Use of admixtures in organic-contaminated cement–clay pastes

Encapsulation, solid-phases identification and leaching of toxic metals in cement systems modified by natural biodegradable polymers

“…Changes in the fresh state properties and long-term stability of the cement mortars can have deleterious effects on the applicability and usefulness of cement mortars loaded with heavy metals. In order to minimize these adverse effects on the properties of the cement, mineral admixtures such as zeolites, metakaolin, bagasse ash, clinoptilolite [17][18][19] and polymeric admixtures, such as polycarboxylate ethers, naphthalene-based superplasticizers, latexes and acrylic polymers can be added to the cement mortars [8,13,[20][21][22].…”

Cement substitution by organoclay – The role of organoclay type

“…2a and c). Although no plasticizer or dispersing agent was used to avoid OC agglomeration, in the contrast to [11], large (30-50 lm) OC grains were not found, possibly due to long OC mixing with water performed in this study (Fig. 2b).…”

“…2d) showing that OC was in sufficiently good contact with matrix. However, essential differences in the fracture surface were not observed; therefore, following [11], surfaces of cavities and pores in the samples were also examined and are shown in Fig. 1e-g. As expected, euhedral crystals of portlandite were clearly visible as in the plain cement paste (Fig.…”

“…Organically modified clays (OC) as adsorbent materials have found their potential application in the treatment of organic hazardous industrial waste and as pre-solidification agents of organic compounds in cement based matrix [7][8][9][10][11][12][13]. Obtained results showed the effectiveness of OC in reduction of pollutant release during the leaching tests, but OC addition retarded the hardening of cement paste and resulted in the reduction of mechanical strength.…”

Long-term leaching test of organo-contaminated cement-clay pastes

“…Dissolution of portlandite is believed to cause the formation of large diameter pores, thus creating an easy path for deionized water for removing the pollutant from the cement matrix [24]. The research here presented, is the follow-up of a previous work [25] where a short-term leaching test was performed. So, in this work the same cement-clay pastes monoliths, simulating waste forms containing a large amounts of a model organic pollutant (2-chloroaniline), were prepared in order to evaluate the leaching performance over a long-term time (14 months).…”