The Process And Mechanism Of Enhance Concrete Mixed With Panzhihua Fly Ash

Fly ash is a kind of typical industrial wastes, have very big pollution to theenvironment. The PanZhihua fly ash output is a huge and cause a great pressure to thesurrounding environment. The traditional fly ash utilization in concrete cementproducts can not alleviate the excessive growth of fly ash production. However, in thefly ash concrete, fly ash doped excessive, will seriously affect the performance andstrength of the concrete. Papers by the PanZhihua fly ash process modification,designed to improve reactant concentration of hydration and reaction speed of thesecondary hydration in order to make the max-dosage concrete’s strength is higherthan the reference concrete, so that larger content of fly ash concrete is applied to thestrength requirements of the higher areas, with high academic and practical value.Paper use Baoliyuan ash as raw material which has a highest yield in PanZhihuaregion, first of all its components, phase, microstructure and physical and chemicalproperties were characterized and find the parts which closely related to themechanical properties of concrete, and then draw up the mixed technology. By theexcess replace method of fly ash, for a standard test to find the best content inconcrete. Then the mechanical grinding to improve the hydration activity of fly ash, itcan be involved in the early hydration of concrete, increase early hydration productssuch as AFt and the later period hydration products such as C-S-H gel and otherhydration products, to improve concrete compactness, thereby increasing the strengthof fly ash concrete. The use of fly ash concrete and reference concrete hydrationsample by XRD, SEM and other modern testing tools characterization on the best mixtechnology, combined with the performance and strength of them, and deduce thestrength enhancement mechanism. The main results achieved by the paper are asfollows:（1） The PanZhihua Baoliyuan ash has a small fineness and a irregular surfacemorphology, the content of SiO₂and Al₂O₃is75.57%, binding form CaO content of 4.47%, SiO₂is mainly present in the active quartz or together with the Al₂O₃inbinding form exists in illite and CaO exists in the anhydrite in binding form; There arequartz, illite, anhydrite and very few mullite which related to concrete in the ash.（2） The best mix technology of fly ash enhance the concrete: the best replace rateand excess replace coefficient of fly ash are30%and1.6; the best grinding time ofPanZhihua fly ash is10min; the grinding aids content are triethanolamine0.04%andethylene glycol0.06%。（3） The concrete mixed by the PanZhihua fly ash with best mix technology thanthe reference concrete enhanced by17.5%and11.5%; workability affect, the slumpdecreased2cm, but to meet the requirements.（4） After grinding, the minerals in PanZhihua fly ash minerals disintegrated, theactive ingredient is dissolved in the hydration system; because of fly ash fineness issmall, the reaction area and reaction speed increased of hydration system; the activeAl₂O₃in the fly ash and the gypsum which formed by the anhydrite in fly ash solublein the hydration system make the concrete formed more AFt in the early time, in orderto improve the early strength of concrete; the secondary hydration reaction betweenthe active SiO₂in the fly ash and the CH formed by the cement hydrated can beaccelerated under the conditions of the increased reaction area, lead to a lot of C-S-Hgel generated and the compactness improved in28d, thereby enhancing the standardstrength of concrete; the decrease of the concrete working performance is due to flyash itself configuration and water needed increased which caused by the surfacedestruction with mechanical grinding, lead to reduced liquidity.