DIATOMITE ASLI AKSU 30806 DEFINITION Diatomite is a

DIATOMITE ASLI AKSU 308******06

DEFINITION Diatomite is a rock composed of clay, sand, volcanic ash and other organic residues, as well as diatomic skeletons of single-celled algae species living in shallow (0 -35 m) depths where photosynthesis occurs intensively in the sweet and salt water reservoirs in the regions where volcanic activity is high. Diatome skeletons contain Si. O 2. n. H 2 O Are essentially amorphous hydrated or opaline silica occasionally with some alumina. Weighted average sizes are between 50 -100 50 m Diatomite is used as industrial raw material

They can absorb water up to three times their weight depending on their clearance. The thermal conductivity is 0. 08 at 100 -300º C and 0. 11 Kcal / m 2. c. h at 0. 10 and 1200º C at 800º C. d. Depending on the impurities contained, the melting degrees range from 1000 to 1500º. Diatomites are resistant to many chemicals, but are affected by strong bases at high temperatures, due to their chemical composition, they are resistant to hydrofluoric acid.

BRIEFLY Low densities Medium refractoriness, High absorption capacities, Small grain size friability has a high surface area value. Refractive Index: 1. 40− 1. 43 / calcined 1. 43− 1. 47 Specific Gravity: 2. 0− 2. 1 / calcined 2. 1− 2. 3 Mohs Hardness: 4. 5− 5 / calcined 5. 5− 6

TYPES Diatomite products are generally differentiated by process and particle size. Natural diatomite Flux-calcined diatomite Calcined diatomite

Diatomite products can be listed in order of importance: Filter aid, Filling material, Insulation (heat, sound, electricity) material, Absorbents, Caustic, Catalyst carrier, Lightweight construction material, Refractory material, Silica source, Regulators in fertilizers.

REFERENCES INDUSTRIAL MINERALS AND THEIR USES-A Handbook & Formulary International Congress on Energy Efficiency and Energy Related Materials (ENEFM 2013) MTA GENEL MÜDÜRLÜĞÜ BİLGİ MERKEZİ- DİATOMİT

9 DOĞUKAN APAYDIN 41920191300 SET RETARDERS EFFECT OF FRESH AND HARDENED CONCRETE

10 WORKABILITY • Retarding admixtures allow a reduction in water content of the concrete without affecting its workability. The extent of reduction is even higher for mixes with higher slump values. In fact the incorporation of a given dosage of a retarding admixture increased the slump by 1. 18 in. (30 mm) in a mix with a slump of 0. 78 in. (20 mm). When added to a mix with 2. 75 in. (70 mm) slump, the same dosage of admixture increased the slump by 3. 15 in. (80 mm).

11 AIR CONTENT. • Some retarding admixtures like lignosulfonates have air-entraining properties. When added at the manufacturer's recommended dosage, they are capable of entraining 2 to 3 percent air. The use of higher dosages can entrain up to 7 percent air, especially in mixes with high slump values. It is important to note however, that retarding admixtures reduce the surface tension in the mix, allowing some of this entrained air to escape. This air loss is further increased with the use of higher retarder dosages. Therefore, it is more efficient to use a proper air-entraining agent to entrain the desired amount of air. Finally, it was found that the dosage of air-entraining agent required to obtain the desired air content is decreased due to the presence of retarders.

12 FINISHING • The extended plasticity in concrete due to the use of retarding admixtures facilitates the placing operation. The concrete can be adequately vibrated, thus reducing the risk of air pockets and cold joints from occurring. Due to an extended setting time, a reduction in the number of finishers is possible, and largerslabs can be finished at one time. This is particularly important in hot weather conditions where setting time is very short.

13 SETTING TIME • Generally, retarding admixtures delay both initial and final setting time. The amount of retardation depends on the dosage of admixture used, the type of cement used, the amount of mixing water, and the temperature of the concrete. A higher dosage of retarding admixture increases the delay in setting time. The effect on cement of the amount of retardation can only be determined by trial batches. These tests should be performed on concrete mixes identical to the ones to be used in the field. In general, it was found that the retarding effects of the admixture are more pronounced in mixes with pozzolanic and slag cements compared to portland cement. Finally, when specific retardation under extremely high concreting temperature is desired, overdosing is possible. In some instances however, this results in acceleration of the initial setting time. This may be avoided by delaying the addition of the admixture for a few minutes as mentioned earlier.

