Outline

  • Abstract
  • Keywords
  • 1. Introduction
  • 2. Standard Requirements for Use of Graded Soil-Aggregate in Bases of Highways
  • 3. Strength Requirements for Stabilized Road Base Material
  • 4. Materials and Methods
  • 4.1. Aggregates
  • 4.2. Portland Cement
  • 4.3. Water
  • 4.4. Tylac® 4190
  • 5. Results and Discussion
  • 5.1. Moisture Content–dry Density Relationship of the Mixtures
  • 5.2. Ucs
  • 5.3. Influence of Cement Content, Water Content, Dry Density, and Tylac® 4190 Content on Ucs
  • 5.4. Influence of Curing Time
  • 5.5. Its
  • 5.6. Resilient Modulus of Elasticity
  • 5.7. Wetting and Drying
  • 6. Conclusion and Recommendation
  • Acknowledgements
  • References

رئوس مطالب

  • چکیده
  • کلید واژه ها
  • 1.مقدمه
  • 2. الزامات استاندارد برای استفاده از مصالح- خاک دانه بندی شده در بستر بزرگراه ها
  • 3. الزامات مقاومتی برای مواد بستر جاده تثبیت شده
  • 4. مواد و روش ها
  • 4.1. مصالح
  • 4.2. سیمان پرتلند
  • 4.3. آب
  • 4.4. Tylac 4190
  • 5. نتایج و بحث
  • 5.1. رابطه چگالی خشکی- میزان رطوبت مخلوط ها
  • 5.2. مقاومت فشاری ساده (UCS)
  • 5.3. تاثیر میزان سیمان، میزان آب، چگالی خشکی، و میزان Tylac 4190 بر مقاومت فشاری ساده (UCS)
  • 5.4. تاثیر زمان گیرش
  • 5.5. مقاومت کششی غیر مستقیم (ITS)
  • 5.6. ضریب ارتجاعی الاستیسیته
  • 5.7. خیس کردن و خشک کردن
  • 6. نتیجه گیری و توصیه

Abstract

This study investigated the effects of the type and amount of Portland cement and carboxylated styrene–butadiene emulsion (Tylac® 4190) on the short-term performance of a road base layer via a laboratory evaluation of stabilized soil-aggregate mixtures. Cylindrical specimens stabilized with Portland cement (0–6%), Tylac® 4190 (5–10%), and a mixture of both these additives were molded, cured for 7, 28, and 60 days, and then subjected to different stress sequences to study the unconfined compressive strength, indirect tensile strength, and indirect tensile resilient modulus. The long-term performance (durability) of stabilized soil-aggregate specimens was investigated by conducting wetting and drying (WD) cycling tests on 7-day-cured soil-aggregate specimens stabilized with cement and Tylac® 4190. The results revealed that the additives improved the strength of the specimens, which has been found to be an important quality indicator of road base mechanical properties. Results of tests conducted to assess the specimens’ resistance to WD cycling showed that the addition of a 4% Portland cement–8% Tylac® 4190 mixture resulted in reductions of 86.99% in both water absorption and permeability, volume changes of 88.55%, and weight changes of 92.84% relative to a sample with only 4% cement after 12 WD cycles. This paper also presents the findings of a correlation study conducted for determining the influences of affective variables using nonlinear regression analysis to establish significant prediction models for strength based on mixture parameters.

Keywords: - - - - - - -

Conclusions

The effects of moisture content, dry density, cement content, Tylac 4190 content, and curing time on the strength of road base materials were investigated via WD cycle tests as long-term performance and UCS, ITS, and ITRM in order to evaluate the shortterm performances of CTB and CTTB mixture. The strength of the road base layer was found to increase with increasing cement content and longer curing time. It should be noted that while selecting an optimum content of Portland cement, it is not cost effective to choose the highest percentage of cement; furthermore, using an excessive amount of cement causes shrinkage cracks, which are a severe problem for pavements because they lead to water infiltration. The results of our tests show that the strength increases with an increase in the Tylac 4190 content up to 8%, after which it decreases. This might be due to the water content (44.92%) of Tylac 4190 causes a reduction in the dry density and strength of the mixture. The test results showed that application of CTTB to soil-aggregate is an effective treatment for effectively improving its strength, reducing water vulnerability, and increasing the bearing capacity of the pavement. All these strength and durability improvements result in a significant increase in the lifetime of the pavement. In addition, the total number of roadway layers in CTTB is lesser than those in the conventional variant because of higher bearing capacity, which effectively reduces the construction time and cost. Results of the WD tests show that Portland cement and Tylac 4190 can improve the resistance of CTTB mixtures to moisture damage and reduce both soil aggregate–cement losses and volume changes (swell and shrinkage). This implies that introducing Portland cement and Tylac 4190 into soil-aggregate mixtures reduces their moisture susceptibility because both these components are effective adhesive agents for mixtures.

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