Sharif Digital Repository

Foam concrete is a new covering layer that can be used for several purposes in civil constructions and because of its unique physical specifications, produces a light concrete in which is isolated against thermal conductivity ,with required strength and favorite quality.This cover is made of cement , sand ,water and foam(chemical substance that produces foam) . The foam is mixed with water in a special machine (mixer) with a high speed centrifugal rotation and produces very small stable bubbles called foam. While cement and sand are mixed in special mixer, makes a fluent concrete that can be used in place, metallic or plastic molds. After dehydration, in accordance with percentage of... 

Superabsorbent polymers are mainly used in baby diapers and in agriculture. A less known emerging and potentially important application is the internal curing of cement based materials. About a decade ago, pioneering works demonstrated that using SAP in concrete reduces autogenous shrinkage and cracking, and improves hydration of the cement matrix. However, problems like workability reduction, and deterioration of mechanical strength of the mixture are reported. In this thesis, nanocomposites using nanosilica and acrylic monomers were prepared and used to address the above problems. Nanocomposites exhibit enhanced mechanical strength and reduced sliding friction, compared with conventional... 

The main objective of this project is the deposition of photo-catalysts on cement and concrete blocks with an emphasis on commercialization. We started with an extensive study of common methods introduced in previous literature, and conclude with a number of suggestions for industrialization. First, slurry and sol-gel deposition of the photo-catalysts on blocks of type 2 commercial cement which is one of the most used materials in construction of buildings and waste-water treatment plants has been examined to reach a method of sample formation. Due to the simplicity of common methods and low quality of formed samples (less than 5 percent aging efficiency), the obtained experience was used to... 

The rheology of oil well cement (OWC) slurries is generally more complicated than that of conventional cement paste. In order to contend with bottom hole conditions, a number of additives are usually used in the OWC slurries. The objective of this research is to develop a fundamental understanding of the important mechanisms that affect the properties of OWC slurry such as rheological properties, free water, compressive strength and thickening time incorporating various chemical and mineral admixtures. The partial replacement of OWC using different nanoparticle weight percent has been proved to be a promising method. The mechanisms underlying the effects of chemical admixtures on the... 

Rammed earth structures have attracted the attention of engineers and researchers in recent years due to their economic advantages, sustainable development, and environmental sustainability. One of the main concerns for public opinion for acceptance of Rammed Earth as a reliable construction material is their durability. Previous studies have investigated the durability of rammed earth materials by conducting wet and dry cycle test, accelerated erosion test, and rain simulation in the laboratory environment. This research studied the durability of cement stabilized rammed earth (CSRE) for one year under the aggressive environments. Three cement contents were considered for preparing the CSRE... 

Rammed earth (RE) is an eco-friendly building material and has been capturing special attention among researchers. Many of the recently studied RE additives are extremely resource- and energy-consuming. On the other hand, the usage of fly ash (FA), which is a sustainable replacement for cement, has been scarcely investigated in RE construction. In this paper, an experimental investigation was performed on the physical and mechanical properties of RE materials stabilized with the combination of cement and alkali-activated FA. This scrutiny consists of density measurements, pulse velocity tests, unconfined compression tests, and direct shear tests. Additionally, the carbon dioxide emission and... 

Casing collapse is a long-standing problem in Kopal oil field, located at a distance of 60 km of east of Ahwaz, Iran. In this field, so far casing collapse has encountered in 18 well-bore out of the 56 drilled-well-bore (~32%) due to creep loading caused by salt flow, which resulted in tremendous economic loss. Among all the different set of factors leading to such a problem, the effects of the local stress distribution on the wellbore wall and casing (resulted from the in-situ stresses, and stress perturbation due to drilling), pore pressure, the casing quality and material, and the applied-cement type are important. In order to investigate these factors and their effects, they should be... 

Studies have shown that use of crumb rubber additive can improve the mechanical and performance properties of hot mix asphalts. Nowadays, different methods are used for adding crumb rubber to asphalt mixtures. However, no comprehensive research has been done to investigate the effects of these different methods in cold mix asphalts. In this research, different crumb rubber modification methods were evaluated to compare their effects on cold mix asphalts’ performance. In this regard, various crumb rubber modification methods, such as pre blending crumb rubber into the asphalt before emulsification, post blending crumb rubber into the prepared asphalt emulsion and blending crumb rubber with... 

Despite major environmental and economic benefits of cold recycled asphalt mixtures, many agencies have not yet made widespread use of this technology due to its so-called poor field performance and lack of accurate information on mechanical properties of cold recycled mixtures. Fiber is one the additives that is sometimes used to enhance asphalt mixture properties. Using fibers to improve the performance of cold recycled asphalt mixture has been studied by a few researchers with somehow contradictory results. In this research, the effects of adding four synthetic fibers (Polypropylene, A-glass, Para-Aramid, and Polyester) and two waste fibers (Waste Polyester and Waste Nylon) with different...