Sand fineness modulus (FM) is an index reflecting the gradation and particle size distribution of sand, which directly affects the workability, strength, durability and economic efficiency of concrete used in the concrete mixer. A well-adjusted FM is crucial for ensuring the quality of concrete produced by the concrete mixer, as it determines the compatibility of sand with other ingredients in the mixing process.
Effect on Concrete Workability
◆ Excessively high fineness modulus (coarse sand, FM = 3.7–3.1)
Coarse sand particles result in high void content, which requires more cement paste to fill the voids. This tends to cause poor fluidity and low slump of concrete mixture, together with insufficient coating, cohesion and water retention—issues that can disrupt the performance of the concrete mixer and affect the final product quality. During placement, segregation, bleeding and grout leakage are likely to occur, impairing the pumpability of concrete used in the concrete mixer.
◆ Excessively low fineness modulus (fine sand, FM = 2.2–1.6)
Fine sand has a large specific surface area and adsorbs more cement paste. Although it improves cohesion and water retention, it easily leads to insufficient fluidity, rapid slump loss and excessive viscosity of the mixture. Such problems make the concrete difficult to compact during vibration, tending to form air bubbles, honeycombing and pitted surfaces that reduce the quality of concrete for the concrete mixer.
◆ Optimal range (medium sand, FM = 3.0–2.3)
Medium sand features balanced particle gradation and moderate void content. When used in mix proportion design, it ensures satisfactory fluidity as well as good cohesion and water retention, making it suitable for most conventional and pumped concrete applications, especially those requiring stable performance in the concrete mixer.
Ninon Vibrating Screen: Precision Control og FM for Sand Making Plant
The vibrating screen is the core equipment in a sand making plant for controlling the fineness modulus of manufactured sand. Ninon's vibratory screen like linear vibrating screen, circular vibratory screen, high-frequency vibratory screen, high-frequency vibratory screen etc., custom-designed for the sand making plant, enables easy and precise adjustment of sand particle size while stabilizing the FM range, ensuring the sand meets the requirements of the concrete mixer.
Square Swing Screen
Linear Vibrating Screen
Circular Vibratory Screen
High-Frequency Vibrating Screen
Featuring a high-efficiency circular motion trajectory, the vibratory screen achieves a screening efficiency of 85%–92%, suitable for particle sizes of 0.074–50 mm in the sand making plant. By flexibly adjusting screen mesh size, amplitude and frequency, the vibratory screen accurately classifies coarse, medium and fine sand, and directly locks in the ideal fineness modulus of 2.3–3.0 to meet various concrete mixer production requirements in the sand making plant.
Combined with Ninon sand makers and air classifiers in the sand making plant, the vibrating screen forms an integrated intelligent screening solution. With stable operation and low energy consumption, it helps the sand making plant efficiently produce high-grade manufactured sand that is compatible with the concrete mixer, making it the preferred choice for sand and stone enterprises to improve quality and efficiency.