Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
Search Results
Article Citation - WoS: 5Citation - Scopus: 5Mechanical Properties of Palygorskite Clay Stabilized With Polyelectrolytes(Elsevier, 2023) Huang, Jianxin; Makhatova, Ardak; Kogbara, Reginald; Masad, Eyad; Sukhishvili, Svetlana; Little, DallasTwo polyelectrolytes of opposite charges, sodium polystyrene sulfonate (PSS) and polydiallyldimethylammonium chloride (PDADMAC), were investigated to stabilize palygorskite clay at varying dosages of 0.2, 0.8, 1.6, and 3.2 % by the dry weight of the soil. Both PSS and PDADMAC improved the unconfined compressive strength of the palygorskite clay. PSS was effective at all the polymer contents studied after 7 days of dry curing and the strength increased with the dosages of PSS added, ranging from 2 MPa (0.2 % PSS) to 3.1 MPa (3.2 % PSS), compared with 1.5 MPa of the untreated soil. PDADMAC, on the other hand, showed comparable strength improvements as PSS did at the high polymer contents of 1.6 and 3.2 % but did not work at 0.2 and 0.8 % dosages. Under wet curing at 100 % relative humidity, PSS improved the strength of the clay by 40 % (620 kPa at 0.2 % PSS) to 77 % (764 kPa at 1.6 % PSS) compared to the untreated clay (440 kPa). PDADMAC exhibited less improvement than PSS under wet conditions but still worked at dosages of 0.8 and 1.6 %. Besides strength, the resilient modulus and fracture toughness of the treated specimens increased by approximately 10 % and 66 %, respectively, when treated with 1.6 % PSS, which was the optimum content based on the strength results. PDADMAC-treated palygorskite, however, exhibited cracking during curing for both tests, showing potential drying crack issues. The adsorption of PSS and PDADMAC on palygorskite clay were also measured using ultraviolet–visible spectroscopy, and binding between these polymers and palygorskite has been confirmed. The measured adsorption capacities of PSS and PDADMAC were comparable (2.9 and 2.7 mg/g, respectively), while the PSS was somewhat more efficient in improving soil mechanical properties. © 2023 Elsevier LtdArticle Citation - WoS: 17Citation - Scopus: 19Development of Ca(oh)2-Based Geopolymer for Additive Manufacturing Using Construction Wastes and Nanomaterials(Elsevier, 2023) Mortada, Youssef; Masad, Eyad; Kogbara, Reginald B.; Mansoor, Bilal; Seers, Thomas; Hammoud, Ahmad; Karaki, AymanRecent growth in additive manufacturing (AM) or 3D printing in the construction field has motivated the development of various materials that vary in its composition and properties. This paper introduces, characterizes, and evaluates the performance of a sustainable and environmentally friendly geopolymer mixture composed of construction wastes. The geopolymer mixture has calcium hydroxide (Ca(OH)2) as the main alkaline activator and incorporates nanomaterials such as nano-silica and nano-clay to enhance its suitability for AM. The combined use of Ca(OH)2 for alkali activation, and nanomaterials for tailoring the behavior of construction wastes for 3D printing, is novel and addresses the shortcomings of conventional alkaline activators. The paper includes the outcomes of the analysis of the mechanical properties, printability, and microstructure of the geopolymer mixture. The 28-day compressive strength of the mixture reached 42 MPa with ambient temperature curing, which is comparable to traditional geopolymers. The inclusion of 1 wt % of nano-silica accelerated the geopolymerization process and led to the largest (35 %) reduction in the setting time. Similarly, incorporating 1 wt % of nano-clay led to reduction of the thermal conductivity from 0.709 W/mK to 0.505 W/mK, due to the introduction of thermal barriers. The printability of the studied waste-based geopolymer mixture was validated through the successful fabrication of a 3D-printed model. © 2023 The Authors