فهرست مطالب ali akbar shirzadi javid

With the architecture, Engineering and Construction (AEC) industry representing a significant share of global energy consumption and greenhouse gas (GHG) emissions, developing sustainable design and reducing buildings environmental impacts has become a priority over the past decades. Adopting building information modelling (BIM) tools and implementing them into life cycle analysis (LCA) techniques at early stages of design has proven to be one of the most effective methods for a buildings sustainability evaluation. It’s quite often that some of these attributes are overlooked due to their insignificance or in order to facilitate the analysis. With our environment constantly going through changes it is reasonable that the construction industry should also aim to adapt to these changes and make use of them. However, the role of local climate features and its effects on a buildings energy output is often so neglected. This research aims to consider the role of climatic attributes and local weather characteristics of a building by using BIM-LCA integration techniques, and see how it affects that buildings energy performance. It is witnessed that by using the proper equipment and construction materials, that matches the respective climate, up to 28% of the buildings energy consumption during the operational phase, can be saved. Admitting changes to the model however, can cause up to 3% increase in the models GHG emissions. Moreover, this work develops a prototype to validate the results.

In recent years, with the advent of building information modeling (BIM), significant progress has been made in the quality of the designs and execution of projects. BIM-based models are widely applied to project safety planning and control of time and cost in construction projects. The use of Building Information Modeling has also shown a positive influence on process of clash detection and clash resolution. During the design stages, BIM drawings and plans produced by individual designers are integrated into a federated model and tested to detect design clashes, which if they are not carefully detected and resolved in the design phase, they risk the safety, time, and cost of the project management in addition to increasing the workload. Because of the confined spaces left for MEP systems, between the various elements, mechanical, electrical and plumbing (MEP) design clashes have traditionally dogged the design process. The purpose of this study is to grouping MEP elements to determine their priority in terms of time and cost in the clash resolution process. This research uses the Delphi method to group MEP elements and then applied the Fuzzy-AHP method to determine the weight of MEP elements.

The Persian Gulf is well known as one of the most aggressive environments in the world because of its high relative humidity, temperature, and concentration of chloride ions. Concrete structures are increasingly being deteriorated in this region. Therefore, Improving the durability of concrete structures in this environment is an important issue. Supplementary cementitious materials (SCMs) can be useful for concrete durability enhancement in such harsh environments. In this paper, the effect of silica fume on deterioration resistance to sulfate attack in seawater within simulated splash, tidal and submerged conditions have been studied in self-consolidating concretes and mortars containing silica fume (SF) with/without natural zeolite (NZ). To achieve this objective, self-consolidating concrete specimens and concrete equivalent mortars (CEMs) with/without 15% natural zeolite and 8% silica fume with a total binder content of 380 kg/m3 and a constant water to cement ratio of 0.45 were fabricated. limestone powder (LP) is also used as an inert filler in all SCC/CEMs. Additionally, both the conventional and SCC mixes were subjected to these durability tests to compare their performance. After 7 days of curing in a saturated calcium hydroxide solution, all of the specimens were subjected to three exposure conditions (tidal, splash, sub-merged) for 28, 90 and 180 days of testing ages. After taking fresh property testes of mortar/concrete samples by SP demand, slump flow, visual stability index, J-Ring, T50, V-funnel tests, several standard hardened property and durability tests were investigated by mortar/concrete compressive strength, chloride permeability, concrete electrical resistivity, mortar capillary water absorption and porosity tests. Moreover, the degree of sulfate attack was evaluated by measuring the expansion of mortar prisms. Traditionally, the extent of sulfate attack is quantified by the expansion of prismatic bars completely submerged in sulfate solution and this exposure regime used to evaluate sulfate attack is not typically representative of that encountered in the field. Wherefore, in this investigation, prismatic bars were placed in different conditions mentioned and exposed to simulated seawater solution then expansion values evaluated. In addition, a reduction in compressive strength of all specimens was denoted by the strength differential factor (SDF). Results demonstrated that the incorporation of SF with NZ mixes in different exposure conditions led to the lowest absolute value of SDFs in all of the simulated-testing environment. Conversely, the lowest level of compressive strength at all testing ages was obtained for ternary blended cements (PC+LP+SF). Therefore, it can be concluded that SF has a negative effect on the compressive strength of SCC exposed to Persian Gulf seawater solution. This is attributed to the Mg-oriented sulfate attack which was more deleterious in SF ternary blended cements. All in all, the results were obtained from a laboratory set-up and indicated that when the durability properties of the concretes in such environments were taken into account, the quarterly use of zeolite and silica fume (PC+LP+SF+NZ) provided the best performance in all exposures. Furthermore, self-consolidating concretes and mortars performed better than normal types. Besides, it is concluded that splash zones affect concrete specimens more harshly than other conditions.

