Papers by Rodrigo Dejeto
International Journal of ADVANCED AND APPLIED SCIENCES
The curing temperature and time are the basic fundamental factors that contribute to the hydratio... more The curing temperature and time are the basic fundamental factors that contribute to the hydration of Ordinary Portland Cement (OPC) paste. The purpose of this work is to investigate the effect of temperature vis-à-vis curing time on the hydration products: Portlandite (CH), calcium silicate hydrate (C-S-H), ettringite (AFt) and monosulfoaluminate (AFm) of Japan OPC paste using the water-cement ratio (w/c) of 0.40 and following intensive procedures in sample preparation and testing. Results showed that the proportion of CH and C-S-H phases dominated the hydration products at higher curing temperature and longer time as revealed in BEI/SEM analysis. The XRD/Rietveld analysis showed that the CH had the highest peaks intensity compared to other crystalline phases cured at 40 o C for 28 days. It has a mineralogical composition equivalent to 20.06% compared to 17.80% as OPC cured at room temperature. There was no C-S-H phase detected since it is non-crystalline/amorphous in nature with composition equivalent to 61.75%. The conversion of AFt to AFm phase from 0.12% to 3.10% was also detected at higher curing temperature and longer time. The CH is the major crystalline phase identified in this study.
Ordinary Portland cement (OPC) is used worldwide as basic construction material. Studying its phy... more Ordinary Portland cement (OPC) is used worldwide as basic construction material. Studying its physical, chemical and microstructural properties is important. In this study, the influence of porosity, degree of hydration and the effect of temperature on the strength of Japan OPC were evaluated using the water/cement ratio (w/c) of 0.40 and intensive procedures in sample preparation and testing. High early compressive strength development, fast degree of hydration and decreased porosity were observed in 3-day cement cured at 40oC. However, the strength and degree of hydration begun to decline after 28 days of curing period which was nearly comparable to cement cured at room temperature. Keywords: porosity, degree of hydration, temperature, compressive strength
Proceedings of the Samahang Pisika ng Pilipinas, 2002
YBa 2 Cu 3 O 6.5 (YBCO123) was synthesized, subjected to a pre-melt process, and its microstructu... more YBa 2 Cu 3 O 6.5 (YBCO123) was synthesized, subjected to a pre-melt process, and its microstructures were characterized via SEM. The microstructural evolution was observed by pre-melting YBCO123 at the melting temperature onset of 1020°C and cooling it down with crystallization cooling rates (CR) 100, 50, 33.3, 20, 10, 5, and 2°C/hr. Microstructural development from a brittle fissured faceted phase with no defined grain boundary and densified melted features to column-like grains and biphasic grains with hexagonal grain boundaries were observed as the CR was varied from fastest to slowest CR.
Mullite from clay is well studied but there has been no report on the Solsona White Clay-alumina
... more Mullite from clay is well studied but there has been no report on the Solsona White Clay-alumina
(SWC-Al2O3) substitution in the mullite compositions. The synthetic mullite obtained from this work is
the product of the synthesis of the beneficiated Solsona white clay (SWC) sourced from Ilocos Norte,
Philippines; Alumina (Al2O3) powder reagent from J.T. Baker Inc., USA; and Siruma silica (SiO2) from
Bicol, Philippines.
The formulation was based on the theoretical composition of mullite that is 71.79% Al2O3 and 28.21%
SiO2; modified with a proportional substitution Al2O3 to the SWC by 5%, 10%, 15%, 20%, and 50% and
kept the SiO2 constant. The five formulations were processed separately and then characterized using
SEM, XRD and EDX.
Formulation with 5%, 10% and 15% SWC revealed the presence of pores, formation of column-like
grains, acicular and small islands of a locally textured grainy structure when sintered at 1150°C for 7hrs;
and the formation of nodular grains when sintered at 1400°C for 7hrs. While formulations with 20% and
50% SWC demonstrates with preferred grain alignment and huge grain growth after sintering at 1150°C
for 7hrs and further transformed into a nucleated particle and amorphous/glassy phase when sintered at
1400°C for 7hrs.
