Research On The Performance Of Polypropylene Fiber Cement Material For Pavement Grouting

This thesis bases on "the project of Guangdong qinglian highway concrete pavement maintenance materials and technology research". For the use of ordinary cement grouting materials, this thesis puts forward a thought of using the crack resistance and toughening polypropylene fiber cement. The fluidity and the slump diameter of the polypropylene fiber cement are tested, for the perspective of the construction. And the maximum volume content under different fiber length has been given, in the first place. The optimum fiber length is selected through the early strength, impact experiments etc. The normal strength, shrinkage, toughness and crack etc. in different fiber volume content are the next systematically researching items, for selecting the best mixture ratio, and applying to practical engineering. The main research contents and results are as follows:According to the construction requirements of the fluidity, the slump diameter and unbleeding, this thesis determines the maximum volume content with different fiber length, and Within the scope of the maximum dosage, this thesis selects a number of different dosage, and selects the optimum fiber length combining with the experiments of strength, impact properties etc. under the same dosage. The optimum fiber length and largest fiber volume content is separate 9mm and 0.4%.This thesis determines the 9mm is the optimum fibre length, and studies the impact of the fluidity and the slump diameter on the different fiber volume content, researching shows that the time of the liquidity is longer and the slump diameter is smaller with the increase of fiber volume content. And with the increase of fiber volume content increasing, plastic shrinkage cracking resistance increases, and the cracking area decreases by 56%-89%. Under natural conditions, the fiber effectively improved the contraction of net cement slurry ability at the fiber volume content of 0.4%, and its resistance to shrinkage effect is best in the age of 28d, and shrinkage rate is reduced by 48.2%.The polypropylene fiber improves the flexural strength of cement slurry test specimens under the volume content of 0.4% of 28 days, the flexural strength gets the largest increase, reaching at 14.1%. In the matrix of net cement slurry mixed with polypropylene fiber, compressive strength has a different degree of increase on the whole, but only in individual age under a certain dosage of compressive strength is slightly reduced.The results show that the polypropylene fiber can enhance the toughness of net cement slurry, using ASTM C1018 method evaluates the bending, compression resilience. Mixed volume content 0.1%?0.4% of the fiber, flexural toughness index I5, I10 respectively increases by 28%?123%,61%?267% than ordinary net cement slurry. Compression toughness index I5,I10 respectively increased by 1.15?1.66 times,1.24? 2.03 times than ordinary net cement slurry. With the increase of fiber volume content, impact resistant performance improves. Under the condition of the same age, the shock resistance significantly better than the other fiber volume content mixed with 0.4% volume content of polypropylene fiber cement slurry;Incorporation of polypropylene fiber, obvious effects on the improvement of the net cement slurry fracture toughness occurs. With the increase of fiber volume content, the improvement increase first increases, then decreases.According to the experimental situation, the best of polypropylene fiber volume content is 0.4%.By electron microscopic scanning analysis, the addition of polypropylene fiber speeds up the process of cement hydration. As the fiber surface is rough, its surface is wrapped with hydrate, that suggests effective bonding built between polypropylene fiber and the surrounding structures.