Strength development of cement-treated sand using different cement - - PowerPoint PPT Presentation

Strength development of cement-treated sand using different cement types cured at different temperatures

11-12 July 2018, Solo, Indonesia 1

Lanh Si Ho1,2, Kenta Eguchi1, Kenichiro Nakarai1*

1Hiroshima University, Japan 2University of Transport Technology, Viet Nam

Minoru Morioka3, Takashi Sasaki3 Denka Co., Ltd, Japan

4th International Conference on Rehabilitation and Maintenance in Civil Engineering Best Western Premier Hotel, Solo Baru, July,11‐12 2018

Shallow mixing Deep mixing

Cement-treated soils are composite materials by mixing soil, cement, and water. Cement-treated soils are used as an improvement method of soft ground such as road- base, dam, air port, other structures etc.

Cement-treated soil used to improve the properties for subgrade of pavement

(https://www.martinmarietta.com/products/cement-treated- materials/)

Cement treated soil used to improve soft ground of dam

(https://www.liebherr.com/en/ita/products/construction-machines/deep- foundation/methods/soil-improvement/ground- improvement.html#lightbox)

2

• 1. Introduction

Strength development of cement-treated clay (Kitazume and

Terashi, 2013)

Original strength of soil Improvement of physical property Cement hydration strength Short-term Long-term Age

Pozzolanic reaction is the reaction between Ca(OH)2 (CH) with clay minerology (SiO2, Al2O3) produces C- S-H, C-A-H, C-A-S-H

3

• 1. Introduction

There are many factors affect strength of cement-treated soils:

• Material (cement type and soil condition)
• Mix proportion (cement content,

water/soil ratio)

• Construction method (Mixing method,

curing , curing temperature, age) etc.

Effect of curing temperature Lime/cement treated soils

Strength development over time under different curing temperature (D. Wang et al., 2016) increased 48C 37C 23C Upper marine clay; cement/dried soil=11.8%

4

• 1. Introduction

Deceased

93C 23C

Normal concrete

Compressive strength of concrete under different temperatures (A.R. Chini and L. Acquaye, 2005)

This study investigated strength development of cement-treated sand using different cement types cured at different temperatures.

Purpose

However, there are no studies considering different cement type cured under different curing temperature.

Mix proportions: Cement: ordinary Portland cement (OPC), high early Portland cement (HPC), and moderate heat Portland cement (MPC) were used to discuss effects of cement type. Sand mixture: Cement/sand=0.08, W/C=1.0, to discuss effects of curing temperature and cement type on strength development of cement-treated soils (high porosity). Mortar with W/C = 1.0: Cement/sand = 0.25, W/C = 1.0, to create the mixture with the same W/C ratio (high porosity -similar to cement-treated soils) for explaining strength development. Mortar with W/C = 0.5: Cement/sand = 0.5, W/C = 0.5, to discuss strength development of mortar with dense structure for comparing. curing condition Sealed at 20C, 40C Compaction The sand mixture specimens Hammer 1.5kg 3 layers 12 times/layer; Mortar: Tapping

50mm 100mm Cylind rical speci men

specimen size Specimen preparation

5

• 2. Methods and measurements

Measurements

6

• 2. Methods and measurements

➢ Unconfined compression test The tests were performed at a constant loading rate of 0.1 mm/min for both mortar and cement-treated sand. ➢ Thermal analysis test The amounts of chemically bound water and Ca(OH)2 (CH) were determined by thermal analysis (TG-DTA) to evaluate the degree of hydration and pozzolanic reaction.

