Author
Mauro Mitsuuchi Tashima
Other affiliations: Polytechnic University of Valencia
Bio: Mauro Mitsuuchi Tashima is an academic researcher from Sao Paulo State University. The author has contributed to research in topics: Portland cement & Compressive strength. The author has an hindex of 21, co-authored 75 publications receiving 1334 citations. Previous affiliations of Mauro Mitsuuchi Tashima include Polytechnic University of Valencia.
Papers
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TL;DR: In this paper, the properties and microstructure of alkali-activated cement pastes and mortars produced using red clay brick waste were investigated, and it was shown that the type and concentration of acid activator can be optimised to produce mortar samples with compressive strengths up to 50MPa after curing for 7 days at 65°C.
241 citations
TL;DR: In this paper, the properties and microstructure of alkali-activated cement pastes and mortars produced from ceramic waste materials of various origins were investigated, and the compressive strength of the developed mortars ranged between 22 and 41MPa after 7 days of curing at 65°C, depending on the sodium concentration and the water/binder ratio.
Abstract: Ceramic materials represent around 45 % of construction and demolition waste, and originate not only from the building process, but also as rejected bricks and tiles from industry. Despite the fact that these wastes are mostly used as road sub-base or construction backfill materials, they can also be employed as supplementary cementitious materials, or even as raw material for alkali-activated binders. This research aimed to investigate the properties and microstructure of alkali-activated cement pastes and mortars produced from ceramic waste materials of various origins. Sodium hydroxide and sodium silicate were used to prepare the activating solution. The compressive strength of the developed mortars ranged between 22 and 41 MPa after 7 days of curing at 65 °C, depending on the sodium concentration in the solution and the water/binder ratio. These results demonstrate the possibility of using alkali-activated ceramic materials in building applications. Ceramic materials represent around 45 % of construction and demolition waste in Spain. In the present study, two different ceramic materials, red ceramic bricks and porcelain stoneware were alkali-activated in order to produce pastes and mortars. The figure shows the microstructure of pastes obtained using a sodium silicate solution and NaOH pellets as activators. Both materials presented differences related to the process and the optimum concentration of activator. Mortars with compressive strengths ranging from 22 to 41 MPa were obtained after 7 days of curing at 65 °C, which make them suitable for building applications.
114 citations
TL;DR: It was demonstrated that sugar cane bagasse ash is an interesting source for preparing alkali-activated binders and a good stability of matrices developed by means of alkali -activation was demonstrated.
Abstract: Blast furnace slag (BFS)/sugar cane bagasse ash (SCBA) blends were assessed for the production of alkali-activated pastes and mortars. SCBA was collected from a lagoon in which wastes from a sugar cane industry were poured. After previous dry and grinding processes, SCBA was chemically characterized: it had a large percentage of organic matter (ca. 25%). Solutions of sodium hydroxide and sodium silicate were used as activating reagents. Different BFS/SCBA mixtures were studied, replacing part of the BFS by SCBA from 0 to 40% by weight. The mechanical strength of mortar was measured, obtaining values about 60 MPa of compressive strength for BFS/SCBA systems after 270 days of curing at 20 °C. Also, microstructural properties were assessed by means of SEM, TGA, XRD, pH, electrical conductivity, FTIR spectroscopy and MIP. Results showed a good stability of matrices developed by means of alkali-activation. It was demonstrated that sugar cane bagasse ash is an interesting source for preparing alkali-activated binders.
100 citations
TL;DR: In this article, the authors used sugarcane bagasse ash (SBA) obtained by auto-combustion for preparing alkali-activated cements by blending blast furnace slag (BFS).
91 citations
TL;DR: In this paper, the pozzolanic reactivity of sugar cane straw ash (SCSA) obtained through an auto-combustion process and the mechanical properties of SCSA-containing systems was assessed.
77 citations
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TL;DR: Alkali activation is a highly active and rapidly developing field of activity in the global research and development community as discussed by the authors, and commercial-scale deployment of alkali-activated cements and concretes is now proceeding rapidly in multiple nations.
873 citations
TL;DR: In this article, the chemistry and structure of geopolymers, reaction mechanism and prime materials involved in geopolymer formation are discussed, and the characterization of geo-mers in terms of microstructural, crystallographic and functional groups is elucidated.
336 citations
TL;DR: In this paper, the properties and microstructure of alkali-activated cement pastes and mortars produced using red clay brick waste were investigated, and it was shown that the type and concentration of acid activator can be optimised to produce mortar samples with compressive strengths up to 50MPa after curing for 7 days at 65°C.
241 citations
TL;DR: In this article, the compressive strength of concrete, bricks and tiles collected from various demolished buildings were mixed with the activating solution (NaOH and Na 2 SiO 3 ), and various synthesis conditions (curing at 60-90°C, 8-14 m NaOH molarity, particle size) were considered.
194 citations
TL;DR: In this article, the median diameter and replacement ratio of Recycled Powder (RP) concrete should be below 30μm and 30%, respectively, to improve the durability of concrete when the RP fineness is superior to the cement fineness.
Abstract: Recycled powder (RP) is the main by-product in the reclamation of construction and demolition (CD in addition, improvement methods and a benefit evaluation of RP concrete are further introduced. Based on statistical data that describe the activity index of RP and the compressive strength of RP concrete, the median diameter and replacement ratio of RP in concrete preparation should be below 30 μm and 30%, respectively. The use of RP improves the durability of concrete when the RP fineness is superior to the cement fineness. Increasing the RP fineness is an effective approach to improving the properties of RP concrete, and a CO2-curing treatment of RCP is an eco-friendly modification method. Furthermore, the use of RP in concrete has good economic and environmental benefits. Therefore, one expects that this review helps the further use of RP in concrete.
188 citations