Cement happens to be one of the most widespread building materials. It is an inorganic binder that is combined with water to produce a plastic mass. It can also be salt solutions and other liquids. Due to its characteristics and features, cement is used to make concrete. Considering that the material is a hydraulic binder, it becomes stronger when in contact with moisture. This distinguishes it from other binders that gain hardness in the air. Like any other building material, cement must be tested for compliance with requirements before being put on sale. For this Cement Testing Technique, tests are organized and entrusted to certified organizations. They are carried out in laboratory conditions, using special equipment.
Types of cement testing technique
Based on the requirements set by the state, several key properties are checked during Cement Testing Technique.
These include:
- Bending and compressive strength.
- The fineness of grinding.
- Normal thickness and time required for setting.
The degree of uniformity of changes in volume
The indicators calculated during testing depend, among other things, on the composition of the cement, the structure of the minerals from which it is made, as well as the presence of additives and their characteristics.
Bending and compressive strength
During cement testing with Cement Testing Tools, the first thing to check is its compressive and bending strength. For testing, beams measuring 40x40x160 mm are made. The solution is prepared at a rate of one part cement to three parts mono-fraction sand. Based on the data obtained during compression testing, a cement grade is formed. Steaming is used to speed up the testing of indicators.
Cooled samples are tested for bending by pressing. The remaining beam fragments are tested for compression. When summing up, the average value obtained from testing several samples is taken into account. Manufacturers are obliged to indicate the ultimate strength of the cement, established after 30 days of hardening.
Fineness of grinding
The fineness of grinding is the specific surface area, which is calculated in cm², as well as the residue formed on sieve No. 009. Under normal conditions, it should not exceed 15% of the total sample weight. The characteristic has a direct impact on the time required for cement to set. The more advanced it is, the earlier the procedure.
The Testing on Cement can be carried out both by the residue on the sieve and by the specific surface. In the first case, the sample is disaggregated, settled, and then sifted on the sieve. After its preparation, the sample is placed it in equal parts – then the liquid parameters are taken and the density is calculated.
Normal density and setting time
The normal density of cement is also called water demand. To determine it, a device is used, equipped with a shortened needle tip. The test requires 500 g of cement, as well as a certain amount of water to obtain a solution of standard density. Mixing of the solution is carried out in a mixer.
The resulting mixture is transferred to a special ring – the remains are cut off with a knife. From the moment the start of mixing is recorded, 4 minutes are counted, after which the pestle is immersed in the solution.
After 30 seconds, the immersion depth is measured. As a result, the optimal state is considered to be one in which at least 7 mm remains from the tip of the pestle to the bottom. The indicator is expressed as a percentage of water and cement mass.
Uniformity of volume change
Uniformity of volume change is the ability of cement to harden without serious deformations – these include all violations that exceed permissible indicators. It is known that during the hardening of the cement mixture, curvatures can occur, as well as the destruction of the structure due to the appearance of cracks.
To promptly identify such processes as per the Cement Testing Types, it is impossible to do without testing the cement in a certified laboratory.
Features of sample preparation
The sample selected for testing is delivered to the laboratory in a special, tightly closed container. This allows the protection of the cement from moisture and contamination by foreign impurities. Subsequently, before testing, the sample is stored in a dry room.
Also, before testing, all samples taken are sifted through a sieve to determine the mass of the residue and record it in the log. One should check the Cement Testing Equipments Price beforehand.
Also read: Advancements in Cement Testing Machines Technology