LDTs placed at centers

3.1 Compressive strength

7

• 3. Results and discussion

At 7 days At 91 days 8% 25% 50% Cement-treated sand Mortar Mortar Cement- treated sand 25% 50% Mortar Mortar

Effect of cement content

Increased Increased 8% Almost constant Almost constant

3.1 Compressive strength

8

• 3. Results and discussion

0.0 0.5 1.0 1.5 2.0 10 20 30 40 50 60 Normalised compressive strength at 7 days (/OPC20C)

Cement content (%)

O,20°C H,20°C M,20°C O,40°C H,40°C M,40°C W/C = 50% W/C = 100%

0.0 0.5 1.0 1.5 2.0 10 20 30 40 50 60

Normalsied compressive strength at 91 days (/OPC20C) Cement content (%)

O,20°C M,20°C H,20°C O,40°C H,40°C M,40°C W/C = 50% W/C = 100%

At 7 days At 91 days 8% 25% 50% Cement-treated sand Mortar Mortar Cement- treated sand 25% 50% Mortar Mortar

Effect of cement content

Increased Increased Much smaller

3.1 Compressive strength

9

• 3. Results and discussion

0.0 0.5 1.0 1.5 2.0 10 20 30 40 50 60 Normalised compressive strength at 7 days (/OPC20C)

Cement content (%)

O,20°C H,20°C M,20°C O,40°C H,40°C M,40°C W/C = 50% W/C = 100%

0.0 0.5 1.0 1.5 2.0 10 20 30 40 50 60

Normalsied compressive strength at 91 days (/OPC20C) Cement content (%)

O,20°C M,20°C H,20°C O,40°C H,40°C M,40°C W/C = 50% W/C = 100%

At 7 days At 91 days 8% 25% 50% Cement-treated sand Mortar Mortar Cement- treated sand 25% 50% Mortar Mortar

Effect of cement content

8%

• When cement content decreased and sand content increased, the effects of

cement content and curing temperature

• n

strength development increased both short and long term in HPC and OPC at 40C

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• 3. Results and discussion

0.0 1.0 2.0 3.0 4.0 HP HPC OPC MPC Compressive strength ratio (40C/20C) C)

3day 7days 28days 91days

3.1 Compressive strength Comparison of cement type

0.0 1.0 2.0 3.0 4.0

HPC OPC MPC Compr pressive streng ngth h ratio

• (40C/20C)

C)

1day 7days 28days 91days

Mortar (W/C=50%, C=50%)

0.0 1.0 2.0 3.0 4.0 HP HPC OPC MPC Compressive strength ratio (40C/20C) C)

1day 7days 28days 91days

Cement-treated sand (W/C=100%, C=8%) Mortar (W/C=100%, C=25%)

For both mortar and cement- treated sand → the strengh ratio increased in

• rder of MPC  OPC HPC

Compressive strength ratio (40C/20C) Compressive strength ratio (40C/20C) Compressive strength ratio (40C/20C)

0.0 1.0 2.0 3.0 4.0 0.0 1.0 2.0 3.0 4.0 0.0 1.0 2.0 3.0 4.0

20 40 60 80 100

HPC OPC MPC Content (%)

Other CaCO3 CaSO4 C4AF C3A C2S C3S

3.1 Compressive strength Comparison of cement type

11

• 3. Results and discussion

Effect of temperature

• n strength

MPC  OPC  HPC

C3S：mainly contribute to early strength development C2S：mainly contribute to long-term strength development

Suggest that

When C2S  C3S Effect of temperature on cement mineral reactions: MPC  OPC  HPC or C2S can reduce negative effect of high curing temperatures

5 10 15 20 25 30 1 10 100

Amount of chemically bound water (%) Age (days)

S-8(O,20°C) S-8(O,40°C) S-8(H,20°C) S-8(H,40°C) S-8(M,20°C) S-8(M,40°C)

3.2 Amount of chemically bound water

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• 3. Results and discussion

Amount of chemically bound water over time of mortars. Amount of chemically bound water

• ver time of cement-treated sand.

