economical based on the available materials in the country is necessary.On the other hand increasing  the quantities of waste materials ,scarcity of land-filling space and because of its ever increasing cost,recycling industrial waste materials has become an attractive proposition to disposal.One of these by-products is waste foundry sand. Waste foundry sand that contains resin, coal powder and bentonite which are solvable in the water and leads to environmental pollution. Therefore, industry owners are looking for a solution to the problem of organic waste due to pressure from environmental organizations.One of these solutions is dumping of construction waste in cement products such as concrete, mortar and grout. In this research, with the aim of reaching mortar and grout with good performance and durability, as well as up to 40 MPa compressive strength of 28 days, the initial mixture ratios were determined and the final mixture was determined by making laboratory samples and correction of ratios. 5 mixtures for mortar and 5 maixtures for grout. In the mixtures for all mortar and grout samples, the ratio of water to cement is fixed at 0.4 and the cement content of the mortar samples is 650 kg/m³. Natural sand mortar samples have been replaced with 10, 15, 20 and 25 percent waste foundry sand. The amount of cement for grout samples is 1100 kg / m3. In grout mixtures, 10, 15, 20, and 25 percent of sand have been replaced by waste foundry sand (WFS). The results  indicate that replacing WFS reduces the workability of mortar and grout. The compressive strength of the mortar samples is reduced by replacing different amounts of WFS at the age of 7 and 28 days. Mortar with 20% replacement of WFS, is the optimum percentage of waste sand in the mortar. However, the compressive strength of the grout samples increases by replacing 10% casting sand. By increasing the replacement value by more than 10%, the compressive strength decreases. Based on various studies in concrete, ultrasonic velocity test (as a non-destructive test) is used to estimate the compressive strength, which has a linear correlation between ultrasonic wave velocity and compressive strength. But the results of this study showed that the non-destructive test of ultrasonic waves does not have the ability to estimate the compressive strength and the flexural strength of the mortar. This result was also observed in Grout samples. Therefore based on the results of this research the ultrasonic velocity test does not have the capability to estimate the compressive and flexural strength of mortar and grout. Despite the decrease in the mechanical properties of the mortar by replacing WFS, the water absorption of the mortar containing this material has decreased, which is up to 15%. But by increasing the replacement percentage by up to 25%, the volumetric absorption of the samples of the grout decreases.

---

This study investigates the effect of steel fibers and its hybrid form with glass fiber on the properties of cement composites. The studied mechanical properties included compressive strength and flexural strength, and the energy absorption rate of the specimens was determined by the flexural toughness. In the mixtures, Portland cement and calcium aluminate have been used as bonding agents the mixes containing 2% steel fiber (% of total volume of the mixture), 2% AR Glass fiber, and hybrid of these fibers were made of glass fiber (2% steel fibers and 2% glass fiber), the length of these fibers was 25 mm. The compressive strength test was performed at the age of 1, 7, 28 and 90 days. Speciments made with calcium aluminate cement had higher compressive strength due to quick formation of microstructure compared to Portland cement mixtures, so that 90-day compressive strength of Portland cement mix was lower compared to the 1-day compressive strength of Calcium aluminate concrete. Incorporating 2% steel fibers also had a slightly enhancing effect on compressive strength. Flexural strength test was carried out at 28 and 90 days. The steel fibers create appropriate mechanical bond with the cementitious matrix, and the ultimate flexural strength was about 2 times higher than non-fibers specimen, due to the congrated geometry of the steel fibers. Substituting glass fiber also increased the ultimate flexural strength due to the high aspect ratio glass fibers and the well formed Interfacial transition zone (ITZ). The hybridization of the aforementioned fibers with steel fibers increases the bending strength due to the synergistic effect. The energy absorption content of the cementitious mix measured by flexural toughness index shows that this energy absorption content increases with the hybridization of the glass and steel fibers, so that the hybrid specimen made with Portland cement had a flexural toughness of 34.4 Nm. The glass fiber increased the toughness due to its excellent energy absorption. The steel fibers in the mixed increased the area under the flexural loading cureve and prevent the mixture from being destroyed by the first crack. In the shrinkage test results the control specimen with the two types of cements did not differ significantly, but the addition of 2% of the fibers (steel fiber and glass fiber) reduced shrinkage by their limiting effect on length change and propagation of micro cracks. When the percentage of glass fiber become higher, similar to the hybrid mix, the shrinkage was reduced further. This experiment was performed uo to 270 days and it was observed that the shrinkage of the hybrid specimen made with Calcium aluminate cement reduced by 65.5% compared to the plain concrete. In this study, the RCMT was carried out at 90 days. The results indicate that the penetration rate of the hybrid specimens and the glass fiber mixtures were lower than those of the steel fibers incorporated mixed. Also, in comparing two types of calcium aluminate cement and Portland cement, specimen made with calcium aluminate cement, the chloride ion penetration was lower than those made with Portland cement due to the improved Interfacial transition zone (ITZ) and less porosity of this type of cement.   

