Nanoengineered concrete with coloidal sílica for repair of concrete structures

Bernardo, Lucas Modotte; Castro, Alessandra Lorenzetti de

doi:10.1590/s1678-86212026000100961

Sumário Anterior Atual Seguinte

Sumário

Article • Ambiente Construído 26 • Jan-Dec 2026 • https://doi.org/10.1590/s1678-86212026000100961 linkcopy

Nanoengineered concrete with coloidal sílica for repair of concrete structures

Concreto nanoestruturado com sílica coloidal para reparo de estruturas de concreto

Authorship SCIMAGO INSTITUTIONS RANKINGS

Pathological manifestations in concrete structures result from failures in design, execution, maintenance, or material degradation, thus requiring effective repair solutions towards extending the structures’ service life. Nanoengineered concrete with colloidal silica can be an efficient alternative as a repair material, for it reduces porosity and increases mechanical strength due to its effect on the interfacial transition zone between the aggregate and the cement paste. This study evaluates the application of a high-strength concrete with colloidal silica as a repair material to conventional concrete structural elements. Cylindrical and prismatic concrete specimens were produced, intentionally damaged, and subsequently repaired with the developed special concrete. Characterization results revealed significant improvement in the mechanical properties of the special concrete even at low colloidal silica contents, being the best compressive strength obtained with the addition of only 1% colloidal silica, by cement mass. The repaired elements showed satisfactory performance in all measured properties, maintaining compressive strength values statistically similar to those of intact conventional concrete after 28 days of repair (39.4 MPa and 40.7 MPa for repaired and intact specimens, respectively). The results highlight the potential of nanoengineered concrete with colloidal silica addition for practical structural repair applications.

Keywords
Special concrete; Repair material; Colloidal silica; Nanotechnology

Tests	Reference standards	Specimens	Test ages (days)
Setting time in cement paste	NBR 16607 (ABNT, 2018b)	---	---
Spread (slump flow)	NBR 15823-2 (ABNT, 2017b)	---	---
Specific gravity in fresh state	NBR 9833 (ABNT, 2008)	---	---
Compressive strength	NBR 5739 (ABNT, 2018a)	Cylindrical (∅ 100 mm x 200 mm)	7 and 28
Specific gravity, water absorption by immersion and void ratio	NBR 9778 (ABNT, 2005a)	Cylindrical (∅ 100 mm x 200 mm)	28
Tension strength in flexure	NBR 13279 (ABNT, 2005b)	Prismatic (40 mm x 40 mm x 160 mm)	28
Static modulus of elasticity by compression	NBR 8522-1 (ABNT, 2021c)	Cylindrical (∅ 100 mm x 200 mm)	28
Dynamic modulus of elasticity	NBR 8522-2 (ABNT, 2021d)	Prismatic (40 mm x 40 mm x 160 mm)	7 and 28
Ultrasonic wave transmission velocity	NBR 8802 (ABNT, 2019)	Prismatic (40 mm x 40 mm x 160 mm)	2, 7 and 28

Tests	Reference standards	Specimens	Test ages (days)
Tests	Reference standards	Specimens	Conventional concrete	Repaired specimens
Compressive strength	NBR 5739 (ABNT, 2018a)	Cylindrical (∅ 100 mm x 200 mm)	7, 28, 150, 178	157, 178
Tension strength in flexure	NBR 12142 (ABNT, 2010)	Prismatic (150 mm x 150 mm x 500 mm)	28, 150	178
Static modulus of elasticity by compression	NBR 8522-1 (ABNT, 2021c)	Cylindrical (∅ 100 mm x 200 mm)	28, 178	178
Dynamic modulus of elasticity	NBR 8522-2 (ABNT, 2021c)	Cylindrical (∅ 100 mm x 200 mm)	7, 28, 150, 178	157, 178
Ultrasonic wave transmission velocity	NBR 8802 (ABNT, 2019)	Cylindrical (∅ 100 mm x 200 mm)	7, 28, 150, 178	152, 157, 178

