Properties of concrete incorporating fine recycled aggregate

Influence of pozzolan from various by-product materials on mechanical properties of high-strength concrete

Use of palm oil fuel ash as a supplementary cementitious material for producing high-strength concrete

This paper presents use of improved palm oil fuel ash (POFA) as a pozzolanic material in producing high-strength concrete. The POFA was ground by ball mill until the median particle size was reduced to about 10μm. It was used to replace portland cement, ASTM Type I, by 10, 20, and 30% by weight of cementitious materials to make high-strength concrete. It was found that high-strength concrete can be achieved by using ground POFA to replace portland cement Type I up to 30%. At the age of 28days, concretes containing 10, 20, and 30% of ground POFA gave compressive strengths of 81.3, 85.9, and 79.8MPa, respectively. Concrete with 20% replacement of ground POFA had the highest strength. It is slightly higher than that of concrete containing 5% condensed silica fume and about 92–94% that of 10% condensed silica fume concrete. The ground POFA content up to 30% had slightly effect on lowering the modulus of elasticity of concrete. In addition, the use of ground POFA reduced the peak temperature rise of concrete u...

Utilization of Palm Oil Fuel Ash in High-Strength Concrete

This report presents guidelines to help bridge designers obtain realistic estimates of prestress losses in high-strength pretensioned concrete bridge girders and thus achieve economical designs. These guidelines incorporate procedures that yield more accurate predictions of modulus of elasticity, shrinkage, and creep of concrete and more realistic estimates of prestress losses than those provided by the procedures contained in current specifications. This report will be of particular interest to engineers, researchers, and others concerned with the design of pretensioned concrete bridge structures.

Prestress losses in pretensioned high-strength concrete bridge girders

The material properties of high-performance concrete (HPC) directly affect the design and construction of prestressed HPC bridge girders and their cast-in-place deck slabs. This paper discusses research experiments conducted over more than 2 years on material properties such as creep, shrinkage, and modulus of elasticity of 3 HPC mixtures with local materials from Nebraska. Test results from this research show that current ACI equations for shrinkage, creep, and modulus of elasticity of concrete do not accurately predict these material properties for HPC. Revised formulas for shrinkage strain and creep coefficient are proposed. Through this study, it was also indicated that it would be desirable to determine experimentally the shrinkage strain, creep coefficient, and modulus of elasticity using the locally available aggregates for the specified HPC mixture proportions.

Maher K. Tadros

Papers

Creep, Shrinkage, and Modulus of Elasticity of High-Performance Concrete