Self-Compacting Concrete (SCC)
Self-compacting concrete (SCC) has gained in significance over the past 3 decades because of its inherent properties. The SCC plays a vital role in cases when compaction is found to be troublesome. It had been developed within the 1980s for the aim of obtaining durable concrete structures.
The SCC is formed by using high powder content with mineral and chemical admixtures, and a lower w/c ratio and coarse aggregate content. The mix composition of the SCC ought to be checked by its filling ability, passing ability, and segregation resistance. To boost the flow of SCC, mineral admixtures like the fly ash, silica fume, and GGBS, has to be used together with cement. Other than mineral admixtures, the utilization of superplasticizer is necessary as a way to reduce water content and increase the workability of the SCC.
Adequate viscosity will be obtained by applying fine-grained materials and viscosity modifying agents. Its properties are greatly influenced by the kind of admixture, by filler, and by the dosage of those components. Moreover, an acceptable choice of mixture size and gradation is very important for the successful production of the SCC. Compared to angular aggregate, rounded aggregate typically enhances flowability and reduces blocking in SCC. Adjustments are to be made to the content of coarse aggregate, fine aggregate, and powder material to attain the required flow properties.
Moreover, it’s understood those flow properties of the SCC reduce with a rise in the size of coarse aggregate. Finer fractions of fine aggregate reduce flowability and increase viscousness. However, the size of the fine aggregate doesn’t have a substantial influence on the compressive strength of mortar. The SCC mix is costlier than conventional concrete because of higher powder content. To reduce the cost of SCC, filler materials like limestone, chalk powder and dolomite fines will be used. Once used as filler, limestone powder improves the particle packing and compressive strength of the SCC, this can be because of the chemical interaction between the cement and stone powder.
The light-weight aggregate (LWA) in the SCC improves its flowability whereas increasing at the same time the material segregation. The LWA doesn’t have enough internal energy of motion compared to normal aggregate concrete. The light expanded clay mixture with a better water absorption capability, and also the ball-shaped fly ash aggregate, exert a powerful influence on the rheology of concrete.
The self-compacting light-weight concrete not only reduces the self-weight of concrete, however it additionally facilitates the self-curing of concrete. Both natural and artificial light-weight aggregates exhibiting a substantial internal porousness could also be used as reservoirs for self-curing water in concrete. Self-curing will be carried out by partly replacement conventional fine aggregate with saturated light-weight aggregate and water-soluble chemicals. The water-soluble chemicals enhance the self-curing by reducing water evaporation throughout the hardening of concrete.
The saturated light-weight aggregate in concrete acts as an internal reservoir and permits water for curing to pass from inside to outside. The self-curing is a good mitigation strategy for self-desiccation and autogenous shrinkage in the self-compacting and self-curing concrete (SCSCC). Strength properties weren’t affected by self-curing once adequate amounts of prewetted LWA were used. However, the utilization of a weaker LWA as a self-curing agent resulted in a lower compressive strength.
Self-Compacting Concrete (SCC) is taken into account as concrete with high workability that’s able to flow under its weight and utterly fill the formwork, even within the presence of dense reinforcement, with no vibration, while maintaining homogeneity. In SCC, the aggregates typically contribute about 60-70% of the entire volume. Aggregate characteristics like form, texture, and grading influence workability, finish ability, bleeding, pump ability, segregation of recent concrete and strength, stiffness, shrinkage, creep, density, porousness, and durability of hardened concrete. In general, it’s ascertained that the results of the form and texture of fine aggregate are rather more vital than the effects of coarse aggregate.
For More Details: Civil engineering
Quarry Dust
Quarry dust is a byproduct of the crushing method which is a concentrated material to use as fine aggregates. In quarrying activities, the rock has been crushed into varied sizes; during the process, the dust generated is named quarry dust and it’s formed as waste. Therefore, it becomes a useless material and also leads to air pollution. Therefore, quarry dust ought to be utilized in construction works, which can reduce the price of construction and also the construction material would be saved and the natural resources will be used properly. Most of the developing countries are struggling to exchange fine aggregate in concrete by an alternate material additionally to some extent or entirely while not compromising the standard of concrete. Read More
Fly Ash
Fly ash is a coal combustion product that’s composed of the particulates i.e. fine particles of burned fuel that are driven out of coal-fired boilers along with the flue gases. Fly Ash is a byproduct obtained from industries wherever coal is burnt like a thermal powerhouse, steel, sugar, fertilizer industries, etc. The Fly Ash is a category of artificial pozzolans and usually comes in the class of non-conventional building material. All over the world Fly Ash is the most widely used pozzolanic material. It’s significantly designed and processed as a partial supplement of cement in concrete to attain improved performance. The use of Fly Ash in concrete not only extends technical advantages to the concrete properties but also contributes to the control of environmental pollution
