Heavy clay and masonry services available
Cermalab manages a SANAS accredited (T0855) materials testing and materials sector training laboratory, serving the heavy clay, ceramic and refractory industries in Africa and offers a wide range of services dedicated to improve quality, competitiveness and profitability to suppliers, manufacturers and users in the ceramics market.
It has the only laboratory of its kind and wide range of expertise in Southern Africa. Our experienced professionals are involved in all aspects of materials testing, improving process technology and evaluating final products according to specified standards. We have a wide range of equipment at our disposal. Our services are offered at a contract basis.
Cermalab is not owned by any ceramics manufacturer and its test results are always impartial. It has an established confidentiality policy which guarantees the utmost discretion in all spheres of operation.
THE HEAVY CLAY AND MASONRY SERVICES AVAILABLE:
1. Raw material investigations:
Chemical (ICP) and mineralogical (XRD) analysis – the tests determine the composition by element and by mineral of the raw materials. These tests are also used to determine flux content, iron content, free silica content, clay content, non-clay content, CaCO3 content and the type and quantity of clay mineral present in the raw material. These tests are therefore extremely useful when comparing stockpiles from one mining season to the next.
Plasticity – the test determines the degree of workability in relation to moisture content of the material.
Critical moisture content – the test determines the critical moisture content at which point the drying shrinkage of the material seizes in order to prevent damage by too rapid drying.
Particle size distribution – the test determines the particle size distribution of the material and hence the ideal product category classification (i.e. solid bricks, perforated bricks, tiles or hollow ware) suitable for the raw material.
Differential thermal analysis (DTA) and thermal gravimetric analysis (TGA) – These tests indicate the stages where reactions such as the expelling of water, dissociation of various types of oxides and the burn-off of carbonaceous materials takes place during the firing of the material. These reactions are the cause of damage to products and knowledge of these enable avoiding or modifying certain minerals or improve control of the firing process.
Thermal expansion - Raw materials expand during firing and can cause damage to products or kiln structures if not sufficiently allowed for during setting.
Laboratory extrusion of samples, material forming properties and drying properties – it is quicker, easier and cheaper to do initially small laboratory extrusion trials on new or altered materials and determine the forming and drying properties rather than doing factory trials first.
Firing to a number of different temperatures to determine fired properties (Loss on ignition, fired shrinkage, breaking and compressive strength, water absorption and colour) – it is quicker, easier, cheaper and more practical to do such tests of new or altered material on a laboratory scale first before doing trials on a factory scale.
All these tests can be done separately or collectively as a full clay analysis.
2. Testing of burnt clay masonry units according to SANS 227:
Shape, appearance, colour, surface texture
These tests can be performed separately or cumulatively as a package deal. The crushing strength (CCS) always involves determining the dimensions and water absorption also as a package deal. These tests are SANS accredited for this laboratory.
3. Testing of burnt clay paving units according to SANS 1575:
Shape, appearance, colour
Modulus of Rupture
These tests can be performed separately or cumulatively as a package deal.
deal. The Modulus of Rupture (MoR) always involves determining the dimensions and water absorption also as a package deal. These tests are SANS accredited for this laboratory
4. Testing of Concrete masonry units according to SANS 1215:
Shape, appearance, colour, surface texture
Expansion on re-wetting
These tests can be performed separately or cumulatively as a package deal. These tests are not SANS accredited for this laboratory.
5. Resistance to salt attack (Salt Weathering)
Durability is the ability of a unit to withstand the combined effects of the weathering agents of moisture, soluble salts and thermal changes to which it is exposed. The durability of face brick walling will vary according to the type of unit, the composition of the mortar, the degree of exposure to weather, atmospheric pollution and other aggressive conditions and to the workmanship employed in the construction of the walling.
In parts of South Africa where the climate and peculiar local conditions combine to produce a harsh environment, certain types of facing units used externally may suffer from accelerated weathering.
The duration of these tests can be anything from one to ten weeks depending on the durability of the bricks.
6. Sinter probe test
This test involves the analyzing of whole bricks determining the gravimetric weight loss and thermal expansion / contraction at various stages during the firing of the brick samples.
7. Coal Analysis
A full coal analysis involves identifying the following properties of a coal sample: Carbon content, volatile content, ash content, moisture content, calorific value and Sulphur content.
8. Quality Control System
Cermalab can assists factories to develop a quality control system manual (based on SABS requirements), give advice on designing quality control systems and do audits on such systems.
9.1 Heavy clay brick making course
The course consists of eight modules and run over a period of sixteen (16) weeks every alternative Wednesday.
THE COURSE CONTENTS:
1. The geology of clays, structural geology, minerals and rocks, weathering
of rocks, clay formation and the properties of clays.
2. Winning of raw materials, raw material storage, unwanted materials occur-
ring in clay reserves.
3. Feeders, conveyers, souring systems, screens, mixers and ejectors.
4. Comminution machinery (crushing and grinding).
5. Shaping methods, cutters and column surface treatment.
6. Drying and drying systems.
7. Firing and firing systems.
8. Testing, soluble salts, scumming and efflorescence.
The course covers all the brickmaking processes, methods and equipment presently used in the industry. The theory is explained in easy understandable terms suitable for the South African conditions.
During the course the learners attend a theoretical session for a day during each two weeks. During the following two weeks the learners will use the theoretical information to prepare an assignment, which they present to the class during the following session. This gives the learner the time and opportunity to learn the module they completed, utilize the information to understand his/her factory’s processes and equipment better, identify problem areas in the factory and propose solutions to those problems. The main objectives being to improve quality, reduce waste and increase yields of the higher-grade products.
9.2 Quality Control Training
The course run over a period of three (3) consecutive days.
The quality control course for brick makers is designed to provide learners with the necessary practical skills to perform the in-process inspection and control of the manufacturing processes.
THE COURSE CONTENTS:
1. When and where to do in-process testing in the factory.
2. Random and representative sampling.
3. Standard process control tests.
4. Testing methods: mix calculations, moisture contents, shrinkage, particle size, column hardness, dimensions wet, dry and fired, lab firings, water absorption and strength.
5. Chemical analysis, mineralogical analysis, differential thermal analysis, thermal gravimetric analysis, thermal expansion.
6. Final product testing: shape, size, grade, dimensions, warpage, efflorescence, strength, water absorption, moisture expansion, soundness, soluble salt content.
7. The use of statistics to collect data, analyze the data, summarize the data and then report the results in an unambiguous and unbiased format.
During the course the learners attend short theoretical sessions in the morning and concentrate on practical testing methods for the remainder of the day. The learners will learn how to perform the tests correctly, develop factory test procedures, determine the mean and standard deviations of a range of measurements, design control charts and plot results.
10. Brickmaking Equipment Representative
Cermalab represents Keller HWC GmbH, Rieter Morando and Tecnofliere in South Africa. With the help of these three companies all the technical solutions a client would require is available with the help of Cermalab. These companies offer solutions from raw material to finished product including material handling and preparation shaping, drying and firing. Cermalab acts as a primary contact for any enquires for the technology these companies offer.
Our physical address is: Eland Tegnopark, 33 Eland str, Koedoespoort Industrial, Pretoria, 0186.
GPS 25°43'04.7ʺ 28°14'51.4ʺ.
Dries van Vuuren
Cell: +27 71 493 0452
Tel: +27 12 841 2445