Current Issue : January-March Volume : 2023 Issue Number : 1 Articles : 5 Articles
Living in a habitat with comfort is requested by all. Cinder block bricks have poor thermal properties, leading people to use fan heaters and air conditioners to regain comfort. To overcome this problem of thermal discomfort in buildings, we used lightweight concrete such as foamed concrete which is a material that has improved thermal properties for thermal comfort. In addition, this material was compared with local materials used for the construction of buildings such as BTC, adobe and BLT mixed with binders. The results showed that foamed concrete is a material that has good thermal and mechanical properties compared to local materials mixed with binders. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m3. It has a thermal resistance of 0.4 m2∙K/W for a thickness of 20 cm. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m3. It has a thermal resistance of 0.4 m2∙K/W for a thickness of 20 cm. For sunshine on a daily cycle equal to 12 hours, the characteristic thickness achieved by this material is 7.29 cm. It also has a shallow depth of heat diffusion having a lower thickness than other materials. This shows that foamed concrete is a promising material for the construction of buildings....
To investigate the axial compression performance of cold-formed thin-walled steel tube lightweight concrete columns, the compressive test was carried out on four groups of 12 specimens. And the effects of factors such as section size, concrete strength, and steel content of the members on the axial compression bearing capacity were investigated. The results show that (1) the main failure of the cold-formed thin-walled steel lightweight concrete column is the local buckling of the steel wall and crushed of the core concrete. The presence of infill concrete suppressed and delayed the buckling of the tube wall. (2) The bearing capacity of cold-formed thin-walled steel lightweight concrete columns increases with the strength of the infill concrete. When the slenderness ratio is same, the bearing capacity and ductility of the columns with more steel content are higher than those of lower steel content. (3) The calculation method of the bearing capacity for the cold-formed thin-walled steel lightweight concrete column was proposed and verified....
Affected by confined aquifer, basal inrush accidents caused by excavation are common in foundation pits, and accurate estimation of the safety thickness of the base is a big concern of engineers. In this paper, a three-dimensional failure mechanism of base inrush was constructed for a rectangular foundation pit. In this mechanism, the strength of the soil mass was assumed to be nonhomogeneous along the depth, and the soil-mass failure satisfied the linear and nonlinear Mohr–Coulomb strength criteria. Then, based on the limit equilibrium theory, the prediction method for the safety thickness of the base against confined water inrush was deduced, and a comparison with existing research works was conducted. Furthermore, the influence laws of soil strength parameters, pit design parameters, and confined water pressure on the critical safety thickness were analyzed. The results show that the critical safety thickness of the base is positively correlated with nonlinear coefficient and confined water pressure but negatively correlated with cohesion, internal friction angle, nonhomogeneity coefficient, and unit weight. The soil strength is a key factor affecting the base safety thickness, which should be paid enough attention to in engineering design and construction. The research findings in this paper can provide a theoretical reference for the prevention and control of basal inrush accidents in confined water strata....
Coral concrete made of coral sand/aggregates has attracted significant interest in the construction of coastal or artificial island buildings by saving significant economic and environmental costs for transporting the conventional building materials from mainland. However, the application of coral concrete is very limited due to the drawback such as low strength, brittleness, and high porosity. This paper develops a new coral concrete composite utilizing coral debris to replace sand and aggregates, sea water, supplementary cementitious waste materials, namely, fly ash and silica fume and modified polypropylene fiber (MPPF) to achieve both sustainable and economic development needs in coastal and island building and construction. The mechanical and durability of the new coral concrete are evaluated and the synergistic effects of fly ash and silica fume on the performance of MPPF coral concrete are discussed. It has been found out that the addition of fly ash and silica fume in MPPF coral concrete can significantly improve the strengths and reduce the chloride diffusion of coral concrete. Compared with those from the specimens without fly ash and silica fume, the compressive, splitting tensile, flexural strengths of MPPF concrete with 10% fly ash and 10% silica fume are improved by 31%, 33%, and 58%, respectively. The new coral concrete composite would be an ideal building material solution for coastal and artificial island applications as most of the materials come from the local wastes....
Due to the poor performance of ordinary Portland cement (OPC) as a solidified soil road and the large pollution in the production process, environment-friendly magnesium oxychloride cement (MOC) was used as the soil curing agent to prepare the solidified soil, exploring the optimal ratio of various raw materials when MOC is used as a curing agent. Analyzing the properties of MOC solidified soil in the application of road subgrade. This paper tests compaction, mechanical properties, and durability of the MOC solidified soil, simulates the development trend of 7 days unconfined compressive strength of MOC solidified soil, and then analyzes the hydration process and strengthens the formation mechanism of MOC in solidified soil. The study found that the addition of MOCas a curing agent to the soil can effectively improve the compaction and mechanical properties of the soil. Matlab simulation found that when the MgO content is 5.5% to 6% and the ratio of raw materials MgO, MgCl2, and H2O is 2.45 :1 :14 to 6.3 :1 : 14, the performance of MOC solidified soil is excellent. Fitting UCS data, it is found that MOC solidified soil has early strength characteristics. The excellent compaction and mechanical properties of MOC solidified soil are due to the formation of a small amount of phase 5 and layered Mg(OH)2 by the hydration of MOC, and the formation of amorphous gel with SiO2 in the soil. This reaction improves soil compaction and reduces internal porosity from a microscopic perspective. The strength loss rate of MOC solidified soil is higher after immersion in water at the initial stage of curing, but it is still better than that of traditional cement-based solidified soil. Poor performance after immersion in water is associated with disruption of the network-like structure. As an environment-friendly soil curing agent, MOC can be used in engineering practice with low environmental humidity....
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