The Experimental Study Of Plastic Expansive Agent Used In Duct Grouts

Building materials industry is a long lasting and huge industry,due to the high demand for new-residential and non-residential construction,cement sales continued to grow in the past few decades.As cement quality directly affect the quality of construction,improve the level of production and use of cement have great significance for saving costs and reducing influence of environmental and energy consumption,it also promote the sustainable development of cement based materials.In this thesis,we studied how plastic expansive agent influence the performance of duct grouts through a single factor experiment.We set five groups with plastic expansive agent which used 0kg,0.0005kg,0.001kg,0.0015kg and 0.002kg,then in the view setting time,fluidity,bleeding rate,free expansion of duct grouts.The microstructure of the compound system was analyzed under the aid of SEM and MIP.The experimental results were proved that add appropriate plastic expansion agent increase the duct grouts' volume,setting time has decreased slightly,the fluidity is almost constant,there is no significant decrease in strength.The plastic expansion agent can react with Ca?OH?₂ to form uniform and fine bubbles which will decrease harmful pores and increase the number of fine pores in cement paste.As the Ca?OH?₂ crystals are unstable the consumption of Ca?OH?₂ improve the macroscopic properties of cement paste.In the study,the plastic expansive agent within 0.0010kg will not remarkably weakens the duct grouts' strength,but the pore structure has been greatly improved,the number of middle hole is increased and the internal structure more compact.So the optimal formulation of plastic expansive agent was 0.001kg.