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Compression index is one of the most important properties of soils widely used for estimation of settlement during design of foundations. In particular, for routine test requirements, limited laboratory facilities and preliminary evaluations, various equations are available in the literature to simply estimate the compression index using some soil index properties. However, applicability of these equations is often limited for the interested site due to their establishment from different databases. Thus, it is more realistic way to employ the correlations developed using local data of region, provided that data is available. In this viewpoint, this paper aims to develop correlations for the compression index dependent upon the soil index parameters of natural moisture content, liquid limit and initial void ratio for fine‐grained soil of Baghdad city. From the developed correlations, it is obtained that the best estimations of compression index is correlated by liquid limit as single variable, and by liquid limit and initial void ratio as double variable. It is clear that use of the developed correlations is more suitable specifically for Baghdad region for preliminary evaluations of foundation settlement Sıkışma indeksi, temellerin tasarımında oturma hesapları için yaygın olarak kullanılan zeminlerin en önemli özelliklerinden biridir. Özellikle rutin deneyler, sınırlı laboratuvar koşulları ve ön değerlendirmeler için, literatürde zemin indeks özelliklerine bağlı olarak basitçe hesaplanabilen sıkışma indeksi denklemleri mevcuttur. Ancak, bu denklemler değişik verilerden oluşturulduğundan, çoğunlukla ilgilenilen bölge için sınırlı kullanım sunmaktadır. Bu yüzden, bölgeye ait yerel veriler ile (eğer veri mevcutsa) geliştirilen korelasyonları kullanmak en gerçekçi yoldur. Bu doğrultuda, bu çalışmada Bağdat şehrine ait ince daneli zeminler için, zemin indeks özelliklerinden doğal su muhtevası, likit limit ve başlangıç boşluk oranına bağlı olarak sıkışma indeksi denklemlerinin geliştirilmesi amaçlanmıştır. Elde edilen denklemlerden, sıkışma indeksinin tek değişkenli ilişkilerde likit limit ile, ve çok değişkenli ilişkilerde ise likit limit ve başlangıç boşluk oranı ile birlikte kullanıldığında en iyi korelasyonları verdiği bulunmuştır. Geliştirilen korelasyonların temel oturması için yapılacak ön değerlendirmelerde özellikle Bağdat bölgesi için kullanılmasının çok daha uygun olduğu açıktır. ©

This article discusses the effects of glass powder (GP) replacements and sodium hydroxide (NaOH) molarity on the rheological, fresh, mechanical and microstructure characteristics of slag-based mechanochemical geopolymer (MG) grout. A conventionally activated geopolymer grout and an ordinary Portland cement (OPC) grout were also investigated for comparison. Four glass powder replacement ratios were used (0%, 10%, 20% and 30% by the total precursor weight) to prepare slag-based mechanochemical geopolymer at three NaOH concentrations (1.25, 2.5 and 3.75 molars). The experimental results showed that the rheological behaviour of MG grouts was considerably reduced, whereas the setting time and the bleeding capacity value increased when slag was substituted with 0%–30% GP. However, after 28 days, the unconfined compressive strength (UCS) improved by 2%–13% when 10%–20% GP was used as a slag replacement, then dropped by 4% when 30% GP was substituted. The results confirmed that both geopolymer grouts irrespective of the activation method had shorter setting time and more stable bleeding capacity than OPC grout. The results also revealed that the UCS of geopolymer grout is enhanced by 18% when the source materials are activated by the mechanochemical method compared to the conventional activation of geopolymer grout. The microstructure results revealed that the activation method had a considerable effect on the microstructure of geopolymer grout because the ball milling process increased the surface area and reduced the particle size of slag compared to conventionally activated geopolymer grout. © 2022 Informa UK Limited, trading as Taylor & Francis Group.