Micro Deval
Abrasion testing is a crucial aspect of evaluating the durability and quality of mineral aggregates used in hot-mix asphalt (HMA) for road construction. As roads are subjected to heavy traffic, environmental forces, and other factors that cause wear and tear, it is essential to ensure that paving materials can withstand these conditions.
Aggregates in HMA must be durable enough to endure production, transportation, construction processes, and long-term effects of loads and environmental stress. Abrasion testing of aggregates provides critical information about their durability and resistance to abrasion and impact.
There are two widely used abrasion tests: the Los Angeles (L.A.) Abrasion Test and the Micro-Deval Test. These tests measure the relative quality and durability of mineral aggregates when subjected to abrasion and impact. The values derived from these tests provide specific information about the durability of a sample aggregate.
The Micro-Deval Test is a popular and economical procedure for aggregate abrasion testing. This test was developed in France during the 1960s and measures the toughness, abrasion resistance, and durability of mineral aggregates as they are ground with steel balls in the presence of water.
To conduct the Micro-Deval Test, a sample is prepared by separating into individual size fractions of the required masses. The sample is then immersed in tap water for at least one hour, and an abrasive charge of magnetic stainless steel balls is added to the test sample with water. The Micro-Deval machine is set to rotate the jars at 100rpm for a specified length of time or for a specified total number of revolutions. The sample is washed over a specified sieve, and the percentage loss is determined by comparing the oven-dried mass of the retained sample to the original total sample weight.
Materials with a low loss in the abrasion test are less likely to degrade during handling, mixing, or placing, and they offer better long-term performance of pavements. There are separate test methods for fine or coarse aggregate materials.
The Micro-Deval Test offers unique benefits, such as smaller equipment size, lower sample quantities, and a simple procedure. Operators can also run two samples through a Micro-Deval Apparatus simultaneously, increasing efficiency and cost-effectiveness.
It is essential to use appropriate equipment for the Micro-Deval Test, such as LexanTM doors with safety interlocks to enclose the dual testing chambers and no exposed moving parts during operation. The multi-function electronic controller and optical sensing enable controlled test duration with elapsed time or total jar revolutions. Compliance with current UK, ASTM, AASHTO, Canadian, and Texas DOT requirements is necessary.
In conclusion, abrasion testing is crucial for evaluating the durability and quality of mineral aggregates used in road construction. The Micro-Deval Test is an economical and accurate procedure for aggregate abrasion testing that offers unique benefits, providing critical information about the durability and resistance of aggregates to abrasion and impact.