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

Lime-cement columns were constructed to improve soft ground as part of a test embankment program at the I-95/Route 1 interchange in Alexandria, Virginia. Two different commercial laboratories performed tests on treated soil, and they produced very different measurements of unconfined compressive strength. Further, both sets of results were different from test results available in the published literature for similar soils. This situation created uncertainties and a conservative design philosophy. The goals of this research project were to assess factors that influence strength gain of lime-cement-soil mixtures, to develop a detailed laboratory test procedure that produces consistent results, and to determine the reasons that the strengths measured by the private firms were so different. A suitable laboratory procedure was developed and applied to three soils: one from the I-95/Route 1 interchange site and two from the site of a potential future application of lime-cement columns in West Point, Virginia, at State Route 33. Key findings from the research were that (1) drying and subsequent restoration of soil moisture prior to treatment can decrease the strength of the mixture, (2) the mixture strength decreases as the ratio of soil water content to cement content increases for 100% cement-soil mixtures, (3) the addition of lime can increase the mixture strength for some soils and decrease the strength for others, and (4) presenting the test results in the form of contour plots of unconfined compressive strength can be very useful. The reasons for the different results from the two private firms are explained by differences in the test procedures that were used.

Factors affecting strength gain in lime-cement columns and development of a laboratory testing procedure

Expansive soil subgrades, which are subjected to dual swell-shrink problem consequent upon absorption and evaporation of water, need to be improved by chemical stabilization or compacted cushion or...

Silica fume stabilization of an expansive clay subgrade and the effect of silica fume-stabilised soil cushion on its CBR

Marine clay deposits are commonly found worldwide. Considering the cost of dumping and related environmental concerns, an alternative solution involving the reuse of soils that have poor conditions is crucial. In this research, the authors examined the strength, microstructure, and wet–dry resistance of triple-binder composites of marine-deposited clays and compiled a corresponding database. In order to evaluate the wetting–drying resistance of the laboratory-produced samples, the accumulated mass loss (ALM) was calculated. The use of slag alone as a binder, at any percentage, increased the ALM up to 2%. However, the use of lime as the third binder seemed to accelerate the chemical reactions associated with the hydration of clay and cementitious material and to enhance the chemical stability, i.e., specimens that included both lime and slag experienced the same ALM as specimens treated with cement only. Scanning electron microscopy analysis confirmed the durability improvements of these clays. The proposed unconfined compressive strength–porosity and accumulated mass loss relationship yielded practical approximation for the fine- and coarse-grained soils blended with up to three binders until 60 days of curing. The laboratory-produced mixes showed reduction of embodied energy and embodied carbon dioxide (eCO2) emissions for the proposed models.

Triple-Binder-Stabilized Marine Deposit Clay for Better Sustainability

The utilization of waste rubber tire powder to improve the mechanical properties of cement-clay composites

CURRENT BRITISH PRACTICE IN THE DESIGN AND SPECIFICATION OF SOIL-CEMENT FOR USE IN THE BASE OR SUBBASE FOR ROADS IS DESCRIBED. THE COMPOSITION OF THE MATERIAL, THE STRUCTURAL DESIGN OF ROADS INCORPORATING SOIL-CEMENT, AND THE METHODS USED TO CONTROL THE QUALITY OF THE MATERIAL IN PRACTICE ARE PRESENTED. THE SUITABILITY OF A SOIL FOR STABILIZATION IS BASED ON REQUIREMENTS SIMILAR TO THOSE IN THE UNITED STATES, GOOD GRADING, LOW PLASTICITY OF THE FINES, AND FREEDOM FROM DELETERIOUS CHEMICAL CONSTITUENTS. THE PEDOLOGICAL CLASSIFI- CATION OF A SOIL PROFILE IS USED TO ESTIMATE THE DEPTH OF SOIL UNSUITABLE FOR STABILIZATION, BECAUSE OF ORGANIC CONTENT. MEASUREMENTS OF THE PH OF A SOIL-CEMENT PASTE 1 HOUR AFTER MIXING ARE USED AS A CHECK ON THE PRESENCE OF DELETERIOUS ORGANIC MATTER. SOIL-CEMENT HAS BEEN WIDELY USED SINCE 1945 FOR THE CONSTRUCTION OF HOUSING ESTATE ROADS AND LOW-TRAFFIC RURAL ROADS. CEMENT-STABILIZED MATERIALS HAVE ALSO BEEN USED FOR THE CONSTRUCTION OF MAIN ROADS, IN PARTICULAR AS THE SUBBASE OF CONCRETE AND BITUMINOUS- SURFACED ROADS. THE QUALITY CONTROL OF SOIL-CEMENT DURING CONSTRUCTION IS BASED LARGELY ON TESTS TO CHECK THE STRENGTH AND STATE OF COMPACTION OF THE LAID MATERIAL.

W A Lewis

Papers

British practice in the design and specification of cement- stabilized bases and subbases for roads