The mixing process performs a critical role in the concrete microstructure, which defines the final product’s quality. Optimizing mixing time and mixing speed during the mixing process can reduce the unit price and energy consumption without impacting product quality. Furthermore, the energy consumption to manufacture self-consolidating concretes (SCC) is more than that of conventional concretes due to their compositions and structures. Due to the fact that rheological and mechanical properties assess the performance of concrete, the effects of mixing energy on the mentioned properties of self-consolidating concretes are taken into consideration simultaneously in the current investigation. Accordingly, different mixtures contained polysaccharide-based viscosity modifying agent and limestone powder are made under different mixing speeds and mixing times. Drawing on the results of mixing time, the optimum time for mixing is 8 min in this study in order to improve the workability and to provide ideal levels of rheological features such as minimum yield stresses (static and dynamic). In the aspect of mixing speed, double increasing from 20 to 40 rpm rises the slump flow by 5%. Besides, accelerating mixing speed increases dynamic yield stress by 37% for 11 min mixed mixtures, which is more than that of other mixing times mixtures’ dynamic yield stress increment. In the aspect of mechanical properties, mixing time increment increases the concrete’s compressive strength. Nevertheless, other mechanical characteristic criteria do not significantly depend on mixing energy.

Designing and developing rheological properties of self-compacting concrete is an important issue in concrete technology. This matter is because of the combination of varied needs in the fresh mode, extremely complexed mixture proportions, and its naturally low yield stress. Selection of chemical admixtures, especially super-plasticizers plays an important role in Designing of self-consolidating concrete (SCC). In this paper, the rheological properties of SCC samples made with various chemical admixtures in various mixing time and temperatures were examined. Super-plasticizers are strongly influenced by the ambient temperature, due to the fact that the temperature dependent on the hydration rate affects the absorbance rate of the super-plasticizer as the ability to absorb the polymer content. The rheological properties of the SCC were examined in various mixing time and temperature. After changing the temperature of the SCC to the ambient temperature, the rheology test was conducted using rheometer in 60 min. In this research, the dosage of rheological parameters and its growth rate with time have been compared in various temperatures. According to the obtained results, Naphthalene sulfonate cause to increase yield stress and to decrease plastic viscosity more than poly-carboxylate in SCC, in other words, poly-carboxylate cause better viscosity in concrete. Also, concrete containing naphthalene sulfonate has less yield stress growth rate and viscosity by increasing the time. On the other hand, slump loss of the SCC containing naphthalene sulfonate is less than the one containing poly-carboxylate. That is to say, naphthalene sulfonate protects the fluidity more than poly-carboxylate in SCC.

All costs within the life-cycle of a building are known as its life-cycle costs. In the design process of a building, the use of a lower initial cost index to select an option among others with similar performance may not lead to an economically optimal choice during the life-cycle. Hence today, building designers and investors require a tool to estimate life-cycle costs at the conceptual design phase to elect an economically-efficient option. The purpose of this study is to provide a framework to estimate life-cycle costs of a building at the conceptual design phase based on building information modeling. For this purpose, the costs of the building's life-cycle, including initial costs (cost of supply and installation based on Iran's national price list and shipping costs), repair and maintenance costs, operating costs (energy consumption) and salvage value at the end of the building’s useful life are regarded in the estimation of its life-cycle costs. The application of the proposed framework was then evaluated and approved for designing a residential building in Tehran. The application of the proposed framework for designing a residential building in Tehran was assessed and validated on two modelsو and the results showed that by increasing the initial costs in the second model by 75%, its annual operating costs decreased by 54% and Total life-cycle costs have dropped by 8% after 18 years. In this way, building designers can estimate the life-cycle costs of a building at the incipient stages of design and improve its design.

