Analysis of Hydration and Optimal Strength Combinations of Cement-Limestone-Metakaolin Ternary Composite

Abstract

Metakaolin (MK) is an aluminosilicate pozzolan material and can contribute to property development of concrete due to the pozzolanic reaction. Limestone (LS) powder presents the dilution effect, nucleation effect, and chemical effect on hydration of cement. When metakaolin and limestone are used together, due to the additional chemical reaction between the aluminum phase in MK and limestone, the synergetic benefit can be achieved. This study presents a hydration model for cement-limestone-metakaolin ternary blends. Individual reactions of cement, metakaolin, and limestone are simulated separately, and the interactions among cement hydration, limestone reaction, and metakaolin reaction are considered through the contents of calcium hydroxide and capillary water. The hydration model considers the pozzolanic reaction of metakaolin, chemical and physics effects of limestone, and synergetic effect between metakaolin and limestone. Furthermore, the gel-space ratio of hydrating concrete is calculated using reaction degrees of binders and concrete mixtures. The strength development of ternary blends is evaluated using the gel-space ratio. Based on parameter analysis, the synergetic effect on strength development is shown and the optimal combinations of cement-limestone-metakaolin ternary blends are determined.

Model-Based Methods to Produce Greener Metakaolin Composite Concrete

“…Third, in future research, the following items should be studied: (1) the cost analysis of reinforced concrete structures, which considers material cost, labor cost, and indirect cost [18]; (2) the service life analysis in the operation stage, such as cracks and shrinkage, corrosion of steel rebar, and freezing and thawing [17]; (3) sustainable design method with various indicators, such as concrete performance, durability, and total cost. Moreover, the global optimal design of reinforced concrete structures with multiple aims should be performed [21,22].…”

“…In our previous studies [21][22][23], a composite hydration model was presented for metakaolin composite concrete. Cement hydration and metakaolin reaction were simulated separately.…”

“…dt, where dα MK dt is the rate of metakaolin reaction. Our previous studies [21][22][23] showed details of equations for the cement hydration rate and the rate of metakaolin reaction.…”

The Fabrication of Portland Composite Cement Based on Pozzolan Napa Soil

“…Pozzolan is a material rich in aluminum and silicon [5], which in its finely divided form and in the presence of water, chemically reacts with calcium hydroxide. This reaction gives rise to hydrated calcium silicate and other byproducts [4,6]. Although pozzolan does not bind materials as effectively as cement, the water it contains causes it to form binding substances through certain reactions [7].…”

Enhanced Mechanical and Microstructural Properties of Portland Cement Composites Modified with Submicron Metakaolin

“…e reason for the widespread use of metakaolin is that it has economic and technological advantages over cement and concrete, which reduces the hydration heat and thus the cost of production per cement unit [11,12]. Moreover, it has been reported that it has higher pozzolanic characteristics and reduces alkali-aggregate reactions [13][14][15][16][17]. However, due to its large particles and high agglomeration, metakaolin reduces the workability and mechanical properties of cement slurry and concrete, which causes the strength of the concrete mixed with metakaolin to be lower than that of the plain concrete [14].…”