Laboratory Investigation On Cement Stabilized Base Of Asphalt Pavement Using Multi-Solid Waste

In recent decades,China has made great progress in various industries,especially in industrial and highway transportation,reaching world advanced levels.However,these industries are also facing some limiting factors,such as the large accumulation of byproducts from industrial production,which not only occupies valuable land resources but also causes ecological environmental damage.The highway transportation industry is facing a severe shortage of aggregates,leading to an increase in the price and construction cost due to a shortage of high-quality stone materials.This article takes phosphogypsum from a phosphoric acid plant in Qinhuangdao,iron tailing sand from a mining site,and tunnel slag from from tunnel excavation in a section of Zunqin Expressway are used as research objects and uses them in semi-rigid base layers,hoping to promote the application of diverse solid waste in base layers.In this paper,the physical and chemical analyses of phosphogypsum and iron tailing sand were carried out first,a series of physical properties of cave slag were analyzed,and the feasibility of replacing equal-size cave slag powder with iron tailing sand was determined by mortar specimens.And on the basis of skeleton-dense grading,all equal size stone dust was replaced with iron tailing sand,and then the cement dosing was determined.The unconfined compressive strength,indirect tensile strength,compressive rebound modulus,temperature shrinkage,dry shrinkage,and frost resistance were studied by adding different contents of phosphogypsum by internal blending method,and water stability,delayed crushability,and leaching of toxic substances were studied according to the properties of phosphogypsum,and the mechanism analysis was carried out by SEM and XRD.The following conclusions were drawn.(1)Cave slag and iron tailing sand demonstrate promising potential as filling materials.(2)The inclusion of phosphogypsum impeded cement hydration,leading to a slight reduction in unconfined compressive strength,splitting strength,and resilience modulus,and a slight increase in warm shrinkage strain.As cement hydration progressed,there was negligible variance in warm shrinkage strain between 90-day P series specimens.(3)An optimal dosage of phosphogypsum may create a strong alkali environment,which dissolves aluminum ions from hydroxylmica and forms ettringite with calcium and aluminum ions in cement,as well as sulfate and calcium ions in phosphogypsum.This mechanism can reduce dry shrinkage strain and effectively prevent the development of reflection cracks.(4)At dosages of no more than 6%,phosphogypsum exhibits no adverse effects on freezing resistance,water stability,or delayed rolling property.