Study On The Control Technology Of The Smoothness Of The Sliding Mode Paving Cement Concrete Pavement

The smoothness of the sliding form paving cement concrete pavement is closely related to the construction technology and the work-ability of concrete.In order to improve the smoothness of the sliding form paving cement concrete pavement at home,the construction technology and the work-ability of concrete were studied respectively,in this paper.Among them,in the aspect of the construction technology,the hand push type cross section was used to measure the influences of every construction procedure on the smoothness of cement concrete pavement in the slid-form construction.And then some solutions were be proposed.In the aspect of the work-ability of concrete,in two angles of the rheological behavior and construction characteristic,the influences of sand ratio,air entraining agent,super absorbent polymer on the work-ability of concrete were researched separately.Based on those influences,sand ratio,the type of air entraining agent,air content,the fineness and dosage of super absorbent polymer were got to make the best work-ability of concrete.Among them,the indexes of the rheological behavior were the plastic viscosity and yield stress.A low viscosity and a high yield stress is good for concrete to work-ability and the smoothness of the pavement.The indexes of the construction characteristic were the time of pulping and surface roughness and edge collapse height,respectively.A short time of pulping and a little surface roughness and a little edge collapse height is also good for concrete to working and the smoothness of the pavement.The main results were as following:(1)In the slid-form construction,there were not any influences of the smoothness of base course and the path of caterpillar track on the smoothness of pavement;there were also not any influences of joint-cutting and groove on the smoothness of pavement.But the path of caterpillar track should be solid and have sufficient bearing capacity.(2)To a certain extent,with the reduced of the pile spacing of datum line,the smoothness of pavement would become better and better,5m pile was better than10 m pile.The pile spacing of datum line was better to be reduced.The more troweled by 3 meters,the worse the smoothness of pavement would become.So the troweling by3 meters ruler should be banned or pushed longitudinally.There were some serious influences of some special circumstances on the smoothness of pavement,such as: rain,stop,etc.So special circumstances should be avoided.And prearranged planning should be prepared.(3)With the increased of the sand ratio of the concrete,in the aspect of the rheological behavior,the yield stress and plastic viscosity decreased first and then increased and then decreased.In the aspect of the construction characteristic,the time of pulping was reduced first and then increased;the surface roughness increased constantly;the edge collapse height increased first and then decreased and then increased.0.45 was the best sand ratio for the concrete in the slid-form construction.(4)Under the optimized sand-ratio condition,with the increase of the air content in the concrete,in the aspect of the rheological behavior,the plastic viscosity of the concrete which be added saponin air entraining agent was increased constantly.On the contrary,its yield stress was increased.The plastic viscosity of the concrete which be added twelve alkyl sodium sulfate air entraining agent was reduced constantly.And its yield stress was reduced first and then increased and then reduced and reduced finally.The plastic viscosity of the concrete which be added 126 A rosin air entraining agent was reduced first and then increased and reduced finally.And its yield stress was reduced first and then increased.In the aspect of the construction characteristic,after adding any air entraining agent,the time of pulping was decreased,the surface roughness and edge collapse height were increased.Twelve alkyl sodium sulfate air entraining agent was the optimized air entraining agent for the concrete in the slid-form construction.And the air content in the concrete should be controlled in 3% to 4% or so.(5)Under the optimized sand-ratio condition,with the increase of the dosage of super absorbent polymer in the concrete,in the aspect of the rheological behavior,the plastic viscosity and yield stress of the concrete which be added any fineness of super absorbent polymer were reduced first and then increased.In the aspect of the construction characteristic,after adding any air entraining agent,the surface roughness was decreased,the time of pulping and edge collapse height were increased.50 mesh was the optimized fineness for super absorbent polymer to let the concrete in the slid-form construction have a best work-ability.And the dosage of super absorbent polymer in the concrete should be controlled in 2% or so.