Compounds (%)	CPII E 32	CPV ARI	AG 80-100	Silica fume	SM200	Limestone filler	Colloidal silica
SiO₂	21.83	16.44	99.74	98.63	99.80	2.60	99.57
Al₂O₃	5.51	3.29	---	---	---	0.43	---
Fe₂O₃	3.06	4.21	0.15	---	---	0.39	---
CaO	64.80	68.96	0.11	0.25	0.09	95.67	0.21
SO₃	2.09	4.33	---	0.33	0.11	---	---
K₂O	0.26	0.39	---	0.58	---	---	---
TiO₂	0.52	0.29	---	---	---	---	---
MnO	0.46	0.14	---	---	---	---	---

	Material	Specific gravity (g/cm³)	Water absorption (%)	Maximum size (mm)		Fineness modulus
Aggregates	“Crushed stone 1”	2.82	0.33	19.00		3.61
Aggregates	“Crushed stone 0”	2.99	0.53	9.50		5.84
	Medium sand	2.56	0.63	1.18		1.16
	Fine sand	2.59	0.15	4.75		2.37
Industrial aggregate	Material	Specific gravity (g/cm³)	d₅₀ (µm)
Industrial aggregate	AG 80-100	2.64	150
Binders	Material	Specific gravity (g/cm³)	d₅₀ (µm)
	CP II E 32	2.95	13.40
	CPV ARI	3.16	9.29
Mineral addition	Material	Specific gravity (g/cm³)	d₅₀ (µm)		Surface area - Blaine (cm²/g)
	Silica fume	2.20	1.40		17900
	SM200	2.70	31.80		2340
	Limestone filler	2.60	13.40		-
Chemical admixture	Material	Specific gravity (g/cm³)	Description		Appearance
Chemical admixture	ADVA 458 UHPC	1.075 – 1.115	Polycarboxylate-based superplasticizer		Orange liquid
Nanomaterial	Material	Specific gravity (g/cm³)	Solids content		Appearance
Nanomaterial	Colloidal silica	1.40	50%		White liquid

Mix design, by mass	Cement	Fine sand	Medium sand	“Crushed stone 1”	Water
Mix design, by mass	1.00	0.78	1.16	2.61	0.47
Material consumption (kg/m³ of concrete)
Cement (CPII E 32)			411
Fine sand			319
Medium sand			478
“Crushed stone 1”			1072
Water			193
Characterization tests
Slump value			130 mm
Specific gravity			2.47 g/cm³
Air content			2.3%
Compressive strength – 7 days			f_cm = 24.83 MPa (SD = 0.06 MPa / CV = 0.25%)
Compressive strength – 28 days			f_cm = 38.77 MPa (SD = 1.43 MPa / CV = 3.70%)

Mixture	Reference high-strength concrete (CI-REF)
Mix design, by mass	Cement	Silica fume		Quartz powder				AG 80-100		Water
Mix design, by mass	1.00	0.21		0.25				1.10		0.20
Material consumption (kg/m³ of concrete)	Cement					870
	Silica fume					183
	SM 200					217
	AG 80-100					957
	Water					174
Behavior in fresh state
Mixture identification	CI-REF		CI-1%		CI-2.5%		CI-5%		CI-10%
Superplasticizer (% of cement mass)	2.50%		2.75%		3.00%		3.75%		5.00%
Spread value (mm)	235		235		230		205		165

Mix design, by mass	Cement		Silica fume		Limestone filler	Fine sand		Medium sand			“Crushed stone 0”		Water
Mix design, by mass	1.00		0.10		0.30	0.29		0.43			0.72		0.19
Material consumption (kg/m³ of concrete)
Cement						792
Silica fume						79
Limestone filler						238
Fine sand						288
Medium sand						342
“Crushed stone 0”						570
Water						151
Mixture		Superplasticizer (% of cement mass)		Spread value (mm)		7 days				28 days
Mixture		Superplasticizer (% of cement mass)		Spread value (mm)		f _cm (MPa)	SD (MPa)		CV (%)	f _cm (MPa)		SD (MPa)		CV (%)
CE-REF		2.20%		250		68.92	1.70		2.46	80.23		3.66		4.56
CE-1%		2.50%		245		68.98	1.96		2.85	88.72		1.80		2.03

