Effect of chemical compounds in water setting times, workability and strength of high- performance- concrete with metakaolin and phosphogypsum admixture

Abstract

Effect of Chemical compounds in water on setting times, workability and strength of High-Performance-Concrete with metakaolin and phosphogypsum admixtures. Water is an important ingredient of concrete as it actively participates in the chemical reaction with cement. Cement is a mixture of complex compounds, the reaction of which with water leads to setting and hardening of cement. All the compounds present in cement are anhydrous but when brought into contact with water they get decomposed, forming hydrated compounds. Since water helps to form the strength giving cement gel, the quality of water required to be looked into very carefully. In practice, very often-great control on properties of cement is exercised, but the control on the quality of water is often neglected. In recent years, the terminology quotHigh-Performance-Concretequot (HPC) has been introduced into the construction industry. Most High-Performance-Concretes produced today contain materials in addition to portland cement to help achieve the strength or durability performance. These materials include fly ash, silica fume and ground-granulated blast furnace slag used separately or in combination. At the same time, chemical admixtures such as high-range water-reducers are needed to ensure that the concrete is easy to transport, place and finish. High-Performance-Concretes are also more sensitive to changes in constituent material properties than conventional concretes. Variations in the chemical and physical properties of the cementitious materials and chemical admixtures need to be carefully monitored. Substitutions of alternate materials can result in changes in the performance characteristics that may not be acceptable for high-performance concrete. This means that a greater degree of ii quality control is required for the successful production of high-performance-concrete and hence the quality of water being used for the production of High-Performance-Concrete (HPC) is very important.