Evaluation of semi-flexible pavement performance

Abstract EN

This study aims at characterization and design new special type of asphalt mixture having
lower asphalt content and higher rutting resistance to be used in paving surface layers at
heavy loads areas.

To achieve this objective, grouting technique of permeable open graded
asphalt mixtures was used.

Such type of pavement is called as a semi-flexible pavement (SFP)
or grouted macadam (GM).

Different compaction efforts were used to achieve the required
percent of connected air voids between the bitumen coated aggregates.

Crushed silica
limestone, crushed sand, and filler were used to prepare highly permeable asphalt mixtures.

Asphalt contents of these mixes were determined theoretically and It was ostensibly examined
by the laboratory.

Marshall molds representing open graded mixtures were prepared and
grouted using a grout composed of ordinary Portland cement (OPC) as well as a mixture of
some concrete additives with different ratios.

Choosing the suitable grout mixture depended
on the flow time, flexural and compressive strengths for lab-produced grout prisms.

Measuring Marshall stability, Marshall flow, and indirect tensile strength test were conducted
on grouted asphalt mixes to identify their properties.

The same tests were conducted on
crushed silica limestone open graded mix of 2C gradation (Egyptian Standards for Roads) for
comparison purposes.

Analyzing the study results, positive effect of grouting open graded
mixes was concluded using a mixture of OPC, fine sand, silica fume and superplasticizer.

The
required bitumen content for surface layers was decreased by percent between 27% to 37%
compared with traditional dense asphalt mixtures.

The resistance of rutting for grouted mixes
was increased through increasing stability and indirect tensile strength by about 3 times and
more compared with traditional open asphalt mixtures.