Change in the concrete temperature causes the expansion of the concrete to become tensile stress. The risk of concrete cracking decreases with decreasing coefficient of thermal expansion (CTE) under temperature changes. In this research, in order to investigate the effect of mineral admixtures on the coefficient of thermal expansion, concrete and cement paste samples containing silica fume, metakaolin and slag with a constant ratio of water to cement materials and the amount of cement materials have been made, and compressive strength, total porosity, Pore size distribution and coefficient of thermal expansion of the samples have been examined. The results indicated that CTE of reference concrete had a descending trend up to 60 days, and diminished by 12%, after which it remained constant. On the other hand, in the slag-containing concrete, after 60 days, the descending trend started and declined by 10% up to 120 days. For the concrete containing silica and metakaolin, at the very early ages, it had 14% less CTE as compared to reference concrete, while with the ageing of the sample, its CTE dropped by around 8%. Across all concretes, reduction of CTE was associated with lowered total porosity. Utilize the experimental data, a model for predicting the coefficient of thermal expansion of concrete at different ages is presented using concrete thermal expansion coefficient at 7-day age. In the following, the relationship between CTE and compressive strength, total porosity and the average diameter of pores has been investigated, which has the highest correlation between the coefficient of thermal expansion and the diameter of pores.

Due to the composition, the production of self-consolidating concrete (SCC) requires more mixing energy to uniform and homogenize the concrete components. This limits the rate of concrete production in comparison with the convectional concrete and therefore is an important financial factor. So mixing energy (mixing time and power) is one of the main factors in concrete production and before large production, the appropriate mixing time and speed should be determined for each mixture. In this study, according to objectives and considering that mixing time and speed are two main factors in content of mixing energy and according to guidelines and regulations, two SCC mix designs (powder type and VMA type) were mixed in three mixing times (3, 8 and 11 minutes) and each of them in two mixing speeds (20 and 40 RPM) and their effect on rheological properties was evaluated. The results showed that in each series of mixtures by increasing the mixing time up to a certain level that is called stabilization time (the shortest mixing time) and in this study is 8 minutes, the workability of concrete increases and after that by mixing up to 11 minutes it decreases 6 percent. Static yield stress in the 8 minutes mixing has minimum amount too and by mixing up to 11 minutes it increases 42 percent. This increment reaches to 62 percent for Dynamic yield stress, so the rheology tests also confirm these results.

Setting time and thixotropy of self-consolidating concrete (SCC) mixtures are two important parameters that affect the early age properties. In order to determine these parameters, there are traditional methods that have advantages and disadvantages such as low accuracy or high cost of testing. The aim of this study is introducing an acceptable method (called plate test) of determining setting time and thixotropy of SCC mixtures. The proposed method is including a rough plate immersed in fresh mixture from one side and attached to the accurate scale from another side. In this study the thixotropy of different self-consolidating concrete mixtures (SCC) containing silica fume and slag were tested. Results of the thixotropy obtained from the plate test were compared with the results obtained from penetration resistance and rheometer respectively. Results showed that the mixture containing slag produced the less temperature comparing with the mixture containing silica fume. It was also shown that the amount of thixotropy obtained from the plate test had a difference of 4% up to 10% in comparison with the rheometer and the results of the setting time had also shown a maximum difference of 9% compared with the results of penetration resistance test. The results proved that the plate test has an acceptable accuracy and can be recommended.

The performance of binary and ternary self-consolidating concrete (SCC) samples immersed in Persian Gulf simulated water including compressive strength, electrical resistance, bulk water absorption, total voids and chloride ions penetration were investigated. Portland cement was partially replaced with 8, 20, and 50% (by mass) of silica fume, metakaolin and slag, respectively. In addition, ternary blends containing the mentioned percentages of metakaolin and silica fume as well as slag and metakaolin were cast. The water to binder ratio was considered 0.45. The results indicated the improvement in the performance of immersed binary and ternary SCC samples compared with control samples. SCC containing the studied supplementary cementing materials showed better performance compared to the plain SCC when immersed in sea water from the view point of resistance against chloride ions attack. The best performance was arrived to the ternary SCC containing metakaolin and silica fume. The samples containing slag did not perform well in the Persian Gulf exposure which can be related to the poor quality of the studied slag.

