الفهرس 
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Abstract
Lightweight aggregate concrete is particularly suitable for use where low density, good thermal insulation or fire protection are required. However, not all of the available aggregates are equally suitable for any particular application. The work presented in this thesis was conducted to study mechanical, physical, acoustic and thermal properties of lightweight aggregate concrete. Leca, vermiculite, and polystyrene foam are selected as coarse aggregates to produce lightweight-aggregate concrete. Leca is expanded-clay aggregate and is manufactured in the rotary kiln. Vermiculite is a mineral flaky material with many thin layers per each flake, while polystyrene particle is expanded foam grains with irregular small pieces. Aerated concrete was also produced and tested. Aluminum powder was used to generate air bubbles in aerated concrete. In order to study the main properties of lightweight concrete, four groups of different lightweight concretes with a total number of thirteen mixes were prepared and investigated. Mix proportioning of different mixes was based on a lot of trial mixes. The variables of this study include -among others- coarse aggregate types, and the ratio of fine to coarse aggregates. Chemical and mineral admixtures such as superplasticizers and silica fume were used. The measured properties include density, compressive strength, flexural strength, bond strength, splitting strength, modulus of elasticity, Poisson’s ratio, stress-strain relationship, and deflection. The study also includes measurements of sound absorption coefficient, sound insulation, thermal expansion, thermal conductivity, and effect of heat on the compressive strength of different concrete mixes. The test results showed that lightweight concrete with a density in the range of 1412 to 2152 kg/m3 and compressive strength up to 32 MPa was successfully produced using local materials in Egypt. On average, the modulus of elasticity ranged from 6 to 17 GPa depending on the density and strength of concrete. The average strength/density ratio was approximately 14.8, 9.9, 8.0 and 3.9 MPa.m3/ton for leca concrete, polystyrene concrete, vermiculite concrete and aerated concrete respectively. Thus, from the strength point of view, leca seems the most suitable aggregate for producing LWC compared to polystyrene and vermiculite. The use of silica fume in LWC did not produce additional strength. The strength of lightweight aggregate particles is the main key-element for achieving and limiting the strength of LWC. Accordingly, the use of silica fume in LWC may not be necessary. However, silica fume can be used in LWC for durability aspects. LWC showed relatively lower ratio of bond/compressive strength compared to traditional concrete. However, normal values for the splitting/compressive ratio as well as the flexural/compressive ratio were recorded. LWC mixes exhibited permeability coefficient, which did not differ more than that of normal weight concrete. This may be due to the existence of high quality matrix around the lightweight aggregate particles. Lightweight concrete has sound absorption coefficient in the range from 0.31 to 0.47 and sound insulation from 45 to 71 dB. The recorded thermal expansion coefficient of this concrete lies in the range from 0.75 (10)-5 to 0.89 (10)-5 cm/cm/oc, while the thermal conductivity varies from 0.51 to 0.70 J/m2.sec.oc/m. The comparison between these results and those of normal-weight concrete emphasizes the merit of using such lightweight concrete in thermal and acoustic insulation purposes. In general, by using a suitable lightweight concrete mix, it is possible to attain a desired degree of thermal or acoustic insulation and to use it economically for structural purposes.