نمونه متن انگلیسی مقاله
This study concentrated on the formulation of self-flowing and an energy efficient lightweight aggregate foamed concrete (LAFC) to be employed as thermal insulation, thermal mass and structural material. Low density concrete mixtures (for the density values from 800 to 1300 kg/m3 ) were prepared by changing the volume of lightweight expanded clay aggregate (ECA) from 49.4% to 20.1%. Flowing properties of concrete mixtures were improved with the help of stable foam. Ordinary Portland cement (OPC) was replaced by the 5% and 10% silica fume (SF) to examine the influence of SF on the properties of LAFC. Compressive strength and tensile strength of LAFC mixtures were respectively enhanced from 6.5 MPa to 24.30 MPa and 0.52 MPa to 1.63 MPa by reducing the volume of ECA from 49.4% to 20.1%. LAFC mixture (800-0SF) with the lowest density exhibited highest porosity and sorption coefficient value of 70.63% and 2.56 kg m2 min0.5. Thermal conductivity, volumetric specific heat capacity and thermal diffusivity of LAFC mixtures were in the range of 0.23–۰٫۴۵ W m1 K1 , 1136–۱۶۳۱ kJ/m3 .K and 0.20–۰٫۲۷۵ mm2 /s respectively. SEM analysis revealed that reduction in the volume of ECA and addition of SF densified the microstructure of LAFC. Finally, LAFC mixtures were classified into Class-I, Class-II and Class-III grade concretes for the structure and insulation purposes as per functional classification of RILEM.
Due to the scarcity of available energy resources, a lot of researches are being conducted on the usage of energy saving and energy efficient materials, and some countries have included the use of these materials in their fundamental policy to conserve the natural resources. In China, construction industry nearly consumes 35% of total energy . In the modern day, construction industry is rapidly growing industry because of the peak demands of contemporary infrastructure. In such cases, environmental stability and energy efficiency of buildings can be increased through the improvement in thermal properties of construction materials. A lot of previous studies have examined the workability, mechanical, thermal and hygroscopic properties of lightweight concrete containing foam and lightweight aggregate. Lightweight concretes, foamed concretes and aerated concretes with excellent thermal properties have been used as exterior wall materials [2–۹]. Foamed concrete belongs to the family of lightweight concrete and it is mainly composed of Portland cement (OPC), foaming agent, and aggregate. The purpose of using foaming agent is to introduce entrapped air in lightweight concrete .