Mechanical Properties and Carbon Sequestration Capacity of CO2-Cured Recycled Aggregate Concrete Incorporating Coconut Shell Biochar

doi:10.16552/j.cnki.issn1001-1625.2025.0724

Abstract

Abstract:

To address the dual challenges of construction waste recycling and carbon sequestration in the concrete industry， this study employed CO₂-mineralized recycled coarse aggregates （RCA） and coconut shell biochar （CSB） as sustainable substitutes for natural aggregates. The effects of RCA （0% to 100% by mass replacement） and CSB （0% to 30% by volume replacement） on the mechanical properties， carbon sequestration capacity， and microstructure of CO₂-cured recycled aggregate concrete were systematically investigated. Results indicate that the concrete with optimal mixture （0% RCA + 20% CSB） achieves a compressive strength of 42.1 MPa （a 38.0% increase compared to the control group with normal curing） and a splitting tensile strength of 3.86 MPa （a 23.7% improvement）. This enhancement is attributed to the hierarchical pore structure of CSB， which regulates moisture to promote secondary hydration and facilitates CO₂ diffusion， thereby driving the densification of CaCO₃. Multiscale characterization via thermogravimetric analysis， Fourier transform infrared spectroscopy， and scanning electron microscopy reveals that a 20% CSB substitution rate not only promotes the polymorphic transformation of CaCO₃ but also maintains the stability of calcium silicate hydrate （C-S-H）， resulting in a 100% increase in carbon sequestration capacity. This study demonstrates a synergistic approach to waste valorization and CO₂ utilization， offering an effective strategy for developing high-performance， low-carbon concrete with significant implications for sustainable construction practices.

Key words: coconut shell biochar, recycled aggregate concrete, CO₂ curing, mechanical property, degree of mineralization

CLC Number:

TB332

HUANG Zhenhui, ZHAO Fei, CHANG Jun, LI Wenzheng, ZHOU Zhi. Mechanical Properties and Carbon Sequestration Capacity of CO₂-Cured Recycled Aggregate Concrete Incorporating Coconut Shell Biochar[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(1): 156-164.

