The determination of air content of freshly made concrete is detailed in EN 123450 and ASTM C236, where the importance of two main applications is highlighted. The primary purpose of entraining air in concrete is to give the required resistance to weathering. The use of chemical additives to increase the workability of concrete often requires an air content check to be made.
The proper control of entrained air in concrete is recognized as one of the most important functions in modern concrete manufacture. For the concrete engineer, the ELE Precision Air Entrainment Meter offers an instrument for the testing and designing of concrete mixes.
|34-3265||Air Entrainment Meter - B Type||info »|
|34-0130||Tamping Rod||info »|
|34-2910||Compacting Bar||info »|
When conducting a compressive strength test on a concrete cylinder it is important that the ends of the specimen are flat and parallel to each other. The trowelled face of a prepared concrete cylinder, or both ends of a concrete core, will require treatment to obtain these conditions.
The sulphur compound method is a hot process and offers a considerable saving in time and labour over the mortar capping method. The method is virtually instant and the compound can often be recovered for further use.
Warning: The sulphur compound, when hot, will give off sulphur fumes, and therefore it is important that good ventilation, or preferably a fume cupboard, is available in the laboratory.
|34-6031||Cylinder Capping Frame||info »|
|34-6100||Flake Capping Compound||info »|
The strength, durability and finish of concrete rely in part on the adequate compaction of the mix. An increasing number of contract specifications call for various forms of vibro-compacted concrete as a means to achieve a better and more consistent mixture. It should however be remembered that fluid mixes may segregate when vibrated in which case it may be more appropriate to compact using a tamping bar or rod during laboratory mix design.
The correct environment for curing concrete test specimens is important to achieve consistent and reproducible test results. Two primary factors must be taken into consideration to satisfy the requirements, namely to maintain a stable temperature and to prevent loss of moisture from the specimen. A standard curing temperature of 20ºC is usually specified and should be maintained at the required degree of accuracy. The use of water to prevent loss of moisture is the method most commonly used. In tropical climates a curing temperature of 25ºC is often acceptable.
The density of both fresh and hardened concrete is of interest to the engineer for numerous reasons including its effect on durability, strength and resistance to permeability. Hardened concrete density is determined either by simple dimensional checks, followed by weighing and calculation, or by weight in air/water buoyancy methods.
The density of hardened concrete specimens such as cubes and cylinders can be quickly and accurately determined using a Buoyancy Balance.
The Buoyancy Balance system developed by ELE consists of a rigid support frame, incorporating a water tank mounted on a platform. The water tank has internal dimensions of 380 x 240 x 280 mm (l x w x h).
A mechanical lifting device is used to raise the water tank through the frame height immersing the specimen suspended below the balance. The balance supplied calculates the specific gravity of the sample automatically.
The balance may also be used as a standard weighing device, thus providing a versatile and comprehensive weighing system in the laboratory.
|34-8100/09||Buoyancy Balance||info »|
The apparatus has been designed and manufactured to the recommendations laid down in BS, EN and ASTM standards where tests are required on laboratory specimens, or on specimens taken from existing structures. The test procedure specifies a method for determining the change in length of a concrete or mortar sample brought about by a change in moisture content.
1. Initial drying shrinkage: the difference between the length of the moulded and cured specimen (under specified conditions), and its final (constant) length when dried
2. Drying shrinkage: the difference between the length of a matured specimen cut from concrete and saturated, and its final (constant) length when dried
3. Moisture movement: the difference between the constant length of a speciman whend dried, and its length when subsequently saturated with water.
|34-8541||Steel Inserts for prism mould 75 x 75 x 254 mm||info »|
|34-8547||Inserts for Prism Mould 1" x 11 1/4"||info »|
|34-8544||Two Gang Prism Mould 1" x 11 1/4"||info »|
|34-8538||Prism Mould 75 x 75 x 254 mm||info »|
|39-1300/24||Data Logger for Humidity Cabinet to EN 196 320 Litre capacity||info »|
|39-1300/01||Humidity Cabinet||info »|
The efficient mixing of concrete prior to moulding specimens in the laboratory for subsequent testing is essential if quality specimens are to be manufactured. The object of mixing is to coat the surface of all aggregate particles with cement paste, and bring the mix to a uniform condition. Pan or rotating drum mixers are suitable for the mixing of small quantities of concrete, which are generally used in a laboratory.
