DAMPAK PENGGUNAAN AMPAS KOPI TERHADAP KUAT TEKAN DAN DAYA SERAP AIR PAVING BLOCK

With the decreasing availability of sand due to excessive exploitation and the increasing volume of organic waste such as coffee grounds, utilizing coffee grounds as a substitute for fine aggregates is expected to support the concept of sustainable development. This study aims to evaluate the effect of adding coffee grounds as a partial substitute for fine aggregates on the compressive strength and water absorption of paving blocks. The paving blocks were made with a cement-to-sand ratio of 1:6 and dimensions of 10.5 cm × 10.5 cm × 6 cm. Substitution was carried out in two conditions: untreated coffee grounds and washed coffee grounds, each at levels of 5%, 10%, 15%, and 20% by weight of fine aggregate. Of all variations, only the mixtures with 5% untreated coffee grounds and 5% washed coffee grounds were suitable for compressive strength testing. Compared to normal paving blocks, the compressive strength decreased by 61.2% for paving blocks using regular coffee grounds, and by 76.6% for those using washed coffee grounds. Water absorption tests showed that the addition of coffee grounds tended to increase the water absorption of the paving blocks. This study concludes that the use of coffee grounds, whether untreated or washed, is not recommended as a substitute material in paving blocks. Abstrak Dengan semakin berkurangnya ketersediaan pasir akibat eksploitasi berlebihan serta meningkatnya volume limbah organik seperti ampas kopi, pemanfaatan ampas kopi sebagai substitusi agregat halus diharapkan dapat mendukung konsep pembangunan berkelanjutan. Penelitian ini bertujuan mengevaluasi pengaruh penambahan ampas kopi sebagai substitusi parsial agregat halus terhadap kuat tekan dan daya serap paving block. Paving block dibuat dengan perbandingan semen terhadap pasir 1:6 dan ukuran 10,5 cm × 10,5 cm × 6 cm. Substitusi dilakukan dalam dua kondisi, yaitu ampas kopi biasa dan ampas kopi yang telah dicuci, masing-masing pada kadar 5%, 10%, 15%, dan 20% dari berat agregat halus. Dari seluruh variasi, hanya campuran dengan 5% ampas kopi biasa dan 5% ampas kopi cuci yang dapat dilanjutkan ke pengujian kuat tekan. Jika dibandingkan dengan paving block normal, penurunan kuat tekan tercatat sebesar 61,2% untuk paving block yang menggunakan ampas kopi biasa, dan sebesar 76,6% untuk paving block dengan ampas kopi cuci. Pengujian daya serap air menunjukkan bahwa penambahan ampas kopi cenderung meningkatkan daya serap paving block. Penelitian ini membuktikan bahwa penggunaan ampas kopi, baik dalam kondisi asli maupun setelah proses pencucian, tidak direkomendasikan sebagai bahan substitusi pada paving block.