Research documents

Virginia Department of Transport – Report

Many pavement subgrades in Virginia consist of wet, highly plastic clay or other troublesome soils. Such soils can be treated with traditional lime and cement stabilization methods. Alternatives, including lignosulfonates and polymers, are available, but their performance record is mixed and solid engineering data are lacking, which prevents reliable design. The goal of this research was to screen a suite of traditional and non-traditional stabilizers against three Virginia soils that have caused problems during construction or resulted in poor performance in service. The selected stabilizers were: quicklime, hydrated lime, pelletized lime, cement, lignosulfonate, synthetic polymer, magnesium chloride, and a proprietary cementitious stabilizer.
A laboratory procedure was developed and applied to three Virginia soils obtained from Northern Virginia, Staunton, and Lynchburg.
Key findings from the research include: (1) traditional lime and cement stabilizers were far more effective than liquid stabilizers (lignosulfonate, synthetic polymer, and magnesium chloride) in increasing strength; (2) the liquid stabilizers were ineffective on soils with a high moisture content; (3) the proprietary cementitious stabilizer was more effective in increasing strength than lime for all cases tested but not was not as effective as the cement stabilizer; (4) quicklime and hydrated lime increased the workability of the soils although they did not produce strengths comparable to cement; (5) the strength of soils stabilized with cement and the proprietary cementitious stabilizer can be estimated based on the water-amendment ratio of the mixture; and (6) the strength of soils stabilized with lime can be estimated based on a combination of the plasticity index and the water-amendment ratio of the mixture.

The benefits of subgrade stabilization are that it improves the strength, stiffness, and durability of soft subgrade soils. Such improvement allows a reduction in the required thickness of overlying pavement courses and/or an increase in pavement life. Quantifying the life cycle cost benefits requires performing pavement design studies based on anticipated traffic levels, desired serviceability, etc. The preferred design method would be a mechanistic design, which requires resilient modulus values for the stabilized subgrade and other pavement layers. Neither resilient modulus testing nor pavement design studies were included in the scope of the work for this project, but they should be included in subsequent phases.

CSIR Report on AnyWay’s RBI Grade 81 – English

This report summarizes an evaluation of the performance of the RBI Grade 81 stabilizing product for use as a road construction stabilizer. The performance of the product was evaluated in terms of the proposed Agreement Certificate testing and includes properties such as the improvement in strength, durability and erodibility. The strength evaluations that were carried out were the Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) strength. The erosion evaluation was carried through a water jet erosion test. The performance of the product was tested at different application rates, namely 2, 4 and 6 percent of the dry weight of the Silbou building sand material. The laboratory results and the evaluation of the product are summarized in this report.

The use of RBI 81 for stabilization of clay soil for road pavements – Politecnico Di Bari, Italy – Italian

The recovery of local materials of insufficient quality, finalized to the use in road circle, it shows a double value: economic and environmental. In fact, the use of available materials in the yard consents of to reduce the entity of the transport of material from the yards of loan and toward the sites of refusal, with evident advantages tied to the reduction of new sites. Nevertheless, the tendency to use such material finds notable difficulties since they don’t obey to the technical prescriptions. Between the grounds that am a little used in the roads those clayey appear certainly; they are diffused in several regions of our Country. The present research reports on the initial phase of experimentation in progress in the Laboratory Tests and Materials of the DVT of the Polytechnic in Bari; the research has two objectives:

  • The evaluation of clay properties mixed with a new product, natural, ecological, denominated RBI-81;
  • The determination of the optimal dosage of the RBI-81 and his/her influence, together to the conditions of seasoning (time, contained of water, etc.), on the mechanical characteristics of the mixtures.

This study, therefore, has experimental theoretical character and is the first one effected in our Country on this new additive.

Brazil paper – effect of curing time

This paper address the topic influence of curing time on the unconfined compression strength of three gneiss residual soils from the North Forrest of Minas Gerais, Brazil, after stabilization with the chemical additive called RB1 Grade 81. The soils group encompassed a mature residual soil, named soils 1 (pedologically classified as a Red- Yellow Latossol), and two young residual soils, named soils 2 and 3.

Additive contents used were as follows: 2%, 4% and 6% related to soils dry mass. Data analysis supported the following conclusions: (i) addition of 4% and 6% of RBI Grade 81 to the soils led to significant increases in their unconfined compression; (ii) at 7 days curing time the mixtures exhibited significant unconfined importance of this parameter on the mixtures stabilization process.

Technion Israel– The Use of ANSS as a stabilizer for fine grained swelling soils

This part of the research is aimed at quantifying the affect of ANSS content on the
swelling properties of a clayey soil of high swell potential. The test program included
a set of experiments with the objective to examine the vertical swell of stabilized and
non stabilized specimens as a function of initial water content, applied vertical
pressure and ANSS content. A second phase of experiments was to evaluate the rate of
vertical swell in response to a change in water content as a function of the initial water
content and ANSS content.
Link to the Executive Summary

The Municipality of Tel Aviv Structural Evaluation of Stabilized Shoulders with ANSS

The Elastic Moduli and the CBR of the stabilized natural soil increased significantly as a result of the stabilization. Stabilizing the sub grade has lead to an increase of the Elastic Moduli of the upper layer by more than twice.
The affect of the stabilized layer on the lower non stabilized layers is very clear through analyzing the results using the dual layer model.
The municipality of Tel Aviv paved 5 test sections next to one of the roads within the city in order to evaluate the performance and durability of stabilized layers through their service period and examine the strength development and other characteristics of various pavement materials stabilized with ANSS.It can be concluded that stabilization of the natural soil contributes to the development of strength and function of the stabilized layer. It is also evident that there is a contribution to the total equivalent strength values of the structure of layers.
Link to the Evaluation