Properties and composition of recycled aggregates from construction and demolition waste suitable for concrete production

A comprehensive laboratory evaluation of the geotechnical and geoenvironmental properties of five predominant types of construction and demolition (C&D) waste materials was undertaken in th...

https://researchbank.swinburne.edu.au/file/9bbb0fa6-5557-4c65-ada9-7a360c041032/1/PDF (Accepted manuscript).pdf

Geotechnical and geoenvironmental properties of recycled construction and demolition materials in pavement subbase applications

Laboratory evaluation of recycled construction and demolition waste for pavements

The use of reclaimed asphalt pavement (RAP) aggregate materials in road construction reduces natural resource depletion and promotes the recycling of RAP materials for other applications. However, product variability and low resilient moduli characteristics often limit RAP applications in road bases. Stabilization of RAP materials with cement was hence attempted in a research study to evaluate the effectiveness of cement treatments in enhancing resilient characteristics of RAP aggregates. The present paper describes the results from a series of resilient modulus tests that were conducted in a laboratory environment using a repeated load triaxial test setup. The effects of three different cement dosages and various confining and deviatoric stress levels on the resilient modulus (MR) response of treated RAP materials were studied. MR values of untreated and cement-treated RAP aggregates ranged from 180 to 340 MPa and 200 to 515 MPa, respectively, which reveal the enhancements with cement treatment. Regressi...

Resilient Moduli Response of Moderately Cement-Treated Reclaimed Asphalt Pavement Aggregates

Use of recycled aggregates from construction and demolition waste in geotechnical applications: A literature review.

As construction and remediation take place throughout New Jersey, the amount of construction and demolition debris increases, while the availability of landfill space decreases. A viable solution for disposing of these materials is to incorporate them into base and subbase applications. An extensive laboratory program was conducted on two types of construction and demolition debris: recycled concrete aggregate (RCA) and recycled asphalt pavement aggregate (RAP). These two materials were compared with dense-graded aggregate base coarse (DGABC), which currently is being used in roadway base applications in New Jersey. Both RCA and RAP were mixed at various percentages with the DGABC to evaluate whether an optimum mix blend could be formulated. The materials were evaluated under a traffic-type loading scheme that included resilient modulus and permanent deformation via cyclic triaxial testing. Laboratory tests indicated that the RAP, RCA, and DGABC blended materials all obtained higher resilient modulus values than the currently used DGABC. The permanent deformation results indicated that the RCA mixed samples obtained the lowest amount of permanent deformation when the material was cyclically loaded to 100,000 cycles. In contrast, the permanent deformation testing on RAP mixed samples resulted in the highest amount of permanent deformation at the same number of cycles. Existing models currently used for quarried base and subbase materials were used to predict the permanent deformation in the recycled materials. Laboratory test results indicated that these models could be used for predicting permanent deformation in unbound recycled materials.

Utilization of Construction and Demolition Debris Under Traffic-Type Loading in Base and Subbase Applications

Laboratory and field investigations were conducted to evaluate the use of recycled asphalt pavement (RAP) in roadway base and sub-base applications. The laboratory resilient modulus test results showed RAP has comparable strength with dense graded aggregate base and sub-base material used in the state of New Jersey. Using the spectral-analysis-of-the-surface-waves method (SASW), the field testing program evaluated the elastic modulus of the RAP base in the field and verified the laboratory results. The field test results showed higher modulus and stiffness for RAP than the dense graded aggregate base normally used in state of New Jersey.

Recycled Asphalt Pavement as a Base and Sub-Base Material

The design performance of a pavement system is evaluated based on the predicted number of load repetitions it will be subjected to throughout its service life. Mechanistic pavement design predicts pavement failure due to cracking and/or rutting. The pavement system includes a bound bituminous layer and unbound base, subbase, and subgrade layer. An investigation is carried out on two types of constructed and demolition debris, recycled asphalt pavement (RAP) and recycled concrete (RCA). A comparison of these two construction with dense graded aggregate (DGA) revealed that RAP and RCA yielded higher resilient modulus values than DGA. Laboratory test results concluded these models could be used for evaluating resilient modulus and permanent deformation.

Behavior of Construction and Demolition Debris in Base and Subbase Applications

To effectively and economically design pavement systems, subgrade response must be evaluated. Understanding the importance of subgrade soil response to various loading conditions, the American Association of State Highway and Transportation Officials (AASHTO) and the Strategic Highway Research Program (SHRP) established and refined a Standard Test Method for Determining the Resilient Modulus of Soils and Aggregate Materials. Mechanistic design methods for flexible pavements require the specification of subgrade resilient modulus. The resilient modulus is measured under laboratory conditions that should reflect the conditions the subgrades are subjected to in the field. In this study, a laboratory-testing program was developed to determine the resilient modulus of typical New Jersey subgrade soils. A total of eight soils were tested at different molded water contents to determine their sensitivity to moisture content and cyclic stress ratio. Repeated loading or pumping of the pavement system may induce excess pore water pressure within the subgrade layer thereby reducing the resilient modulus, leading to the premature failure of the pavement. A sensitivity analysis was conducted using an elastic layer computer program to demonstrate the effect of subgrade stiffness on the design thickness of the asphalt layer. As expected, the subgrade stiffness has a dramatic effect on the eventual thickness of the asphalt layer. Laboratory results were used to calibrate a statistical model for effectively predicting the resilient modulus of subgrade soils at various moisture contents and stress ratios. This model will prove to be a valuable tool for pavement engineers to effectively and economically design a pavement system.

Resilient modulus properties of new jersey subgrade soils

The utility of noncontacting proximity sensors for the measurement of small strains in resilient modulus tests is evaluated. The proximity sensor measurements of resilient modulus were compared with those obtained from linear variable differential transformers. The important issue of granular soil sample preparation and its effect on the magnitude of resilient modulus was evaluated. Two methods were proposed to facilitate sample preparation and to provide good contact between the soil and the loading platen. The effect of conditioning sequence on sample integrity was also investigated for the two proposed methods of compaction. In addition to the experimental program, a number of constitutive models, used for prediction of resilient modulus of granular soils, were examined; and model predictions were compared with the test data.

W J Papp Jr

Papers

Utilization of Construction and Demolition Debris Under Traffic-Type Loading in Base and Subbase Applications

Recycled Asphalt Pavement as a Base and Sub-Base Material

Behavior of Construction and Demolition Debris in Base and Subbase Applications

Resilient modulus properties of new jersey subgrade soils

Measurement of Soil Resilient Properties Using Noncontacting Proximity Sensors