REVIEW PAPER ON GRAVEL-SAND MIXTURE TREATMENT USING CEMENT AND BITUMEN EMULSION

ABSTRACT

The article discusses treatment of gravel-sand mixture with cement adding bitumen emulsion for roads base. This paper studied how the content of bitumen emulsion in cement treated base (CTB) impacts the properties of mixture. This paper focuses on studies conducted on materials treated or stabilized with cement and bitumen emulsion.

АННОТАЦИЯ

В статье рассматривается обработка гравийно-песчаной смеси цементом с добавлением битумной эмульсии для основания дорог. В этой статье изучалось, как содержание битумной эмульсии в цементно-обработанной основе (CTB) влияет на свойства смеси. Эта статья посвящена исследованиям, проведенным на материалах, обработанных или стабилизированных цементно-битумной эмульсией

Keywords: Base, Cement-bitumen emulsion treated base, Gradation, Maximum dray density, Optimum moisture content, gravel-sand mixture, Cement, bitumen emulsion.

Ключевые слова: основание, основание обработанные цементно-битумной эмульсией, зерновой состав, максимальная сухая плотность, оптимальное влажность, гравийно-песчаная смесь, цемент, битумная эмульсия.

Stabilization offers the ability to improve the materials used in roads.  These improvements include increased strength, and the ability to retain most of their strength when wet. Stabilization with low rates of added bitumen emulsion or cement can decrease resistance to frost, while higher rates can increase a soil’s resistance to frost. When gravel sand mixtures using as base course of roads is requires a stabilizing effect in order to provide a longer life to pavements. One of the most popular techniques to achieve this is by treatment by cement. But a number of factors lead to a decrease in the pace of construction, an increase in estimated costs and a discrepancy in strength indicators. To solve above problems and to improve the quality of base layers, we focused our research to use gravel-sand mixtures treated with cement and addition of bitumen emulsion for road base.     

[3] focused on analyze the use of combined cement and bitumen emulsion in base course stabilization in details and examine its replacement with conventional pavement in regions with low quality materials and limited construction period. Results showed that, based stabilized using combined cement and bitumen emulsion increases the bearing capacity of the pavement effectively. This causes considerable increase in number of allowable equivalent standard axle load (ESAL) and consequently, the lifetime of the road will increase respectively. The total roadway layers in second variant decreased in compare to conventional variant, which, influence the construction time period effectively. Base stabilization is capable for high limit of loading in the regions with lack of proper material. In spite of high chemical binding costs, not only in developed countries but also, in undeveloped countries, using stabilization variant may affect the construction costs effectively.  In figure 1 shows the UCS versus bitumen emulsion for various cement percentages. The results indicate that, in all plot curves, the UCS increase with increase in cement value. The plot curves also show that, the UCS reaches to its maximum value when bitumen emulsion is 3%.

Figure 1. UCS versus bitumen emulsion (28 days)^[3]

[1] was investigated in the laboratory  the physical characteristics and chemical compositions of three selected lateritic soils on their engineering behavior in the natural untreated state and their response to treatment with bitumen emulsion mixed with cement in varied proportions. His research results showed that, addition of 0.5% cement to each percentage of asphalt-emulsion for sample A improved the strength characteristics. With 2% asphalt emulsion, the CBR value increased from 85% to 145% at 6% emulsion content. This later reduced to a CBR value of 100% at 8% emulsion content. Adding 1% cement to the varied percentages of emulsion brought the CBR value to a maximum of 150% with 6% emulsion, but reduced to 120% at 8% emulsion. Mixing 2% cement for the modification gave CBR values of 120% and 200% with 2% and 4% emulsion contents respectively.  He concluded  that beneficial effects were obtained by adding small amounts of cement to soil-asphalt-emulsion mixes, and specifically the results led to the following conclusion, (i) Pre-treatment of fine grained soils with cement facilitates mixing in of asphalt-emulsion and hence improves workability; (ii) Addition of cement increases the strength of soil-asphalt-emulsion mixtures; (iii) Curing of treated samples increases their compressive strengths; (iv) For treated samples, there is an optimum amount of additive which gives a maximum compressive strength depending on the type of soil; (v) Addition of cement to asphalt-emulsion highly favors soils of high plasticity that does not respond appreciably with only asphalt-emulsion; (vi) Modification of asphalt- emulsion with small amounts of cement will lead to reduction in cost of stabilized soils especially the clay soils which will require a high quantity of cement for their treatment; (vii) It has been possible to obtain samples of soils stabilized with small percentages of cement added to asphalt-emulsion and possessing strengths as those of samples stabilized with higher amounts of cement.

