Durability and Compressive Strength of High Cement Replacement Ratio Self-Consolidating Concrete

Abstract

This study examines durability and mechanical properties of sustainable self-consolidating concrete (SCC) in which 80% of the cement is replaced with combinations of recycled industrial by-products including fly ash, silica fume, and ground granulated blast furnace slag (GGBS). The water to binder (w/b) ratio of SCC mixes studies was maintained at 0.36. The study proposes empirical relationships to predict 28-day compressive strengths based on the results of three-day and seven-day compressive strengths. In addition, the chloride penetration resistance of the various sustainable SCC mixes was determined after three days, seven days, and 28 days of moist curing of concrete standards. It was concluded that fly ash, silica fume, and GGBS contribute favorably to enhancing strength development, fresh properties, and durability of SCC in comparison to ordinary Portland cement (OPC). The compressive strength of the sustainable SCC mixes falls within ranges suitable for structural engineering applications. Replacing cement with 15% silica fume produced a 28-day average compressive strength of 95.3 MPa, which is 44.2% higher than the control mix. Replacing cement with 15% or 20% silica fume reduced the chloride ion permeability to very low amounts compared to high permeability in a control mix. replacement of cement in SCC mixes results in loss of concrete compressive strength during the early stages, but, in many cases, a significant increase in compressive strength develops during later stages.Adding 3.8% silica fume improves compressive strength, splitting, tensile strength, and durability of SCC mixes Quercia [5]. It was found that replacing 15% of cement by silica fume resulted in a 28-day compressive strength of 95.3 MPa, which was 44% higher than the control SCC mix examined in the study by Mohamed and Najm [6]. Due to their spherical morphology, which reduces inter-particle friction, both silica fume and fly ash enhance workability and is essential for producing high strength concrete.Partial replacement of cement in SCC with various industrial byproduct wastes such as limestone power, cement kiln dust, and pulverized steel slag improves resistance to chloride penetration [7]. Other studies, however, contend that, under laboratory conditions, the durability of SCC and traditional vibrated concrete may be comparable [8] and that using Rapid Chloride Penetration Test (RCPT) to assess durability of SCC does not produce reliable results. However, the same study acknowledges that the quality of compacting vibrated concrete onsite is unlikely to reach the quality of SCC. As a result, concrete structures built with SCC may still be more durable.Partial replacement of cement with GGBS in SCC enhances compressive strength and durability. In one study, it was shown that replacing 70% of cement in a particular SCC mix resulted in strength as high as the control SCC mix [9].Alkali-silica reaction (ASR) may lead to significant long-term damage and degradation of concrete properties [10]. GGBS is known to improve concrete resis...

Effect of Mix Constituents and Curing Conditions on Compressive Strength of Sustainable Self-Consolidating Concrete

“…Mixes with such a high GGBS content were shown to exhibit very high resistance to chloride penetration even after one day of curing [35]. Similarly, quaternary mixes containing 20% OPC and 80% SCMs (GGBS, silica fume, and fly ash) were shown to have very high resistance to chloride penetration [36]. Figure 9 shows that both 100% OPC concrete and 10% OPC mix increased in compressive strength but the ratio of 100% OPC concrete to the 10% OPC concrete decreased from 1.77 after three days of curing to 1.36 after 56 days days of curing.…”

Fresh Properties and Sulfuric Acid Resistance of Sustainable Mortar Using Alkali-Activated GGBS/Fly Ash Binder

“…This is because of the slow dissolution of fly ash and formation of polymerization products at ambient temperature which delays of filling of voids when fly ash content is high. Curing temperature generally affects both hydration of OPC and polymerization of fly ash, therefore, influences rate of strength development [40,41]…”

A Review of Durability and Strength Characteristics of Alkali-Activated Slag Concrete

“…In binary OPC + GGBS concrete, the resistance to chloride penetration increases with increase in GGBS content. Concrete in which 80% of OPC was replaced with GGBS experienced very low passing charge in chloride penetration test, even after one day of curing [56].…”

“…Effect of silicate modulus on compressive strength of the AAS mortars with different alkali dosages before carbonation (after steam curing) and after 56 days of carbonation [56,62]. …”