Mixture & Absorption Test
Mixture Property
Medium and coarse grained aggregate
Rc > 3MPa
Rimm > 80%
Test not necessary if compliance with above
Limits not usually necessary
Strength
Immersed Strength
Frost Heave Limits
SO4 and S Limits
Fine–grained, i.e. Clays and chalks (Rc typically ~ 1MPa.)
Rit > -0.2/0.25MPa
Rimm > 80%
Aim for no heave but pragmatically <2 or 3 mm
Yes limits required – refer to BP/16
Rc denotes compressive strength.
Rit denotes indirect tensile strength.
Rimm denotes the ratio of the strength of the specimens cured unprotected in water after an initial period of sealed curing, to the strength of the specimens cured totally in sealed conditions.
It should be noted, that these recommendations apply to all HBM irrespective of the frost susceptibility of the aggregate or soil in the unbound state.
Capillary Absorption Test
UK Materials
Fresh wet density – kg/m3
28 day sealed cube strength – N/mm2
28 day immersed cured cube strength – N/mm2
Capillary absorption – mg/mm2
Cat cube strength from D
specimens – N/mm2
1950
2.4
2.0
0.05
2.45
Asian Materials
1940
2.6
2.25
0.37
1.8
The very rigorous Capillary Absorption Test (CAT) is used to assess the weathering performance for pre-cast concrete cast stone durability specifies a maximum CAT value of 1 mg/mm2
Comparative results for different "concretes" are given below.
Material/Type
Age
Average Density – kg/mm2
Limestone Rock
Cast Stone
CIC ecoProactive™
18 million years
28 Days
28 Days
2400
1990
1950
CAT – mg/mm2
0.3 & 0.52
0.19 & 0.30
0.05 & 0.37
This test method was used in view of the fact that both pre-cast stone which is instantly de mouldable and HBM are produced from similar consistency mixes requiring machine compaction to achieve the desired close finish and durable performance.
