Properties of cement mortar incorporated high volume fraction of GGBFS and CKD from 1 day to 550 days

This study aims to investigate the effect of cement replacement with high volume fraction of ground granulated blast furnace slag (GGBFS) and cement kiln dust (CKD) on mechanical, durability and microstructural properties of cement mortar from 1day to 550 days. Compressive strength and ultrasonic pulse velocity (UPV) were used to evaluate the mortars' performance. Besides, statistical analyses were conducted to predict mortars' mechanical and durability performance as well as investigate the influence of mortars’ properties (mixture and curing time) on their performance. The results indicated that replacing the cement with up to 60% GGBFS and CKD showed a comparable behavior to the cement after 28 days of curing onward. The statistical analysis revealed that the developed models achieved high level of agreement between the predicted and observed results with a coefficient of determination (R2) of more than 0.97. The findings in this study announced on the development of promising binder that can be used in different construction sectors with the benefits of reducing the CO2 emissions

Use of nano-silica to increase early strength and reduce setting time of concretes with high volumes of slag

Cement and Concrete Composites345650-662CCOC

Comparative study of the reactivity and performance of different nontraditional and natural pozzolans in cementitious system

The shortage of conventional supplementary cementitious materials opens up the prospect for broader utilization of nontraditional and natural pozzolans (NNPs). The NNPs used in the study included three calcined clays, three volcanic ashes (also referred to as natural pozzolans), three ground bottom ashes, and two fluidized bed combustion ashes. The study focused on assessment of the performance of these NNPs in portland cement systems by evaluating the following parameters: (a) development of the heat of reaction in cement pastes containing 25, 30, and 35 % of NNPs by weight of cement (bwoc) by means of isothermal calorimetry; (b) measurement of the consumption of calcium hydroxide (CH) in cement pastes containing 0, 25, 30, 35, 40, and 45 % (bwoc) of NNPs after 7, 28, and 56 days of curing using thermogravimetric analysis technique; (c) determination and quantification of the reaction products by quantitative x-ray diffraction in cement pastes containing 0 and 25 % (bwoc) of NNPs after 7, 28, and 56 days of curing; and (d) measurement of the 7- and 28-day compressive strength of mortar cubes. In all cases, the cumulative heat values of pastes containing NNPs were higher than those of reference pastes containing inert fillers, confirming that all NNPs were undergoing pozzolanic reaction. For most of the NNPs, the highest amount of CH consumed was observed in systems with 35 % replacement level. The early-age CH consumption correlated well with the content of alumina in NNPs whereas the later-age data correlated better with the silica content of the NNPs. In terms of compressive strength development, the highest early-age values were observed in mortars containing calcined clays, whereas other NNPs contributed to strength development at latter ages.Peer reviewe