Figures/Tables 11

References 32

[1]	蒋正武，高文斌，杨　巧，等. 低碳混凝土的技术理念与途径思考［J］. 建筑材料学报， 2023， 26（11）： 1143-1150.
	JIANG Z W， GAO W B， YANG Q， et al. Technical principles and approaches for low carbon concrete［J］. Journal of Building Materials， 2023， 26（11）： 1143-1150 （in Chinese）.
[2]	元　强，张胶玲，张苏辉，等. CO₂矿化再生骨料物理性能影响因素与机理［J］. 建筑材料学报， 2024， 27（10）： 895-903.
	YUAN Q， ZHANG J L， ZHANG S H， et al. Influencing factors of physical properties of CO₂ mineralized recycled aggregate and its mechanism［J］. Journal of Building Materials， 2024， 27（10）： 895-903 （in Chinese）.
[3]	ZHAN B J， XUAN D X， POON C S. Enhancement of recycled aggregate properties by accelerated CO₂ curing coupled with limewater soaking process［J］. Cement and Concrete Composites， 2018， 89： 230-237. DOI URL
[4]	WANG C Q， GUO J， WANG X Z， et al. Dynamic mechanical properties and damage constitutive model of high-toughness recycled aggregate concrete under high strain rate impact loads［J］. Journal of Building Engineering， 2025， 106： 112589. DOI URL
[5]	WU J Y， JING H W， GAO Y， et al. Effects of carbon nanotube dosage and aggregate size distribution on mechanical property and microstructure of cemented rockfill［J］. Cement and Concrete Composites， 2022， 127： 104408. DOI URL
[6]	DUNG N T， HAY R， LESIMPLE A， et al. Influence of CO₂ concentration on the performance of MgO cement mixes［J］. Cement and Concrete Composites， 2021， 115： 103826. DOI URL
[7]	SONG S Y， LIU Z X， LIU G M， et al. Application of biochar cement-based materials for carbon sequestration［J］. Construction and Building Materials， 2023， 405： 133373. DOI URL
[8]	陈铁锋，高小建. 生物炭对碳化养护水泥砂浆的改性机理［J］. 建筑材料学报， 2023， 26（8）： 831-837.
	CHEN T F， GAO X J. Modification mechanism of biochar on carbonation-cured cement mortar［J］. Journal of Building Materials， 2023， 26（8）： 831-837 （in Chinese）.
[9]	ROYCHAND R， LI J， KILMARTIN-LYNCH S， et al. Carbon sequestration from waste and carbon dioxide mineralisation in concrete： a stronger， sustainable and eco-friendly solution to support circular economy［J］. Construction and Building Materials， 2023， 379： 131221. DOI URL
[10]	YE P， GUO B L， QIN H Y， et al. Investigation of the properties and sustainability of modified biochar-doped cement-based composite［J］. Cement and Concrete Composites， 2024， 153： 105684. DOI URL
[11]	ROSA L， BECATTINI V， GABRIELLI P， et al. Carbon dioxide mineralization in recycled concrete aggregates can contribute immediately to carbon-neutrality［J］. Resources， Conservation and Recycling， 2022， 184： 106436.
[12]	李善武，樊展霖，刘剑辉，等. 温度和相对湿度对CO₂养护钢渣制品性能的影响［J］. 建筑材料学报， 2025， 28（1）： 33-41.
	LI S W， FAN Z L， LIU J H， et al. Effect of temperature and relative humidity on performance of CO₂ curing steel slag products［J］. Journal of Building Materials， 2025， 28（1）： 33-41 （in Chinese）.
[13]	邹庆焱，史才军，郑克仁，等. 预养护对砌块混凝土二氧化碳养护的影响［J］. 建筑材料学报， 2008， 11（1）： 116-120.
	ZOU Q Y， SHI C J， ZHENG K R， et al. Effect of pre-conditioning on CO₂ curing of block concretes［J］. Journal of Building Materials， 2008， 11（1）： 116-120 （in Chinese）.
[14]	应敬伟，蒙秋江，肖建庄. 再生骨料CO₂强化及其对混凝土抗压强度的影响［J］. 建筑材料学报， 2017， 20（2）： 277-282.
	YING J W， MENG Q J， XIAO J Z. Effect of CO₂-modified recycled aggregate on compressive strength of concrete［J］. Journal of Building Materials， 2017， 20（2）： 277-282 （in Chinese）.
[15]	ZHANG T， CUI J Z， CHEN M， et al. Durability of concrete containing carbonated recycled aggregates： a comprehensive review［J］. Cement and Concrete Composites， 2025， 156： 105865. DOI URL
[16]	BHAGAT T S， PANCHARATHI R K. Performance， microstructure and carbon sequestration potential of agro biochar based cement mortars［J］. Cement and Concrete Composites， 2025， 156： 105867. DOI URL
[17]	SHI X S， LYU S X， WANG Q Y， et al. Experimental study on the effect of carbonate ions on ITZs of geopolymeric recycled concrete［J］. Construction and Building Materials， 2024， 446： 137919. DOI URL
[18]	冷　勇，余　睿，范定强，等. 碳化再生粗骨料环保型超高性能混凝土的制备［J］. 建筑材料学报， 2022， 25（11）： 1185-1189+1218.
	LENG Y， YU R， FAN D Q， et al. Preparation of environmentally friendly UHPC containing carbonized recycled coarse aggregate［J］. Journal of Building Materials， 2022， 25（11）： 1185-1189+1218 （in Chinese）.
[19]	MEDINA C， ZHU W Z， HOWIND T， et al. Influence of mixed recycled aggregate on the physical-mechanical properties of recycled concrete［J］. Journal of Cleaner Production， 2014， 68： 216-225. DOI URL
[20]	ELGAALI H H， LOPEZ-ARIAS M， VELAY-LIZANCOS M. Accelerated CO₂ exposure treatment to enhance bio-receptivity properties of mortars with natural and recycled concrete aggregate［J］. Construction and Building Materials， 2024， 449： 138423. DOI URL
[21]	JIANG L B， WANG Z， XU H Z， et al. Nanoparticle stabilized carbon dioxide foam： improving hydration， carbonation and pore structure of foamed concrete［J］. Composites Part B： Engineering， 2025， 305： 112714.
[22]	SEO J H， PARK S M， LEE H K. Evolution of the binder gel in carbonation-cured Portland cement in an acidic medium［J］. Cement and Concrete Research， 2018， 109： 81-89. DOI URL
[23]	BERSISA A， MOON K Y， KIM G M， et al. Microstructural characterization of CO₂-cured calcium silicate cement［J］. Developments in the Built Environment， 2024， 19： 100518. DOI URL
[24]	LIU J， LIU G， ZHANG W Z， et al. Application potential analysis of biochar as a carbon capture material in cementitious composites： a review［J］. Construction and Building Materials， 2022， 350： 128715. DOI URL
[25]	REN Z S， WANG L， WANG H， et al. Carbonation behavior of solidified/stabilized cadmium in phosphogypsum slag-based cementitious materials［J］. Construction and Building Materials， 2024， 437： 136848. DOI URL
[26]	KALKREUTH J， ULLRICH A， GARBEV K， et al. Accelerated carbonation of hardened cement paste： quantification of calcium carbonate via ATR infrared spectroscopy［J］. Journal of the American Ceramic Society， 2024， 107（4）： 2627-2640. DOI URL
[27]	GUNN P F E， ONN C C， MO K H， et al. Enhancing carbon sequestration in cement mortar using high volume local rice husk biochar coupled with carbonation curing［J］. Case Studies in Construction Materials， 2024， 21： e03591.
[28]	王　丹. 钢渣碳酸化过程中碳酸钙生长与性能关系［D］. 大连：大连理工大学， 2020.
	WANG D. Relationship between calcium carbonate growth and properties during carbonation of steel slag［D］. Dalian： Dalian University of Technology， 2020 （in Chinese）.
[29]	TAN S L， LIU W， QING L B， et al. Evaluation on the ability of carbon capture， utilization and storage of cementitious pastes incorporated with CO₂-free and CO₂-saturated biochar［J］. Construction and Building Materials， 2025， 482： 141691. DOI URL
[30]	SHI X C， SHUI Z H. Effect of eggshell powder addition on the properties of cement pastes with early CO₂ curing and further water curing［J］. Construction and Building Materials， 2023， 404： 133231. DOI URL
[31]	ZHANG Y， MAIERDAN Y， GUO T B， et al. Biochar as carbon sequestration material combines with sewage sludge incineration ash to prepare lightweight concrete［J］. Construction and Building Materials， 2022， 343： 128116. DOI URL
[32]	CHEN T F， ZHAO L Y， GAO X J， et al. Modification of carbonation-cured cement mortar using biochar and its environmental evaluation［J］. Cement and Concrete Composites， 2022， 134： 104764. DOI URL

