Experimental Study On The Build Embankment Capability Of Borate-ash Stabilizing Crushed-stone

As the perfection of our highway building, it has become a new hotspot that building the low-level regional highway network. Boron-ash, the industrial flotsam, the research on that has huge economic value and social value. Borate-ash, is the flotsam of producing Borax with magnesian borate deposits. Producing one ton borax can make four tons borate-ash. Borate-ash has great Alkalinity, and makes the problems that occupying earth and polluting environment. Though people have some achievements in applying of borate-ash, the research of borate-ash has not started on highway project yet. It is necessary to start the research of applying borate-ash in highway project, according the territory condition and the result of other research. The paper steps from the theory of producing borate-ash, researches the volumetric weight, degree of fineness, chemical composition. It studies the feasibility of borate-ash stabilized crushed-stone through making indoor experiment, improving borate-ash can be the material stabilizing the crushed-stone roadbase with chemical reagent.The paper has three chapter, and the third, the fourth, the fifth chapters are essential parts.Chapter 1 for the introduction of the paper, introduce the economic sense and the Social sense, represent the international and domestic researching situation of borate-ash. And through the present researching situation of the Semi-rigid base course, the paper bring up the build embankment capability index of the Semi-rigid base course. At last, the paper represent the researching content and the method.Chapter 2 first give the chemical composition of the borate-ash and the flying ash. Because of that, the method of the replacing the flying ash with the borate-ash is brought up. It briefly represent mechanism of the combination, according to that choosing the type of the chemical reagent. Carrying the experiment of testing the unconfined compressive strength of the combination for 7d. 8 groups have been tested, 5:4:0~1:4:0 and 4:4:2~1:4:2(lime: borate-ash: flying-ash). According to the unconfined compressive strength, define the 3:4:0 and 4:4:2 are the best in each situation. Then in this two type of combination, punching the Na2CO3 and NaOH, dose is respectively 0.5%,1%,1.5%. Using the index, unconfined compressive strength, make sure that NaOH is the better one.Chapter 3 first bring up the structural type of semi-rigid base course,and briefly represent the mechanism of the semi-rigid base course. Before the build embankment capability experiment, analyzing the characteristic of the material, make sure the gradation range, and using the method of planning solve to design the gradation. After testing the maximum dry density, optimum water content, volume density and apparent density of the aggregate, the paper study the semi-rigid base course design method, and design two type of the mix proportioning. At last, comparing the calculated value of maximum dry density and aoptimum water content with the compaction test value of that.Chapter 4 is the research of the experiment. Based on the maximum dry density and aoptimum water content, adding NaOH at the dose of 0%,1%,1.5%, the paper test the unconfined compressive strength by making the test specimen 150 mm×150mm. It get the conclusion that the specimen of 4:4:2 are all better than 3:4:0 in unconfined compressive strength, at the same age or the same dose, except the group with no NaOH aged 7d. It represent that the active principle of SiO2,A l2 O3 in the borate-ash is less active than that in flying-ash. The unconfined compressive strength have no increase between aged 7d and aged 28d of the group of 3:4:0 with no NaOH. Its unconfined compressive strength do not have much increase till aged 90d. So it is essential to add the NaOH. According to the < highway engineering standard specifications>( JTJ034-2000), the only index for the semi-rigid base course is that its unconfined compressive strength should be higher than≥0.8Mpain secondary road. It represent that 3:4:0 and 4:4:2 both should add NaOH to meet the specification. The group of 3:4:0 adding 1% NaOH is better than adding 1.5% NaOH. It shows that 1% NaoH can dissolve SiO2,Al2 O3 sufficiently into acidgroup and get stable with Ca 2+ . If it has been brought up to 1.5%, then the unconfined compressive strength become lower. When the mixture ratio come to 4:4:2, its unconfined compressive strength have the highest value when adding 1.5%NaOH. It shows that 1.5%NaOH is not best dose in the mixture ratio of 4:4:2. But considering the convenience of building and the economic issue, the dose of NaOH should not be higher anymore. According to the result of unconfined compressive strength, 1% NaOH is the most economic dose. Adding 1% NaoH into the semi-rigid base course material, making the specimen to test the index of splitting strength, rebound modulus, flexural-tensile strength, flexural-tensile modulus and freeze-thaw strength. It aimed at testing the two mixture ratio (4:4:2 and 3:4:0) semi-rigid base course material can be satisfied with the index of low rank highway.Chapter 5 is based on the Pavement mechanics elastic layered system theory, calculating the Ultimate Stress of base course and sub base course. So it can improve that borate-ash stabilizing crushed-stone can meet the index of low level highway. It separately use the different thickness of Subbase, Base, and Surface Courses and the flexure modulus get from Chapter 4. Chapter 6 is the last part of the paper, It gives a summary of the work done in this essayand provides suggestions to the possible work which would be needed afterwards.