Concrete

Making Concrete in Cold Conditions

Published

9 years ago

February 28, 2017

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Cold weather is defined as a period when the average daily temperature falls below 4?C for more than three successive days. These conditions warrant special precautions when placing, finishing, curing and protecting concrete.

Concrete production always faces a problem during cold weather. There are two main problems associated with cold weather. The general rule is that the concrete has to gain strength till about 500 psi (35 kg per cm2).

Concrete can freeze before it gains strength which breaks up the matrix;
Concrete sets more slowly when it is cold – very slow below 6? C; below 4? C, the hydration reaction basically stops and the concrete doesn’t gain strength.
But these are concrete temperatures, not air temperatures. So when it’s cold, the concrete has to be protected until it can handle the cold on its own. The general rule is that the concrete has to gain strength till about 500 psi (35 kg per cm2). Almost the same time that the concrete achieves 500 psi compressive strength, hydration of the cement consumes enough of the water in the original mix so that even if it does freeze, there’s not enough water left in the pores to damage the concrete. With most concrete, even at 6?C, this happens during the second day.

To help it reach that 500 psi strength, the mix can then be changed to get it to set more quickly or protect the concrete from the cold – or more likely do both.

Changes to Concrete Mix during Cold Weather
Many of the problems with cold weather can be overcome by the ready mix producer. Here are a few things to keep in mind:
Hot water: A ready mixed concrete producer will usually have, and use, hot water in the concrete when the weather turns cold. Most producers will try to have the concrete be at least 180C when it leaves the plant, which is generally good enough depending on air temperature and thickness of the concrete element. The slump has to be specified at less than 100 mm and air-entrained concrete should be used to reduce bleeding.

Accelerators: Since colder weather leads to colder concrete, the set time can be delayed. Accelerators added to the concrete can keep it on schedule. Addition of 2 per cent (by weight of cement) of calcium chloride is the traditional way to accelerate the hydration reaction – it is very effective and reasonably cheap. But – a big but -that much chloride can lead to corrosion of any steel embedded in the concrete (like rebar) and can lead to a mottled surface appearance with coloured concrete.

Non-chloride accelerators are also widely available and are very effective. They won’t discolour the concrete, but they are a bit expensive. Accelerators are not anti-freeze agents – they simply increase the rate of the hydration reaction.

Fly ash: Producers should typically stay away from using fly ash or slag cement in cold weather, since those materials set more slowly and generate less internal heat; slag can cause the same effect.

To make the reaction a bit hotter, the ready mix producer can add some extra cement (typically 60 kg per cubic metre) or can use Type III (high-early strength) cement, which hydrates more rapidly.

Producers have to be careful with water reducers in cold weather, since they can slow the set time. Besides, cooler concrete seldom needs water reduction since the cooler temperatures prevent slump loss. For admixtures added at the job site, they shouldn’t be used if they have frozen. The chemicals may have separated.

Precautions before Placing Concrete in the Cold
When cold weather comes on unexpectedly, the following tips will help:
Frozen ground: Concrete should be never placed on frozen ground or onto ice or snow. There are a couple of problems with this. First, frozen ground will settle when it thaws, cracking the concrete. Second, when the ground is cold, the concrete in contact with it will be cold and will set more slowly. Crusting might also occur, with the top part of the concrete set and the bottom still soft. If the ground is frozen, it can be thawed using hydronic heat pipes and blankets (such as those from ground heaters), or electric blankets.

Anything that will come in contact with the concrete should be warmed up, including forms and any embedment, to at least 00C. If it’s not too cold and everything is covered with tarps the day before the pour, it will stay dry and warm enough.

Concrete

Cement Makers’ Margins To Fall Rs 50-75 Per Tonne Amid West Asia Conflict

Crisil Sees Margins Easing Despite Steady Demand

Published

14 hours ago

July 29, 2026

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Crisil said operating margins of Indian cement manufacturers are expected to decline by Rs 50-75 per tonne (t) this fiscal to Rs 925-950 per t due to higher input costs triggered by the West Asia conflict. The analysis covered 18 cement companies accounting for nearly 90 per cent of India’s domestic cement capacity and noted margins had improved sharply to around Rs 1,000 per t in fiscal 2026.

Crisil noted that the reduction would be driven mainly by higher power and fuel costs, which account for about 30 per cent of total costs, as petcoke and imported coal prices have surged amid geopolitical uncertainties. Freight costs, which account for about a quarter of total costs, are also expected to remain elevated because of higher diesel prices. The impact on profitability is likely to be more pronounced in the first half of the fiscal year before easing commodity prices moderate cost pressures later.

