Based On Active Magnesium Oxide Of Carbonation Masonry Production Technology Research And Development

At present,the main masonry are fired clay brick,autoclaved silicate brick and concrete hollow block.In more than ten years ago our country put forward the "ban stick",because the production of the clay brick destroyed a large number of cultivated land resources.The autoclaved silicate brick and the concrete hollow block relatively have less damage on cultivated land resources,but the main raw material-portland cement?PC?has serious environmental problems:?1?resources and energy consumption seriously.China's cement industry for the production of one ton of cement clinker average consumption of 0.95 tons of limestone,0.13 tons of clay and 0.11 tons of standard coal,and is an irreversible process,that is unsustainable.?2?carbon dioxide emissions and air pollution is serious.Cement production process will release a lot of carbon dioxide,the production of 1 ton of cement to the atmosphere emissions of 0.95 tons of carbon dioxide,the cement industry emissions of carbon dioxide accounted for about 10% of the world's anthropogenic emissions of carbon dioxide,in addition to carbon dioxide,the cement production process,There are a lot of dust,dust and sulfur dioxide,nitrogen oxides,fluorine gas and other toxic gases into the atmosphere,causing great pollution to the environment.In addition,cement products need a certain conservation time,usually takes more than a month to reach the design strength,to bear the load.In view of the above technical problems,activated magnesium oxide is used to instead of the traditional portland cement for the block of curing agent in this study.Through the carbonization technology,activated magnesium reacted to basic magnesium carbonate to increase the compressive strength and the durability of the block.At the same time,The microcapsules teste of the samples were carried out to analyze the carbonation.The main test process and results are as follows:?1?Through the laboratory test,the raw materials of aggregate,active magnesium oxide and water were mixed evenly in a small mixer,and then small size masonry samples were made through the sample preparation.After short-term curing,the samples were transferred to a small carbonization tank to carbonize,and then tested the compressive strength and the degree of carbonation?the absorption rate of carbon dioxide,determined by chemical neutralization method?.Through the design of a variety of test methods,compare the test results,the active magnesia carbonated block the best ratio: sand 37%,gravel 53%,3% fly ash,3.5% of ordinary cement,activated magnesium oxide 3.5 %;The best carbonization environment is: humidity 60%,temperature 20 ?,20% CO₂;the best molding method: 10 MPa pressure molding;the best water-cement ratio of 1.0.?2?On the basis of?1?,the optimal carbonized masonry is selected,and the durability tests such as dry and wet cycle and freeze-thaw cycle are carried out according to the relevant national standard and compared with conventional cement masonry.The activated magnesia carbonized block achieves or even more than 80% compressive strength during carbonation,and its maximum compressive strength can be achieved by carbonation for 14 days,saving half of the time relative to the maintenance of ordinary cement blocks for 28 days,and the activated magnesia carbonized blocks Of the compressive strength is 2-3 times the ordinary cement block,and its durability is better than conventional cement masonry.?3?On the basis of?1?and?2?,selecting typical masonry specimen,carbide micro chemical test,a preliminary plan tests including X-ray diffraction?XRD?,scanning electron microscope?SEM?,thermogravimetric analysis?TGA?,such as the analysis of the carbonation reaction mechanism of sample,and the interaction mechanism between carbide products and the environment.The results show that the carbonization of activated magnesia produces magnesium carbonate and basic magnesium carbonate,effectively filling the pores inside the block,and the carbonized product is a networked microstructure with very strong cementation ability.These are reactive oxidation Causes of High Strength of Magnesium Carbonated Blocks.?4?On the basis of the indoor test,the best carbonized masonry raw materials are used for commercial production of carbonized masonry by developing the corresponding production equipment and technology at the factory,and the quality of the masonry is tested according to the relevant national standards.The economic and environmental effect are analysed to lay the foundation for the promotion and application.The results show that active magnesia can reduce the energy consumption of about 48.1% and 50.53% CO₂,and have great social and economic benefits compared with ordinary cement block.