Reasonable Choice of vibration parameters is no trivial matter
Although the building construction, the process can be used for a variety of mechanical compacting concrete process method , but many vibrators plant or vibration based method, vibration compacting concrete is the most common method of application .
Over the years, many architectural design units, construction units and field operations staff is very confused in effect on the intrinsic quality of concrete vibration parameters , in particular the choice of concrete solidification process rationale and vibration parameters is very vague , resulting in mass concrete structures uneven, varying the intensity of the standard . If the vibration parameters are chosen unreasonable , will produce concrete segregation , resulting in concrete particles sink , seriously affecting the quality of the internal components of concrete .
Thus scientific rational choice vibration parameters , effectively improve the strength of concrete components , construction machinery industry and its many vibrator manufacturers should pay attention to the problems and discussing.
Here we vibration theory and concrete solidification process conducted in-depth research , scientific look reasonable selection of vibration parameters to improve the strength of concrete structures will play a crucial role in how .
First, the effects of vibration parameters on the strength of concrete structures : the vibrator vibration parameters include frequency , amplitude, exciting force and the specific construction time process control and vibration , concrete structures primarily composed of cement, sand , water, aggregate ( stone ) and steel and other components. If the vibration parameters are chosen irrational, causing light concrete density is not high , the impact strength of concrete, causing heavy concrete segregation phenomenon, which seriously affect the quality of concrete structures , resulting in decreased strength of concrete structures .
Second, the process of compacting concrete elements : concrete during vibration formation of more complex internal structure , we usually put concrete compacting process is divided into two stages, namely the stage of fine and coarse aggregate mortar stage .
Generally divided into three regions . A water-filled region called the area ( bleeding area ) , is the weakest part of the concrete , the concrete is also the birthplace of the main channel seepage and cracks. Area two mortar is relatively normal , commonly referred to as the normal area . Region III is the most concrete and most dense parts , called dense area.
Third, the impact of secondary vibration on concrete strength : As the relative proportion of each mineral particles are larger than the water in the concrete , if excessive vibration will produce segregation , bleeding caused by the weight of the water layer formed sinking particles than the major influence , thus affecting quality of concrete structures . Similarly, if the vibration strength is small, it can not produce enough power to eliminate the internal friction of concrete , air bubbles can not be effectively excluded , resulting in concrete strength.
Since the end of the first vibration, concrete temporarily in a state of equilibrium , but due to the hydration process of cement in concrete , water evaporation precipitation , subsidence and solidification shrinkage of concrete and other reasons , there are some still inside the concrete pores , bubbles , cracks , etc. concrete and coarse aggregate , steel stick together .
In order to effectively eliminate this effect , in a rear end of the vibration to be increased once before the initial setting of the concrete vibration, i.e., the secondary vibration of concrete, the secondary vibration of concrete down to better eliminate residual air bubbles formed when the concrete , cement capillary bore holes and cavities and gels such as cement and aggregate reinforced contact points , the secondary vibration that is , without changing the material and case mix , changing the internal structure of concrete by vibration , making dense the actual test confirmed the initial setting of the secondary vibration than once before the vibration can improve the strength of concrete by 30%.