Sample No.	Mix ratio/（kg·m^-3）
Sample No.	Cement	NCA	RCA	Sand	CSB	Water
R0_CSB0	390	1 150	0	670	0	195
R50_CSB0	390	575	575	670	0	195
R75_CSB0	390	287	863	670	0	195
R100_CSB0	390	0	1 150	670	0	195
R0_CSB10	390	1 150	0	603	12	195
R50_CSB10	390	575	575	603	12	195
R75_CSB10	390	287	863	603	12	195
R100_CSB10	390	0	1 150	603	12	195
R0_CSB20	390	1 150	0	536	24	195
R50_CSB20	390	575	575	536	24	195
R75_CSB20	390	287	863	536	24	195
R100_CSB20	390	0	1 150	536	24	195
R0_CSB30	390	1 150	0	469	36	195
R50_CSB30	390	575	575	469	36	195
R75_CSB30	390	287	863	469	36	195
R100_CSB30	390	0	1 150	469	36	195

Sample No.	Mix ratio/（kg·m^-3）
Sample No.	Cement	NCA	RCA	Sand	CSB	Water
R0_CSB0	390	1 150	0	670	0	195
R50_CSB0	390	575	575	670	0	195
R75_CSB0	390	287	863	670	0	195
R100_CSB0	390	0	1 150	670	0	195
R0_CSB10	390	1 150	0	603	12	195
R50_CSB10	390	575	575	603	12	195
R75_CSB10	390	287	863	603	12	195
R100_CSB10	390	0	1 150	603	12	195
R0_CSB20	390	1 150	0	536	24	195
R50_CSB20	390	575	575	536	24	195
R75_CSB20	390	287	863	536	24	195
R100_CSB20	390	0	1 150	536	24	195
R0_CSB30	390	1 150	0	469	36	195
R50_CSB30	390	575	575	469	36	195
R75_CSB30	390	287	863	469	36	195
R100_CSB30	390	0	1 150	469	36	195

Sample No.	m₆₀₀/%	m₈₀₀/%	U/%
R0_CSB0	89.59	86.59	3.00
R0_CSB10	91.94	86.15	5.79
R0_CSB20	89.85	83.83	6.02
R0_CSB30	91.38	84.51	6.87

Sample No.	m₆₀₀/%	m₈₀₀/%	U/%
R0_CSB0	89.59	86.59	3.00
R0_CSB10	91.94	86.15	5.79
R0_CSB20	89.85	83.83	6.02
R0_CSB30	91.38	84.51	6.87

Sample No.	Price/（yuan·m^-3）
Sample No.	Cement	NCA	Sand	CSB	CO₂	Total
R0_CSB0	202.80	134.55	123.95	0	-0.84	460.46
R0_CSB10	202.80	134.55	111.55	12	-1.62	459.28
R0_CSB20	202.80	134.55	99.16	24	-1.69	458.82
R0_CSB30	202.80	134.55	86.76	36	-1.93	458.18

Mechanical Properties and Carbon Sequestration Capacity of CO₂-Cured Recycled Aggregate Concrete Incorporating Coconut Shell Biochar

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