This report presents information on the characterization of cementitiously stabilized layers and the properties that influence pavement performance. It also contains recommended performance-related procedures for characterizing these layers and performance-prediction models for incorporation into the mechanistic–empirical pavement analysis methods. Individual chapters highlight pavement distresses of hot-mix asphalt pavements and concrete pavements, laboratory tests and model development, and model calibration. The material contained in the report will be of immediate interest to state materials, pavement, and construction engineers and others involved in the different aspects of pavement design and construction.

Characterization of Cementitiously Stabilized Layers for Use in Pavement Design and Analysis

The efficiency of typical chemical and mechanical soil stabilization techniques in mitigating the swelling problem of an expansive soil is investigated through a comprehensive experimental study. Chemical stabilization was generated by traditional agents consisting of lime and cement, and by a commercially branded polymer (CBR PLUS). Mechanical stabilization was applied by means of fiber-reinforcement and swell–shrink cycles. Chemically-treated and fiber-reinforced soil samples were tested for swelling potential in a conventional oedometer apparatus; while swell–shrink cycles were applied using a modified temperature-controlled oedometer. Swell–shrink cycles were applied under room temperature for wetting cycles while the drying process was conducted under a constant temperature of 40 ± 5 °C, and swelling and shrinkage potential were recorded during successive cycles to a point in which swell–shrink equilibrium was attained. Typical strength tests were also conducted for each stabilization scenario which led to maximum reduction in swelling potential. In addition to the experimental program, the swell–time relationship for various stabilization scenarios was simulated using a two-parameter rectangular hyperbola function (2P-RH). Results indicated that all of the proposed stabilization scenarios can guarantee a significant reduction in swelling potential. In the case of lime and cement, reduction in swelling potential was observed to be a function of agent percentage and curing time; whereas for polymer-treated samples the effect of curing was found to be insignificant. Regarding fiber-reinforced samples, reduction in swelling potential was a function of fiber percentage, aspect ratio and fiber tensile strength. Overall, traditional agents proved to be more effective compared to non-traditional techniques. The proposed non-traditional methods, however, displayed promising results posing as great alternatives to lime and cement.

Swelling Potential of a Stabilized Expansive Soil: A Comparative Experimental Study

A selected commercially available sulphonated oil (SO) and a polymer were evaluated for use as soil stabilizers in a laboratory-based investigation. Two naturally occurring soils (Mercia mudstone [MM] and Oxford clay [OC]) and limestone quarry fines (LQF) were treated with the SO, a polymer, and a combination of the SO and the polymer for assessment of changes in their engineering properties. Untreated specimens also were tested to serve as a control condition. Stabilizer performance was evaluated based on the provisions of ASTM D4609-08 (2008). The test results indicated that performance was dependent on both the soil type and the stabilizer dosage. Generally, treatment did not lead to substantial changes in index properties or maximum dry density. However, the optimum moisture content for LQF was substantially reduced (17–35 %) together with improvements in both dry strength (unconfined compressive strength [UCS]: 38 % for MM, 26 % for OC, >500 % for LQF; static flexural strength [SFS]: 60 % for MM and OC, >500 % for LQF) and swell characteristics (20 % for OC, 21–61 % for MM). Applied in the proper context, the stabilizers are suitable for the treatment of soils for low-volume roads.

Soil stabilization using proprietary liquid chemical stabilizers: sulphonated oil and a polymer

The efficiency of a commercially manufactured sulphonated oil (SO) agent in treating a highly expansive soil was investigated through an extensive experimental program. A total of six SO to water m...

A sulphonated oil for stabilisation of expansive soils

Swelling behavior of some soils, especially soils with high clay content, has a great impact on forest roads. Moisture variation in expansive soils results in their volume change. If the soil can not swell freely, it will apply pressure to surrounding structures which may eventually cause some damage or complete destruction. Therefore, it is essential to assess the swelling potential of the foundation soils and take appropriate measures to overcome such problem. In the present study, the effects of RPP as a polymer stabilizer to control swelling of expansive soils were investigated. For this purpose, different tests including Atterberg Limits, standard compaction, swelling potential, and swelling pressure, were conducted on control and treated soil samples using different Percentage of Polymer (RPP) (0.019, 0.04 and 0.06%). Also California Bearing Ratio (CBR) tests were conducted on control and treated samples based on manufacturer recommendation. To assess the effect of time on performance of polymer treated soil, samples with 0.019% RPP content were prepared and kept in sealed plastic bags for 7 and 14 days periods and then tested for Atterberg Limits, swelling potential and swelling pressure. The results showed that soil treatment with RPP, resulted in improvement of CBR and maximum dry density and reduction in Atterberg Limits, swelling potential and swelling pressure. The results also indicated that the curing 7–14 days periods had no significant effect on plasticity and swelling properties of the treated samples.

Effect of polymer stabilizer on swelling potential and CBR of forest road material

During road construction, especially on unsurfaced earth and gravel roads, many problems can arise including deterioration of the surface and dust on the road. Because road maintenance is costly and disruptive to traffic flow, stabilization of some local road materials during construction is necessary. This paper discusses experimental research conducted on the use of the chemical soil stabilizer Con-Aid for stabilization of low cost roads and rehabilitation of existing roads. Con-Aid is a water-soluble, anionic compound with surface-active properties, and is non-toxic and environmentally friendly. Two types of soils in Botswana were used in the research, and lab tests on treated and untreated soil samples were carried out to establish the engineering properties of the soil. It is recommended that Con-Aid be used as a stabilizer on low cost roads, as it will reduce construction and maintenance costs, ensure that the roads remain passable in rainy season, and dust-free in dry season.

T Abadjieva

Papers

Chemical stabilisation for low cost roads in botswana