Institute of Advanced Science Extension (IASE), Mar 20, 2018
The curing temperature and time are the basic fundamental factors that contribute to the hydratio... more The curing temperature and time are the basic fundamental factors that contribute to the hydration of Ordinary Portland Cement (OPC) paste. The purpose of this work is to investigate the effect of temperature vis-à-vis curing time on the hydration products: Portlandite (CH), calcium silicate hydrate (C-S-H), ettringite (AFt) and monosulfoaluminate (AFm) of Japan OPC paste using the water-cement ratio (w/c) of 0.40 and following intensive procedures in sample preparation and testing. Results showed that the proportion of CH and C-S-H phases dominated the hydration products at higher curing temperature and longer time as revealed in BEI/SEM analysis. The XRD/Rietveld analysis showed that the CH had the highest peaks intensity compared to other crystalline phases cured at 40 o C for 28 days. It has a mineralogical composition equivalent to 20.06% compared to 17.80% as OPC cured at room temperature. There was no C-S-H phase detected since it is non-crystalline/amorphous in nature with composition equivalent to 61.75%. The conversion of AFt to AFm phase from 0.12% to 3.10% was also detected at higher curing temperature and longer time. The CH is the major crystalline phase identified in this study.
Conference Presentations by Rodrigo Dejeto
Proceedings of the Samahang Pisika ng Pilipinas, 2002
YBa 2 Cu 3 O 6.5 (YBCO123) was synthesized, subjected to pre-melt process and its microstructures... more YBa 2 Cu 3 O 6.5 (YBCO123) was synthesized, subjected to pre-melt process and its microstructures characterized via SEM. The microstructural evolution was observed by pre-melting YBCO123 at the melting temperature onset 1020°C and cooling it down with crystallization cooling rates (CR) 100, 50, 33.3, 20, 10, 5 and 2°C/hr. Microstructural development from a brittle fissured faceted phase with no defined grain boundary and densified melted features to column-like grains and biphasic grains with hexagonal grain boundaries were observed as the CR was varied from fastest to slowest CR.
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Papers by Rodrigo Dejeto
(SWC-Al2O3) substitution in the mullite compositions. The synthetic mullite obtained from this work is
the product of the synthesis of the beneficiated Solsona white clay (SWC) sourced from Ilocos Norte,
Philippines; Alumina (Al2O3) powder reagent from J.T. Baker Inc., USA; and Siruma silica (SiO2) from
Bicol, Philippines.
The formulation was based on the theoretical composition of mullite that is 71.79% Al2O3 and 28.21%
SiO2; modified with a proportional substitution Al2O3 to the SWC by 5%, 10%, 15%, 20%, and 50% and
kept the SiO2 constant. The five formulations were processed separately and then characterized using
SEM, XRD and EDX.
Formulation with 5%, 10% and 15% SWC revealed the presence of pores, formation of column-like
grains, acicular and small islands of a locally textured grainy structure when sintered at 1150°C for 7hrs;
and the formation of nodular grains when sintered at 1400°C for 7hrs. While formulations with 20% and
50% SWC demonstrates with preferred grain alignment and huge grain growth after sintering at 1150°C
for 7hrs and further transformed into a nucleated particle and amorphous/glassy phase when sintered at
1400°C for 7hrs.
Conference Presentations by Rodrigo Dejeto
(SWC-Al2O3) substitution in the mullite compositions. The synthetic mullite obtained from this work is
the product of the synthesis of the beneficiated Solsona white clay (SWC) sourced from Ilocos Norte,
Philippines; Alumina (Al2O3) powder reagent from J.T. Baker Inc., USA; and Siruma silica (SiO2) from
Bicol, Philippines.
The formulation was based on the theoretical composition of mullite that is 71.79% Al2O3 and 28.21%
SiO2; modified with a proportional substitution Al2O3 to the SWC by 5%, 10%, 15%, 20%, and 50% and
kept the SiO2 constant. The five formulations were processed separately and then characterized using
SEM, XRD and EDX.
Formulation with 5%, 10% and 15% SWC revealed the presence of pores, formation of column-like
grains, acicular and small islands of a locally textured grainy structure when sintered at 1150°C for 7hrs;
and the formation of nodular grains when sintered at 1400°C for 7hrs. While formulations with 20% and
50% SWC demonstrates with preferred grain alignment and huge grain growth after sintering at 1150°C
for 7hrs and further transformed into a nucleated particle and amorphous/glassy phase when sintered at
1400°C for 7hrs.