## How do you calculate VMA and VFA?

VFA = (VMA-Va)/VMA x 100 ▪ VMA = 100 – (Gmb x Ps)/Gsb ▪ Va = (Gmm-Gmb)/Gmm x 100 ▪ Pba = 100 x ((Gse-Gsb)/(Gsb x Gse)) x Gb ▪ Gse = (100-Pb)/((100/Gmm)-(Pb/Gb)) ▪ Pbe = Pb-(Pba/100) x Ps Page 24 ▪ What goes into determining the volumetric properties of a mix?

### How is optimum bitumen content calculated?

The optimum asphalt content is determined by judging the appearance of the asphalt through the pyrex dishes. The optimum binder content should be determined by observing the excessive mixture draindown, or filling of un-compacted air voids through the pyrex dish.

**What is VMA in bitumen?**

1.1 Voids in the mineral aggregate (VMA) are the void spaces between the aggregate particles of the compacted mix. This void space includes the air voids and the effective asphalt content.

**How is bitumen content calculated?**

How Much Bitumen Used in Road Construction Per Kilometre?

- Find out the dimension (Width and thickness)
- Calculate Volume of Asphalt = (Long * Width * Thickness) m^3.
- Find out the density of Asphalt (2330 or 2450 Kg/m^3)
- Calculate the quantity of Asphalt= ( Density* Volume) Kg/MTon.

## What happens if VMA is low?

Lower VMA values means that the intergranular space available for asphalt binder is reduced. This reduces the amount of effective asphalt binder that can be used in the mix, which in turns, leads to a lower binder film thickness around the aggregate particles.

### What is VMA and VFA?

Let’s look at VMA, which stands for “Voids in Mineral Aggregate.” VMA is the space between the rocks that can be filled with asphalt. The space filled with asphalt is known as VFA (Voids Filled with Asphalt). The remaining space is air voids. VMA is critical to a mixture’s durability and crack resistance.

**How do you calculate specific gravity of aggregate?**

Apparent Specific Gravity of Aggregates: It is calculated by measuring the weight of the oven-dry aggregate divided by its absolute volume excluding the natural voids in the aggregate particles.

**What is GMM and GMB?**

Percent air voids is calculated by comparing a test specimen’s bulk specific gravity (Gmb) with its theoretical maximum specific gravity (Gmm) and assuming the difference is due to air. Once Gmm is known, portable non-destructive devices can be used to measure HMA density in-place.

## What is VMA in mix design?

Voids in the mineral aggregate (VMA) are the air-void spaces that exist between the aggregate particles in a compacted paving mixture, including spaces filled with asphalt. VMA represents the space that is available to accommodate the asphalt and the volume of air voids necessary in the mixture.

### What is Marshall mix design?

The Marshall Mix Design method was originally developed by Bruce Marshall of the Mississippi Highway Department in 1939. The main idea of the Marshall Mix Design method involves the selection of the asphalt binder content with a suitable density which satisfies minimum stability and range of flow values.

**What is flow value of bitumen?**

The flow values for the asphalt concrete with mineral filler range from 2.3 mm – 3.3 mm, while that with hydrated lime range from 2.4 – 3.4 mm. The optimum bitumen content for both mixtures was found to be 6.5%.

**What is optimum bitumen content?**

The optimum bitumen content of bituminous mixtures is determined based on the average values that satisfy the sets of requirements for Marshall stability, Marshall flow, air voids, VMA and VFB.