| The proposed research explores the feasibility of utilizing Precipitated Calcium Carbonate
(PCC), a by-product of the sugar beet industry, as a sustainable and economically viable
alternative to Ordinary Portland Cement (OPC) for geothermal well cementing applications.
Cementing and casing operations account for approximately 30–40% of total geothermal well
construction expenses. Through the successful replacement of a portion of OPC with PCC, this
study aims to develop high-performance, cost-effective cement blends tailored for the highly
intensive geothermal environment.
The first phase consists of PCC being incorporated into concrete as a partial replacement of
cement, at 5%, 10%, 15%, 20%, and 25% increments by weight, and mechanical properties are
obtained. The benchmark mix with 0% PCC replacement achieved compressive and tensile
strengths of 4540 psi (31.3 MPa) and 427 (2.9 MPa) psi, respectively. Incorporating 5% PCC
enhanced the mechanical performance, increasing compressive strength by 9.47% to 4970 psi
(34.3 MPa), and tensile strength by 2.93 % to 439 psi (3 MPa). However, further increments
of PCC led to a reduction in both compressive and tensile strength.
The second phase involved thermal cycling of optimized concrete mixes (0%, 5% and 10%
PCC replacement) between 10°C and 250°C for 10, 20 and 30 cycles to simulate geothermal
well conditions. Results indicated that after 10 cycles, the 5% PCC mix showed superior
strength, achieving an average compressive strength of 4657.55 psi compared to 4589.01 psi
for the control mix (0% PCC). After 20 cycles, the compressive strengths for 0% and 5% PCC
mixes showed similar strengths, averaging 4546.97 psi and 4539.95 psi, respectively, while the
10% PCC mix showed a significant loss in strength. After 30 cycles, all mixtures showed
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strength reductions, but the 5% PCC mix still maintained strength close to the control. Based
on these findings, incorporating PCC at a minimum level of 5% can effectively reduce cement
consumption, thereby lowering carbon emissions and contributing to more sustainable and
cost-efficient geothermal well cementing practices.
Keywords: Precipitated Calcium Carbonate (PCC), Geothermal Well Cementing,
Compression Strength, Split Tensile Strength, Modulus of Elasticity, Thermal Cycling. |