[5] studied effects of a native South African granular material stabilized with cement and bitumen emulsion as a base layer in pavement construction. The material stabilized¹ with cement-bitumen emulsion (2-3%) was subjected to Unconfined Compressive Strength (UCS) and Indirect Tensile Strength (ITS) tests for 1, 4, 7 and 28 days curing. The UCS and ITS requirement was evaluated with respect to a base layer for design traffic application of less than six million equivalent¹ single axles. The results of UCS and ITS tests for the stabilized material showed improved strength and have the potential for use as a base course material for the design traffic. The result revealed that 2.5% cement and bitumen emulsion meets the minimum strength characteristics for the base layer. Relative to 2% cement and 2% bitumen emulsion, ITS obtained for 4 and 7 days of curing increased approximately by 24%, 41% and 24%, 53% respectively. Figure 2 shows the effect of the cement content on the UCS of the mixture for 1, 7 and 28 days of curing. Analysis of the results of his study shows that, the granular soil modified with both cement and bitumen emulsion have excellent potential for use as a base course for traffic applications of less than six million equivalent single axles.  Based on the study findings, the use of 2.5% cement and bitumen emulsion in the base layer are recommended. The results showed that the addition of both the cement and bitumen emulsion significantly increased UCS as well as ITS thus improving moisture resistance and durability compared to the virgin material.  Bitumen stabilization is a quick construction method and has a lower cost than reconstruction.  Relative to 2% cement and 2% bitumen emulsion contents, ITS obtained for 4 and 7 days of curing increased approximately 24%, 41% and 24%, 53% respectively.

Figure 2. Plot of UCS against Cement content ^[5]

[4] study investigated the effects of the addition of a bitumen emulsion and Portland cement on the long-term performance of road base. The specimens stabilized with Portland cement (0–6%), bitumen emulsion (0–6%) and Portland cement–bitumen emulsion mixture were subjected to different stress sequences in order to study the unconfined compressive strength (UCS), flexural strength (FS), wetting and drying (WD), soaked and unsoaked California bearing ratio (CBR), dynamic creep (DC), and wheel-tracking (WT) characteristics of 7-day-cured specimens.  The results of UCS, FS and CBR tests revealed that the additives significantly improved the strength of the mixture. The WD cycling tests showed that the addition of a 4% Portland cement–3% bitumen emulsion mixture resulted in a 179.4% reduction in water absorption, a volume change of 256.3%, and a weight change of 211.95% as compared to the sample with 4% cement after 12 WD cycles.  The results from samples treated with 4% cement, 3% bitumen emulsion, and the 4% cement–3% bitumen emulsion mixture are summarized in Fig. 3 in terms of CBR performance versus depth of penetration for both unsoaked and 4-day soaked conditions. From the figure, it is clear that the best improvement for both soaked and unsoaked conditions was obtained from the 4% cement–3% bitumen emulsion mixture. The average CBR of 4% cement, 3% bitumen emulsion, and the 4% cement–3% bitumen emulsion mixtures are 289.7%, 129.2%, and 308.4%, respectively, for unsoaked conditions and 292.6%, 84.68%, and 315.67%, respectively, for the 4-day soaked condition. This result indicated that use of the 4% cement–3% bitumen emulsion mixture increases the CBR by 7% and 139% as compared to the use of 4% cement and 3% bitumen emulsion, respectively. Further, it can be seen from Fig. 3 that the effect of the 4-day soaked condition on the CBR value was negligible for all modified specimens except the samples with no additives and 3% bitumen emulsion, in which the soaked CBR value decreased by 25.4% and 36.4%, respectively, as compared to the unsoaked condition. In this study, the results of the swelling tests are less than 0.10%, which can be considered negligible. The average swelling potential of the soil-aggregate compaction with no additives at OMC was 0.031%, whereas the average swelling potential of 4% cement, 3% bitumen emulsion, and the 4% cement–3% bitumen emulsion mixture was 0.017%, 0.023%, and 0.013%, respectively.

