The effectiveness of lightweight aggregate (LWA) as an internal curing agent (ICA) to reduce concrete shrinkage is evaluated for repair concrete used in cultural heritage works (RCCHW) using curing periods of 30 days. Normal weight aggregate is replaced by LWA at volume replacement levels ranging from 10 to 14%. The mixtures contain Portland cement maintaining the paste content at approximately 24.1% of concrete volume. Comparisons are made with mixtures containing low-absorption granite and high-absorption limestone normal weight coarse aggregates. At the replacement levels used in this study, LWA results in a small reduction in concrete density, no appreciable effect on concrete compressive strength, and a decrease in concrete shrinkage for drying periods up to 30 days. With a curing period of 14 days, all mixtures with LWA exhibited less shrinkage than the mixtures with either low- or high-absorption normal weight aggregates.