Papers by Author: Iqbal Khan Mohammad

Abstract: Microstructural properties such as pore structure and hydration play a decisive role in determining the properties of a concrete. This paper presents the investigation on pore structure and hydration process of high strength concrete. Pore structure study was conducted using mercury intrusion porosimetry and hydration progress was monitored using thermogravimetry analysis on various blended combinations of cementitious materials incorporating fly ash and silica fume as partial cement replacement. It was found that silica fume refined the pore structure efficiently and reduced the calcium hydroxide content as early as 1 day. All ternary blended systems containing fly ash and silica fume exhibited lower calcium hydroxide content and refined pore structure in comparison to their respective blended pastes.

Abstract: Nondestructive testing (NDT) is a technique to determine the integrity of a material, component or structure. The commonly NDT methods used for the concrete are dynamic modulus of elasticity and ultrasonic pulse velocity. The dynamic modulus of elasticity of concrete is related to the structural stiffness and deformation process of concrete structures, and is highly sensitive to the cracking. The velocity of ultrasonic pulses travelling in a solid material depends on the density and elastic properties of that material. Non-destructive testing namely, dynamic modulus of elasticity and ultrasonic pulse velocity was measured for high strength concrete incorporating cementitious composites. Results of dynamic modulus of elasticity and ultrasonic pulse velocity are reported and their relationships with compressive strength are presented. It has been found that NDT is reasonably good and reliable tool to measure the property of concrete which also gives the fair indication of the compressive strength development.

Abstract: Measurement and prediction of absorption of concrete by saturation method is presented. Measurement of absorption of concrete consisting of supplementary cementitious materials was conducted by using vacuum saturation method in accordance to RILEM. Pulverized fuel ash and silica fume were incorporated as partial cement replacements for the preparation of various combinations of cementitious composite systems. Absorption of cement matrix containing ordinary Portland cement, pulverized fuel ash and silica fume at various ages is reported. Based on the experimentally obtained results, analytical prediction models were developed. These models enabled the establishment of isoresponse contours showing the interactive influence between the various parameters investigated.