Application On Rubblization Of Old Portland Cement Concrete Pavement

Rubblization is one of techniques of treatment methods of old PCC. The treatment methods of old PCC has developed for more than twenty years in foreign countries (like America). A set of equipments and correlative technique has come into being, including Crack and Seat, Break and Seat and Rubblization. MHB is one of the Rubblization equipments in common use. MHB comes into our country in 2002. The correlative studying have been operated from then on. This paper study it from the following aspect: analyzing its working principles; improvement its decision-making procedure, the mechanism of intensity, constructing and quality controlling etc. Firstly, based on foreign engineering experience and result of research, combining with test trial road, soil condition is the most important factor to rubllization, elsewhere DBL has little influence. Through in-situ observation, the concrete's delamination situation and mechanics characters are analyzed. Occluding and wedging theory is proposed, it explains the intensity source of breaking slabs. Based on rupture mechanics and finite-element, through the computing of actual structure, comparing the following scheme:direct adding asphalt pavement on rubblization slabs, graded rubble and original slabs, are analyzed, the conclusion is that the asphalt pavement on the rubblization slabs has better condition, the merit of rubblization is validated. Through the comparison of different design method, a new design method, based on specification for design of China, is proposed. At last, proposed detail standard of construction and quality controlling.After rubblization, the old slabs will be divided to three sub-layers, they have distinctive difference in dimension of granules, and have different characters. Using the occluding and wedging theory explains the mechanism of intensity. Through the in-situ test's analysis, the suitable range of equivalent rebound modulus on the rubblized slabs. Compared with the same parameter on old asphalt pavement, the suitability of using rubblized slabs as base layer (or under base layer) is confirmed.In stress analysis procedures, the main purpose is to confirm the efficiency of rubblization for improving the stress situation of asphalt overlay. Using the FEA method, based on actual structure, this paper compares the tension stress and strain of asphalt overlay on rubblized slabs and non-rubblized ones, as to intensity factor in rupture mechanics, the stress situation of rubblization better than non-rubblized ones. This directly testifies that rubbliztion will have very effective influence on dissipating the stress concentration in asphalt overlay. For further realizing the rubblized sub–layers, graded gravel of the same height has been used to replace the rubblized slabs, the intensive stress and strain of asphalt layer on the rubblized slabs will be less than on the graded gravel, and it shows that the intensity of rubblized layer is better than graded gravel layer. The degree of rubblization directly correlates with the dimension, height, modulus of the upper layer of rubblized layers, different modulus and height have been used to computed the stress of the asphalt overlay, the suitable range of height has been proposed.Impact compaction is a commonly used technique to crack the old PCC slabs and use them in-situ. For comparing the MHB rubblization and impact compaction technique, combining with test road, this paper analyzed the rebound modulus and deviation on the surface of slabs after cracked by the two equipments. The conclusion is:after cracked by MHB equipment, there are a higher average rebound modulus and less deviation, its road performance is better than cracked by...