3.2 Ready-mixed concrete

The cube compressive strengths of ready-mixed concretes of C8/10 to C30/37 strength class for reaching a slump of 100–150 mm (slump class S3 according to [23]) without the use of plasticizers are listed in Table 5. The consistency and cube compressive strength of ready-mixed concretes prepared with different plasticizers with slump values ≥220mm [slump class S5] are reported in Table 6. Laboratorymade ready-mixed concrete specimens were prepared with the following types of plasticizers coming from various producers: M1, no admixture; M2, lignosulfonate; M3, modified polycarboxylate (<22% polycarboxylate content); M4,


Fundamental Properties of Industrial Hybrid Cement Important for Application in Concrete DOI: http://dx.doi.org/10.5772/intechopen.88060

#### Table 5.

Ready-mixed concrete compositions with H-Cement at slump S3.


#### Table 6.

Properties of fresh ready-mixed concrete mixtures C20/25 with different kinds of plasticizers.

polycarboxylate (30% water-reducing effect); M5, modified polycarboxylate (more than 22% polycarboxylate content); M6, polycarboxylate (35% water-reducing effect); M7, melamine; and M8, lignosulfonate modified by polycarboxylate.

The results show that H-Cement is suitable for the production of ready-mixed concrete between C8/10 and C30/37 strength classes [29]. Workability of the concretes made from H-Cement is dependent on the specific plasticizer type being used. Admixtures based on a lignosulfonate and a combined lignosulfonate/ polycarboxylate mixture are found best to ensure the workability of fresh concrete mixtures and also after the elapsed 60 min.

#### 3.3 Shrinkage-reducing property

The concretes were prepared from the cement mixture made of two cements, HC and PC, in the selected ratios (expressed as % wt.) as reported in Table 7. The specimens were stored in water at (20 1)°C and in air at (20 1)°C with 60% RH and at (40 1)°C with an average RH of 15% in order to minimize the length changes within the 90-day period of curing. The concretes were prepared with a constant water-to-cement ratio of 0.475 according to the proportion: 400 kg/m<sup>3</sup> of cement (PCHC 1.00 or HCPC 1.00) or cement blend, 190 l of water and dried river aggregates—0/4 mm, 630 kg; 4/8 mm, 390 kg; and 8/16 mm, 775 kg from Jelka (Slovakia). No admixture was used at the concrete production to preclude its influence on the measured length changes. The measurements were performed on the prisms 100 100 400 mm having a length comparator according to STN

3.2 Ready-mixed concrete

Too plastic consistency at w/c = 0.5.

\*

132

Table 4.

Table 3.

Chemical and mineralogical composition of HC and PC.

Compressive Strength of Concrete

The cube compressive strengths of ready-mixed concretes of C8/10 to C30/37 strength class for reaching a slump of 100–150 mm (slump class S3 according to [23]) without the use of plasticizers are listed in Table 5. The consistency and cube compressive strength of ready-mixed concretes prepared with different plasticizers with slump values ≥220mm [slump class S5] are reported in Table 6. Laboratorymade ready-mixed concrete specimens were prepared with the following types of plasticizers coming from various producers: M1, no admixture; M2, lignosulfonate;

Le Chatelier (soundness) mm 0.5 0.01 Content of CrVI ppm 1.0 1.23 Content of C3A % wt. 2.0 0.5 7.5 0.8 Hydration heat J/g 185 359

% wt. CaO SiO2 Al2O3 Fe2O3 MgO Na2O Na2O SO3 TiO2 HC 30.73 48.57 20.13 6.81 2.13 2.51 3.22 4.67 1.14

PC CaO SiO2 Al2O3 Fe2O3 MgO K2O SO3 P2O5 Cl

Abbreviations: Q, quartz; ARC, arcanite; ANH, anhydrite; PER, periclase; G, gypsum; BAS, bassanite; Cc, calcite.

Technical parameters Unit HC PC Initial setting time Minute 200 20 190 20 Final setting time Minute 300 40 250 30 Standard consistency % 32 2.0 29.1 1.8

2-day compressive strength MPa 17.5 3.0

28-day compressive strength MPa 36.5 4.0

90-day compressive strength MPa 41.5 3.0

2-day flexural strength MPa 3.5 0.5

28-day flexural strength MPa 4.4 0.4

90-day flexural strength MPa 9.0 0.3

Comparison of characteristic values of H-cement and reference PC.

C3S C2S C3A C4AF Q ARC ANH PER 33.66 11.75 11.54 6.64 28.34 1.30 1.18 0.50

64.09 21.54 4.07 2.64 1.24 1.05 3.37 0.34 0.07 C3S C2S C3A C4AF ARC G BAS PER Cc 61.63 7.18 7.86 8.72 1.39 4.22 3.57 0.51 3.34

w/c = 0.4\*

w/c = 0.4

w/c = 0.4

w/c = 0.4

w/c = 0.4

w/c = 0.4

33.7 2.0 w/c = 0.5

59.2 1.6 w/c = 0.5

63.1 1.9 w/c = 0.5

6.4 0.4 w/c = 0.5

8.9 0.4 w/c = 0.5

9.3 0.3 w/c = 0.5

M3, modified polycarboxylate (<22% polycarboxylate content); M4,


731320 [30] (the related ASTM Standard: C157/C157M-08) and are illustrated in Figures 1 and 2. Mechanical properties of the specimens are listed in Table 8. The results show that H-Cement has reduced shrinkage. All concretes slightly expand when permanently cured in water. H-Cement concrete (HC concrete) expands by 21.6% less than PC concrete after 90-day immersion in water. The shrinkage of HC concrete exposed for 90 days in 20°C/60% RH air cure and 40°C/

