Stabilization treatment of a dispersive clayey soil using granulated blast furnace slag and basic oxygen furnace slag

Zero-waste approach in municipal solid waste incineration: Reuse of bottom ash to stabilize fly ash

A review of the use of lateritic soils in the construction/development of sustainable housing in Africa: A geological perspective

Enhancement of cement-based solidification/stabilization of a lead-contaminated smectite clay.

RoadCem (RC) is an additive produced based on nanotechnology and comprises of synthetic zeolites and alkali earth metals as some of its components. The geotechnical properties of a soil stabilized by adding RC to partly replaced cementitious materials are studied. Various combinations of the additives were investigated with the objective of reducing the amount of OPC by 50% by an inclusion of RC and ground granulated blast furnace slag (GGBS) in the stabilized soil. Laboratory studies involving index property testing, oedometer swell-deformation, unconfined compression tests and microstructural examinations were carried out on both the natural and 7-& 28- day cured samples of the stabilized soil. The influence of RC on the mechanical properties of the stabilized soil was examined by comparing the performance of the stabilized soil mixtures that contain the RC and the mixtures without the RC added. Results indicated the positive effect of RC as noticed by the tremendous strength gain in 7 days with the OPC reduced by 50% in the stabilized soil. Swelling decreased significantly to 0% after 28 days curing with the settlement also reasonably reduced for nearly all the percentages of the OPC substituted. The stabilized soil’s microstructure revealed the mechanism of cementation observed as an encapsulation or “wrapping effect” as a result of the presence of RC. A comparison of the RC-modified soil containing the by-products GGBS and PFA indicated that GGBS was more effective in the enhancement of engineering properties than PFA. Overall, as well as meeting some of the standards set for road pavement applications, the results obtained from this research are very promising for the ongoing discussions on reducing carbon foot-printing by OPC replacement.

Performance of clay stabilized by cementitious materials and inclusion of zeolite/alkaline metals-based additive

Pozzolanic consolidation of stabilized soft clays

In recent years, the use of nanoclays in different projects are reported. However, there has been very little attention on the application of nanoclays in geo-environmental projects. In this paper the possibility of application of nanoclays for retention of heavy metal (HM) contaminant were investigated. To achieve this objective a series of experiments were performed on bentonite, kaolinite and nanoclays samples. The buffering capacity, retention properties and XRD experiments show that among Cation Exchange Capacity (CEC), specific surface area, and carbonate, the main factor that controls the soil-HM interaction is carbonate phase. The CEC is the second important factor. Furthermore, after interaction of soil samples with HM the intensity of basal spacing of minerals in XRD decreased. In Cloisite 15A which had the minimum interaction with HM, the minimum reduction in peak intensity was observed (200 Cps). In addition, the contaminant retention of soil samples are in accordance to following order: Bentonite> Cloisite®Na > Kaolinite> Cloisite®30B > Cloisite®20A > Cloisite®15A

Geo-environmental behaviour of nanoclays in interaction with heavy metal contaminants

Recently there have been many researches on the subject of soil-contaminant interaction. However, there are very few researches on the potential of nano-clays to increase the contaminant retention of soils. In addition, reviewing the previous studies shows that the application of nano-clays in geo-environmental engineering has not been taken into consideration. The main objective of this paper is to indicate the special potential of nano-clays for heavy metal contaminant retention. To achieve this purpose, a series of geo-environmental experiments were performed to establish the fundamental aspects of nano-clay and contaminant interaction. To compare the geo-environmental behavior of nano-clay and bentonite, different concentrations of calcite were laboratory added to nano-clay samples. Series of batch equilibrium testing, and buffering capacity experiments were performed and were compared with the experimental results on bentonite, before and after addition of carbonate to nano-clay samples. It is shown that mixtures of nano clay and 8% carbonate have more contaminant retention than that of bentonite sample. In the other part of this paper the process of nano-clays and heavy metal contaminant interaction were investigated by application of XRD analysis. In addition, it is shown that even though carbonate has more impact than surface area on contaminant sorption by soils, the large specific surface are of nano clays is responsible for their very high contaminant retention ability. Therefore, the enhanced nano-clay with carbonate will be very capable for use in geo-environmental projects. The achieved results of this paper show that among bentonite, kaolinite, and four Cloisite nano-clay samples, the order of contaminant retention of samples are as follows:

Bentonite > Cloisite®Na+ > Kaolinite > Cloisite®30B > Cloisite®20A > Cloisite®15A

However, with addition of laboratory added carbonate to the nano-clay samples, the above order will be changed according to the following order:

Cloisite®Na+ > Cloisite®15A ≥ Cloisite®20A > Cloisite®30B > Bentonite

This shows a larger retention by mixture of nano-clays/8% carbonate in comparison with bentonite

M. Amiri

Papers

Pozzolanic consolidation of stabilized soft clays

Geo-environmental behaviour of nanoclays in interaction with heavy metal contaminants

The special potential of nano-clays for heavy metal contaminant retention in geo-environmental projects