Materials laboratories

Contact: Roger Perrett

Materials testing

Instron tensile testers

There are three Instron tensile testing machines in the lab, 2 static and 1 hydraulic testers. Each of these can test the tensile, compression and durability strength of a material, testing the mechanical properties and performance of various materials.

These machines are used to conduct testing for teaching and research – one current project has been working with doctors from the medical school to test the strength of sutures for medical use.

Each of the static machines can test up to 30kN and the hydraulic tester can apply a maximum load of 25kN. Smaller load tests can be applied and analysed using a 500N load cell. Materials tested can vary from acrylic, copper, steel, polypropene and structures combining a number materials and different types of glue.

The hydraulic Instron machine has the capacity to provide cyclic testing which can be used for durability tests. This tester is generally but not exclusively used for research

Torsion tester

Torsion tests are carried out by applying a rotational motion to determine the torque value of a material. One of the common uses for the Torsion tester is to ‘twist’ different metals until breaking point or failure. The Torsion tester is designed to measure the strength of a material against maximum twisting and is a very common test to see how much torque can be applied before a material breaks or cracks

Strain gauge application kits

These kits can measure a deflection in a material when force is applied. This is done by converting pressure, tension or weight into an electrical resistance which is then measured. Strain is a result of external pressure being applied to an object and is defined by the deformations that occur internally.

This is an incredibly important measurement technique as it is used to measure the tensile and compressive strain that can occur from expansion and/or contraction in construction work.

 

Geotechnics testing

Oedometer tester

This piece of equipment is used to measure a soil’s consolidation properties at a weight ratio of 10:1. Tests are carried out by applying different loads to a soil sample and measuring the compacting and swelling of soils to establish the deformation response. By saturating the soil with water during the test, the user is able to work out the effective stress and deformation response when adding or removing weight to the sample. Oedometer testing is carried out to correctly predict how soils will react to changes in ground stress levels.

Uniaxial tensile tester

This is commonly used to obtain the mechanical characteristics of isotropic materials, such as soil from drill cores, without putting any constraints on them. The samples are compacted on one axis by applying a controlled rate of load evenly distributed across surface of sample allowing its maximum load to be found before shearing. Samples are able to fail in any plane as it is not constrained.

Triaxial

This is used to test the shear strengths of materials when pressure is placed on top of them. The Triaxial allows shearing in any direction, as well as allowing more water to be added to test saturation levels. The test provides enough data to determine the strength properties for soils to measure the total compressive strength of materials.

Slake durability test

Used in Civil Engineering to test rocks and hard soil to determine the strength and rate of erosion after a 10 minute cycle. The Slake durability test simulates how rocks get eroded from rubbing up against similar and harder materials found in rivers and coats. The test material is then dried to work out how much material was lost in this erosion. This allows us to see how durable the sample type of rock/hardened soil is.

 

Concrete processing

This laboratory is primarily the area in which concrete samples are produced for testing. The lab contains the equipment required to produce and prepare standardised concrete cubes and beams to be tested for strength and durability.

Concrete sample cubes

These 100mm2 or 150mm2 sample cubes are used to create different types of concrete samples to test strength and durability. Undergraduate projects often introduce additional materials to explore the combined properties.

Concrete mixer

Standard industry concrete mixer used to mix samples.

Concrete vibrating table

The vibrating table is used for proper compaction of concrete while casting specimens for compressive strength determination.

Slump cone

The slump cone, also known as Abrams cone, is used to see if the consistency of concrete is correct and to determine the workability of the concrete. When students develop their own concrete mixture, it’s important to use the slump cone to ensure it will create a strong, reliable concrete that can be used in the industry.

Climavent

The Climavent is a local extraction ventilation system that ensures a safe and comfortable working environment and achieves optimum dust control by extraction dust and fumes at the source.

Concrete grinder

The Concrete grinder is used to prepare test samples with a smooth and polished finish so that a linear load can be applied across the test area of the sample.

Sieve shaker

This is used for soil analysis and particle content to effectively determine particle distribution, and how much sand, clay etc. is in the soil. By using a sieve shaker, engineers, geologists and soil scientists identify the type of soil they are working with so they can better understand the soil composition. It operates by separating rock/soil particles between 50 milometers and 106 micrometres and can take ten minutes to complete a cycle.

Compactor

The compactor consists of a 2.5kg weight which is dropped from a prescribed height into a soil sample in a mould. The mould rotates to distribute the blows uniformly over the surface of the specimen. 

Compression frame 4

This frame is a general use frame for load testing and currently contains a hydraulic piston and load cell with and applied maximum load of 1000kN.

Concrete testing

The concrete testing laboratory contains our compression testing machines for the applied compression, flexure and durability testing of concrete and other materials or structures.

Hydraulic controller

The hydraulic controller has attached 3 loading frames which can be used to apply different tests.

Hydraulic frame

The hydraulic frame is driven from the control unit and can apply compressive loads up to 2000kN. The applied pre-load is 20kN, and all material samples must have a compressive strength greater than the pre-load to perform properly.

Flexure frame

This three or four point loading frame tests the strength and durability of reinforced concrete beams by lowering and applying the centre or two points ram load to the centre of a beam sample. The applied load causes the beam to flex and the displacement and load can be recorded.

Sheer box frame

The sheer box frame allows you to see the relationship between different soils by sheering the soils along one plane. The box can be submerged in water or left to dry, but as more force is applied to the bottom half of the box, the soil shifts or separates. The data from this test can be used to plot a stress strain graph for the soil. Adding more weight to the sample allows you to see how the soil reacts with added compaction. This information would go into groundwork design.

Split cylinder / Cube

Split cylinder testing is a method which can determine the tensile strength of concrete in an indirect way. It tests the concrete by applying pressure by compression onto the cylinder so it cracks into two halves – thus defining the tensile strength.

Point load rock tester

This hydraulic machine can measure the thickness, pressure and breaking point of rocks, determining the peak force of the material as well as the fracture toughness of concrete. The machine comes complete with a heavy duty protector to encase the breaking rock.

Drying oven

The drying oven operates between 0-200°C and is used to remove the moisture from soils and aggregate samples. The moisture content percentage can be calculated from the soil weight prior to and post oven-drying. This is an important measurement to determine the water content in the soil of interest.