Plastic shrinkage occurs in fresh concrete usually within few hours after mixing the concrete and risk of its cracks endangered concrete structures especially in the elements with high surface to volume ratio such as slabs or highway pavement. An experimental investigation on capillary pore pressure, tensile strength and plastic shrinkage of concrete is presented here. The aim of research is to study the relationship between capillary pore pressure build up in concretes, early age tensile strength and plastic shrinkage strain. Capillary pore pressure apparatus was created for the first time in Iran for this research. Test was done in a climate chamber with the constant evaporation rate of 0.7 kg/m²/h .Eight types of concrete in two categories such as normal concrete and self-consolidating concrete were tested including mixture without any mineral admixtures and containing of pozzolanic materials such as silica fume and metakaolin. The results indicated that there is no strong relationship between capillary pore pressure and plastic shrinkage strain and it can be concluded that other parameters such as tensile strength development can play an important role in the plastic state of concrete. However, it should be mentioned that capillary pressure is the main cause and driving force of concrete shrinkage and the onset of capillary pressure is directly related to the onset of shrinkage. The results also showed that early age tensile strength can be effective factor in controlling cracks of concrete. No cracks appeared in the mixtures containing of silica fume and metakaolin in comparison with the reference mixture. However capillary pore pressure in these mixtures was higher than pressure in the reference mixture.

The highest part of chemical ions present in the seawater is related to the chloride ion. In this research, the effect of chloride curing condition on the properties of concrete containing zeolite as a mineral admixture and micro-nano bubble water is evaluated. Based on the experiments including X-ray diffraction, compressive strength, water absorption, chloride permeability and electrical resistance, it was determined that the addition of zeolite and micro-nano bubble water to the mixture improved the properties of concrete in the chloride conditions. Also results show that the chloride curing condition causes an improvement in the properties of concrete at the age of 28 days because of the formation of Friedel salt. With increasing age of concrete up to 90 days and decomposition of Friedel salt composition in samples, the process of improvement is reduced. The highest effects on improving the mechanical properties and durability of concrete at the age of 28 days is related to the sample containing 15% zeolite and 100% micro-nano buble water under chloride curing conditions. Improvement contents in the mentioned situation are 47, 78, 254, 84 and 49 percent corresponds to the compressive strength, tensile strength, electrical resistance, chloride permeability and water absorption test respectively.

In this study, the effects of spraying nanoparticles with different geometries (nano-SiO2, nano-halloysite, and nano-montmorillonite) on surface characteristics of concrete pavement in terms of microstructure. The initial and final setting times of mixtures were determined to investigate the proper spraying time for applying on the pavement surface at early ages. To precisely investigate the microstructural properties, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) were used. The results revealed that spraying nanoparticles improved the abrasion and skid resistance as well as transport properties of the concrete surface, especially at the initial setting time. According to the tribology testing, the surface friction coefficient of sprayed samples compared to the reference sample (not sprayed) was increased 28%, on average. AFM results verified that this growth is due to the improved surface roughness and van der Waals forces. Based on the FTIR results, the abrasion resistance of the samples gradually diminished by increasing the depth due to reduction of nanoparticles penetration, thus, reducing its positive effect. In addition, a good relationship with regression coefficient of 0.79 was found between the surface tensile strength and the abrasion resistance of the specimens.

Self-consolidating concrete (SCC), despite its many positive advantages, increases the formwork lateral pressure of the mixture due to its high fluidity, leading to the increased cost of formwork construction in the in situ concrete structures. The thixotropy property, as the most significant functional feature including the effect of mixture proportions on lateral pressure, was selected to investigate the behavior of fresh concrete in the mold. In the present study, the thixotropy and formwork pressure characteristics (including maximum lateral pressure and pressure drop rate) of 15 SCC mixtures were investigated by considering a number of mixtures proportions variables including cement content, water-to-cement ratio, and mineral admixtures. In addition to studying the effect of these variables on the thixotropy level and the lateral pressure of the formwork, the relationship between the methods of measuring the thixotropy level (hysteresis methods, the area of structural breakdown, and the yield stress growth rate) was evaluated considering the mechanism of these methods. In this study, formwork pressure simulator device was used to measure maximum lateral pressure and lateral pressure drop rate. In addition, the effects of mixture proportioning variables on thixotropy and its relationship with the formwork pressure were studied. Using these indices, the ability to predict the behavior of concrete in the mold was investigated through modeling. The presented predicting model of the formwork pressure based on thixotropy value showed an acceptable correlation coefficient (R2 > 0.77).

