Table 3.

Chemical and mineralogical composition of HC and PC.


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.

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

Concrete strength class Cube compressive strength (MPa)

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

Entrapped air (% vol.)

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

C8/10 4.8 10.4 16.0 C12/15 5.7 11.4 18.7 C16/20 6.9 14.6 22.2 C20/25 8.0 16.8 25.0 C30/37 14.6 29.4 42.6

Fundamental Properties of Industrial Hybrid Cement Important for Application in Concrete

2 days 7 days 28 days

Slump (mm) Cube compressive strength (MPa)

After mixing After mixing After 60 min 2 days 28 days 56 days 90 days

M1 1.2 220 120 11.0 23.6 24.8 26.3 M2 2.1 220 130 11.0 25.0 27.1 28.4 M3 1.7 220 60 10.6 21.8 22.5 22.6 M4 1.6 220 70 9.3 21.2 22.5 22.7 M5 1.7 220 110 10.1 23.6 26.6 25.4 M6 1.4 220 170 8.6 22.6 24.1 23.7 M7 2.3 220 40 7.1 24.0 24.6 29.9 M8 1.3 220 190 9.4 22.2 21.1 24.6

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

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

mixtures and also after the elapsed 60 min.

3.3 Shrinkage-reducing property

Table 5.

Table 6.

133

Concrete mixture

#### Table 4.

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