1) Graduate Student, Brigham Young University, Civil & Environmental Engineering Department, allison8tanner@gmail.com


Lightweight aggregate has been used successfully for structural and non-structural applications, and its most common use has been in lightweight concrete. Limited research has been done on light-weight grout though and there are no standards in place. The research performed in this study is intended to increase the knowledge of light-weight grout specifically made with expanded shale aggregate.

The research presented herein is a pilot study and consists of preliminary aggregate and grout testing that resulted in the mix design of six grout types: three fine grout designs and three coarse grout designs. Conventional normal weight aggregate was employed in the first grout mix. A lightweight aggregate batch was made with the same material proportions, as well as the same target water-cement (w/c) ratio and cement content. The weight of the cement was increased by 30 percent in the third grout type of each set to determine the effect on strength. The slump, component temperature, unit weight, air content, segregation, cement content, w/c ratio, and compressive strength for each grout type was gathered throughout testing.

Results of the testing show that all six grout types studied in this research reached the minimum 28-day strength of 13.8 MPa (2000 psi) ASTM standard. In addition, the results indicate that the cement content in expanded shale lightweight grout would need to be increased to reach comparable compressive strengths to that of the normal weight grout. The comparison between the compressive strength to cement content ratio of the different grouts indicate that normal weight grout is more efficient. These strength-cement ratios do not account, however, for the benefits of reduced dead loads, improved thermal insulation and improved sound insulation that could potentially influence the choice of the material used in and the life-cycle cost of the construction.


Keywords: Lightweight aggregate, lightweight grout, compressive strength, water-cement ratio, expanded shale, masonry