Potential of Local Clay for the Development of Limestone Calcined Clay Cement in East Java

¹ Department of Civil Engineering, Petra Christian University Jl. Siwalankerto No. 121-131, Siwalankerto, Kec. Wonocolo, Surabaya, Jawa Timur, Indonesia 60236
² Research & Development of PT Semen Indonesia (Persero) Tbk. Jl. Veteran No.93, Kec. Gresik, Kab. Gresik, Jawa Timur, Indonesia 61122

^* Corresponding author: antoni@petra.ac.id

Abstract

Limestone Calcined Clay Cement (LC3) offers an innovative and sustainable alternative to traditional binders, utilizing calcined clay and limestone as partial substitutes for Ordinary Portland Cement (OPC) clinker. This study investigated the potential of local clays found in East Java, Indonesia, for LC3 production. Clay samples from three sites in East Java, with pure kaolin as a benchmark, were assessed. A formulation with 50% OPC clinker substitution was employed, integrating limestone powder, calcined clay, and gypsum. The clays underwent drying, grinding, sieving, and calcination at both 700°C and 800°C. For comparison, a sample of local Trass, typically used in Portland Composite Cement, was also evaluated. Compared to OPC, the LC3 samples exhibited reduced workability and a faster initial setting time. However, the LC3 mortar displayed commendable compressive strength, achieving a Strength Activity Index exceeding 75% at 28 days. The calcination temperature influenced the ultimate strength, especially in specimens with a higher kaolin concentration. One of the local clays, sourced from Trenggalek, with a kaolinite content of 49%, achieved a compressive strength of 43 MPa at 28 days. This value closely parallels the strengths of both OPC (49 MPa) and the metakaolin (42 MPa) mixtures.