scholarly journals Physical and Chemo/Mechanical behaviors of fly ash and silica fume belite cement pastes- Part I

NanoNEXT ◽  
2021 ◽  
pp. 1-15
Author(s):  
Darweesh H.H.M
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Total Porosity ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Heat Of Hydration ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Belite Cement

Physical, chemical and mechanical properties of high belite cement (HBC) blended with high pulverized fly ash (HPFA) with stable ratio of silica fume (SF) in comparison with Portland cement (OPC) were investigated. Results showed that the water of consistency and setting times (Initial and final) tended to increase with the increase of HPFA content. The bulk density and compressive strength were also improved and enhanced with the increase of HPFS content at all hydration times, but only up to 15 % HPFA, and then decreased with further increase.  However, the total porosity slightly decreased, but started to increase with further increase of >15 % HPFA. The free lime content of the pure OPC and HBC gradually were increased as the hydration times progressed up to 90 days, while those of blended cements increased only up to 7 days and then decreased onward. The results were confirmed by measuring the heat of hydration and ultrasonic pulse velocity for the optimum cement pastes comparing with those of both OPC and HBC. The heat of hydration of the optimum cement pastes was decreased at all hydration times and become lower than those of OPC and HBC. The ultrasonic pulse velocity test (USPV) proved that the uniformity and quality of the matrix of the hardened cement pastes are good with no cracks.

Effect of Treated Sago Pith Waste Ash and Silica Fume to the Mechanical Properties of Fly Ash-Based Geopolymer Brick

2021 ◽  
Vol 879 ◽  
pp. 100-114
Author(s):  
Izwan B. Johari ◽  
Md Azlin Md Said ◽  
Mohd Amirul B. Mohd Snin ◽  
Nur Farah Aqilah Bt. Ayob ◽  
Nur Syafiqah Bt. Jamaluddin ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Partial Replacement ◽  
Rebound Hammer ◽  
Compressive Strength Test ◽  
Sago Pith Waste

This paper investigates the effect of partial replacement of fly ash with sago pith waste ash and silica fume in fabricating the geopolymer mortar concrete. The mixtures of geopolymer mortar concrete were prepared by replacing sago pith waste ash and silica fume at 5% of total weight of fly ash. There were six specimens of geopolymer mortar cubes and bricks fabricated in this study. The specimens are tested with compressive strength test, rebound hammer test and ultrasonic pulse velocity test. The results from the tests are compared with some existing published works as to clarify the effect of replacing the fly ash with sago waste and silica fume on the strength of concrete. Comparisons had been made and concluded that the molarity of alkaline solution, Al3O2 and CaO influenced the development of compressive strength along the curing time of fly ash based geopolymer concrete.

scholarly journals Ultrasonic Pulse Velocity and Morphology of High Strength Concrete with PVC Waste Aggregate

2020 ◽  
Vol 8 (5) ◽  
pp. 3783-3788 ◽  
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
High Ratio ◽  
Hardened Cement ◽  
Strength Concrete ◽  
Residual Properties

In this paper, morphology and ultrasonic pulse velocity (UPV) of high strength concrete with a relatively high ratio of condensed silica fume and PVC waste aggregate as sand replacement have been examined. The plastic aggregate was obtained from shredding PVC waste sheets used for secondary roofing and covering walls. Variables tested were PVC plastic grading and ratio of sand replacement with such plastic, in addition to curing time of concrete. Results of scanning electron microscopy showed that there is a good bond between PVC aggregate particles and hardened cement paste. There was a relatively small reduction of UPV value of concrete, increased with increasing PVC aggregate content, reached 14.3% at 40% PVC content. The UPV lost is slightly increased with increasing concrete age from 7 days to 56 days. Results also showed that the effect of PVC aggregate grading on the residual UPV is not important. Based on the measured residual properties of high strength with silica fume and PVC granules, there is a high degree of silica fume hydration and the existence of PVC particles has no effect on such hydration.

scholarly journals Evaluating the Durability of Green Cement Mortar Using Ultrasonic Pulse Velocity

2021 ◽  
Vol 877 (1) ◽  
pp. 012049
Author(s):  
Ali Abdulridha ◽  
Saif S. AlQuzweeni ◽  
Rasha S. AlKizwini ◽  
Zahra A. Saleh ◽  
K. S. Hashem
Keyword(s):  
Silica Fume ◽  
Cement Mortar ◽  
Experimental Studies ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cement Kiln Dust ◽  
Cement Kiln ◽  
Negative Consequences ◽  
Kiln Dust

