Studi pengaruh penggunaan limbah kertas pada mortar dengan penambahan silica fume dan superplasticizer terhadap kuat tekan, kuat lentur, susut, modulus elastisitas, densitas, dan daya serap air = Study of using waste paper for mortar with addition of silica fume and superplasticizer for, compressive strength, flexural strength, shrinkage, elastic modulus, density, and absorption