Pulse Velocity Measurements in Fly Ash Blended Cementitious Systems Containing 43 Grade Cement

Investigations on the different supplementary cementitious materials based on the hardening properties and the optimized dosage in cementitious systems find the right choice of pozzolanic material. It is essential to combine various additive/admixtures in concrete in proper proportions to maximize the benefits resulting in cost savings in construction. In the recent years, production technology and composition of hydraulic cements affect the setting and early age behavior of cementitious material. The addition of fly ash in cement is one viable technology to derive maximum benefits in terms of the economy and improved pozzolanic reaction. Ultrasonic pulse velocity testing is a feasible method for evaluating the hardening properties of cementitious materials. In this study, an attempt was made to derive the engineering basis for understanding the development of hardness during hydration of fly ash (FA) based cementitious systems. The tests conducted using pulse velocity technique proved to be an effective method for characterizing the early strength gain properties of different cementitious systems. 1. Introduction During recent years many variations have been made in the production technology, and its performance exceeded expectations. In addition, mineral admixtures like fly ash have been combined with Portland cement content improve the demonstrated excellent performance, both in mechanical as well as in durability aspects [1, 2]. The addition of pozzolanic admixtures converts the leachable calcium hydroxide into insoluble nonleachable calcium hydroxide in the cementitious products [3]. One such effect relates to the setting and early strength gain of concrete. Such delays are not desirable on site as tasks cannot be completed as per schedule. It is well known that chemical reactions between cement and water react with cement pastes, mortars, and concrete from fluids to rigid bodies [4]. The term setting has been used to describe the onset of rigidity in fresh cement pastes, mortar, and concrete. The setting phenomena are altered some factors, such as water/binder (w/b) ratio, curing regime temperature, and admixtures [5–8]. Thermodynamically, the initial set is marked by a rapid temperature rise, which corresponds roughly to the beginning of the main factor of chemical reactions that temperature rise will reach a maximum rate around the final set [9]. Chemical admixture becomes inevitably an important component to make a high early strength of hardened concrete [10]. The objective of this study is to establish the scientific and engineering bases for