A cement paste or mortar is composed of a mineral skeleton with micron to millimeter-sized grains, surrounded by water filaments. The cohesion or shear resistance in the cement paste and mortar is caused by capillary forces of action. In the case of mortar mixes, there is friction between the particles. Therefore, the mortar mixture shows both friction between particles and cohesion, while the paste shows only cohesion, and the friction between particles is negligible. The property of the cement paste is greatly influenced by the rheological characteristics like cohesion and internal angle friction. It is also interesting that when studying the rheology of fresh concrete, the rheological behavior of cement paste and mortar has direct applicability. In this paper, the rheological characteristics of cement paste and mortar with and without mineral admixtures, that is, fly ash and ground granulated blast-furnace slag (GGBS), were studied. A cement mortar mix with a cement-to-sand ratio of 1:3 was investigated, including fly ash replacement from 10% to 40%, and GGBS from 10% to 70% of the weight of the cement. A suitable blend of fly ash, GGBS, and ordinary Portland cement (OPC) was also selected to determine rheological parameters. For mortar mixtures, the flow table was conducted for workability studies. The flexural and split tensile strength tests were conducted on various mortar mixtures for different curing times. The results indicate that in the presence of a mineral mixture of fly ash and GGBS, the rheological behavior of paste and mortar is similar. Compared with OPC-GGBS-based mixtures, both cement with fly ash and ternary mixtures show less shear resistance or impact resistance. The rheological behavior of the mortar also matches the rheological behavior in the flow table test. Therefore, it is easy to use the vane shear test equipment to conduct cohesion studies to understand the properties of cement paste and mortar using mineral admixtures. The strength results show that the long-term strength of GGBS-based mixtures and ternary mixed mixtures is better than that of fly-ash-based mixtures. For all mixtures, the strength characteristics are greatest at a w/b ratio of 0.6.
This paper presents the free and forced vibration characteristics of a hybrid honeycomb core sandwich structure consisting of a top and bottom FG-CNT reinforced polymer composite face sheet in a thermal environment. Different thermal fields like the uniform, linear and nonlinear temperature fields in the thermal environment along the thickness direction are considered to study the dynamic characteristics of the hybrid honeycomb core sandwich structure. The mathematical model is developed using Hamilton’s principle along with the third-order shear deformation theory. Five unknown modal coefficients are found using the modal superposition principle to calculate the forced vibration response. From the free and forced vibration results, it is observed that the FG-V[Formula: see text] grading pattern face sheets with lower cell size honeycomb core and with higher cell wall thickness honeycomb core show better vibration characteristics. It is noticed that the sandwich structure with honeycomb core and FG-V[Formula: see text] CNT reinforced polymer composite face has a higher critical buckling temperature in the thermal environment. Furthermore, for different percentages of critical buckling temperature, the natural frequencies and vibrating patterns for uniform, linear and nonlinear temperature fields are the same for the sandwich structure with UD, FG-V[Formula: see text] and FG-[Formula: see text]V CNT reinforced polymer composite faces. In addition, the resonant peak of the sandwich structure with FG-V[Formula: see text] CNT reinforced polymer composite face in nonlinear temperature field shifts more toward the right, while that of the uniform temperature field shifts more toward the left in the velocity response.
To find the energy required during the mixing process of self-compacting concrete in a ready-mixed concrete plant and correlate the results with the yield stress of concrete. Power consumption required during the mixing of concrete is measured with a wattmeter connected to the mixing unit’s power supply. A coaxial cylinder viscometer is used to measure the yield stress of concrete. The clamp meter measures the power when the impeller rotates inside the coaxial cylinder viscometer, which is filled with concrete. When the impeller rotates in a coaxial cylinder filled with concrete, the power is measured by a clamp meter. Torque is obtained through the power relationship, which is an essential factor in determining the yield stress. The cost of a rheometer is so high that all construction industries, research institutions, and researchers cannot measure rheological parameters. Nowadays, all rheometers are automated; hence, the cost is very high. Tattersall’s approach of power requirement in mixing the concrete and calculating the yield stress reduces the complexity in determining the rheological parameter.
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