Ternary mixes with high mineral additions contents and corrosion related properties

Abstract

The choice of blended cements and materials with cementitious properties in concrete is currently seen as a choice that increases the environmental sustainability of the construction industry. The developments with non‐traditional binders (such as the simultaneous incorporation of several types of supplementary cementitious materials) have highlighted new challenges to be researched. In the present paper ternary binders were prepared by mixing ordinary Portland cement (OPC) plus two blended components: low calcium fly ash, blast furnace slag, and/or limestone filler. Several physical and mechanical properties of ternary blend systems have been analyzed in mortar form at several curing ages: 2, 7, 28, and 90 days. Additionally preliminary tests of corrosion performance of reinforcement in these types of mixes have been considered. The results indicate that the use of appropriate content components in ternary blends will allow binders to fulfill the specified mechanical requirements. The best results are obtained when two additions with antagonist properties are mixed, as fly ashes and slags or slags and filler limestone. Besides, certain influence of the effect on durability performance is detected, in particular associated with the stability of the passive state and corrosion of reinforcements in presence of chlorides.

Microstructural verification of the strength performance of ternary blended cement systems with high volumes of fly ash and GGBFS

“…As similarly reported in earlier studies [5][6][7]15], the ternary blended concrete specimens showed considerably lower mechanical properties at early ages (see Fig. 5) compared to OPC since it was still too early for the high portions of mineral admixtures (i.e., fly ash and GGBFS) to produce significant degrees of pozzolanic reactions for strength increase.…”

“…Because the vast use of industrial by-products such as ground granulated blast furnace slag (GGBFS) and coal-fired fly ash (fly ash) enable significant cost savings for concrete production as well as lead to a more ecologically sustainable society, GGBFS and fly ash are commonly incorporated into Portland cement (cement) concrete mixtures in South Korea. In particular, the most important technical benefit is the reduction of thermal cracking due to the lower heat generation of the cement hydration than the use of only Portland cement for concrete production [2][3][4][5][6]; thus, there have been extensive attempts to increase the ratio of GGBFS and fly ash in the cement concrete mixtures in South Korea. However, most previous studies have investigated relatively low replacement ratios of the industrial by-products between 20% and 50% in concrete production and only a few studies examined higher substitution ratios over 60% [7][8][9].…”

Influence of the synergy between mineral additions and Portland cement in the physical-mechanical properties of ternary binders

“…This effect is more relevant when additions with different hydration mechanism are combined (11,15,(17)(18)(19)(20)(21)(22)(23). The future of CEN (European Committee for Standardization) is on the way to include the ternary blends in the standards (9).…”

“…Different studies showed that ternary blends using PC with relatively high alkali and C 3 A content had lower initial mechanical strength than plain PC (5,18,19,22,24), while in mixes with PC containing low alkali and/or C 3 A content this effect is less relevant (11,15,20,21,23,25). Dehuai and Zhaoyuan (24) found that in ternary blends composed of 50-70% PC with 8% C 3 A and 0.9% Na 2 O eq .…”

Passive corrosion of steel reinforcement in blended cement-based material in the context of nuclear waste disposal

“…The behaviour of steel embedded in blended cement is not so well known. The electrochemical study of corrosion resistance in ternary mixes (incorporating slag and fly ash) indicates that a passive state is reached and even suggests a lower corrosion rate after passivation compared to Ordinary Portland Cement mortar [11]. In contrast, the electrochemical impedance spectrometry (EIS) response of steel electrodes immersed in synthetic pore solution of a blast furnace slag cement (CEM III type, according to European standards) presents an active behaviour at 5 days [12].…”