Improving the geotechnical behavior of sand through cohesive admixtures

Peer review under responsibility of National Water Research Center.

Figures & data

Table 1 Physical properties of the used admixtures.

	L.L (%)	P.L (%)	P.I (%)	Free swell (%)	Montmorillonite content (%)	Kaolinite content (%)	Illite content (%)
Toshka soil	84	33	51	100	66	30	2
6th of October soil	92	40	52	160	70	20	6
Bentonite	365	45	320	270	93	1	1

Table 2 Minerals of the natural tested sand and the used admixtures.

	TDS (ppm)	CL (ppm)	SO3 (ppm)	CaCO3 (%)
Natural soil (Abu Rawash sand)	150	61	–	2
Toshka soil	2150	1210	235	2.5
6th of October soil	1840	450	201	4
Bentonite	2374	358	15	–

Fig. 1 Grain size distribution curve of the natural siliceous sand (S₁).

Fig. 2 Modified proctor curve for the natural tested sand.

Fig. 3 Mohr circles results for natural soil.

Fig. 4 Effect of fines type and fines content on the liquid limit of the mixtures.

Fig. 5 Effect of fines type and fines content on the plastic limit of the mixtures.

Fig. 6 Effect of fines type and fines content on the plasticity index of the mixtures.

Fig. 7 Effect of fines type and fines content on the free swell of the mixtures.

Fig. 8 Modified proctor curves for the used Toshka mixtures.

Fig. 9 Modified proctor curves for the used 6th of October mixtures.

Fig. 10 Modified proctor curves for the used bentonite mixtures.

Table 3 Modified proctor compaction relationship for natural and improved soils.

Mixing ratios	4%	8%	12%	16%	20%
Toshka soil mixtures
Optimum moisture content (%)	12.08	11.90	11.00	11.23	13.30
Maximum dry density (gm/cm^3)	1.90	1.95	1.99	2.03	2.03
6th of October mixtures
Optimum moisture content (%)	8.40	9.70	9.60	10.70	10.60
Maximum dry density (gm/cm^3)	1.88	1.90	1.93	2.02	2.08
Bentonite mixtures
Optimum moisture content (%)	13.65	10.75	9.30	6.50	10.50
Maximum dry density (gm/cm^3)	2.00	1.96	2.04	2.05	1.97

Fig. 11 California bearing ratio curves for the Toshka mixtures after four days soaking in water.

Fig. 12 California bearing ratio curves for the 6th of October mixtures after four days soaking in water.

Fig. 13 California bearing ratio curves for the bentonite mixtures after four days soaking in water.

Fig. 14 Cohesion strength of the tested mixtures.

Fig. 15 Friction angle of the tested mixtures.

Fig. 16 Consolidation test (e-log p Curve) for the Toshka mixture.

Fig. 17 Consolidation test (e-log p Curve) for the 6th of October mixture.

Fig. 18 Consolidation test (e-log p Curve) for the bentonite mixture.

Fig. 19 Swelling ratio of sand mixtures.

Table 4 Permeability values of the improved soils.

Mixing ratios	4%	12%	20%
Toshka soil mixtures
Permeability values (cm/s)	9.40E-06	9.40E-06	9.40E-06
6th of October mixtures
Permeability values (cm/s)	8.71E-06	8.71E-06	8.71E-06
Bentonite mixtures
Permeability values (cm/s)	6.01E-06	6.01E-06	6.01E-06