الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Sustainable development is a major concern, so countries attempt to implement strategies to reduce greenhouse gas emissions during production of construction materials. Rammed earth (RE) is an ancient construction technique that utilizes the available soil to create bricks and thick walls that are used as bearing walls. Rammed earth is considered environmentally friendly since it reduces the use of non-renewable natural resources. Although cement is commonly used as soil stabilizer with ratios from 5% to 7% by weight of soil, these percentages are unacceptable from sustainability perspective, as cement production contributes to global warming by emitting tons of carbon dioxide. On the other hand, there are lots of industrial and agricultural wastes that are piling up daily. Therefore, minimizing the use of cement and reducing its negative impact on the environment in addition to getting rid of the industrial and agricultural wastes are considered a challenge.
The main objective of this research is to produce eco-friendly compressed earth bricks using alkali-activated agricultural and industrial wastes as soil stabilizers to minimize the use of cement, and investigate the physical, thermal and mechanical properties of the produced earth bricks. In addition to conducting numerical simulation for the thermal behavior of rammed earth walls.
The experimental investigation comprises three phases: Phase one was designed to investigate the physical and chemical characteristics of the used soil and the available pozzolanic materials; Fly ash (FA), silica fume (SF), rice husk ash (RHA), ground granulated blast-furnace slag (GGBS), and metakaolin (MK).
Phase two was designed to develop eco-friendly stabilization materials using pozzolanic materials from agricultural wastes and industrial by-products. The efficiency of the developed stabilization materials was investigated through studying the effect of incorporating alkali-activated pozzolanic materials as partial or full substitution of cement on the compressive strength of mortars cured at ambient temperature.
Phase III was designed to investigate the physical, thermal, and mechanical properties of compressed earth bricks (CEB) made by the developed stabilization materials as partial or full replacement of cement. The potential of producing CEB with low thermal conductivity using polystyrene foam and rice husk as partial replacement of soil was also investigated. A total of twenty-one mixtures of stabilized soil were used in manufacturing bricks of dimensions 250x120x60 mm. The produced CEB units were cured at ambient by covering them with wet burlaps and plastic sheets for 28 days. The testing of CEB units included density, water absorption, pitting erosion, thermal properties, compressive strength, flexural strength, and masonry compressive strength.
The results of the experimental investigation showed that using alkali-activated fly ash and GGBS as cement replacement by ratios of 80% and 100%, respectively was superior in stabilizing CEB with competitive compressive strength to those stabilized by cement. The incorporation of rice husk with percentage of 0.25% by weight of soil (5% by volume) has a significant effect on enhancing the compressive strength and water resistance of the produced CEB. The addition of polystyrene foam (PF) by percentages up to 0.5% by weight of soil (55% by volume) was significant in decreasing the dry density and thermal conductivity of the produced CEB. This reduction will contribute to reducing heat transfer by conduction for exterior walls.
Three-dimensional finite element modeling has been developed using ANSYS software for evaluating heat transfer through RE walls and CEB walls. The input data includes dimensions of the used bricks and walls, indoor and outdoor temperature and thermal transmittance (U-value). The study parameters included thermal conductivity of different wall types and different wall thickness. Analytical verification was conducted using the relevant specifications and showed good agreement with the numerical results.
In addition, an analytical study was performed to obtain the optimum CEB wall thickness that meet the thermal design conditions to satisfy the requirements of the Egyptian code for thermal insulation. Also, the optimum thickness of insulating material was evaluated in case of using it. These data were used in the thermal simulation of rammed earth.
Thermal simulation model has been established for analyzing an office building prototype composed of CEB walls using Design Builder software with additional supplementary software such as CC World Weather Generator. The data defined in the model was weather data files for years; 2020, 2050 and 2080, construction wall materials, and HVAC system. The parameters of the study included the type and thicknesses of walls, thickness of insulating material if used and global warming effect. The results revealed the effect of the type and thicknesses of walls in addition to the thickness of EPS insulating layer in reducing the total energy consumption and carbon dioxide emissions.