A Review on Sustainable Concrete with the Partially Substitutions of Silica Fume as a Cementitious Material

1. Introduction

Self-compacting concrete (SCC) is a unique kind of concrete that is flowable, non-segregating, and expands into the formwork by its own mass without the aid of external vibrators, even when there is heavy reinforcement present. SCC is becoming more popular in civil engineering. SCC continues to explore a variety of applications and characteristics [ 1 ]. Four parameters, including flowability, viscosity, passing ability, and segregation resistance, may be used to differentiate SCC from conventional concrete. If the concrete has all four of the aforementioned traits, it is referred to as SCC [ 2 ]. In terms of history, the SSC idea was initially established in 1986 [ 3 ]. However, in 1988, Japan was the first nation to successfully create a prototype of SCC. Similar to ordinary concrete, the SCC building is unsustainable due to its high natural resource use.

5,6,9,10,11,

According to the idea of environmental development, environmental resources should be preserved as limited commodities and wastes should be adequately controlled [ 4 7 ]. The growing quantities of composed trash, up to 2500 million tons annually around the globe, encouraged the development of a contemporary method of dumping [ 8 ]. There are various options to use leftover raw materials in concrete in the cement manufacturing sector [ 5 12 ]. Waste may be used in concrete as cement, or fine or coarse aggregate.

14,

In the construction industry, concrete is the most often used man-made construction resource, and hydraulic cement is an essential component of this material [ 13 15 ]. Nearly 30 billion tons of concrete were produced in 2015, using approximately four enormous volumes of hydraulic cement annually [ 16 ]. The findings presented at the World Cement Association Conference demonstrate that the yearly rate of global cement production has increased [ 17 ]. There has been significant industrial expansion as a result of the expanding need for cement in modern structures and infrastructure, notably in developing nations like China, Russia, and Japan [ 18 ]. The capacity to manufacture 59.5 million tons of cement per year was built due to the projection of future demand for expanding infrastructure. The cost of cement has increased by roughly 150% in only 10 years [ 19 ]. Therefore, it’s crucial to use alternative materials wherever feasible, instead of cement [ 20 ].

22,

The use of a mineral additive is one of the ways SCC differs from conventional concrete. Viscosity-increasing additives, or fillers, are used in SCC to prevent the separation of big particles. When casting concrete underwater, or for SCC in tunnels, an additive to improve viscosity is often employed. To enhance the viscosity of SCC, mineral admixture fillers may be added to the slurry [ 11 ]. The performance of SCC with various pozzolanic materials substituted for cement has been studied by researchers [ 21 23 ]. According to Siddique et al. [ 24 ], the use of mineral admixtures raises the slump without raising the cost of the mixture, and lowers the amount of superplasticizer required. According to earlier research, fly ash-containing mixtures had less compressive capacity values at early ages. The sluggish pozzolanic reaction between the binder (OPC) and fly ash (FA) was the root cause of this issue [ 25 ]. Furthermore, the rate of pozzolanic reaction of secondary cementitious material also depends on the temperature.

Silica fume (SF) is a poisonous material that harms the environment and its surroundings. Nearly all SF was discharged into the environment up until the mid-1970s. There were many uses for SF even as environmental concerns about it increased. SF is a very pozzolanic substance due to its tiny particle size and high concentration of amorphous silicon dioxide, as seen in the Table 1

2 to react to produce more CSH and earlier strength [

Silica fume’s amorphous structure makes it very reactive; they are round and have a sizable surface. SF particles are packed densely with cement grains because they are 100 times smaller than OPC grains, which allows calcium hydroxide and SiOto react to produce more CSH and earlier strength [ 30 ]. SF increases the concrete’s packing density because of its microscopic size. SF concrete has been applied extensively in high-strength concrete for highway bridges, marine constructions, and parking decks, because of its outstanding performance [ 31 ]. The benefits of using SF in concrete are shown in Figure 1

2 content and electrical resistivity was found to be 0.95 with a positive slope for reference SCC and 0.97 with a negative slope for samples containing pozzolans. It can be suggested to apply the electrical resistivity as a simple method to calculate CH content in cement paste. Leung and Kim [

To accomplish sustainable construction and formwork, silica fumes have recently grown in prominence as a partial alternative for cement. SF was used by Ardalan and Joshaghani [ 32 ] in SSC in combination with pumice. An increase in SSC workability and compressive strength was observed. A study [ 33 ] found that the greatest mechanical qualities were produced by a ternary combination of nano-silica (2.5%) and micro silica fumes (2.5%). A researcher [ 34 ] studied the use of electrical resistivity of SSC (containing SF and metakaolin) to determine the amount of calcium hydroxide. The correlation coefficient of the relationship between Ca(OH)content and electrical resistivity was found to be 0.95 with a positive slope for reference SCC and 0.97 with a negative slope for samples containing pozzolans. It can be suggested to apply the electrical resistivity as a simple method to calculate CH content in cement paste. Leung and Kim [ 35 ] conducted research on the SSC’s moisture absorption capabilities after replacing some of the cement with flaky ash and SF. With partial substitution, moisture absorption was reduced, but compressive strength was increased. The link between moisture absorption and compressive strength was not found. SF in SSC (created using leftover concrete aggregates) have reduced porosity and moisture absorption, according to researchers [ 36 ]. Fouroghi et al. found that a SF concentration of 5% in SSC had the best pore characteristics [ 37 ].

Some literature shows that SF improved the strength and mechanical properties of SCC; however, information is scattered, and no one can easily judge the exact benefits of SF in concrete. Furthermore, according to the author’s best information, most researchers focus on reviewing the properties of conventional concrete with the substitution of SF, while no research considers the SF benefits in SCC. Therefore, a detailed assessment is essential to explore the benefits of SF in SCC. The aim of this review is to collect information on SSC with the substation of SF. The review focuses on the general background of SSC, the physical and chemical composition of SCC, the impact of SF on fresh properties, strength properties, and the durability aspects of SCC. The results depict that SF reduced the filling and passing ability of SCC, but is still within the limit defined by the guidelines for SCC. However, for a higher dose, the review recommends a higher dose of plasticizer. Improvement in the strength and durability of SCC was also observed, but a higher dose of SF adversely affects strength and durability properties, due to a lack of flowability. Different scholars recommend different optimal percentages of SF, due to changes in the source. However, the typical optimum dose range of SF varies from 10 to 15%. Finally, the review also identifies a research gap for future research that must be explored before being used practically.