14 REFERENCES • Ramachandran, V. S. , and Malhotra, V. M. , Concrete Admixtures Hand: : : . ()ok: Properties, Science, and Technology, Noyes Publications, Park Ridge, New Jersey, 1984. • Wallace, G. B. , and Ore, E. L. , "Structural and Lean Concrete as Affected by Water. Reducing, Set-Retarding Agents", ASTM Special Technical Publication No. 266, pp. 38 -94, 1960. • Perenr. hio, W. F. , Whiting, D. A. , and Kantro, D. L. , "Water Reduction, Slump Loss and Entrained Air-Void Systems as Influenced by Superplasticizers", American Concrete Institute Special Publication 62, Detroit, pp. 137 -155, 1979. • Rixom M. R. , "Chemical Admixtures for Concrete", E. & F. N. Spon Ltd, London, 1978.

CANVAS CONCRETE HAKAN TURAN

WHAT IS CANVAS CONCRETE? • Concrete Canvas is a flexible, concrete impregnated fabric that hardens when hydrated to form a thin, durable, water proof and fire resistant concrete layer. • CC is available in 3 thicknesses: CC 5, CC 8 and CC 13, which are respectively 5, 8 and 13 mm thick.

BENEFITS • Rapid installation - CC can be laid at a rate of 200 m 2/hour, up to 10 times faster than conventional concrete solutions. The speed at which Concrete Canvas can be installed results in reduced line and lane possession for rail and road projects. • Safe and easy to install - CC is available in man portable rolls for applications with limited access. The concrete is pre-mixed so there is no need for mixing, measuring or compacting on site. • Requires minimal maintenance - CC provides excellent weed suppression, preventing the growth of root growing vegetation which cause the majority of blockages and restricted flows in channels. CC also effectively encapsulates a channel’s profile, reducing or eliminating silt generation and maintaining the hydraulic capacity of the channel.

BENEFITS • Long-term scour protection - CC is twice as abrasion resistant as standard OPC concrete, has excellent chemical resistance, good weathering performance and will not degrade in UV. • The fibre reinforcement prevents cracking, absorbs energy from impacts and provides a stable failure mode

MATERIAL ATTRIBUTES • Rapid Installation • Easy to Use • Lower Project Costs • Eco-Friendly • Strong and durable • Design life of 50 years • Water Proof

HOW IT WORKS? • Concrete Canvas consists of a 3 -dimensional fibre matrix containing a specially formulated dry concrete mix. A PVC backing on one surface of the Canvas ensures the material has excellent impermeability. The material can be hydrated either by spraying or by being fully immersed in water. Once set, the fibres reinforce the concrete, preventing crack propagation and providing a safe plastic failure mode. • CC is available in 3 thicknesses: 5, 8 and 13 mm.

METHOD OF HYDRATION • It can be hydrated using saline or non-saline water. The minimum ratio of water to concrete cloth by weight should be 1: 2. Concrete cloth cannot be over hydrated so an excess of water is recommended. Concrete cloth should be immersed in water at least 90 seconds. • Setting Working Time 1 -2 hours subject to ambient temperature. CC will achieve 80% strength at 24 hours after hydration.

APPLICATIONS • Ditch Lining • Slope Protection • Bund Lining • Remediation • Mining Vent Walls

Used in Shelters Ditch Lining

REFERENCES • International Research Journal of Engineering and Technology (IRJET) • Royal Academy of Engineering www. ingenia. org. uk / Will Crawford • Mineral Products Association www. mineralproducts. org • Li, Hui, et al. "Application design of concrete canvas (CC) in soil reinforced structure. " Geotextiles and Geomembranes 44. 4 (2016): 557 -567 • Concrete Canvas Ltd, London, United Kingdom