Strength development mechanism of cement-treated soil

Mortar Cement-treated sand

5 10 15 20 25 30 1 10 100

Amount of chemically bound water (%) Age (days)

S-8(O,20°C) S-8(O,40°C) S-8(H,20°C) S-8(H,40°C) S-8(M,20°C) S-8(M,40°C)

3.2 Amount of chemically bound water

13

• 3. Results and discussion

Strength development mechanism of cement-treated soil

Mortar Cement-treated sand

The high water cement ratio caused the increase in amount of chemically bound water from the early age due to cement type (HPC) and curing temperature (40C)

> 20% > 20%

3.3. Relationship between amount of chemically bound water and strength

14

• 3. Results and discussion

Strength development mechanism of cement-treated soil

3 days 91 days

0.5 1.0 1.5 2.0 2.5 3.0 0.5 1.0 1.5 2.0 2.5 3.0

Ratio of compressive strength at 3 days(/OPC 20C) Ratio of chemically bound water at 3 days (/OPC20C)

S-8(O,40°C) S-8(H,20°C) S-8(H,40°C) M100(O,40°C) M100(H,20°C) M100(H,40°C) M50(O,40°C) M50(H,20°C) M50(H,40°C) O,20°C

0.5 1.0 1.5 2.0 0.5 1.0 1.5 Ratio of compressive strength at 91 days (/OPC 20C) Ratio of chemically bound water at 91 days (/OPC20C)

S-8(O,40°C) S-8(H,20°C) S-8(H,40°C) M100(O,40°C) M100(H,20°C) M100(H,40°C) M50(O,40°C) M50(H,20°C) M50(H,40°C) O,20°C

The increase of chemically bound water led to the increase in strength both short and long term

The strength increase by curing temperature in cement-treated soil was influenced greatly by cement type, and the strength increase both short and long term was caused by the increase in amount of chemically bound water

This phenomenon may be caused by a high water cement ratio and a large amount of sand

3.3. Relationship between amount of chemically bound water and strength

15

• 3. Results and discussion

Strength development mechanism of cement-treated soil (pozzolanic reaction)

2 4 6 8 10 12 14 16 5 10 Compressive strength (N/mm2) Amount of CH (%)

M100(O,20°C) M100(O,40°C) M100(H,20°C) M100(H,40°C)

1 2 3 4 5 6 5 10 Compressive strength (N/mm2) Amount of CH (%)

S-8(O,20°C) S-8(O,40°C) S-8(H,20°C) S-8(H,40°C)

Mortar W/C =100% Cement-treated sand Strength increased with CH increase Strength increased with decrease of CH → pozzolanic reaction For cement treated sand used OPC and HPC at 40C, curing temperature increased amount

• f chemically boud water and accelerated pozzolanic reaction → strength increase

The pozzolanic reaction occurred in the cement-treated sand under high curing temperature caused by a large amount of sand

• The results showed that the compressive strength of cement-treated

sand increased in order of MPC, OPC, and HPC under high curing temperatures.

• The compressive strength of cement-treated sand using HPC was much

higher than that using OPC and MPC under 20C both short and long-term, due to the higher amount of chemically bound water.

• Finally, the pozzolanic reaction was promoted in cases of cement-treated

sand using HPC and OPC under high temperature. This may be related to the high percentage of sand in the mixtures.

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• 4. Conclusions

• 1. https://www.martinmarietta.com/products/cement-treated-

materials/

• 2. https://www.liebherr.com/en/ita/products/construction-

machines/deep-foundation/methods/soil-improvement/ground- improvement.html#lightbox

• 3. Kitazume, M. and Terashi, M. (2013): The deep mixing method, Taylor

& Francis Group, London, UK.

• 4. A.R. Chini L. Acquaye, Effect of elevated curing temperatures on the

strength and durability of concrete, Materials and Structures, 38(2005) 673-679.

• 5. D. Wang, R. Zentar, N.E. Abriak, (2016). Temperature-Accelerated

Strength Development in Stabilized Marine Soils as Road Construction Materials, Journal of Materials in Civil Engineering, 04016281.

17

References

Thank you for your kind attention!