To recap, for the first nine months of 2021, our adjusted EBITDA increased 7% to a record $1.1 billion.
Specifically, on a consolidated basis, Products and Services revenues increased 18% to $1.5 billion.
Adjusted gross profit increased 11% to $450 million.
Adjusted EBITDA of $490 million increased 13% on a comparable basis, and adjusted diluted earnings per share of $4.25 grew 11% on a comparable basis.
As a reminder, the prior year quarter included $70 million or $0.87 per diluted share of non recurring gains on surplus land sales and divested assets that affect quarter over quarter comparability.
Organic aggregate shipments increased 6%, notwithstanding contractor capacity constraints and wet weather in several markets that govern the overall pace of construction activity.
Total aggregate shipments, including shipments from acquired operations, increased 10%.
Organic aggregates average selling price increased 2%, reflecting a higher percentage of lower-priced base stone shipments during the quarter.
That's why we updated our full year 2021 organic pricing growth guidance to now range from 2.5% to 3.5%.
Our Texas Cement business established a new quarterly record for shipments, which increased 4% to over one million tonnes.
Cement pricing increased 8% as the second round of price increases this year went into effect on September first.
Ready mixed concrete shipments increased 23%, driven by large nonresidential projects and operations acquired late last year in Texas.
Concrete pricing grew 2% following the implementation of midyear price increases in Texas.
Asphalt shipments increased 116% overall, driven by contributions from our Minnesota based operations acquired earlier this year.
For the third quarter alone, total energy costs increased $28 million or nearly 50% company wide as compared with last year.
Aggregates product gross margin of 34.2% included higher diesel and other production costs as well as a $6 million negative impact from selling acquired inventory that was marked up to fair value as part of acquisition accounting.
Excluding the acquisition impact, adjusted aggregates product gross margin was 34.9%, a 150 basis point decline versus prior year.
Cement product gross margin declined 250 basis points driven by higher raw material cost and a $6 million increase in natural gas and electricity costs.
Ready-mixed concrete product gross margin improved modestly to nearly 10% as shipment and pricing gains offset higher costs for raw materials and diesel.
Magnesia Specialties continued to benefit from improving domestic steel production and global demand for magnesia chemical products, generating product revenues of $72 million, a 30% year over year increase.
Revenue growth more than offset higher costs for energy and contract services, driving a 100 basis point improvement in product gross margin to 39%.
We have raised our full year capital spending guidance to $475 million to $525 million to include anticipated Lehigh West region capital expenditures.
Additionally, our Board of Directors approved a 7% increase in our quarterly cash dividend paid in September, underscoring its confidence in our future performance and a resilient and growing free cash flow generation.
Our annualized cash dividend rate is now $2.44.
Since our repurchase authorization announcement in February 2015, we have returned nearly $2 billion to shareholders through a combination of meaningful and sustainable dividends as well as share repurchases.
In early July, we issued $2.5 billion of senior notes with a weighted average interest rate of 2.2% and a weighted average tenor of 15 years, primarily to finance Lehigh West region transaction.
Our net debt to EBITDA ratio was 1.9 times as of September 30.
Leverage on a pro forma basis, inclusive of reach acquisitions, is modestly above 3 times debt to EBITDA.
Consistent with our practice of repaying debt following significant acquisitions, we are committed to return into our target leverage range of two to 2.5 times within the next 18 months.
We now expect full year adjusted EBITDA to range from $1.500 billion to $1.550 billion.
The Infrastructure Investment and Jobs Act, which contains a five year surface transportation reauthorization and provides $110 billion in new funding for roads, bridges and other hard infrastructure projects passed the United States Senate in August with 69 bipartisan votes.
Texas, Colorado, North Carolina, Georgia and Florida, which accounted for over 70% of our 2020 Building Materials revenues, are well positioned from both the DOT funding and resource perspective to efficiently deploy increased federal and state transportation dollars in advance the growing number of projects in their backlogs.
Caltrans, California's Department of Transportation, manages a $17 billion annual budget.
Additionally, the Road Repair and Accountability Act of 2017, commonly referred to as Senate Bill one or SB1, provides $54 billion or approximately $5 billion annually through 2030 to fund state and local road, freeway and rail projects.
For reference, aggregate shipments to the infrastructure market accounted for 36% of third quarter organic shipments, showing sequential growth since this year's second quarter, but still well below our 10 year historical average of 43%.
Aggregate shipments to the nonresidential market accounted for 35% of third quarter organic shipments.
Aggregates to the residential market accounted for 24% of third quarter organic shipments.
In summary, we believe our industry is about to see public and private sector construction activity coalesce for the first time since its most recent 2005 peak, supporting both increased shipments and an attractive pricing environment for construction materials.

Summary:
Adjusted EBITDA of $490 million increased 13% on a comparable basis, and adjusted diluted earnings per share of $4.25 grew 11% on a comparable basis.
Leverage on a pro forma basis, inclusive of reach acquisitions, is modestly above 3 times debt to EBITDA.