Test	Results	Unit
Specific gravity in the fresh state	2.49 ± 0.06	g/cm³
Water absorption by immersion	1.69 ± 0.01	%
Void ratio	3.47 ± 0.03	%
Specific gravity in the hardened state	2.53 ± 0.03	g/cm³
Tension strength in flexure at 28 days	13.05 ± 0.03	MPa
Static modulus of elasticity at 28 days	48.5 ± 1.17	GPa
Dynamic modulus of elasticity at 7 days	51.6 ± 1.48	GPa
Dynamic modulus of elasticity at 28 days	54.4 ± 1.13	GPa
Ultrasonic wave transmission velocity (2 days)	4632.05 ± 60.62	m/s
Ultrasonic wave transmission velocity (7 days)	5143.53 ± 40.62	m/s
Ultrasonic wave transmission velocity (28 days)	5281.23 ± 14.66	m/s

Parameter	CE-REF	CE-1%
Initial setting time (min)	520	266
Final setting time (min)	610	336

Age (days)	Identification	Conventional	Repaired CE-1%
28	f_ct,f,m (MPa)	4.40	---
	SD (MPa)	0.01	---
	CV (%)	0.22	---
150 (REPAIR)	f_ct,f,m (MPa)	5.01	---
	SD (MPa)	0.35	---
	CV (%)	7.08	---
178	f_ct,f,m (MPa)	---	3.95
	SD (MPa)	---	0.09
	CV (%)	---	2.15

Identification	Age (days)
	28			178
	E_ci,m (GPa)	SD (GPa)	CV (%)	E_ci,m (GPa)	SD (GPa)	CV (%)
Conventional	32.3	1.72	5.26	35.0	1.65	4.72
Repaired CE-1%	-	-	-	33.1	0.89	2.69

Identification	Parameters	Age (days)
Identification	Parameters	7	28	150	157	178
Conventional	EL (GPa)	37.0	42.8	43.0	-	43.8
	SD (GPa)	0.41	1.66	1.38	-	0.01
	CV (%)	1.11	3.87	3.21	-	0.02
	EF (GPa)	37.0	41.9	42.7	-	43.6
	SD (GPa)	1.74	1.28	1.44	-	0.01
	CV (%)	4.70	3.06	3.37	-	0.02
Repaired CE-1%	EL (GPa)	-	-	-	38.1	41.3
	SD (GPa)	-	-	-	0.61	0.01
	CV (%)	-	-	-	1.61	0.03
	EF (GPa)	-	-	-	37.7	42.7
	SD (GPa)	-	-	-	0.93	0.06
	CV (%)	-	-	-	2.46	0.15

Age (days)		7	28	150	152	157	178
Conventional	VPU (m/s)	4441.47	4681.50	4756.37	-	-	4782.33
	SD (m/s)	18.22	6.22	51.79	-	-	45.38
	CV (%)	0.41	0.13	1.09	-	-	0.95
Repaired CE-1%	VPU (m/s)	-	-	-	4575.90	4631.63	4840.73
	SD (m/s)	-	-	-	33.16	35.94	16.56
	CV (%)	-	-	-	0.72	0.78	0.34

location_on

Associação Nacional de Tecnologia do Ambiente Construído - ANTAC Av. Osvaldo Aranha, 93, 3º andar, 90035-190 Porto Alegre/RS Brasil, Tel.: (55 51) 3308-4084, Fax: (55 51) 3308-4054 - Porto Alegre - RS - Brazil
E-mail: ambienteconstruido@ufrgs.br

rss_feed Acompanhe os números deste periódico no seu leitor de RSS

[1] Note: f_cm = mean compressive strength; SD = standard deviation; and CV = coefficient of variation