Paper Type

Master's Thesis


College of Computing, Engineering & Construction

Degree Name

Master of Science in Civil Engineering (MSCE)



First Advisor

Dr. Nick Hudyma

Second Advisor

Dr. Alexandra Schonning

Third Advisor

Dr. N. Mike Jackson


Weathering has a negative effect on both physical and engineering properties of rock specimens and rock masses. When rock masses are weathered it is often difficult to obtain core segments that are the correct size for unconfined compressive strength testing. Thus engineers must use index testing to estimate the strength of specimens for design purposes. This thesis relates the unconfined compressive strength to index strength tests of Ocala limestone. The relationships developed include weathering states of the specimens and proximity of unconfined compressive strength specimens to index specimens.

One hundred and ninety five specimens were classified using International Society for Rock Mechanics (ISRM) weathering designations, had their unit weight determined, and were tested under unconfined compression, point load, or indirect tensile conditions. Qualitative results show the average unit weight decreases with an increase in weathering state and the range of index strength values decreases with an increase in weathering state. The data also shows low index strength test results across a wide range of unit weights.

Quantitative relationships were also developed with the strength data. All of the developed relationships were linear. Point load strengths have better correlations with unit weight than indirect tensile strengths. Unconfined compressive strength was correlated to index strength and weathering using three different approaches. For all approaches, indirect tensile strength has a better correlation with unconfined compressive strength than point load strength. Specimen pairs from the same weathering state also have a better correlation than specimen pairs from different weathering states. Unconfined compressive strength was also correlated to index strength results by incorporating specimen proximity. Once again, indirect tensile strength is a better predictor of unconfined compressive strength than point load strength. Specimen pairs, consisting of unconfined compressive strength and index strength test specimens, had better correlations when the two specimens are located close together.