The rating agency said steady domestic demand and strong balance sheets should keep credit profiles stable despite the moderation in margins. Green energy currently accounts for 35-40 per cent of the sector’s total electricity consumption and is expected to partly cushion higher energy costs. Operating cash flows are likely to remain resilient, supported by projected 6-7 per cent growth in cement demand this fiscal.

Crisil highlighted that demand growth will be driven primarily by infrastructure spending, which meets about one-third of sector consumption, and by a nearly 18 per cent higher budgetary allocation for core ministries that should support project execution. Weaker rural housing demand amid pressure on agricultural incomes from a possible below-average monsoon may be offset by improved urban housing demand supported by favourable home-loan rates and a strong pipeline of Pradhan Mantri Awas Yojana-Urban projects. Ongoing capacity additions will keep capital expenditure elevated and may lift net debt to EBITDA to between 1.2 and 1.4 times from around 1.0 time last fiscal, though ratios are expected to remain healthy.

Concrete

UltraTech Board Approves Rs 50 bn Fundraise Via NCDs

Company to issue half a million debentures for expansion plan

Published

2 days ago

July 28, 2026

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UltraTech Cement’s board of directors has approved raising Rs 5,000 crore (Rs 50 bn) through non?convertible debentures issued in rupees.

The finance committee cleared a proposal to issue up to 500,000 fully paid, unsecured, listed, rated, redeemable, rupee?denominated, non?convertible, non?cumulative debentures of Rs 1 lakh each (Rs 0.1 mn each), aggregating to the Rs 5,000 crore programme.

As of June 2026 the firm reported net debt of Rs 15,875 crore (Rs 158.75 bn) and said its capacity expansion projects under execution are backed by capital expenditure of about Rs 17,000 crore (Rs 170 bn) over the next two to two?and?a?half years.

UltraTech spent Rs 9,500 crore (Rs 95 bn) on capital expenditure in financial year 2026 and in April the group crossed 200.1 mn tonnes per annum of domestic grey cement capacity and 205.5 mn tonnes per annum of global capacity.

The chief financial officer indicated the company would take consolidated capacity beyond 242 mn tonnes per annum, with grey cement capacity reaching 212.7 mn tonnes per annum by the end of financial year 2027. He noted the net debt?to?earnings before interest, taxes, depreciation and amortisation ratio stood at 0.87 times as of June 2026 and the company was confident of ending financial year 2027 with the ratio below one time.

In the first quarter of financial year 2026?27 UltraTech’s net profit attributable to owners rose 16.8 per cent year?on?year to Rs 2,599.3 crore (Rs 25.993 bn) and revenue from operations increased 15.9 per cent to Rs 24,648.20 crore (Rs 246.482 bn). The board approval is expected to complement internal cash flows as the company advances its expansion programme.

Concrete

Lokesh Lays Stone For Rs 31 Billion Cement Unit In Kadapa

Line-2 expansion to make Kadapa a major cement hub

Published

1 week ago

July 20, 2026

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Andhra Pradesh Education and IT Minister Nara Lokesh on Wednesday laid the foundation stone for the Line-2 expansion of Dalmia Bharat Cement at Chinnakomerla village in Mylavaram Mandal in Kadapa district. The project carries an investment of Rs 31 billion (bn) and is slated for completion by the third quarter of the financial year 2028. The expansion is intended to boost industrial growth and employment generation across the Rayalaseema region.

Once commissioned, the Kadapa facility will become Dalmia Bharat’s largest integrated cement manufacturing ecosystem in southern India, creating over 1,000 direct and indirect jobs and opening new business avenues for regional micro, small and medium enterprises and transport operators. Lokesh said the expansion signalled growing corporate confidence in the state and reflected the practical ease of doing business that secured repeat investment.

He placed the project within the government’s wider economic targets and recalled the Yuvagalam padayatra commitment to generate two million (mn) jobs within five years, noting that the state would cultivate talent while industry created opportunities. Lokesh highlighted Andhra Pradesh’s competitive pursuit of major manufacturing accounts, mentioning past successes and a personal initiative to engage global investors when persuading them to anchor expansion in the state.

The plant will leverage Kadapa’s abundant limestone reserves to scale production and sustainability. Clinker capacity is planned to rise from two point five million tonnes per annum (mn tpa) to six point one mn tpa, while overall cement output will increase from three point six mn tpa to nine point six mn tpa. The unit is designed to operate on over eighty per cent renewable energy and deploy waste heat recovery, zero liquid discharge, water recycling and advanced AI systems to optimise efficiency. Industries Minister TG Bharat, BC Welfare Minister S. Savitha and Jammalamadugu MLA C. Adinarayana Reddy attended the ceremony.