Study On The Properties Of Basalt Fiber Pervious Concrete With Function Of Water Purification

Pervious concrete,as a type of eco-friendly material,has unique porous structure that can make road surface runoff infiltrate rapidly,alleviate the waterlogging problem and recharge groundwater.Besides,it also helps to filter and purify the runoff.Based on coordinating the contradiction between the mechanical properties,water permeability and purification property of pervious concrete,a kind of basalt fiber pervious cement concrete with function of water purification is developed to promote the application of pervious concrete in the construction of sponge city.Using the single-factor-analysis method,the influences of basalt fibers with various lengths and contents on mechanical properties and water permeability of pervious concrete were studied in this paper.The experimental results show that basalt fiber can improved mechanical properties of the pervious concrete.Furthermore,the increasing range of 28-day strength is larger than that of 7-day strength.Besides,the increasing range of flexural strength is larger than that of compressive strength,which enhances the toughness and ductility of pervious concrete.Basalt fiber has a negative effect on the permeability of pervious concrete,but the permeability of pervious concrete is greater than the specification requirements.The influences of basalt fiber,diatomite and fly ash on mechanical properties,water permeability and purification characteristics of pervious concrete were studied by the orthogonal experimental method.The experimental results show that the effects of basalt fiber,diatomite and fly ash on mechanical properties and water permeability of pervious concrete follow the sequence: diatomite,basalt fiber and fly ash.Appropriate amount of basalt fiber can significantly improve the mechanical properties of pervious concrete.However,diatomite has a negative effect on the mechanical properties and water permeability of pervious concrete.And appropriate amount of fly ash can improve the mechanical properties and water permeability of pervious concrete.The influences of various admixtures on the water purification of pervious concrete were studied by using the self-made runoff sewage.The experimental results show that the pervious concrete structure itself has a certain purification effect on runoff sewage.Diatomite can significantly improve the water purification characteristics of pervious concrete.However,basalt fiber and fly ash have no significant effect on pollutant removal.The results of scanning electron microscopy show that basalt fiber forms a relatively steady three-dimensional network structure in cement paste,which has obvious binding effect on cement paste and can improve the strength and toughness of pervious concrete.Some diatomite particles exist as complete or partially complete particles in the cement paste,which can well absorb heavy metal ions in sewage and improve water purification capacity.Appropriate amount of fly ash makes the hydrate dense and the cement paste continuous,which can significantly improve concrete strength.Considering comprehensively to coordinate the contradiction between the mechanical properties,water permeability and purification characteristics of composite modified pervious concrete,an optimum content of the admixture,ie.0.9% for basalt fiber,4.6% for diatomite and 15% for fly ash,is suggested.Which provides a reference for the engineering application of basalt fiber pervious concrete with function of water purification in the construction of sponge city.