Effect of sugarcane biomass waste in cement slurries submitted to high temperature and pressure

Marcos A.S Anjos,Antonio E Martinelli,Dulce M.A Melo

doi:10.1016/j.msea.2011.08.056

Marcos A.S Anjos, Antonio E Martinelli + Show 1 more

Open Access

https://doi.org/10.1016/j.msea.2011.08.056

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Abstract

Abstract Cementitious materials are subjected to changes in their microstructure and mechanical behavior when submitted to high service temperatures. In the oil industry, Portland-based slurries are used where conditions imply high temperatures and high pressures, e.g., steam injection or recovery of heavy oils. The present study investigated the hydration behavior and mechanical strength of cement slurries containing sugarcane biomass waste or silica flour, submitted to high temperature and pressure cycles using a curing chamber. The slurries were initially cured for 28 days at 22 °C. After that, they were placed in a curing chamber for 3 days at 280 °C and 17.6 MPa. The results showed a decrease in the compressive strength of the slurries submitted to high temperature high pressure. The decrease in strength was less marked in the slurry containing 40% of sugarcane biomass waste, as a consequence of the formation of silica-rich phases, i.e., xonotlite and tobermorite. When the slurries were placed in the curing chamber at 280 °C and 6.9 MPa for 7 days (after initial curing for 14 days at 38 °C), the slurry containing 59% sugarcane biomass waste showed an increase in compressive strength, contrary to what was observed for all the other slurries tested.

Highlights

Cementitious materials submitted to high temperatures depict microstructural changes that result in loss of mechanical strength and increase in permeability
The slurry containing 40% sugarcane waste (SBW40) showed the lowest loss in strength (39.9%), maintaining a compressive strength of 19.2 MPa, exceeding that of the slurry containing silica flour (SF40), which was 17.3 MPa. These findings demonstrate the potential of sugarcane biomass waste as a substitute for silica flour in oil well cements submitted to high temperatures
The hydration analysis of slurries containing 40% sugarcane waste and 40% silica flour submitted to the first curing cycle at high temperature revealed the presence of silica-rich phases such as xonotlite and tobermorite, with Ca:Si ratios of 1 and 0.83, respectively

Summary

Introduction

Cementitious materials submitted to high temperatures depict microstructural changes that result in loss of mechanical strength and increase in permeability. Both effects are deleterious to applications, such as oilwell cementing, where mechanical stability and zonal isolation are constantly required. The effect of the temperature on the mechanical strength of concrete affected by fire was studied and revealed mild loss of strength above 200 ◦C, but markedly above 400 ◦C [3,4]. The formation and stability of hydrated calcium silicates at high temperatures and pressures are highly relevant to the strength and durability of the hardened slurries. Large amounts of Portlandite (Ca(OH)2) and hydrated calcium silicate, both rich in calcium, in hydrated slurries is considered harmful, since they result in high permeability and low compressive strength [9]

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