Figure 3. CBR test results for the mixtures. Here, ‘‘C’’ denotes cement and ‘‘BE’’ denotes bitumen emulsion; US denotes unsoaked and S denotes soaked ^[4]

[2] studied the behavior of mineral-cement-emulsion mixture (MCE) under load, whether is it similar to asphalt mixtures (viscoelastic behavior) or to cement treated materials (elastic behavior). To reply this address nine mineral cement-emulsion blends with diverse combinations of cement and emulsion substance he tested in laboratory using Simple Performance Test (SPT).  For each blend solidness moduli and stage points were surveyed for three distinctive temperatures (4, 20 and 40 deg. C) and 9 load frequencies. Performed tests revealed complex behavior of mineral-cement-emulsion mixes, which is intermediate between elastic and viscoelastic. Inverse combinations of cement and emulsion substance appeared either more flexible or more viscoelastic behavior. He concluded that, conducted tests showed that behavior of MCE mixtures is very complex. Diverse sorts of chemical and physical bonds made by diverse authoritative specialists don't appear unequivocal impact. The clear border between mastery of particular sort of bound wasn’t obvious, as the properties of MCE blends made for all combinations of authoritative specialists depended emphatically on the temperature and recurrence. The firmness of blends expanded with the increment of the sum of cement and diminished with the increment of the amount 1 of the asphaltic emulsion. In the midst of tried authoritative operators cement had more grounded impact on the properties of the MCE blends.

Conclusion

Today we live in a world full of development and striving for even greater comfort and convenience. This leads to innovations and revolutions in all areas without exception, but, on the contrary, has a negative impact on the environment, as resources are depleted and various natural sources are polluted. Thus, as follows from the above review of the literature, the use of both cement and bitumen emulsion for processing the base material will increase its physical and mechanical properties and the service life of the pavement. In the conditions of Uzbekistan, the treatment of the base using this method (cement-bitumen emulsion), along with high results, leads to an improvement in the quality of roads, a reduction in environmental impact and a reduction in construction costs.

References:

1. Ayibiowu, Oluyemi B.D. Effect of cement on asphalt - emulsion stabilized lateritic soils. International Journal of Scientific Research and Innovative Technology-2016 Vol. 3 No. 5.
2. Bohdan D. Mariusz J. The influence of binding agents on stiffness of mineral-cement emulsion mixtures, Modern Building Materials, Structures and Techniques, MBMST-2016. Vol. 1
3. Marandi S.M., Safapour P. Base Course Modification through Stabilization using Cement and Bitumen, American Journal of Applied Sciences -2009. Vol.З P.30-42.    
4. Mojtaba Sh. B. Amiruddin B. I. Effects on engineering properties of cement-treated road base with slow setting bitumen emulsion, International Journal of Pavement Engineering -2015
5. Oladapo S. Abiola, R. W. Evaluation of Cement and Bitumen Emulsion on Strength Characteristics of Native South African Granular Soil as Base Course Material, FUOYE Journal of Engineering and Technology-2019. Vol. 4. Issue 1