The results of research on BETALIT done by Russian institutes

The results of testing High Energy Mixed Concrete (HEMC) received 1997 by Dr. A.S.Bychkov (VNIISTROM, Mechanical Test Laboratory, 140080 Moskovskaya obl. Pos. Kraskovo)

MECHANICAL PROPERTIES

1. The proportioning of weight parts: 1:3 (1 part of cement and 3 parts of sand), and 1:2 a91 part of cement and 2 parts of sand). The quantity of water and admixture of superplasticizer had been chosen to get a consistency of mixture 14-16 cm of flowability.

2. The properties were determined as:

compressive strength by testing the cubes 10x10x10 cm and prisms 10x10x40 cm
chord modulus of elasticity at a level of 40% of ultimate load
deformations and Poisson's Ratio of prisms, corresponding to the maximum of load
deformation of creep (for HEMC 1:3)
The results were compared with the data for the sand-concrete (concrete prepared using the ordinary mixing).

BETALIT	Cubic Strength MPa	Prism Strength MPa	Longitudinal Deformation mm/m	Initial (chord) Modulus of Elasticity MPa	Poisson's Ratio
1 : 3	35.3	31.8	3.23	18,400	0.16
1 : 2	63.2	51.7	3.93	21,100	0.18
Sand - Concrete Sand-Concrete	Class B25 Class B40		1.84 2.30	24,000 28,500	0.20 0.20

Conclusions based on the test results are given below:

HEMC shows deformations around 1.5 times more than traditional concrete when tested for compression in either short or long time loading under the same conditions. HEMC can be used in the areas of construction where the high strength and the high elasticity of concrete are required, and where the ability of the material to redistribute stress without cracking is necessary. For example, it can be used for statically non-determined structures that are built on weak grounds; off-center compressed elements of structures, and other similar cases.

Freezing - Thawing test

Data of HEMC:

Cement-sand ratio 1:3

The average Compressive Strength - 52.3 Mpa. The average Density of dry samples - 2109 kg/cu.m.

The test method: specimens - cubes with 100 mm of edge saturated with the 5% water solution of sodium chloride. Freezing in air with temperature minus 20^oC. Thawing in 5% water solution of sodium chloride.

Requirements for the road concrete: average loss of compressive strength no more than 5%, loss of weight - 3%.

Strength of fully saturated specimens (Mpa)		Strength after 150 cycles		Loss of the average Strength, %	Strength after 200 cycles			Loss of the average strength,%
Indi- vidu- al	Ave- rage	Indi- vidu- al	Ave- rage	Loss of the average Strength, %	Indi- vidu- al		Ave- rage
49.2 52.5 54.4 52.5 51.4 53.4	52.3	61.2 61.7 56.9 55.6	58.8	Gain of strength 12.6%	53.7 56.2 61.2 55 69 56.2	56.9		Gain of strength 8.9%

Change of mass

The saturated specimen's mass, g

Loss of

the

average

mass,

Evaluation of the

Freezing - thawing

resistance

Before test

After 200 cycles

Indivi-

dual

Average

Indivi-dual

Average

2304

2288

2312

2296

2295

2280

2296

2290

2272

2300

2280

2275

2283

0.57%

F200 and more

Conclusion:

HEMC's freezing-thawing resistance is not only satisfactory, but is actually increased in strength, as observed in the process of the test.

Abrasion resistance

Requirements for the road concrete: the loss of the mass must be no more than 0.7-g/sq. sm. of the surface exposed to abrasion.

Dimension of specimens

Surface of

Abrasion,

Sq. sm.

Mass, g

Loss of mass, g

Abrasion

Resistance

(loss of

mass per

sq. sm.)

Before

test

After

test

specimens

Average

70*70*70

796

788

770

805

789

782

763

799

6.5

0.133

Conclusion:

The abrasion resistance of HEMC corresponds to the requirements for the materials used in pavements with increased traffic. The index of abrasion resistance of HEMC approaches that of hard rocks. HEMC is recommended as a pavement material either by itself or as mortar in concrete.

The results of the test, received by the experts of the Transport Construction Institute and the Central Laboratory of Construction Materials ( Moscow).

MECHANICAL PROPERTIES OF CONCRETE

WITH High Energy Mixed MORTAR PART

Using high-energy mixing in producing of construction mixture to prepare the mortar part of the conventional concrete is one of the most effective ways to improve its properties.

Data for Concrete:

The proportion of the concrete mixture, where the mortar component is prepared individually in a special mixer and then mixed with the crushed stone aggregate of the granite, was: 1 part of the Portland cement, 2 parts of sand and 4 parts of the crushed aggregates. Water and the plasticizer are of the required quantity to attain the slump of the ending mixture, which equals 5-6 cm. This concrete is typical for making reinforced concrete transport constructions such as desks of bridges, tubing for tunnels, road panels and pipes.

The data of the properties of 3 kinds of concrete are listed in the tables as follows:

#1 -- the concrete, prepared with the conventional method

#2 -- the concrete, with HEM mortar part

#3 -- the concrete, with HEM mortar part, where the amount of cement was decreased by 15%

Mechanical properties of concrete

Properties	Units	Variant
Properties	Units	#1	#2	#3
Compressive strength	MPa	31.2	43.2	40.7
Modulus of elasticity	MPa	29,000	32,300	30,800
Beginning of the cracking under compressive loading (by O.Berg): - with the pulse-velocity method - with the method of stress-strain curves	% of ultimate loading	33 72	38 83	36 78

Durability of concrete

Variant #	Amount of Cement Kg/cu.m of the mixture	Compressive strength of the concrete, MPa
		Before testing	After number of cycles of freezing -20^oC and thawing in water + 20^oC
		Before testing	200	300
1	375	28.3	36.3	destroyed
2	372	42.5	47.9	55.6
3	322	37.5	40.5	44.5

Conclusion:

Concrete made with HEM mortar part is recommended for the construction of roadways, able to bear very heavy traffic.

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