No-Fines By removing fines (sand or fine aggregates), concrete is a lightweight concrete made consisting of only coarse aggregate, cement, and water. The benefits, drawbacks, and proportions of no-fines concrete are explored. Frequently, only single-sized coarse aggregate with a size passing through 20 mm and retaining a thickness of 10 mm is employed. Because of some of the advantages it has over normal concrete, no-fines concrete is gaining popularity. The single-sized aggregates produce a good no-fines concrete that, in addition to having big voids and so being light in weight, has an architecturally appealing appearance.
The Benefits of No-Fines Concrete
Due to the lack of fine aggregates, no fines concrete is a lightweight concrete, with a density of about 25% to 30% less than normal concrete. As a result, the structure’s self-weight is reduced. It has less drying shrinkage than standard concrete since it does not contain sands or fine particles. It has a better thermal insulating property than regular concrete, making it suitable for external wall building. Because it contains no fine particles, the amount of surface area required for cement application is significantly decreased. As a result, when compared to regular concrete, the amount of cement used per cubic metre is lowered. As a result, it is cost-effective.Because lightweight concrete contains no fine particles, it has no effect on quality due to coarse aggregate segregation.
Without the use of any form of concrete vibrator, no fines concrete may be compacted just by tamping with rods. No-Fines Concrete’s Limitations This concrete has a higher permeability than conventional concrete because there are no fine particles to fill the spaces. As a result, constructing reinforced concrete with no fines concrete is not a smart idea, as the reinforcement can readily corrode. An extra coat of masonry plaster is necessary to make this concrete impermeable, which raises the expense.Workability of no particles concrete cannot be determined using standard concrete tests such as the slump or compaction factor test. Workability values and test techniques are unknown.
No-Fines Concrete Mix-Proportion
No-fines The aggregate/cement ratio in concrete is usually between 6:1 and 10:1. The aggregates utilised are typically 20 mm in size and kept on 10 mm.Unlike conventional concrete, where the water/cement ratio is the most important factor, the strength of no-fines concrete is determined by the water/cement ratio, aggregate cement ratio, and concrete unit weight. For an acceptable consistency, the water/cement ratio should be between 0.38 and 0.52. The water-to-cement ratio must be carefully chosen. If the water/cement ratio is too low, the paste will be so dry that the aggregates will not be effectively coated with paste, resulting in insufficient particle adhesion.
If the water/cement ratio is too high, the paste runs to the bottom of the concrete, especially when vibrated, and fills the spaces between the aggregates, making that portion dense. Due to the thinness of the paste, this condition also inhibits the adhesion of aggregate to aggregate. There is no standard method for testing the consistency of no-fines concrete, such as the slump test or the compacting factor test. Perhaps the best guidance for determining the appropriate water/cement ratio is a good, experienced visual assessment and trial and error method. When utilising typical aggregates, no-fines concrete can have a density of 1600 to 1900 kg/m3, however when using lightweight aggregate, the density can be as low as 800 kg/m3.
Mix Proportion of No-fine concrete
No-fines Concrete does not represent a significant difficulty in terms of compaction. It is not necessary to use mechanical compaction or vibrating processes. For complete compaction, simple rodding is sufficient. Because the particles are in point-to-point contact and the concrete does not flow, no-fines concrete does not provide considerable side push to the formwork. As a result, the side of the formworks can be removed in a shorter time than traditional concrete. When utilised as a structural part, however, formwork may be required to be retained for a longer period of time due to the lower strength of concrete. No-fines concrete has compressive strengths ranging from 1.4 MPa to 14 MPa. The compressive strength of no-fines concrete is shown in Table 12.5.
Because no-fines concrete has a poor bond strength, no reinforcing is used in conjunction with it. If reinforcement is required with no-fines concrete, it is recommended that the reinforcement be smeared with cement paste to enhance the bond and prevent rusting.
Limitations Of No Fines Concrete
This form of concrete lacks cohesion while in the plastic stage due to the lack of fine particles. As a result, removing the formwork takes a lengthy time.It has a higher permeability than traditional concrete. As a result, from a durability standpoint, walls made with no fines concrete require an additional coat of mortar. In this form of concrete, reinforcing is often not advised. If reinforcement is required, however, put a thin layer of cement paste on the reinforcement before utilising it. This will improve steel-to-concrete bonding as well as corrosion resistance. There is no standard test method for measuring the consistency or workability of no particles concrete (such as slump or compaction factor). Only via careful visual inspection and the trial-and-error method.
It’s a type of concrete built using coarse particles and cement. The mixture contains no penalties. Additionally, single-size aggregates are added to improve the performance of the concrete mix once it has been put. When graded aggregates are employed, the cavities are filled. However, with a single size, the concrete will have more spaces. Mix designs for no fine concrete are created based on the concrete’s necessary strength, as some places may demand higher strengths to handle the loads. For example, if we pour concrete in a path where automobiles pass, the concrete should be able to withstand the weight of the vehicle. This can be thought of as.
Disadvantages of No Fine Concrete
Drainage is one of the most effective methods.Typically designed in hydraulic constructions and used as subsurface drainage without interfering with above-ground operations.It is suitable for usage as a gravity structure.Concrete with a low densityDue to the low cement continent and the lack of use of find aggregate, the cost is low.Because of the voids in the concrete, thermal conductivity is poor.Because of the low heat transfer and high vacancy ratio, it acts as insulation. External walls can be built with this material.When compared to normal-weight concrete, less weight saves money on the building.Concrete segregation is low.When compared to regular concrete, there is less drying shrinkage.The concrete may be compacted without the use of mechanical vibration. It’s possible that the Rodding approach will suffice.Negative Consequences of No
No-Fines By deleting the fines from normal concrete, concrete is a method of generating light concrete. The term “no-fines concrete” refers to a type of concrete in which the fine aggregate fraction has been removed. Only coarse aggregate, cement, and water are used to make this concrete. Frequently, simply a single size of coarse aggregate, passing through 20 mm and remaining on 10 mm, is employed. Because of some of the advantages it has over normal concrete, no-fines concrete is gaining popularity. The single-sized aggregates produce a good no-fines concrete that, in addition to having big voids and so being light in weight, has an architecturally appealing appearance. No-Fines Concrete Mix-Proportion No-Fines Concrete Mix-Proportion No-Fines Concrete Mix-Proportion No-Fines Concrete Mix-Pro The aggregate/cement ratio in concrete is usually between 6 and 8.
The principal advantages claimed for no-fines concrete are economy in materials.
A mix with an aggregate:cement ratio of 8:1; a water-cement ratio of 0.4; and a density of 1850 kg/m3.
Concrete Technology Questions and Answers – No Fines Concrete, High Density Concrete.