Abstract Various experimental studies have highlighted the negative consequences of Portland cement on health and the environment, such as toxic emissions and alkaline sewage. The development of environmentally acceptable substitutes for cement is thus one of the objectives of current investigations. The proposed environmental alternatives to cement, nevertheless, might have detrimental impacts on the concrete’s characteristics. This investigation intends to study the suitability as alternatives to cement in cement mortar, using industrial wastes like silica fume and cement kiln dust. As a replacement for cement, the cement mortars developed in this research continue from 0% to 60% silica fume and cement kiln dust. Ultrasonic pulse velocity tests at 1 to 4 weeks of age were conducted on hardened specimens. The findings showed that a low reduction in the pulse velocity resulted from high proportions of silica fume and cement kiln dust replacements, whereas an improvement in the characteristics of the mortars with low replacement ratios. Using low kiln dust and silica fume of 20 to 40%, the durability of mortars may increase.

scholarly journals Effects of a Real Exposure Class XC4 Mediterranean Climate Environment in the Behavior of Mortars Made Using Ternary Binders with Addition of Slag, Fly Ash and Limestone

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5848
Author(s):  
Javier Ibáñez-Gosálvez ◽  
Teresa Real-Herraiz ◽  
José Marcos Ortega
Keyword(s):  
Fly Ash ◽  
Mediterranean Climate ◽  
Mechanical Performance ◽  
Ultrasonic Pulse Velocity ◽  
Pore Network ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cement Industry ◽  
Granulated Blast Furnace Slag ◽  
Compressive And Flexural Strengths

For improving the contribution of the cement industry to mitigate global warming, many strategies have been put into practice, such as the use of eco-friendly cements with the incorporation of additions substituting clinker. Nevertheless, the use of ternary binders for the production of commercial cements is still reduced, particularly in Spain. The purpose of this research is to characterize the long-term influence produced by the exposure to a real in situ inland Mediterranean climate condition in the pore network, parameters related to durability and mechanical performance of mortars made with ternary binders, which incorporated limestone, fly ash, and ground granulated blast-furnace slag, in comparison with mortars without additions and binary blended mortars. The site verified the specifications of exposure class XC4 of Eurocode 2. The ternary and binary binders accomplished the prescriptions of cement type CEM II/B. The pore network was studied with mercury intrusion porosimetry and electrical resistivity. Water absorption, diffusion coefficient, carbonation depth, ultrasonic pulse velocity, compressive and flexural strengths have been determined. The exposure to the environment produced after 250 days an increase in porosity, a loss of pore refinement, a rise of the carbonation depths, and a reduction in the mechanical strengths, highlighting the better overall performance of ternary mortar with both fly ash and slag.

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

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
V. M. Sounthararajan ◽  
A. Sivakumar
Keyword(s):  
Fly Ash ◽  
Cost Savings ◽  
Ultrasonic Pulse Velocity ◽  
Cementitious Materials ◽  
Ultrasonic Pulse ◽  
Pozzolanic Reaction ◽  
Pulse Velocity ◽  
Supplementary Cementitious Materials ◽  
Pozzolanic Material ◽  
Cementitious Systems

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.

scholarly journals Empirical Investigation on Compressive Strength of Geopolymer and Conventional Concretes by Nondestructive Method

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
B. Ravali ◽  
K. Bala Gopi Krishna ◽  
D. Ravi Kanth ◽  
K. J. Brahma Chari ◽  
S. Venkatesa Prabhu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Nondestructive Method ◽  
Geopolymer Concrete ◽  
River Sand ◽  
Rebound Hammer ◽  
Compressive Strength Of Concrete

Need of construction is increasing due to increase in population growth rate. The geopolymer concrete is eco-friendly than ordinary concrete. Current experimental investigation was conducted on ordinary and geopolymer concrete using nondestructive testing (NDT) tests like ultrasonic pulse velocity (UPV) test and rebound hammer (RH) test. Cube specimens of dimensions 150 mm × 150 mm × 150 mm are used to conduct these tests at 7, 14, and 28 days. Proportions considered for concrete are cement-fly ash-river sand (100-0-100% and 60-40-100%), cement-fly ash-robo sand (100-0-100% and 60-40-100%) whereas geopolymer concrete fly ash-metakaolin is taken in proportions of 100-0%, 60-40%, and 50-50%. Alkaline activators (sodium hydroxide and sodium silicate with molarity 12M) were used in preparing geopolymer concrete. The major objective of the current study is to obtain relation between compressive strength of concrete and UPV values.

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