Test procedures require that specimens are cast in a number of standard sizes convenient for compressive and flexural strength determination. The engineering tolerances specified for moulds are very stringent and the internal finish of the surface must be of a high order to comply with the recommendations laid down in many International Standards. Moulds must not deform during manufacture of concrete specimens if the specimen dimensions are to be maintained.
These cube moulds are designed to produce accurate specimens while avoiding distortion over the length of the mould.
|Model No.||Mould Type||Specimen Size|
|34-4520||4 part||100 x 100 mm||info »|
|34-4570||4 part||150 x 150 mm||info »|
|34-4620||4 part||200 x 200 mm||info »|
|34-4650||2 part||100 x 100 mm||info »|
|34-4670||2 part||150 x 150 mm||info »|
These cylinder moulds are designed to produce accurate specimens while avoiding distortion over the length of the mould.
|Model No.||Specimen Size|
|34-5230||150 x 150 mm||info »|
|34-5210||100 x 200 mm||info »|
|34-5260||150 x 300 mm||info »|
|34-5240||Cast Iron 100 x 200 mm||info »|
|34-5250||Cast Iron 150 mm x 300 mm||info »|
The correct sampling and mixing of fresh concrete is important if test results are to be reliable. Most of the equipment necessary for efficient sampling and mixing is standard laboratory equipment detailed in the Laboratory Equipment section.
To ensure that concrete achieves its maximum possible strength and yet retains its ease of placing on site, it is essential that the design of the concrete mix, in relation to the water-cement ratio and workability, is closely controlled.
•Test is appropriate for concrete mixes of medium and high workability.
The test is carried out by filling the slump cone with freshly mixed concrete, which is tamped with a steel rod in three layers. The concrete is levelled off with the top of the slump cone, the cone removed, and the slump of the sample is immediately measured.
|81-0220||Large Aluminium Scoop||info »|
|34-0192||Slump Test Set||info »|
|34-0130||Tamping Rod||info »|
|34-0160||Base Plate||info »|
|34-0140||Steel Rule||info »|
|34-0110||Slump Cone||info »|
|34-0180||Slump Cone Funnel||info »|
• Simple and economical to use.
• Reduces testing time.
• No special calibration required.
• Plated for rust resistance and long life.
The K-Slump Tester was developed to determine the slump and workability of fresh concrete. The device can be used for in-place measurements and for measurements inside of test molds and forms. The device is used as an indicator to correlate to the standard slump test.
In operation, the K-Slump Tester is wetted and inserted into the concrete for 40 seconds. The K-Slump reading is then taken on the scale to the height that the concrete has penetrated the tester. The tester is then removed from the concrete vertically and the workability reading is taken on the scale as the height of concrete retained in the tester. After the readings, the unit is easily cleaned with water.
|Model No.||Desc||Weight, kg|
|34-0580||K-Slump Tester||450 g||info »|
•Test appropriate for concrete mixes of low and very low workability
This method is a mechanised variation of the slump test and includes a determination of the workability of concrete. It is based on the principle of subjecting the concrete to vibration after removal of the slump cone.
The assembly is mounted upon a small vibrating table operating at a fixed amplitude and frequency. The time to complete the required vibration gives an indication of the concrete workability.
Special Note: The consistometer must be operated from an electrical supply of 50 Hz in order to comply with the fixed test frequency specified.
|34-0300/06||Vibro Consistometer||220 - 240 V AC, 60 Hz, 1 ph||info »|
|34-0300/10||Transparent Disc for Vibro Consistometer 34-0300||-||info »|
|34-0300/01||Vibro Consistometer||220 - 240 V AC, 50 Hz, 1 ph||info »|
This test will be of interest to those involved with concrete having a high workability. The test determines the flow index as an arithmetic mean of the diameter of the specimen after working on a flow table. The apparatus consists of a mould, flow table, wooden tamper, metre rule, a float and stopwatch.
|34-0450||Flow Table||info »|
This method covers the determination of setting time of the mortar fraction of concrete mixes and is only suitable on mortars with slump values greater than zero. The definition of the initial and final setting time is taken as the period from when water was first added to the mix until the measured penetration resistance is 500 lbf/in² and 4000 lbf/in² respectively.
|82-2820||Syringe with rubber bulb||info »|
|34-0810||Set of needle points||info »|
|29-3925||Proctor Penetrometer - complete with set of needle points||info »|
|38-2695||Pocket Concrete Penetrometer||info »|