Seiring dengan majunya perkembangan, banyak ditemukan peneliti melakukan aksi ramah lingkungan dalam pembuatan beton. Demi membentuk beton ramah lingkungan yaitu membatasi pengaplikasian semen serta menggantikannya dengan limbah atau bahan yang mampu meningkatkan kekuatan beton. Silica fume dan fly ash merupakan bahan pengganti semen yang dapat meningkatkan kuat tekan beton. Penelitian ini menggunakan bahan pengganti semen yaitu silica fume dan fly ash serta pengganti pasir yaitu copper slag. Persentase silica fume dan fly ash yang digunakan masing-masing 0%, 5%, 10%, 15%, 20% dan 25% serta copper slag 40%. Pengujian kuat tekan dilakukan pada umur 7 hari, 14 hari dan 28 hari serta pengujian absorpsi pada umur 28 hari. Nilai kuat tekan tertinggi untuk sampel beton dengan variasi 2 yakni dengan substitusi silica fume 5% + copper slag 40%, menghasilkan kuat tekan sebesar 26,53 MPa. Nilai kuat tekan tertinggi untuk sampel beton dengan variasi 10 yakni dengan substitusi fly ash 15% + copper slag 40% menghasilkan kuat tekan sebesar 26,74 MPa. Sehingga fly ash + copper slag memiliki nilai kuat tekan beton tertinggi dibandingkan silica fume + copper slag. Nilai absorpsi tertinggi pada silica fume 0% + copper slag 40% sebesar 3,976%. Sedangkan fly ash 25% + copper slag 40% menghasilkan nilai absorpsi tertinggi sebesar 5,923%.

Along with the progress of development, many researchers found environmentally friendly actions in the manufacture of concrete. In order to form environmentally friendly concrete, namely limiting the application of cement and replacing it with waste or materials that can increase the strength of concrete. Silica fume and fly ash are cement substitutes that can increase the compressive strength of concrete. This study uses a cement substitute, namely silica fume and fly ash and a substitute for sand, namely copper slag. The percentages of silica fume and fly ash used were 0%, 5%, 10%, 15%, 20% and 25%, respectively, and 40% copper slag. The compressive strength test was carried out at the age of 7 days, 14 days and 28 days and absorption testing was carried out at the age of 28 days. The highest compressive strength value for the concrete sample with variation 2 is by substitution of 5% silica fume + 40% copper slag, resulting in a compressive strength of 26.53 MPa. The highest compressive strength value for the concrete sample with a variation of 10 is with the substitution of 15% fly ash + 40% copper slag resulting in a compressive strength of 26.74 MPa. So that fly ash + copper slag has the highest compressive strength value of concrete compared to silica fume + copper slag. The highest absorption value was at 0% silica fume + 40% copper slag at 3.976%. Meanwhile, 25% fly ash + 40% copper slag produced the highest absorption value of 5.923%.