---

Poorly graded sandy soil could cause numerous geotechnical problems in large areas across the world. Weak soils have insufficient bearing capacity and this may be the cause of many issues in roads infrastructure, embankments, buildings foundation, and other geotechnical projects. Stabilizing the soil by chemical stabilizers like ordinary Portland cement (OPC) is one of the most conventional methods for enhancing the engineering proprieties of soil, usually by different percentages of binder/soil ratio. Some environmental and economical issues of utilizing OPC as binder are the serious concern of researches during few decades. Alkali-activated materials (AAM), with lower destructive impact on environment and more economical profits, have been one of the attractive materials as a new generation of binders recently. These materials can be utilize in different geotechnical applications such as: soil stabilizing, different kinds of mixing method, and grouting. The current study has aimed to evaluate the mechanical and durability properties of stabilized sandy soil by AAM, the used slag for AAM binder is Ground Granulated Blast furnace Slag (GGBS) and the slag is activated by different kinds of novel alkali activators. The activators are combination of Na₂SiO₃ and NaOH, Na₂CO₃ and Ca(OH)₂, and Na₂SO₄ and Ca(OH)₂; namely, Ac₁, Ac₂, and Ac₃, respectively. In order to evaluate mechanical properties of stabilized soil samples, unconfined compressive strength (UCS) test, and to investigate the durability properties of stabilized soil samples, freezing-thawing cycles are applied to specimens. Additionally, scanning electron microscopy (SEM) test are implemented on Ac₂- and Ac₃-based stabilized samples to investigate the morphological aspects of stabilized soil. Studied parameters of this study are the effect of curing time on mechanical behavior of stabilized soil samples, and the effect of types of activator on mechanical and durability properties (volume changes and soil-cement losses) of stabilized soil samples. Curing time of 14, 28, and 90 days are considered for UCS test, and 28 days are considered for freezing-thawing cycles durability test. The amount of binder for soil stabilization is considered in a constant value of 5 wt.% of dry soil for UCS and freezing-thawing tests. The 90-day UCS value for OPC-based stabilized sample is 0.75 MPa, for As₁-based stabilized sample is 2.63 MPa, for As₂-based stabilized sample is 2.28 MPa, and for As₃-based stabilized sample is 4.5 MPa. As seen, AAM-based stabilized soil samples show greater UCS value in the same binder/soil ratio and curing time. As₃ showed the most effective activator with higher UCS value as a soil stabilizer. In the test of freezing-thawing, except As₂-based stabilized sample, other samples survived all 12 cycles. As₂-based soil stabilized sample only survived 7 cycles of freezing and thawing. The most amount of volume changes for OPC-based stabilized soil is 12.82% for 12 cycles, while this amount is 6.65% for As₂-based stabilized soil for 7 cycles. As₁- and As₃-based stabilized soil have showed fairly stable volume changes; i.e. with the most amounts of volume changes of 5.93% and 4.17% for 12 cycles. This results show AAM-based stabilized samples are more soundness than OPC-based stabilized samples and are more stable during volume changes.