In this paper, the effect of using natural zeolite as a supplementary cementitious material and micro-nano bubble as a substitute for concrete mixture water has been evaluated on the mechanical properties and durability of concrete. The evaluated parameters for properties of modified concrete include: compressive strength, tensile strength, Bending strength, electrical resistivity and water absorption. The results indicate that the use of zeolite and micro-nano bubble in concrete increases the mechanical properties and the durability of concrete. The greatest improvement is related to the two-phase samples from the combination of 10% zeolite and 100% micro-nano bubble, which compressive strength, tensile strength, bending strength and electrical resistivity increase by 15, 14.88, 5.65 and 194.12% respectively, and water absorption decrease by 25.22%. In general, according to the results, it can be concluded that zeolite and micro-nano bubble, improve the mechanical properties and durability of concrete and their combination has the most positive effect on modified concrete.

Several studies have been done on the rheological properties and setting time of cementitious mixes, but the relationship between these two important features has not been studied so far. Therefore, the aim of this study is to investigate the relationship between rheological properties and setting time in self-consolidating concrete mixtures. In this study, six self- consolidating concrete mixture proportions were considered, in which the effect of water-cement ratio changes, silica fume and slag was used. The electrical resistivity method has been used in determining its setting time, and the performance of this method has been evaluated in determining the rheological properties. Since the electrical resistivity method is not standardized in determining the setting time, therefore, to verify the results, the standard penetration resistance method is also used according to the ASTM-C403. In the study of rheological properties, the studies have been done in two sections of efficiency and rheometer analysis. From the results, it was found that mixtures that have higher slump flow have recorded less time to take. It was also found that concrete mixtures that have higher yield stress (static and dynamic)  have shorter setting time. In this way, the relationships between these two important variables (rheological properties and setting time) were evaluated by the relationships.

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 doesnt have effective results in concrete breathability and have a similar performance to unprotected concrete. The results show using SCC dont have much different effect on quality of the materials function instead of ordinary concrete. Another important result is that protection materials which dont let to enough evaporate, are cause of much corrosion in compare of those that let concrete to breath.

Plastic shrinkage occurs in fresh concrete usually within few hours after mixing the concrete and risk of its cracks endangered concrete structures especially in the elements with high surface to volume ratio such as slabs or highway pavement. An experimental investigation on capillary pore pressure, tensile strength and plastic shrinkage of concrete is presented here. The aim of research is to study the relationship between capillary pore pressure build up in concretes, early age tensile strength and plastic shrinkage strain. Capillary pore pressure apparatus was created for the first time in Iran for this research. Test was done in a climate chamber with the constant evaporation rate of 0.7 kg/m²/h .Eight types of concrete in two categories such as normal concrete and self-consolidating concrete were tested including mixture without any mineral admixtures and containing of pozzolanic materials such as silica fume and metakaolin. The results indicated that there is no strong relationship between capillary pore pressure and plastic shrinkage strain and it can be concluded that other parameters such as tensile strength development can play an important role in the plastic state of concrete. However, it should be mentioned that capillary pressure is the main cause and driving force of concrete shrinkage and the onset of capillary pressure is directly related to the onset of shrinkage. The results also showed that early age tensile strength can be effective factor in controlling cracks of concrete. No cracks appeared in the mixtures containing of silica fume and metakaolin because of tensile strength improvement up to 55 and 32 percent respectively, in comparison with the reference mixture. However capillary pore pressure in these mixtures was higher than pressure in the reference mixture.

The aim of this study was to evaluate the effect of self-consolidating concrete mixture components on yield stress (static and dynamic yield stress), and plastic viscosity. Accordingly, mixtures with different water-cement ratio and the amount of limestone powder were made. In addition, cement has been replaced with different percentages of silica fume, slag and metakaolin. The results show that increasing of water to cement ration cause decreasing of yield stress and plastic viscosity. On the other hand, increasing in limestone content leads to yield stress reduction. Over time, this yield stress increased while the plastic viscosity of mixtures showed no significant change. By replacing the silica fume, yield stress increased but plastic viscosity unchanged while metakaolin cause increasing in both parameters. The aim of this study was to evaluate the effect of self-consolidating concrete mixture components on yield stress (static and dynamic yield stress), and plastic viscosity. Accordingly, mixtures with different water-cement ratio and the amount of limestone powder were made. In addition, cement has been replaced with different percentages of silica fume, slag and metakaolin. The results show that increasing of water to cement ration cause decreasing of yield stress and plastic viscosity. On the other hand, increasing in limestone content leads to yield stress reduction. Over time, this yield stress increased while the plastic viscosity of mixtures showed no significant change. By replacing the silica fume, yield stress increased but plastic viscosity unchanged while metakaolin cause increasing in both parameters.