Fundamental Properties of Industrial Hybrid Cement Important for Application in Concrete

15% RH air cure is about 48 and 58% smaller than that of PC concrete. The

20 and 40°C air cure is 32.3 and 30.6 MPa, 41.0 and 38.5 MPa and 42.0 and

Depending on its cement blend composition and curing regime, however, blending HC with PC contributes to raising the compressive strength values compared to plain HC concrete. The 90-day compressive strength of HCPC 1.00 (100% wt. HC), HCPC 0.50 (50% wt. of both cements) and PCHC 1.00 (100% wt. PC) in

The andesite aggregate with a proven susceptibility to ASR according to the criteria for evaluation of the chemical test according to STN 721179 [16] was used

HCPC 1.00 100 W20 27.2 46.6 5.4 34.2

HCPC 0.95 95 A20 29.3 41.4 2.8 32.9

HCPC 0.90 90 A20 31.3 41.3 2.9 34.8

HCPC 0.85 85 A20 32.4 41.4 3.0 37.2

HCPC 0.50 50 W20 35.7 50.3 5.5 49.1

PCHC 0.85 15 W20 40.5 55.1 5.5 50.6 PCHC 0.90 10 W20 40.5 55.9 5.5 50.7 PCHC 0.95 5 W20 41.0 56.6 5.5 51.4 PCHC 1.00 0 W20 41.6 56.6 5.6 54.5

Abbreviations: W20, water at 20°C; A20, air at 20°C; A40, air at 40°C; DME, dynamic modulus of elasticity; BC, basic curing specified by 1-day cure in the chamber at (20 1)°C at 100% RH air and 27-day curing in water at

Mechanical properties of the concretes made from a mixture of HC and PC stored for 90 days in water at 20°C

(W20), in air at 20°C/60% RH (A20) and at 40°C/15% RH (A40) after 28-day basic curing.

HC (% wt.) Curing 28-day basic curing 90-day curing Compressive strength (MPa)

DME (GPa)

A20 27. 6 41.7 2.4 32.3 A40 28.7 36.7 2.3 30.6

A40 30.0 36.7 2.4 31.8

A40 32.0 36.6 2.5 33.0

A40 33.2 36.6 2.6 34.7

A20 38.1 41.2 3.3 41.0 A40 38.5 36.5 3.2 38.5

A20 40.2 39.3 3.7 42.0 A40 39.1 33.4 3.8 39.0

Prism strength (MPa) Flexural Compressive

shrinkage-reducing effect is also recorded by the blended systems.

39.0 MPa, respectively.

Concrete mixture

(20 1)°C.

Table 8.

135

3.4 ASR-mitigating property

DOI: http://dx.doi.org/10.5772/intechopen.88060

#### Table 7.

Content of cements in the concrete mixtures with w/c = 0.475.

Figure 1. Length changes of concrete stored 90 days at 20°C and 60% RH.

Figure 2. Length changes of concrete stored 90 days at 40°C and 15% RH.

Fundamental Properties of Industrial Hybrid Cement Important for Application in Concrete DOI: http://dx.doi.org/10.5772/intechopen.88060

731320 [30] (the related ASTM Standard: C157/C157M-08) and are illustrated in Figures 1 and 2. Mechanical properties of the specimens are listed in Table 8.

The results show that H-Cement has reduced shrinkage. All concretes slightly expand when permanently cured in water. H-Cement concrete (HC concrete) expands by 21.6% less than PC concrete after 90-day immersion in water. The shrinkage of HC concrete exposed for 90 days in 20°C/60% RH air cure and 40°C/ 15% RH air cure is about 48 and 58% smaller than that of PC concrete. The shrinkage-reducing effect is also recorded by the blended systems.

Depending on its cement blend composition and curing regime, however, blending HC with PC contributes to raising the compressive strength values compared to plain HC concrete. The 90-day compressive strength of HCPC 1.00 (100% wt. HC), HCPC 0.50 (50% wt. of both cements) and PCHC 1.00 (100% wt. PC) in 20 and 40°C air cure is 32.3 and 30.6 MPa, 41.0 and 38.5 MPa and 42.0 and 39.0 MPa, respectively.

#### 3.4 ASR-mitigating property

Cement mixture in

Compressive Strength of Concrete

Content of cements (% wt.) Curing regime

PCHC 1.00 0 100 In water at 20°C and in air at 20 and 40°C

HCPC 0.50 50 50 In water at 20°C and in air at 20 and 40°C

HCPC 1.00 100 0 In water at 20°C and in air at 20 and 40°C

HC PC

PCHC 0.90 10 90 PCHC 0.85 15 85

HCPC 0.90 90 10 HCPC 0.95 95 5

Content of cements in the concrete mixtures with w/c = 0.475.

Length changes of concrete stored 90 days at 20°C and 60% RH.

Length changes of concrete stored 90 days at 40°C and 15% RH.

PCHC 0.95 5 95 In water at 20°C

HCPC 0.85 85 15 In air at 20 and 40°C

concrete

Table 7.

Figure 1.

Figure 2.

134


The andesite aggregate with a proven susceptibility to ASR according to the criteria for evaluation of the chemical test according to STN 721179 [16] was used

Abbreviations: W20, water at 20°C; A20, air at 20°C; A40, air at 40°C; DME, dynamic modulus of elasticity; BC, basic curing specified by 1-day cure in the chamber at (20 1)°C at 100% RH air and 27-day curing in water at (20 1)°C.

#### Table 8.

Mechanical properties of the concretes made from a mixture of HC and PC stored for 90 days in water at 20°C (W20), in air at 20°C/60% RH (A20) and at 40°C/15% RH (A40) after 28-day basic curing.
