主講人 : Prof. Paliakarakadu Assen Muhamed Basheer

Cembureau reported that the cement production has increased ten times during the past few decades and is expected to increase exponentially in the coming decades. Therefore, the CO2 emissions from cement production is expected to increase significantly from the current value of 7% of global CO2 emissions. Construction industry has implemented the strategy of partial replacement of Portland cement (PC) with supplementary cementitious materials for improving both the performance as well as the carbon footprint, but this is not sufficient to meet the target of net-zero emissions by 2050. Therefore, exploring carbon capture and storage in concrete through carbon sequestration is tried recently. Existing methods are reported to capture ≈1% CO2 by weight of binder (bwob), which is significantly lower than the true potential of any binder system. Therefore, new strategies are required, one of which is the addition of dry ice during mixing of concrete. This paper explores the possibility of sequestering large quantity of CO2 (say 10% bwob) in concrete by estimating appropriate time to add dry ice to concrete during mixing. For this, the effects of adding 0, 1% and 10% dry ice bwob at 0, 45, and 90 minutes after the addition of water to the mix were investigated for cementitious systems with 100%PC, 75% PC + 25% PFA (pulverised fly ash) and 50%PC + 50%GGBFS (ground granulated blast furnace slag).  The investigation consisted of measuring the flow characteristics, setting time, compressive strength of cement mortars. Additionally, microstructural and mineralogical characteristics were investigated using SEM, EDX, XRD, FTIR and TGA. It was found that adding 1% and 10% dry ice at 0, 45, 90 minutes did not compromise the flow characteristics and setting time of the cementitious systems; the 28-day compressive strength of mortar with 1 and 10% dry ice was ≈5 and 10% respectively higher than that of mortar without dry ice. The mineralogical analysis revealed that with the addition of 10% of dry ice at 0,.45 and 90 min, calcite content was increased by ≈6% and portlandite content was reduced by 1%, with no change in pH of the hydrated binder systems. It was also found that sequestration using dry ice led to the formation of carbonation product such as aragonite, vaterite and carboaluminates – indicating that unlike other sequestration process, CO2 sequestration using dry ice could capture large concentration of CO2 and fewer CO2 escaped during the sequestration process.  The microstructural analysis using SEM indicated that the addition of dry ice at 90 min could lead to significant cracking of the hydrated system – indicating durability concerns. Therefore, it is concluded that the dry ice should be added to cementitious systems earlier than 90 min to achieve the enhanced CO2 sequestration, which will not compromise fresh or hardened properties of concretes manufactured with PC, PFA and GGBFS binders and would significantly contribute to achieving the net zero carbon agenda compared to the existing approaches.

主講人簡介：

Prof. Paliakarakadu Assen Mmhamed Basheer為英國皇家工程院院士、愛爾蘭工程院院士、獲帝國勛章（CBE），科學博士（DSC），美國混凝土工程協會（ACI）Fellow、英國土木工程師協會（ICE）Fellow、英國混凝土技術協會（ICT）會長、英國Research Excellence  work（REF）評審專家、英國EPSRC、歐盟FP、美國NSF及波蘭、芬蘭、沙特、印度等國家基金評審專家，英國赫瑞-瓦特大學（Heriot-Watt University - HWU）能源、地球科學、基礎設施和社會學院院長（2023年9月-至今）。目前，Basheer教授是英國 Concrete Society會員、RILEM會員，ACI 130, 211, 235, 236與365技術委員會專家、RILEM下 RILEM TC-ITZ, TC-IDC, TC-TMC, TC-NEC, TC-CTC與TC-PSC技術委員會專家；在歐盟合作項目中，Basheer教授參與了COST Actions 509, 521, 530和534項目。Basheer教授是Construction and Building Materials、Journal of Civil Structural Health Monitoring、Structural Engineering等期刊編委。

Basheer教授從事土木工程教學與科研超30年，研究方向為混凝土結構無損監測技術、混凝土材料健康監測技術、結構全壽命評估與固體廢棄物在土木工程中應用。在上述研究方向，已在英國EPSRC、工業部及多家企業獲得超過1千萬英鎊項目資助，并且指導博士后15人、博士26人、碩士29人，發表論文超400篇。Basheer教授以AutoClam表層混凝土滲透性原位測試系統與原位氯離子遷移測試系統研究成果在1991年與1999年先后獲得ACI下 James Instruments年度最佳無損檢測技術獎；1991年獲CANMET的優秀青年科學家獎；鑒于Basheer教授在科研、教學與工程應用方面的成績，愛爾蘭土木工程師協會在2012年向其頒發了終身成就獎；2015年12月18日-19日，由印度土木工程師協會在Mumbai以其名組織召開了Advances in Science and Technology of Concrete國際研討會。Basheer教授目前為重慶大學、浙江大學、濟南大學等國內高校的客座教授。