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. 2021 Jun 17;14(12):3341.
doi: 10.3390/ma14123341.

Lightweight Reactive Powder Concrete Containing Expanded Perlite

Stefania Grzeszczyk  1 , Grzegorz Janus  1
Affiliations

Lightweight Reactive Powder Concrete Containing Expanded Perlite

Stefania Grzeszczyk et al. Materials (Basel). .

Abstract

This paper presents the test results of the lightweight concrete properties obtained by adding expanded perlite (EP) to an RPC mix in quantities from 30% to 60% by volume of the concrete mix. It has been shown that in these cases it is possible to obtain concrete containing 30% by volume with density of approximately 1900 kg/m3 and the compressive strength > 70 MPa, with a very low water absorption value (3.3%), equal to the water absorption value of RPC without lightweight aggregate (3.3%). However, with the increased quantity of perlite (from 45% to 60%), the concrete density reduction is not observed, as the expanded perlite demonstrates very low resistance to crushing. With the increased amount of perlite, the longer periods of mixing time for all the mix components are required to obtain the homogeneous and fluid concrete mix, what causes grounding down EP. Therefore, using larger quantities of this aggregate in RPC is not recommended. The lightweight RPC shows very good freeze-thaw resistance in the presence of de-icing salt (the scaling mass is lower than 0.1 kg/m2). The above is explained by the compact microstructure of this concrete and the RPC mix location in open pores on the perlite aggregate surface, which consequently affects the strengthening of the aggregate-matrix contact without an interfacial transition zone (ITZ) visible. It has been demonstrated that pozzolanic activity of expanded perlite is much lower than the activity of silica fume and quartz powder, and its impact on increasing the RPC strength is minimal.

Keywords: compressive strength; density; expanded perlite aggregate (EP); lightweight RPC; water absorption.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Image of expanded perlite.
Figure 2
Figure 2
XRD pattern of expanded perlite.
Figure 3
Figure 3
Microstructure of expanded perlite grain in 500 times magnification with EDS analysis in point 1.
Figure 4
Figure 4
Flow diameter of RPC mix without lightweight aggregate (a), and containing 30% EP (b), 45% EP (c), and 60% EP (d).
Figure 5
Figure 5
Distribution of EP in the structure of lightweight RPC 30% EP (a), 45% EP (b), and 60% EP (c).
Figure 6
Figure 6
Density of RPC and density of RPC containing EP in quantities 30%, 45%, and 60% by volume.
Figure 7
Figure 7
Compressive strength of lightweight RPC containing EP in quantity 30%, 45%, and 60% by volume.
Figure 8
Figure 8
Flexural strength of lightweight RPC containing EP in quantity from 30%, 45%, and 60% by volume.
Figure 9
Figure 9
Microstructure of lightweight RPC with 30 vol.% of EP, cured for 28 days in 350 times magnification with EDS analysis in point 1, 2, and 3.
Figure 10
Figure 10
Microstructure of lightweight RPC with 30 vol.% of EP, cured for 28 days in 2000 times magnification with EDS analysis in point 1 and 2.
Figure 11
Figure 11
Microstructure of lightweight RPC with 60 vol.% of EP, cured for 28 days in 350 times magnification with EDS analysis in point 1, 2, and 3.
Figure 12
Figure 12
Microstructure of lightweight RPC with 60 vol.% of EP, cured for 28 days in 2000 times magnification with EDS analysis in point 1, 2, and 3.
Figure 13
Figure 13
XRD RPC +30% EP after 28 days of curing.
Figure 14
Figure 14
XRD RPC + 60% EP after 28 days of curing.
Figure 15
Figure 15
Compressive strength of RPC containing 30 vol.% of expanded perlite without and with addition of 1% Ca(OH)2.
Figure 16
Figure 16
XRD patterns: (a) RPC +30% EP after 2, 7, and 28 days of curing, (b) RPC + 30% EP + 1% Ca(OH)2 after 2, 7, and 28 days of curing.
Figure 17
Figure 17
Change in density and compressive strength depending on the amount of EP in the RPC.
See this image and copyright information in PMC

References

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