Research On Preparation And Performance Of Cement Based Simulation Charcoal For Electric Heating Furnace

In recent years, a heating decoration facility – furnace, which contains the western history and culture, gradually enters the domestic market. With the improving of the quality of people’s lives, the properties of high performance, low energy consumption and no pollution are requested for the furnace products. In order to meet the needs of the majority of producers and consumers, simulated charcoal, which is made of lightweight heat-resisting concrete and gets the properities(e.g., such as short production cycle, light weight,heat resistance), are studied and used as the decorative charcoal for electric heating furnace.For the fly ash based geopolymer and calcium aluminate cement, the effects of different kinds and dosage of mineral admixtures(slag, metakaolin and potassium feldspar) on the properties(e.g., mechanical strength, the linear shrinkage rate, mechanical strength, and reheating strength) of above two cementious materials have been studied. The results are as follows:(1) After the addition of slag into fly ash based geopolymer, the geopolymers’ mechanical strength at room temperature increases firstly and then decreases. The mechanical strength increases with the increasing amount of metakaolin, while decreases with the increasing content of potassium feldspar. All samples shrink and crack after fired at 1000 ℃ for 5 hours. The effect of mineral admixtures on inhibiting the cracking of fly ash based geopolymer is as follow order: potassium feldspar > metakaolin > fly ash > slag.(2) As for the defects of calcium aluminate cement, such as shrinkage after being fired, the decrease of strength at middle temperature, and efflorescence in high humidity environment, low cement ratio(calcium aluminate cement:silica fume: high bauxite clinker powder = 1:0.72:2.58) is taken in this study. When the silica fume is replaced by fly ash and metakaolin, respectively, the fluidity of the matrix slurry drops, but the appearance of efflorescence is inhibited obviously, and the linear shrinkage rate of the matrix reduces. When the ratio of metakaolin and silica fume is 2:3, the samples cured at room temperature and the samples after fired get better strength, and their reheating strength still retains above 77.7%. Furthermore, as the addition of fly ash increases, the matrix’s surface cracking conditions deteriorates, the mechanical strength firstly increases and then decreases, and the reheating strength drops.Based on the above study, a better composition of the matrix material is as follows: high alumina cement content is 23.3%, silica fume content is 10%, metakaolin content is 6.7%, high bauxite clinker powder is 60%, and sodium tripolyphosphate agent is 0.2%.The effects of ceramsite, expanded perlite, basalt fibers on the bulk density, the flexural strength, the shrinkage rate after firing are studied. The results show that as the matrix of ceramsite heat-resistant concrete increases, the liquidity, the mechanical strength at room temperature, the line shrinkage after being fired, and the bulk density increase. When cement-sand ratio is 1.50:1, the concretes get smooth surface, and flexural strength and compressive strength under normal temperature reach to 3.6 MPa and 23.8 MPa, respectively. In addition, flexural strength and compressive strength of samples fired at 1000℃ are 8.1 MPa and 42.3 MPa, respectively. The dry density and the density of the samples after being fired is 1583.7 kg/m3 and 1574.8 kg/m3, respectively. As the matrix content increases, the liquidity and the mechanical strength at room temperature of expanded perlite heat-resistant concrete increase, the line shrinkage, mechanical strength after fired, and the bulk density change irregularly. The addition of basalt fibers leads to the decrease of liquidity, while the mechanical strength at room temperature increases. The most obvious enhanced effect occurs when the volume content of basalt fibers is 0.10%. Basalt fibers are helpful to reduce the line shrinkage and improve the mechanical strength of the ceramsite heat-resistant concrete after fired, and the improvement is related to the dispersion degree of fibers.Based on the optimal ratio of substrate materials, when the cement-aggregate is 1.50:1, basalt fiber content is 0.1%, and accelerating agent is 0.06%, the concrete meets the technological requirements of the simulation charcoal used for electric heating furnace. And the properties such as heat resistance, fracture resistance also meet the performance requirements of related enterprise.