Tables at a glance

Table 1

Table 2

Table 3

Table 4

Table 5

Table 6

Table 7

Figures at a glance

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Figure 2

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Figure 3

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Figure 4

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Figure 5

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Figure 6

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Figure 16

Table 1: Mix proportions of concrete

	Cement (kg)	RHA (kg)	Fine aggregate (kg)	Coarse aggregate (kg)	Water (kg)	Water/ Cement binder ratio
CTL	399.12	0	798.24	1597.00	219.52	0.55
5% RHA	379.16	19.96	798.24	1597.00	219.52	0.55
10% RHA	359.21.	39.91	798.24	1597.00	219.52	0.55
15% RHA	339.25	59.87	798.24	1597.00	219.52	0.55
20% RHA	319.30	79.82	798.24	1597.00	219.52	0.55

Plate 1

Plate 1: Length change test

Table 2: Oxide Composition of Rice Husk Ash (RHA)

S/N	Elements	Proportion (%)
1	SiO2	87.23
2	Al2O3	0.35
3	Fe2O3	0.46
4	CaO	0.10
5	MgO	0.81
6	Na2O	0.04
7	K2O	2.97
8	SO3	0.36
9	MnO	0.28
10	Pb2O5	2.62
11	TiO2	0.05
12	ZnO	0.12
13	Cr2O3	0.03
14	BaO	0.06
15	LOI	3.18

Table 3: Physical Properties of Aggregate

Type of Test	River Sand
Natural moisture content (%)	11.34
Bulk density (kg/m3)	2233.05

Table 4: Particle size distribution for the constituent materials

Sieve size	Coarse aggregates% Passing	River sand % Passing	RHA % Passing
14.0mm	100.00
12.0mm	68.42
10 .0mm	32.70
6.0 mm		100.00
5.0 mm	1.96	93.94
4.0 mm	0.36	92.24
3.0 mm		90.46
2.36 mm		88.10
1.80 mm		86.58
1.70 mm		83.23	100.00
600 µm		66.59	63.80
500 µm		63.57	55.10
212 µm		22.95	8.20
150 µm		12.25	1.70
0.75 µm		9.60	0.60
pan	0.00	0.00	0.00

FIGURE 1

Figure 1: Setting time of the OPC/RHA binder

Table 5: Compacting factor, Slump test and Air Entrainment values

Percentage replacement (%)	0	5	10	15	20
Compacting Factor mp / mf	0.81	0.86	0.89	0.91	0.93
Slump values (cm)	9.50	5.00	7.50	7.00	3.00
Air Entrainment (%)	2.45	2.00	1.80	1.75	2.30

FIGURE 2

Figure 2: Compressive Strength Test Result for Concrete Immersed in Na2SO4 Moderate Solution (30,000 mg/L concentration)

FIGURE 3

Figure 3: Compressive Strength Test Result for Concrete Immersed in Na2SO4 Severe Solution ((50,000 mg/L concentration)

FIGURE 4

Figure 4: Compressive Strength Test Result for Concrete Immersed in MgSO4 Moderate Solution ((30,000 mg/L concentration)

FIGURE 5

Figure 5: Compressive Strength Test Result for Concrete Immersed in MgSO4 Severe Solution ((30,000 mg/L concentration)

FIGURE 6

Figures 6: Percentage of Compressive strength deterioration of concrete after 7 days immersion in sulfate

FIGURE 7

Figures 7: Percentage of Compressive strength deterioration of concrete after 28 days immersion in sulfate

FIGURE 8

Figures 8: Percentage of Compressive strength deterioration of concrete after 56 days immersion in sulfate

FIGURE 9

Figures 9: Percentage of Compressive strength deterioration of concrete after 90 days immersion in sulfate

FIGURE 10

Figure 10: Length change for Concrete Immersed in Na2SO4 and MgSO4 Moderate Solutions

FIGURE 11

Figure 11: Length change for Concrete Immersed in Na2SO4 and MgSO4 Severe Solutions

FIGURE 12

Figure 12: Percentage Water Absorption for Concrete Immersed in Na2SO4 and MgSO4 Moderate Solutions

FIGURE 13

Figure 13: Percentage Water Absorption for Concrete Immersed in Na2SO4 and MgSO4 Severe Solutions

FIGURE 14

Figure 14: Percentage Weight Loss for Concrete Immersed in Na2SO4 and MgSO4 Moderate Solutions

FIGURE 15

Figure 15: Percentage Weight Loss for Concrete Immersed in Na2SO4 and MgSO4 Severe Solutions

FIGURE 16

Figure 16: Penetration Depth for Concrete Immersed in Na2SO4 and MgSO4 Moderate and Severe Solutions

Table 6: ANOVA Result of the Compressive strength at 90 days

	Sum of Squares	df	Mean Square	F	Sig.
Between Groups	1868.579	24	77.857	17.051	.000
Within Groups	228.307	50	4.566
Total	2096.886	74

Table 7: LSD test for Compressive strength of concrete samples at 90 days sulfate attack

i	j	MD(i-j)	p	Remark
1	2	-10.43333*	.000	*
	3	-14.63333*	.000	*
	4	-12.60000*	.000	*
	5	-12.50000*	.000	*
	6	2.40000	.175	NS
	7	-6.46667*	.001	*
	8	-10.60000*	.000	*
	9	-7.66667*	.000	*
	10	-6.90000*	.000	*
	11	3.00000	.092	NS
	12	-6.53333*	.000	*
	13	-11.50000*	.000	*
	14	-7.86667*	.000	*
	15	-7.10000*	.000	*
	16	2.90000	.103	NS
	17	-6.50000*	.000	*
	18	-10.20000*	.000	*
	19	-8.10000*	.000	*
	20	-7.96667*	.000	*
	21	3.10000	.082	NS
	22	-5.93333*	.001	*
	23	-9.63333*	.000	*
	24	-7.63333*	.000	*
	25	-7.60000*	.000	*

*Mean Difference is significant at p < 0.05, NS= Not Significant, 1-OPCCRL90, 2 -RHA5CRL90, 3 -RHA10CRL90, 4 -RHA15CRL90, 5 -RHA20CRL90, 6 -OPCNa2SO4M90, 7 -RHA5Na2SO4M90, 8-RHA10Na2SO4M90, 9 -RHA15Na2SO4M90, 10 -RHA20Na2SO4M90, 11 -OPCNa2SO4S90, 12 -RHA5Na2SO4S90, 13 -RHA10Na2SO4S90, 14 -RHA15Na2SO4S90, 15 -RHA20Na2SO4S90, 16 -OPCMgSO4M90, 17 -RHA5MgSO4M90, 18 -RHA10MgSO4M90, 19 -RHA15MgSO4M90, 20 -RHA20MgSO4M90, 21-OPCMgSO4S90, 22 -RHA5MgSO4S90, 23 -RHA10MgSO4S90, 24 -RHA15MgSO4S90, 25 -RHA20MgSO4S90