Aggregate (composite)

About: Aggregate (composite) is a research topic. Over the lifetime, 31015 publications have been published within this topic receiving 354178 citations.

Properties of concrete

Abstract: 1. Portland Cement. 2. Cementitious Materials Of Different Types. 3. Properties Of Aggregate. 4. Fresh Concrete. 5. Admixtures. 6. Strength Of Concrete. 7. Further Aspects Of Hardened Concrete. 8. Temperature Effects In Concrete. 9. Elasticity, Shrinkage And Creep. 10. Durabilty Of Concrete. 11. Effects Of Freezing And Thawing And Of Chlorides. 12. Testing Of Hardened Concrete. 13. Concretes With Particular Properties. 14. Selection Of Concrete Mix Proportions (Mix Design). Appendices. Index.

Composition of reactive powder concretes

Abstract: Development of an ultra-high strength ductile concrete designated RPC (Reactive Powder Concrete), was made possible by the application of a certain number of basic principles relating to the composition, mixing and post-set heat curing of the concrete. RPC 200, which can be used under job site conditions similar to those for conventional high performance concretes, can be used in the construction of prestressed structures incorporating no passive reinforcement. RPC800 is suitable for precasting, and can achieve compressive strength values exceeding 600MPa. A value of 810MPa has been obtained with a mixture incorporating steel aggregate.

Influence of Amount of Recycled Coarse Aggregates and Production Process on Properties of Recycled Aggregate Concrete

Abstract: In this study recycled coarse aggregates obtained by crushed concrete were used for concrete production. Four different recycled aggregate concretes were produced; made with 0%, 25%, 50% and 100% of recycled coarse aggregates, respectively. The mix proportions of the four concretes were designed in order to achieve the same compressive strengths. Recycled aggregates were used in wet condition, but not saturated, to control their fresh concrete properties, effective w/c ratio and lower strength variability. The necessity to produce recycled aggregate concrete with low–medium compressive strength was verified due to the requirement of the volume of cement. The influence of the order of materials used in concrete production (made with recycled aggregates) with respect to improving its splitting tensile strength was analysed. The lower modulus of elasticity of recycled coarse aggregate concretes with respect to conventional concretes was measured verifying the numeral models proposed by several researchers.

Aggregate stability and assessment of soil crustability and erodibility: I. Theory and methodology

Abstract: Summary Crusting and erosion of cultivated soils result from aggregate breakdown and the detachment of soil fragments by rain, and the susceptibility of soil to these processes is often inferred from measurements of aggregate stability. Here, theories of aggregate breakdown are reviewed and four main mechanisms (i.e. slaking, breakdown by differential swelling, mechanical breakdown by raindrop impact and physico–chemical dispersion) are defined. Their relative importance depends on the nature of the rain, as well as on the soil's physical and chemical properties. The relations between aggregate breakdown, crusting and water erosion are analysed, and existing methods for the assessment of aggregate stability are reviewed. A unified framework for the measurement of aggregate stability is proposed to assess a soil's susceptibility to crusting and erosion. It combines three treatments having various wetting conditions and energies (fast wetting, slow wetting, and stirring after pre-wetting) and measures the resulting fragment size distribution after each treatment. It is designed to compare different soils, or different climatic conditions for a given soil, not to compare time-dependent changes in that soil.

XLVI. A theory of the plastic distortion of a polycrystalline aggregate under combined stresses.

Abstract: Summary A general relationship between stress and plastic strain in a polycrystalline aggregate is derived for any metal in which individual crystals deform by slipping over preferred planes under a critical shear stress. Full account is taken of the non-uniform distortion due to mutual constraints between the grains of an aggregate. It is shown that a plastic potential exists which is identical with the yield function. Upper and lower bounds are obtained for an approximate calculation of this function for any applied system of combined stresses.