Mechanical properties of mortar produced with the replacement of natural sand by scheelite residue

Medeiros, B. A.; Neves, G. A.; Barbosa, N. P.; Menezes, R. R.; Ferreira, H. C.

doi:10.1590/0366-69132019653752571

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Articles • Cerâmica 65 (375) • Jul-Sep 2019 • https://doi.org/10.1590/0366-69132019653752571 copy

Mechanical properties of mortar produced with the replacement of natural sand by scheelite residue

Propriedades mecânicas de argamassa produzida com substituição da areia natural por resíduo de scheelita

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The residue generated by industrial activities represents a cost, since the generators are responsible for its management, transportation, treatment and disposal. Rio Grande do Norte State in Brazil is the greatest producer of scheelite residue. The aim of this research was to characterize this mining residue, identify its similarity with natural sand and produce a coating mortar with it. In the composition of mortar, a Brazilian Portland cement type CPII-F32 and an industrialized calcium hydroxide as a binder were used. Laser granulometry, bulk and relative density, EDX, XRD and thermal analysis were done to obtain a physical and chemical characterization of the residue. Mechanical tests (tensile bond strength and compressive strength), SEM and water absorption test were done to analyze the behavior of mortar. All tests confirmed that mechanical properties were according to standards for tile mortar.

Keywords:
mining residue; scheelite characterization; mechanical property; mortar

Table I Three different compositions of mortar with 100% residue replacing the fine aggregate.

Composition	Ratio	Cement	Calcium hydroxide	Aggregate (residue)
T128	Volume	1	2	8
T128	Mass	1.00	0.71	9.09
T129	Volume	1	2	9
T129	Mass	1.00	0.71	10.22
T1210	Volume	1	2	10
T1210	Mass	1.00	0.71	11.36

Table II Chemical composition (wt%) of scheelite residue (as collected).

CaO	SiO₂	Al₂O₃	Fe₂O₃	Sc₂O₃	MgO	WO₃	Other oxides
47.30	31.82	9.75	6.57	-	2.46	0.15	1.93

Table III Values obtained by the spectrometry and parameters established by the standard.

Parameter	Leached extract (mg/L)	Maximum limit* (mg/L)	Solubilized extract (mg/L)	Maximum limit* (mg/L)
Ba	0.69	70.00	<0.10	0.70
Al	<0.10	-	<0.10	0.20
Cu	0.55	-	0.01	2.00
Mn	1.15	-	0.04	0.10
Fe	0.07	-	<0.01	0.30
Zn	0.02	-	0.08	5.00
Sulphates (SO₄ ^2-)	101.50	-	131.90	250
Chlorides (Cl^-)	525.40	-	503.40	250

Table IV Density and incorporated air content in different mortar compositions.

Composition	Fresh density (g/cm³)	Incorporated air content (%)
T128	2.30	10.50
T129	2.42	6.92
T1210	2.46	6.10

Table V Results of tensile strength in flexure and compressive strength.

Composition	Specimen	Tensile strength in flexure (MPa)	Compressive strength (MPa)		Tensile strength in flexure (MPa)	Compressive strength (MPa)
Composition	Specimen	7-days-old			28-days-old
T128	A	0.89	2.79	2.80	1.19	3.30	3.31
	B	0.88	2.84	2.84	0.93	3.24	3.23
	C	0.88	2.82	2.81	1.05	3.05	3.04
	D	0.88	2.80	2.81	1.14	3.07	3.06
	E	0.87	2.80	2.80	0.98	3.16	3.17
	F	0.89	2.78	2.79	1.14	3.24	3.23
Average		0.88	2.80		1.07	3.17
Standard deviation		0.01-0.01	0.02-0.40		0.12-0.14	0.12-0.14
T129	A	0.83	2.68	2.67	0.98	3.05	3.04
	B	0.83	2.65	2.64	1.10	3.04	3.04
	C	0.82	2.63	2.63	0.93	2.94	2.93
	D	0.84	2.70	2.71	0.89	3.06	3.05
	E	0.84	2.65	2.64	0.91	3.04	3.02
	F	0.82	2.66	2.66	0.91	3.03	3.04
Average		0.83	2.66		0.95	3.02
Standard deviation		0.01-0.01	0.03-0.05		0.06-0.15	0.04-0.09
T1210	A	0.79	2.20	2.22	0.86	2.94	2.95
	B	0.78	2.12	2.11	0.93	2.93	2.94
	C	0.78	2.23	2.23	0.93	2.95	2.93
	D	0.75	2.19	2.18	0.91	2.99	2.98
	E	0.79	2.19	2.19	0.84	2.94	2.93
	F	0.78	1.98	2.05	0.86	2.94	2.95
Average		0.77	2.15		0.89	2.94
Standard deviation		0.02-0.02	0.17-0.08		0.04-0.05	0.01-0.05

Table VI Results of water absorption and capillarity test.

Composition T129	Absorption at 10 min (g/cm²)	Absorption at 90 min (g/cm²)	Capillary coefficient (g/dm²/min^1/2)
A	0.14	0.36	7.2
B	0.15	0.36	7.6
C	0.13	0.33	7.0
D	0.14	0.35	7.6
E	0.16	0.42	8.4
F	0.13	0.35	7.5
Average	0.14	0.36	7.55
Maximum absolute deviation	14.3%	11.7%	11.3%

Table VII Results of the tensile bond test.

Specimen	Weight (kgf)	Strength (MPa)	Weight (kgf)	Strength (MPa)
	With scheelite aggregate		With natural sand
1	57	0.28	60	0.29
2	24	0.11	35	0.16
3	35	0.17	39	0.19
4	39	0.19	-	-
5	57	0.28	37	0.18
6	57	0.28	48	0.23
7	-	-	47	0.24
8	48	0.23	57	0.28
9	47	0.23	24	0.11
10	-	-	-	-
11	60	0.29	57	0.28
12	60	0.29	58	0.28
Maximum deviation		0.30		0.28
Average		0.23		0.22
Minimum deviation		0.16		0.15

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