Experimental Study Of Pumice Concrete

Pumice, which is a kind of widely distributed and resourceful nonmetallic minerals in China, is a rich mineral and waiting for being mined in many chinese provinces, such as Heilongjiang, Liaoning, Neimenggu, Shanxi, Xinjiang, Yunnan, Hainan. As a kind of vitreous lava with clustered porosity, pumice is condensed from molten rock material erupted from vulcano.Pumice produced in Tianchi Lake area of Changbaishan Mountain was researched in this thesis. Based on the sufficient study on pumice’s physical and chemical properties, activation of pumice, firing of pumice cement, admixtures technology of pumice and lightweight aggregate concrete using pumice were researched and analyzed thoroughly and systematically. Major work and conclusions include:1Study of pumice’s physical and chemical properties.Volume density, density, pore structure, compressive strength and chemical compositions of natural pumice were tested. Volume density of natural pumice is520kg/m3, density is2.5g/cm3,compressive strength is4.4MPa. Total porosity of natural pumice is79.1%:porosity of pore smaller than200μ m is42.1%, these pores are among7u m and140μ m. Chemical compositions analysis showed that pumice is system of RO-R2O3-SiO2, SiO2reaches more than40%and CaO/SiO2is0.03.2Study of pumice’s gelling property。Natural pumice was ground into fine powder and was researched on its gelling property. Then the powder was directly used as raw material for Portland cement or concrete mixture.The compressive strength of the cement clinker is32.5MPa, which can be used for masonry cement. When pumicecontent is20%and40%combined with P.Ⅱ52.5R as cement admixture, the strenths meet the strength requirements of P.P42.5and P.P32.5Cement respectively. The results show that the volcanic activity of pumice is low. Alkali proocation tests indicate that the optimal amount of excitant is10%. Alkali inspire cementitious materials with strenth of32.5MPa and42.5MPa can be be got, when pumice powder’s content is70%or30%.When pumice powder was used as concrete mixture, the results show that compressive strength of concrete decreased with increase of powder’s content tardily. The penetration coefficient of chloride ions was lowest when powder powder’s content is20%.3Study of pumice lightweight aggregate.grain composition, Cylinder pressure strength, bulk density, apparent density, porosity, voidage, water absorption, density natural pumice of were tested. The results show that cylinder pressure strength is only0.8MPa, bulk density is340～410kg/m3, apparent density is660～820kg/m3, water absorption is41.4%～-52.2%.After the strengthen treatment of pumice aggregate was carried out using " Making Shells", cylinder pressure strength is2.5MPa,1h water absorption is under15%, which meet the requirement of Super lightweight aggregate with500kg/m3density grade. The28d compressive strength of LC15pumice lightweight aggregate conrete is16.2MPa, the volume-weight is1460kg/m3.4Study of pumice concreteThe mechanical properties (compressive strength, bending strength, tensile strength, axial compressive strength, static modulus of elasticity), durability(freezing resistance property, Chlorine ion penetration), functionality (thermal insulation property, radar absorbing property) of concrete with natural pumice were tested. The results show that compressive strength of pumice concrete is14.4MPa, static modulus is1.18*104MPa, heat conductivity is0.316W/m·K. The absorption of electromagnetic of wave can be up to-5dB within2～18GHz. The concrete can Resist100times freeze-thaw test without damage.Paper is a exploration on the use of pumice in concrete and provides a useful research data to improve the pumice concrete technology.