---

Clay soils often cause problems in construction projects. In cold regions, freezing and thawing of clay soils can cause significant changes in the geotechnical characteristics of the soil. Frozen and thawed soils have shown changes in volume, strength, compressibility, frozen moisture content, bearing capacity and microstructural changes. In road construction projects in cold regions, freezing and melting is one of the factors affecting the unstability of soil engineering behavior, including the durability and performance of pavement and pavement layers.  Therefore, the purpose of this research is to evaluate the effect of freezing and melting cycles on the parameters of the durability of calcareous stabilized clay bed based on compressive strength test results. 400 kg of soil samples were collected from the subgrade of the RAZ-PASIN rural road. In the first stage, granulation experiments, Atterberg and ... on 20 soil samples were performed. The second stage was the dry maximum dry matter and optimum moisture content of the soil-cement mixture. The third step was to determine the percentage of suitable cement for mixing, soil-cement mixed density with different percentages (6%, 8%, 10%, 12% and 14%) with limestone cement type 1 and type 2. In the fourth stage, 24 cylindrical specimens were added to the soil sample by adding (8%, 10%, 12%) of type 1 and type 2 calcareous cement and tested for compressive strength. In the fifth step, the indirect tensile strength and the stress-strain modulus of the mixed soil-cement were determined. The results indicated that the maximum dry matter density of the soil-cement mixture was obtained by adding 10% of type 1 and type 2 calcareous cement. The results also showed an increase in the compressive strength of the composite made with type 1 lime Portland cement compared to Type 2 lime Portland cement, and all specimens containing 8% calcareous cement additive exhibit more than 35 kg / cm2 after 7 days of resistance treatment. This means that samples made with Portland cement have a sufficient durability against atmospheric agents. If the use of calcareous Portland cement is used only for bed consolidation as a layer of pavement layers and the appropriate weight percentage of Portland Type II cement is selected to be 8% for the consolidation of the studied soil, the cost of the Rural Road Project will be compared. The Late Valley showed a 13% reduction in the cost of supplying calcareous Portland cement compared to Type II Portland cement (Table 10). This is due to a 15% reduction in energy costs (gas and electricity consumed) in the manufacture of calcareous Portland cement compared to Type II Portland cement. By comparing the results of compressive strength of soil-mixture of type 1 calcareous Portland cement and type 2 cement, it can be concluded that the effect of type 1 calcareous Portland cement in obtaining compressive strength is better than type 2 calcareous Portland cement due to increasing Lime is made of cement composition. This increased resistance is due to the ion exchange reaction and the agglomeration-compaction reaction between lime and soil and is achieved by lime contact with most fine-grained soils. Thus, the calcium ions in the lime are replaced by the lower-capacity positive ions in the soil. This results in the accumulation of calcium ions around the clay particles.

---

Reinforcement corrosion in concrete structures is considered as one of the main important issues that degrade the durability of RC structures. One of the most important effects of reinforcement corrosion is to reduce the bond between concrete and rebar. Bond strength enables the force transfer from reinforcing steel bar into concrete and guarantees the composite manner of reinforced concrete structures. Many empirical models have been developed to estimate bond strength during the corrosion propagation period. The experimental results are different depending on the test conditions and how to prepare the samples. Models presented by different researchers, even for the same basic assumptions, have fundamental differences in the predicted bond strength, which causes uncertainty in the choice of model and results. In this paper by regression of existing empirical results, some different models are presented for each bar diameter. The reinforcement diameter and corrosion current density are two basic variables in bond degradation models that have been considered for investigation of uncertainty in proposed models. Based on the results, the bond reduction during the corrosion propagation is exponential and the effect of the uncertainty of the corrosion current density is greater than the bar diameter. The effect of uncertainties on the coefficient of variation of the results is more than the effect on the mean. The bond reduction for the smaller diameter bars was lower than the larger bars such that for 10 and 16 mm diameters at 15% corrosion, the bond to primary bond ratio was 0.46 and 0.28, respectively.